UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their application in industry

VOL. 31 OCTOBER 1987 NO. 4

Contents

Emission Control for Gas Turbines I 62

Johnson Matthey Metals Loans Scheme 171

Platinum Ternary Alloys 172

Direct Methanol Fuel Cells 173 Fabricating Platinum Disc Microelectrodes 181

An Exchange of Ideas on Catalysis I 82

Corrosion in Nitric Acid Plants 185

The Chemistry of the Platinum Group Metals 186

Weldability Test for Thin Iridium Sheet 193

Exhaust Gas Pollution Control 194

High Temperature Gas Thermometry and the Platinum Metals 196 Abstracts 208

New Patents 215

Index to Volume 31 220

Communications should be addressed to The Editor, Platinum Metals Review Johnson Matthey Public Limited Company, Hatton Garden, London ECl N 8EE Emission Control for Gas Turbines PLATINUM-RHODIUM CATALYSTS FOR CARBON MONOXIDE AND HYDROCARBON REMOVAL By H. J. Jung and E. R. Becker Johnson Matthey, Catalytic Systems Division

Johnson Matthey are reporting successful commercialisation of oxidation catalystsfor the clean-up of gas turbine exhaust. The reduction of carbon monoxide and hydrocarbons is achieved with a platinum-rhodium catalyst which minimises the formation of sulphur trioxide. The catalyst system, supported on an energy saving, low pressure drop metal monolith, has been used continuously for five years on large industrial gas turbines.

The catalytic control of atmospheric pol- bines in a large stoichiometric excess of oxygen lutants from automobiles has been firmly consists of two parts. The first level of control established in the U.S.A. and Japan, and is is practised by injecting water or steam into the increasingly being adopted by European and combustion zone to lower the combustion tem- other industrial countries. Nitrogen oxides, perature. This “wet firing” allows nitrogen carbon monoxide and hydrocarbons in car oxide levels to be reduced by 50 per cent, from exhaust gas are reduced by controlling the 100 ppm to 50 ppm. The second step is the air : fuel ratio and by simultaneous conversion selective catalytic reaction of ammonia with the of all three pollutants in either a dual bed remaining nitrogen oxide, a process known as catalytic converter or in a single bed “three- Selective Catalytic Reduction (SCR). The way” catalytic converter ( I). The accumulated ammonia is injected into the flue gas and the benefits from this control technology (2) have mixture is then passed over a base metal oxide not been paralleled in the control of emissions catalyst, typically supported on alumina or from stationary sources. Over half of the man- titania (4). The SCR method can achieve made carbon monoxide, hydrocarbons and nitrogen oxide levels below 10 ppm, and it is nitrogen oxides reaching the atmosphere is used in Japan, California and West Germany. emitted from stationary sources including While the waterheam injection minimises power station boilers, industrial boilers, sta- nitrogen oxides formation, it increases the tionary internal combustion engines and gas amount of carbon monoxide and hydrocarbons turbines (3). Strict emission limits for control- in the combustion products which then require ling nitrogen oxides, carbon monoxide, hydro- flue gas treatment to lower the emissions. The carbons and sulphur oxides have been enacted well-established catalytic oxidation technology by many states in the U.S.A. and in West used for automotive emission control can be ex- Germany. tended to control carbon monoxide and hydro- With the exception of rich-burn internal carbon emissions from gas turbines. Johnson combustion engines, all stationary combustion Matthey, a leader in automotive catalyst tech- is carried out using a large excess of oxygen, in nology, has developed oxidation catalyst and order to maximise fuel efficiency. This pre- reactor technology for this purpose, the tech- cludes a direct extension of automotive three- nology being introduced into the market in way catalyst technology to stationary sources. 1982. It is currently available as a stand-alone The control of nitrogen oxides from gas tur- product or in conjunction with Johnson

Platinum Metals Rev., 1987, 31, (4), 162-170 162 Fig. 1 A Johnson Matthey emission control reactor is located in the centre of this picture, between the gas turbine and the stack. This reactor contains several catalyst panels measuring 10 feet by 14 feet, and purifies 4 million cubic feet of flue gas per hour. The steam from this plant is pumped underground to assist in the recovery of viscous oil

Matthey SCR catalyst and control systems as superheater and 260OC at the inlet of the econo- shown in Figure I. This paper describes the miser. When duct burners are used to make oxidation catalyst and the reactor technology. more steam, the temperature at the inlet to the superheater can be as high as 65oOC. Reactor Design Each application has a unique set of emission Automotive oxidation reactors are required to objectives which the catalyst and reactor are treat relatively small volumes of gas over custom designed to achieve. The main design approximately 2,000 hours of operation at tem- considerations which most oxidation reactors peratures varying from ambient, during start- have in common are: up, to occasional excursions up to 1,0ooOC. In High reactor productivity to minimise contrast, gas turbine exhaust reactors treat volume and cost. much larger quantities of gas, for example, 7.5 Low pressure drop to maximise useful work million cubic feet per hour (SCFH) for a 20 from the expanding gas. MW gas turbine. The catalyst temperature is Low sulphur dioxide conversion to sulphur controlled between 250 and 65ooC, and the trioxide to minimise sulphate particulate catalyst is required to operate without replace- emissions. ment for more than 20,000 hours. A typical gas Continuous operation exceeding 20,000 turbine exhaust heat recovery system, where hours. combustion gases are expanded through a tur- Some co-generation installations require fre- bine to produce electricity, is shown in Figure quent start-up and shut-down features, for 2. Before they go to the stack the exhaust gases which thermal shock resistance is required. pass through a superheater, boiler and econo- Proper relationship to the SCR reactor to miser, where heat is recovered in the form of meet overall emission control objectives, that low and high pressure steam. The exhaust tem- is to minimise the reconversion of ammonia perature is normally 470°C at the inlet to the to nitrogen oxides. The interaction of the

Platinum Metals Rev., 1987, 31, (4) 163 Fig. 2 The typical features of a gas turbine exhaust heat recovery system are shown. Although most oxidation Heat Recovery reactors have a number of Boiler common design considera- tions, each application has a unique set of emission objec- tives which catalyst and re- - 470 actor are designed to achieve Gas in - f'4: - -- 262 - Li- -1 - - - ~ 160 Steam out 239 Tcmperat ure Profile

Water in

SCR reactor with the oxidation reactor has and saturated hydrocarbons, while minimising been reported elsewhere (5). the oxidation of sulphur dioxide. The productivity of a reactor is measured by the hourly gas volume which each unit volume Metal Honeycomb Substrate of reactor can clean up to the specified emission Industrial emission control reactors must level. This is referred to as the gas hourly space result in only a low pressure drop at high flow velocity (GHSV). The productivity of oxidation rates, since minimising co-generation operating reactors equipped with noble metal catalysts costs depends upon minimising the pressure varies from 50,000 to I 50,000 gas volumes per drop. It is generally assumed by turbine hour, per volume of reactor. The oxidation re- operators that every 4 inches of water gauge actor consists of four components: backpressure causes a 0.4 to I. 5 per cent loss of 111 A panel of catalyst blocks which fits into power output. The thin walls of metal substrate the reactor housing, sized to minimise the allow a minimum pressure drop for a given pressure drop of the flue gas through the amount of catalyst coating. Thus the combined reactor. thickness of support and catalyst coating is less [21 A metal honeycomb substrate which pro- than the wall thickness of a ceramic substrate of vides the low pressure drop unit cell of the equivalent surface area. catalyst panel, and forms the interfacial Johnson Matthey's metal honeycomb tech- area between the gas and the catalyst. This nology was originally developed for automotive area is relevant when the reactor is operated emission control in the 1970s (6). The high in the mass transfer limited region of the temperature-resistant ferritic stainless steel temperature range. monoliths and the catalyst coating technology [3l A high surface area refractory oxide coating developed then have now been adapted and which provides the internal surface area for modified to suit the large industrial catalyst the dispersion of the catalyst ingredients. blocks used in SCR and oxidation reactors. 141 The active catalyst material. These blocks measure 2 ft square by 3.5 inches The active catalyst material used in the deep and constitute one cubic foot of effective Johnson Matthey reactors described here is a reactor volume. In addition to the low pressure combination of platinum and rhodium. This drop characteristics, the metal substrate offers catalyst provides high carbon monoxide conver- significant advantages over ceramic substrate in sion and high conversion of both unsaturated situations where thermal shock is experienced.

Plarinum Metals Rev., 1987, 31, (4) 164 Fig. 3 The use of heat resistant metal substrates provides low pressure drop characteristics and superior resistance to ther- mal shock. A common foil con- figuration is shown here

A number of metal substrate designs are available. The most common is a stack of alternate layers of flat and corrugated foil strips, Figure 3. Cell densities of 100, 200 and 400 cells per square inch (16, 31 and 62 cells per square cm) are fabricated by this technique. A high surface area alumina than platinum, palladium and platinum- washcoat applied to this monolith serves as the rhodium catalysts prepared using conventional support for the catalyst ingredients. Proprietary impregnation techniques. The carbon mon- coating technology ensures that the adhesion of oxide and hydrocarbon conversion data were the washcoat to the metal is as good as the adhe- obtained in a tubular reactor operating at sion to a ceramic substrate. I 10,000 GHSV, using a simulated gas turbine exhaust gas consisting of: 80 ppm carbon Platinum-Rhodium Catalyst monoxide, 31 ppm ethylene, 31 ppm ethane, Although base metal oxides such as COO, Cr 0, and CuO have some activity for carbon monoxide and hydrocarbon reactions, noble 100- metals are more active catalysts (7, 8). Among the noble metals, platinum and palladium have 80- I been used most widely because of their relative u 60- cost and their thermal stability (9). Rhodium is u a good oxidation catalyst but is less economical. 5- 40. The choice of noble metal precursors and v) w fabrication technology significantly affects the U ;20- metal dispersion, the catalyst distribution v within the high surface area support material 100 200 300 400 500 600 and consequently the activity and stability of TEMPERATURE .‘C the resulting catalyst system. Extensive re- Fig. 4 Carbon monoxide light-off curves search has been carried out to develop and show how conversion varies with temperature, and with catalyst: implement these dispersion and stabilisation (a) Johnson Matthey platinum-rhodium phenomena, and this research forms the basis catalyst “A” of Johnson Matthey’s leading technological (b) conventional impregnated platinum catalyst “E” position in the environmental catalyst field. (c) conventional impregnated platinum- As shown in the Table, a platinum-rhodium rhodium catalyst “D” catalyst prepared using Johnson Matthey pro- (d) conventional impregnated palladium catalyst “F” prietary technology is significantly more active

Platinum Metals Rev., 1987, 31, (4) 165 Oxidation Activity of Noble Metal Catalysts

Conversion, per cent At 150°C At 48OOC Relative dur 1 light-off steady-state Desig- metal nation Formulation loading co CO C,H,/C,H, A Johnson Matthey Pt-Rh 1 .o 92 24 100 85 B Johnson Matthey Pt-Rh 0.45 82 15 100 74 C Conventional impregnated Pt-Rh 1.71 84 10 100 74 D Conventional impregnated Pt-Rh 0.60 30 0 100 55 E Conventional impregnated Pt 2.63 40 4 100 69 F Conventional impregnated Pd 1.85 -23 0 99 65

46 ppm sulphur dioxide, 3 per cent carbon di- lyst shows a lower activation energy, but much oxide, 8 per cent oxygen, 10 per cent water and lower activity. the balance nitrogen. The high activity of this Hydrocarbons are more difficult to oxidise proprietary platinum-rhodium catalyst enables than carbon monoxide. Some qualitative rules the size of the reactor used in gas turbines to be for the relative ease of oxidising hydrocarbons reduced, compared to a reactor employing a have been published by Stein (10).The ease of conventional oxidation catalyst. oxidation is as follows: [a1 Branched chain > straight chain Carbon Monoxide and Hydro- [bl Acetylenes > olefins > saturated carbon Light-Off Temperatures [cl C" > . . . c, > c, > c, The activity of a catalyst is often measured by The catalytic oxidation of saturated hydro- the lowest temperature required to achieve con- carbons over a platinum filament was also version of the reactant, the so-called light-off studied by Hiam and co-workers (11). They temperature. The carbon monoxide light-off reported the ease of oxidation as: curves for four of the catalysts featured in the n-butane > isobutane > propane > ethane. Table are shown in Figure 4. The Johnson Mat- As shown in Figure 5, the Johnson Matthey they platinum-rhodium catalyst requires only platinum-rhodium catalyst exhibits similar IZOOCto exceed 50 per cent carbon monoxide features. For the ethylenelethane mixture the conversion, compared with 16oOc for a highly ethylene reacts first at about 130°C and the loaded platinum catalyst. Both show the conversion exceeds 90 per cent above 200OC. characteristic steep conversion versus tem- Ethane starts to react at about 400OC and con- perature dependence, indicating a high acti- version exceeds 80 per cent above 48oOC. vation energy. The conventionally prepared Butane is easier to oxidise than ethane; its con- platinum-rhodium catalyst and the palladium version reaches 80 per cent at 43oOC. The non- catalyst require higher temperatures to reach 50 methane hydrocarbons in the exhaust of tur- per cent conversion, while the palladium cata- bines fuelled with natural gas are predominantly

Platinum Metals Rev., 1987, 31, (4) 166 ethane and propane. Where high conversions of than that for carbon monoxide and hydro- saturated hydrocarbons are required, a relative- carbons. As illustrated in Figure 7, an 800OC ly high operating temperature of between 450 thermal treatment lowers sulphur dioxide con- and 500OC is recommended. version at 48oOC from 70 per cent to 18 per cent, but after thermal treatment the catalyst Oxidation of Sulphur Dioxide still provides 80 per cent conversion of and Sulphur Trioxide ethane/ethylene, and 100 per cent conversion of Most gas turbines are fuelled with natural carbon monoxide. gas. The flue gas from these turbines contains only minor amounts of sulphur dioxide which Catalyst Stability are of small significance compared with the par- Catalysts are degraded in use by mechanical ticulate emission requirements. However, some vibration, by particulate abrasion and pore installations burn refinery gas which contains 50-300 ppm sulphur, while other installations are permitted to burn oil as a back-up fuel. 100 When refinery gas or liquid fuels are burned, the exhaust gas contains sulphur dioxide. An 5 80. effective carbon monoxidehydrocarbon oxi- " U 1 1 C~.lC2HI dation catalyst is normally also active for the n 60- z oxidation of sulphur dioxide. However, this P oxidation needs to be minimised to reduce the 40. downstream formation of sulphate particulates z U from sulphur trioxide. The activity of the 20. Johnson Matthey platinum-rhodium catalyst for sulphur trioxide formation can be reduced 100 200 300 400 500 600 by increasing the rhodium content in the cata- TEMPERATURE .'C Fig. 5 These light-off curves show the lyst, or by thermal treatment. This concept has relative ease of oxidising hydrocarbons with been applied to minimise sulphate formation in the Johnson Matthey platinum- automotive catalysts (12, 13, 14). rhodium catalyst "A" Sulphur dioxide oxidation over various auto- motive catalysts has been reported by Truex, who showed that the conversion is strongly _'-- I dependent on the platinum : rhodium ratio, and decreases rapidly as the rhodium content is Pt ' Rh = 9 by weight increased (15). A similar rhodium effect has been measured with the Johnson Matthey platinum-rhodium catalyst, as shown in Figure 6. At a gas turbine exhaust temperature of Pt:Rh=2 by weight 48ooC, a 9 : I platinum-rhodium catalyst gives I 71 per cent sulphur dioxide conversion, while a 100 200 300 400 500 600 TEMPERATURE.'C 2 : I platinum-rhodium catalyst gives only 37 Fig. 6 At a fixed conversion temperature, per cent sulphur dioxide conversion. Both of the oxidation of sulphur dioxide is strong- these catalysts had been calcined at 650OC ly dependent upon the platinum :rhodium because initial tests showed less difference in ratio. These data show the effect of vary- ing the proportions of the two elements in their performance, as a function of the a Johnson Matthey platinum-rhodium platinum : rhodium ratio. catalyst, the low rhodium catalyst being Controlled thermal treatment reduces the superior at any particular temperature oxidation activity for sulphur dioxide more

Platinum Metals Rev., 1987, 31, (4) 167 Fig. 7 Thermal treatment can change the oxidation acti- vity of a catalyst for various gases by differing degrees. The information presented here relates to Johnson Mat- they platinum-rhodium catalyst “A”: (a) CO, fresh (b) CO, treated at 80OOC (c) C2H,/C2H,, fresh (d) C2H,/C2H,, treated at 800 O C (e) SO?, fresh (f) SO,, treated at 80OOC

TEMPERATURE:^ 100 Fig. 8 The light-off be- haviour of the Johnson Mat- they platinum-rhodium 80 catalyst “A” is affected by thermal ageing. This is shown

d here for carbon monoxide, an E : ethylenelethane mixture and L 60 sulphur dioxide a (a) CO aged at 5OOOC for 23 2 2 hours a 4c (b) CO aged at 65OOC for > 258 hours 5 (c) C,H,/C2H,, aged at 5OOOC for 23 hours 20 (d) C2H,/C,H,, aged at 65OOC for 258 hours (e) SO?, aged at 5OOOC for 23 hours 1 ) 2 00 3 00 4 00 500 6 00 (f) SO2, aged at 65OOC for TEMPERATURE .‘C 258 hours

d co c rrL 80 z p 60- 6 ? z ‘... _., ’...... ,..... 2 40- 0 nW 502 5 20 + >z 2 20- 01 c6 5000 10000 15000 20000 2: U TIME, hours 246810 Fig. 9 From the thermal deactivation POISON CONTENT, (grnollg catalyst coating) x 10‘ curves for Johnson Matthey platinum- rhodium catalyst “A”, it is projected that Fig. 10 The poison susceptibility of after the catalyst has been aged for three Johnson Matthey platinum-rhodium catalyst years at 48OOC conversions of carbon “A” has been determined using a number monoxide and ethylene/ethane will still ex- of synthetic poisons; the deactivation they ceed 95 and 65 per cent, respectively cause is shown here

Platinum Metals Rev., 1987, 31, (4) 168 fouling, thermal shock, thermal sintering and The poison susceptibility of the Johnson poisoning by trace impurities. Mechanical Matthey platinum-rhodium catalyst is deter- vibration and thermal shock affect catalyst per- mined by using synthetic poisons. Aqueous formance if they attack the physical integrity of solutions of ferric nitrate, sodium nitrate, the catalyst. The main causes of catalyst de- orthophosphoric acid, arsenic(II1) oxide and activation in normal turbine operation are ther- colloidal silica are applied to the catalyst at mal sintering, poisoning of the catalyst metals various concentrations, and the activity is and fouling of the catalyst pores. measured after thermal treatment. The faster, Thermal sintering of the alumina support is mass transfer controlled carbon monoxide and of little concern since the operating tempera- ethylene conversions at 48oOC are unchanged ture is below 700OC. However, sintering of by any of these poisons up to a level of 2 per noble metals on the support is significant at tur- cent, based on total catalyst coating weight. bine operating conditions. The effect of pro- However, the slower, kinetically controlled longed thermal exposure on the activity of the ethane and sulphur dioxide conversions de- Johnson Matthey platinum-rhodium catalyst is crease notably on exposure to these poisons. shown in Figure 8. At low temperatures, where Figure 10 shows the degrees of catalyst de- conversion is controlled by the reaction rate, activation due to poisoning, estimated from the conversion is greatly decreased, reflecting the ethane conversion at 48oOC. On a molar basis loss of intrinsic catalytic activity. Catalysts are the severity of poisons are in the order: designed to operate at temperatures where As > Fe > Na > P > SO,. small changes in activity do not significantly Silica can act as a poison or a masking agent, affect conversion. At these higher tem- depending on its source and the precursor peratures, where bulk mass transfer of the car- chemistry. In these tests, however, the colloidal bon monoxide and hydrocarbons to the catalyst silica acts as a masking agent rather than as a controls conversion, the drop in performance is catalyst poison. much less. However, the activity for sulphur Where the contents of poisons and foulants in dioxide oxidation, which is reaction rate con- the turbine exhaust are high, extra catalyst can trolled at the catalyst surface, is significantly be introduced to maintain high conversion of reduced. saturated hydrocarbons. A thermal deactivation model has been obtained from laboratory ageing experiments Commercial Operation conducted at temperatures from 450 to 7oooc, The longest running Johnson Matthey car- for various lengths of time. From the model, bon monoxidehydrocarbon oxidation reactor is the activity-time behaviour can be projected, installed in the Texaco refinery in Long Beach, as illustrated in Figure 9 for operation at California. Here a refinery gas containing 50 48oOC. From this it is predicted that the ppm sulphur is burnt in a water injected 35 catalyst will still give carbon monoxide con- MW United Technologies FT4 gas turbine. versions in excess of 95 per cent and ethylenel The exhaust contains 100 to 200 ppm carbon ethane conversions greater than 65 per cent monoxide depending on the turbine load. The after thermal ageing for three years. Actual oxidation reactor was guaranteed to reduce car- catalyst durability in commercial operations is bon monoxide emissions below 13 ppm for two described below. The decrease in hydrocarbon years. The reactor contains 150 cubic feet of conversion is primarily due to loss of ethane catalyst and is operated at 460OC. From start- oxidation activity. If high hydrocarbon con- up in 1982 when the catalyst reduced the car- versions are required, the catalyst volume can bon monoxide emission to below 5 ppm, the be increased. When the catalyst is operated at original catalyst has provided nearly five years 480°C, the sulphur dioxide conversion drops of satisfactory performance, maintaining the gradually to below 30 per cent after I year. carbon monoxide levels below the required

Platinum Metals Rev., 1987, 31, (4) 169 nificantly less. Catalyst life for natural gas fuelled turbines is therefore expected to be longer than that for the catalyst in the refinery gas fuelled Texaco installation.

Conclusions Oxidation catalyst technology developed to reduce automotive exhaust emissions has been extended to reduce the carbon monoxide and hydrocarbon emissions from gas turbines. Platinum-rhodium catalysts have been developed to maximise activity for carbon monoxide and hydrocarbon conversion, while minimising the undesired conversion of sulphur dioxide to sulphate. Commercial opera- Fig. 11 A section of the surface layer showing tion of metal supported catalyst arrays in large iron oxide crystals, a band of platinum + rhodium gas turbines has been successful for five years of and a region containing arsenic and sulphur operation, and continues to be an effective means of reducing carbon monoxide and hydro- 13 ppm. The ethane oxidation activity carbon emissions from stationary sources. deteriorated to 10per cent of its original acti- vity after two years. At that time a proprietary catalyst wash treatment, which primarily References removes foreign materials from the catalyst , I B. Harrison, B. J. Cooper and A. J. J. Wilkins, Platinum Metals Rev., 1981, 25, (I), 14 restored the original carbon monoxide activity 2 M. P. Walsh, Platinum Metals Rev., 1986,30, (3), and 70 per cent of the original ethane oxidation 106 activity. The irreversible deactivation of the 3 B. Harrison, A. F. Diwell and M. Wyatt, catalyst is therefore estimated at 30 per cent. Platinum Metals Rev., 1985, 29, (z), 50 4 J. R. Kiovsky, P. B. Koradia and C. T. Lim, Ind. A transmission electron micrograph of the Eng. Chem., Prod. Res. Den, 1980, 19, 218 catalyst after two years of service is presented in 5 R. Lis, H. Jung and E. R. Becker, 80th Annual Figure I I. The catalyst surface is covered with Meeting of A.P.C.A., New York, Paper No. 87-52.2, 21 June 1987 iron oxide particles which have crystallite sizes 6 A. S. Pratt and J. A. Cairns, Platinum Metals ranging from 40 nm to 120 nm. The catalyst Rev., 1977, 21, (3), 74 contains 1.8 per cent iron. Other contaminants 7 V. V. Popovskii, Kinetics and Catalysis, 1972, 13, 1065 are I .3 per cent sodium, I .o per cent sulphur 8 J. G. Firth, 3. Catal., 1974, 34, 159 and 1.0 per cent arsenic. These contaminants 9 G. J. K. Acres, Platinum Metals Rev., 1970, 14, are distributed fairly uniformly throughout the (11, 2 porous washcoat and appear to arise from cor- K. C. Stein, 52nd Annual Meeting of A.P.C.A., rosion of upstream steel parts, vaporised Los Angeles, 21-26 June 1969 L. Hiam, H. Wise and S. Chaikin, 3. Catal., lubricating oil components and impurities in 1968, 9, 272 the fuel, air and water. B. J. Cooper, B. H. Harrison, E. Shutt and I. The surface area of a sample from the used Lichtenstein, S.A.E. Paper No. 770367, 1977 catalyst was 80 m’/g compared with m2/g B. J. Cooper, E. Shutt and M. J. Scullard, S.A.E. 150 Paper No. 760035, 1976 for a fresh catalyst. This loss of surface area is R. H. Hammerle and T. J. Truex, S.A.E. Paper attributed to micropore blockage by the con- No. 76009% 1976 taminants. In turbines fired with natural gas, T. J. Truex, Symp. on the Status of Automotive Sulfate Emissions, 2nd Joint Conf. of the Chem. which is cleaner, exhaust catalyst contamina- Inst. of Canada and Am. Chem. Soc., Montreal, tion and degradation are expected to be sig- 31 May I977

Platinum Metals Rev., 1987, 31, (4) 170 Johnson Matthey Metals Loans Scheme A CONTINUING COMMITMENT TO INNOVATION By D. T. Thompson Johnson Matthey Technology Centre

Towards the end of the eighteenth century bide hydroformylation (Low Pressure 0x0) the Spanish authorities were providing Euro- process based on a homogeneous rhodium pean chemists and institutions with substantial catalyst system derived from the observation at amounts of platinum, without charge, in order Imperial College, London, by Professor Sir that its properties could be investigated and Geoffrey Wilkinson using Loan Scheme applications identified. When the metal became rhodium, that rhodium catalysts commercially available, Johnson Matthey was have considerably increased activity compared one of the leading supply houses that made with cobalt, and led to the achievement of an ef- similar arrangements with eminent scientists. ficient processing technology, for the conver- The page reproduced here is from a Johnson sion of propylene to butyraldehydes. The pro- Matthey catalogue in use in the early years of cess is characterised by more efficient use of this century. Later the final word “furnished” feedstock, higher normal : is0 product yield was altered to “published”, and the offer has (>Io: I compared to 3-4: I for cobalt continued to be a feature of the Com- pany’s commitment to progress in platinum metals technology. In more recent years the Loans Scheme has grown on a worldwide basis, especially in the United Kingdom, but the principles have re- mained the same; metals and metal !S FURTHER.\NCI: 01’ compounds are supplied to university staff working in areas likely to lead to SCIENTIFIC RESEARCH innovative science, and the valuable residues are returned to Johnson PROFESSORS

Matthey in due course. The relation- and recognired ship developed through the loan of the metal can then lead to new work Scientific Investigators supported under the Science and will with pleasure be supplied Engineering Research Council’s with hIetalr of the Platinum Croup. in moderate quantities, (SERC) CASE award system or to ful- and for periods to I* armnaed. ly funded projects supported by Johnson Matthey. FREEOF CHARGE,

It is interesting to recall that the on condition that the precious metals are ultimately returned (m any form). and Company has derived a number of its that the results of the nnvestigations are furnished commercial successes of the past few years from discoveries stimulated by the Loans Scheme. The successful Johnson Matthey-Davy McKee-Union Car-

Platinum Metals Rev., 1987, 31, (4), 171-172 171 catalysts), lower pressure operation and long moting and maintaining this protection is still catalyst life (>I year). under active investigation, and this work was Following the discovery in the late 1960s of reported here earlier this year (2). the anti-tumour properties of certain platinum Johnson Matthey has similarly supported ammine and amine complexes by Professor research work on the rhodium-platinum cata- Rosenberg at Michigan State University, the lyst gauzes used for ammonia oxidation. Using development of the first platinum based cancer Field Ion Microscope and Scanning Electron drug, Cisplatin, was considerably aided by Microscope techniques the nucleation and metal loans. The search for second generation growth of large cage-like features which drugs both in the United States of America and develop on the gauze surfaces have been the U.K. also received support from platinum investigated and a new insight into the loans. This particularly applied to a group of mechanism of this very well established com- U. K. academics whose work was co-ordinated mercial reaction has now been gained (3, 4) and funded by Johnson Matthey and with benefit to the users in terms of catalyst life Rustenberg Platinum Mines. Synthetic studies and noble metal inventory. and biological screening unearthed a large The Loans Scheme and Johnson Matthey number of active platinum compounds, while support of innovative research continues to structure/activity and structure/toxicity rela- operate on a worldwide basis in order to tionships were established. Pharmacology, tox- encourage work in any technological area that icity and clinical studies have led to the recent could benefit from the generation of new ideas successful commercialisation of Carboplatin for the use of the platinum group metals and (ParaplatinTM)some sixteen years later. their compounds, and to increase awareness of The development of car exhaust catalysts, their properties. For these reasons, Johnson another very important area for Johnson Matthey welcomes proposals from academics Matthey, was greatly assisted by university with innovative approaches to platinum metals studies and loans, initially in support of technology; these will be considered for fundamental research on alloy catalysts and support. later in the characterisation of catalyst systems for this application. For example, studies at References Nottingham University increased the under- I E. A. Hyde, R. Rudharn and C. H. Rochester, J. Chem. Soc., Faraday Trans. I, 1983,79, (IO), 2405; standing of the mode of interaction between 19% 80, (9, 531 nitric oxide and rhodium supported on alumina 2 G. J. Tatlock, T. J. Hurd and J. S. Punni, (I). This led to an understanding of the mode Platinurn Metals Rev., 1987, 31, (I), 26 of operation of rhodium/platinum “three-way’’ 3 A. R. McCabe and G. D. W. Smith, Platinum Metals Rev., 1983, (I), 19 catalyst systems which were able to remove 27, 4 A. R. McCabe, G. D. W. Smith and A. S. Pratt, simultaneously hydrocarbons, carbon monox- Platinum Metals Rev., 1986, 30, (z), 54 ide and nitrogen oxides. Research work at Liverpool University on the addition of platinum to nickel based alloys has Platinum Ternary Alloys been supported by Johnson Matthey via a col- Please note that the following alterations should be made to the data given in “Some laborative CASE award and the Loans SERC Ternary and Higher Order Platinum Group Scheme. The addition of platinum to nickel Metal Alloys”, which appeared in Platinum based alloys can have a profound effect on their Metals Rev., 1987, 31, (2), 74-90. oxidation and hot corrosion resistance. On page 83, in Figure 12 the temperature Improvements in gas turbine blade perfor- given as 12oo~Cshould be 125oOC; also Figures 12 and 13 should be transposed, but not the mance in aggressive environments are linked related captions. On page 85, within Figure 16, with the protective nature of surface oxides and Pt-55Pd-55Rh should read Pt-55Pd-IgRh. coatings. The precise role of platinum in pro- Any confusion caused is greatly regretted.

Platinum Metals Rev., 1987, 31, (4) 172 Direct Methanol Fuel Cells RECENT DEVELOPMENTS IN THE SEARCH FOR IMPROVED PERFORMANCE By D. S. Cameron, G. A. Hards, B. Harrison and R. J. Potter Johnson Matthey Technology Centre

Unlike other fuel cell types, the direct methanol fuel cell does not require a separate hydrogen generation system and therefore has greater com- mercial potential, particularly for powering portable appliances. However, the limiting factor for the cost-egective pegormance of such systems is the catalytic activity of the electrodes, in particular the anode. The single most active anode material is platinum, which is usually dispersed on a high sugace area carbon support. It has been found that the addition of small amounts of metals such as lead, rhenium, ruthenium and tin to the platinum produces a significant increase in ac- tivity. The best of these bimetallic systems is based on a mixture of platinum and ruthenium. However, further worthwhile improvements in anode activity could result from a more fundamental understanding of the methanol decomposition reaction. In recognition of this, the Commis- sion of the European Communities has initiated a research programme which involves collaboration between universities and industry in four member states. This article is based largely upon a paper given at the CEC-ltalian Fuel Cell Workshop in Taormina, Sicily, in June 1987.

Fuel cells convert chemical energy to direct double advantage of using a relatively safe current electrical energy without intermediate liquid fuel at a low operating temperature, and steps (I).Most fuel cells are powered by hydro- in the longer term they could find application as gen and oxygen (air) which on combining give alternative power sources for vehicle pro- water as a by-product. However, the direct pulsion. methanol fuel cell (DMFC) functions by oxidis- The possibility of using fuels such as alcohols ing the liquid fuel to carbon dioxide and water. and aldehydes in fuel cells was first recognised This removes the need for an external hydrogen by Kordesch in 1951 (2), although serious fuel supply and offers the prospect of pro- investigations did not commence until the early ducing compact systems ranging in size from a 1960s.Methanol has attracted most interest as few watts up to several kilowatts. The potential a fuel because it is inexpensive, widely available market for DMFCs is both as an alternative to and can be handled and distributed to the con- storage batteries and also as an independent sumer very easily. The DFMC can operate power generator where higher output is re- using either acid or alkaline electrolytes, and quired. Probable applications include use in both of these systems have been studied exten- video cameras and recorders, and in boats and sively over the last 25 years, notably by Shell caravans, where in many cases batteries can on- and Esso. In the period 1960 to 1970 Esso ly be used for short operating periods before Research and Engineering worked under con- recharging is required, whereas fuel cells are tract to the U.S. Army (3) to develop a 100 watt capable of continuous operation provided that system for use in military equipment, in they are supplied with fuel. DMFCs have the response to a requirement for a lightweight

Plarinurn Metals Rev., 1987, 31, (4), 173-181 173 Fig. 1 Many of the potential applications of direct methanol fuel cells are in domestic and leisure markets. Hitachi have constructed a golf cart with a direct methanol fuel cell in a hybrid system alongside a lead acid battery

power source for use in communications equip- used in conjunction with lead acid batteries, for ment. The initial unit developed by Esso gave example in golf carts, as shown in Figure I (I8). 55 mA/cm2 at 0.4V, using noble metal electro- In their systems, Hitachi have generally used catalysts, but durability was limited. Shell pro- platinum as the cathode catalyst and a combina- duced a prototype 40 cell, 300 watt stack in tion of platinum and ruthenium in the anode. 1963 (4), and later extended their studies to As noted earlier, direct methanol fuel cells develop the DMFC for automotive power can be designed to operate either in acid or applications (5-9). Shell studied methanol oxi- alkaline electrolyte. Ideally, a good electrolyte dation (anode) catalysts extensively and found should have high ionic conductivity, produce that a platinum/ruthenium system was among no corrosion of the cell or catalyst materials and the most active of the ones tested, although it cause no poisoning effects or detrimental side did not meet their activity target. Both Shell reactions. In this context, alkaline electrolytes and Esso terminated this research and develop- offer superior electrochemical performance and ment in the late 1970s~because the catalytic improved fuel cell output, compared to acid activity which had been developed for methanol systems. However, the seemingly intractable oxidation was insufficient for effective com- problem of carbonate build-up in cells with mercialisation. Other DMFC systems have alkaline electrolyte, due to the reaction: been investigated by Cathro and Weeks (IO), CO, + OH- = HC0,- Brown Boveri (I I),the U.S. Army for military has so far precluded their commercialisation. communication systems (12-14)and the Royal Consequently most research has focused on Institute of Technology, Stockholm, for elec- acid electrolyte systems. tric wheelchairs (IS,16). A schematic representation of an acid electro- More recently, Hitachi has reopened in- lyte DMFC, together with the principal re- vestigations into acid electrolyte DMFCs (17) actions involved, is shown in Figure 2. A and interest in these power sources has been methanol molecule reacts with a water molecule rekindled. Hitachi foresee the applications as at the anode liberating carbon dioxide, 6 pro- being mainly in the leisure and domestic tons and 6 electrons-a very high electron yield. markets, initially as lightweight hybrid systems The carbon dioxide produced in the reaction is

Platinum Metals Rev., 1987, 31, (4) 174 EXTERNAL LOA Fig. 2 In the direct methanol RBON DIOXIDE fuel cell, methanol reacts with water at the anode and oxygen is reduced at the cathode. Carbon A I dioxide and water are the re- + WATER action products THANOL/C;ULPHUR IC ACID

AIR METHANOL

CATHODE MEMBRANE

6H’r3/102.6ei 3HI0 CH30HrH20-COp * 6H’. 6e-

OVERALL CH,OH .1/202-C02 + 2H20

rejected by the acid electrolyte. Oxygen is the oxidation of methanol on a platinum elec- reduced at the cathode, producing water, which trode. This is reviewed in detail in the literature is removed by the air flowing through the (7, IS), but a brief outline is given here. cathode compartment. The maximum voltage Several views have emerged over the past attainable from the overall reaction in the decade concerning the details of the electro- methanol-air cell is in theory 1.186 V, but in oxidation mechanism. One of the most widely practice this is not achieved. There are several accepted theories has been put forward by reasons for this reduced voltage: Breiter (20). He proposed a “parallel paths” [a1 The reversible methanol oxidation poten- reaction scheme, one path going by way of for- tial is not observed due to the occurrence maldehyde and formic acid to carbon dioxide, of additional reactions involving formal- and the other by adsorption and dehydrogena- dehyde and formic acid species, and a tion of the methanol molecule on the platinum mixed potential results. catalyst followed by further oxidation of the [bl The overpotential required to achieve tenaciously held dehydrogenated organic frag- useful currents is very high due to poison- ment to carbon dioxide: ing of the catalyst. COH dC0, [cl The oxygen reduction electrode also has a mixed reversible potential due to perox- CH,OH - ide formation, and suffers from a high 4 overpotential, although not as severe as CH, 0 -w HCOOH --C CO, the methanol electrode. Traces of formaldehyde and formic acid have The main problem still to be overcome with indeed been identified in solution, but it is the the DMFC is primarily electrocatalytic and is simultaneous build up of the dehydrogenated associated with the need to reduce substantially -COH residue that is thought to be respons- the overpotential at the anode. To explain the ible for the rapid diminution of the current. nature of the problem it is necessary to look at Much work has been carried out to investigate the generally accepted reaction mechanism for the nature of the adsorbed poison (7, 19) and

Platinum Metals Rev., 1987, 31, (4) 175 most evidence points to the reaction occurring potential region. Several workers have by a stepwise removal of the hydrogens from measured initial currents which were 10,000 to the methanol molecule to leave a fragment of 100,000times higher than the so-called steady composition - COH strongly chemisorbed to state current which was found after a few the platinum, as follows: minutes on an anode test (24). The reason for the rapid deactivation is thought to be build-up OH of the -COH residue on the catalyst surface, I since, while platinum effectively adsorbs CH,OH + 3Pt-+ C + 3Ht + 3e- (i) /I \ methanol at low potentials, it does not perform PtPtPt so well in the adsorption of water, and for this reason is not a particularly effective catalyst. However, recent workers have used in-situ The activity of a methanol oxidation elec- spectroscopic studies to show that the adsorbed trode depends on several factors including species is likely to be CO single bonded to a catalyst formulation, the catalyst support, the platinum atom (21,22). The next stage involves electrode structure and the operating con- the reaction of the “poison” with adsorbed ditions selected. Most work has concentrated H, 0 or OH to form CO, . High potentials are on examining the effect of changing the catalyst required for the adsorption of such oxygen- formulation. Platinum group metal-containing containing species and thus this reaction only catalysts are the only systems to date to show proceeds at potentials substantially anodic to any activity for methanol oxidation at low the methanol reversible potential. There is potentials. Many workers have made bimetallic again some argument as to the nature of this and trimetallic catalysts with platinum in the oxygen-containing species since catalyst activity hope that poisoning by the methanolic residue is observed at potentials lower than that at would be significantly reduced or eliminated. which the electrosorption of water to produce Most of the d block elements have been tried adsorbed OH species is expected. Wieckowski as well as germanium, tin, lead, arsenic, has suggested that the oxidation proceeds via an antimony, bismuth, sulphur, selenium, tel- adsorbed (possibly strained and therefore lurium and lithium. Various theories have been reactive) water molecule (23). However, the put forward to explain the promoting effect of generally accepted scheme involves the reaction the additional elements and this area remains of the - COH species with OH species adsorb- controversial (25, 26). The best element com- ed on platinum as follows: binations reported are platinum/ruthenium,

3Pt + 3H,O 4 3Pt-OH + 3H+ + 3e- (ii) platinumhin, platinum/rhenium, platinum/ OH Pt titanium, platinum/osmium, platinum/ I I rutheniumhin and platinum/ruthenium/gold. C + Pt-OH-C=O + H,O (iii) Although it is not certain by which method /I \ I these elements enhance activity, increases of up PtPtPt Pt to 40 times have been recorded. Platinum/ ruthenium is often reported to be the most Pt I active combination, and Shell, Esso and more recently, Hitachi, have favoured this system. C=O + Pt-OH Pt-COOH (iv) I A European Research Programme Pt The Commission of the European Com- Pt-COOH + Pt-OH --t 2Pt + CO, + H,O (v) munities (CEC) has recently initiated work on This mechanism assumes that the catalyst direct methanol fuel cells as part of the ‘“on must be dual functional, that is to say it must Nuclear Energy Research and Development electrosorb methanol and water in the same Programme”. The direct methanol fuel cell

Platinum Metals Rev., 1987, 31, (4) 176 Fig. 3 In the methanol electro- oxidation process the activity of > 700 a platinum catalyst can be E enhanced by the addition of metal W promoters. Ruthenium has the I greatest effect and is currently the O600 favoured promoter > A Half cell conditions: 5 Sulphuric acid 3M I- Methanol 1M F 500 Temperature 60' C 2 0 5 40C v) 4 W I 30C CURRE~T.mA.permg PLAiiNUM

Fig. 4 The performance of the methanol oxidation electrode can be iduenced by changing the 700 > electrolyte. In alkaline solution, E that is at high pH, the reaction is w enhanced significantly but 2 600 alkaline electrolytes suffer the disadvantage of carbonation Y) J which ultimately causes de- r! activation I- 500 &w :

3 2 I

CURRE~T.mA.permg PLAiiNUM

Fig. 5 The performance of the 75v- direct methanol fuel cell may be enhanced by increasing the stack 700- operating temperature, although 650- the temperature. increase muat be > limited to prevent methanol loss €.600- by vaporisation 4 dI 550-

L.l L.l ;soo- i 5 450- I-w 2 400.

350.

"10' ' ' 102 . . ' CURRENT.rnA. per mg PLATINUM

Platinum Metals Rev., 1987, 31, (4) 177 I Commission of the European Communities Fuel Cell Programme Participant Subject of Study

Johnson Matthey Noblelbase metal catalysts for methanol oxidation, half cell and ITechnology Centre (U.K.) full cell studies University of Oxford Fundamental studies of the anode reaction on noble metal and (U.K.) base oxide materials in collaboration with Johnson Matthey Technology Centre University of Ultra high vacuum studies of electrochemical behaviour of Southampton (U.K.) methanol oxidation on platinum single crystals C.N.R.S. (France) Electrochemical characterisation of methanol oxidation on platinum single crystal surfaces I Universitb de Poitiers Liquid chromatographic and infrared reflectance spectroscopic (France) studies of methanol electro-oxidation on polycrystalline platinum surfaces

Universitat Bonn Investigation of co-catalysts for methanol electro-oxidation on (Germany) platinum Siemens A.G. (Germany) Investigation of catalytic materials for methanol electro- oxidation-in collaboration with Bonn University

University of Cork (Eire) Development of low-level noble metal cathodes for the reduction of oxygen

programme is due for completion in the studied in detail at the Johnson Matthey Autumn of 1989 and has the following targets Technology Centre and an optimum catalyst for performance: power density 5omW/cm2, formulation has been identified. Electro- noble metal loading

Platinum Metals Rev., 1987, 31, (4) 178 In addition, the activity of the oxidation catalyst has been found to be very dependent on operating conditions; the effect of increasing temperature on catalytic activity being shown

PtlRu Catalyst in Figure 5. It is evident that, at temperatures as low as 8ooC, activities in excess of 100 mA/mg Pt can be obtained. Figure 6 shows the Arrhenius plots for platinum and platinum/ Pt Catalyst ruthenium catalysts with apparent activation energies of 36 kJ/mol and 49 kJ/mol, respec-

27 28 29 30 31 32 33 34 tively, although the margin of error makes 1 I T. K x 1o-~ precise interpretation difficult. These results Fig. 6 An Arrhenius plot for platinum and suggest that ruthenium promotes the activity of platinum/mthenium catalysts indicates that ruthenium promotes the activity of platinum platinum but does not change the mechanism of but does not change the mechanism of the the anode reaction. At temperatures above the anode reaction boiling point of methanol (65OC) loss of fuel due to evaporation must be considered, while operation at higher pressures (>I atm) would which may not be apparent on planar electrode necessitate separation of methanol from the car- surfaces. bon dioxide and water vapour exhaust gases. Thus the interpretation of Figure 4 requires The effect of sulphuric acid concentration on some caution. However, from thermodynamic activity is shown in Figure 7, where it can be considerations the open-circuit potentials of the seen that activity increases as the acid concen- anode and cathode reaction are predicted to tration is decreased. This can be rationalised shift to more negative values as the pH of the most easily in terms of competition between the electrolyte increases. electrolyte ions and methanol/water for catalyst

750

700

650 0.5M H2SO. A 1.OM HzS04 A 2.OM HZSO4 600 0 3.OM H2S0, > E 0 5.OM H2S04 $550

0? ? 500 _I 4 450 Wk- Fig. 7 The activity of an acid P direct methanol fuel cell is in- 400 creased as the concentration of the electrolyte is lowered. In practice, a compromise between 350 anode and cathode activity and electrolyte conductivity must be 300 achieved 10’ I CURRENT, rnA. per rng PLAT1 NUM

Platinum Metals Rev., 1987, 31, (4) 179 sites. A decrease in acid strength appears that is to say a porous electrode must take the desirable in terms of catalyst activity and also in structure of the electrode into account. In this terms of electrode stability since many poten- respect the improvements obtained with bi- tially useful catalyst materials dissolve in highly metallic catalysts need careful interpretation as acidic media. However the conductivity of the the addition of a second metal in the catalyst system must be kept as high as possible in order dispersion may change both the physical as well to avoid resistive losses and this will place con- as the chemical nature of the active site (26). siderable constrains on the choice of electrolyte. However, further refinement of the platinum/ The performance of a variety of fuels during ruthenium bimetallic catalyst prepared on tra- electro-oxidation in 3M sulphuric acid on a ditional carbon dispersions is unlikely to yield platinumhthenium catalyst is illustrated in an order of magnitude improvement in anode Figure 8. The best activities are obtained with activity. formic acid despite the fact that this molecule What is needed is a far greater understanding only liberates 2 electrons during oxidation com- of the chemistry of the overall catalytic process pared with methanol which liberates 6 elec- coupled with a knowledge of how to reproduce trons. Unfortunately the aggressive chemical the desired “molecular scale” properties in a nature of formic acid precludes its use in com- practical electrode. mercial systems. The majority of research has centred around the identification of the precise nature of the Conclusions poisoning species formed on platinum. This is The development of advanced anodes for the obviously a very important aspect and recent direct methanol fuel cell has been limited not developments in the use of spectroscopic only by the complexity of the electrode re- techniques to probe the electrochemical inter- actions but also by the difficulties inherent in face in-situ promise to finally resolve the issue. studying porous electrodes. Clearly, any In addition, there are a number of other aspects attempt to improve the performance of a real, of the electro-oxidation reaction that require

650 Ethylene glycol

,600. E ui r’550-

“7>

J 500- 5 I- F 450- ? ForGic acid 4ooy//H Fig. 8 Other fuel cells may be oxidised directly in a fuel cell, although none is as attractive as 350 Sodium formate methanol in terms of electron I/ yield, cost, availability and case I& lb3 of handling CURRENT. mA. per mg PLATINUM

Platinum Metals Rev., 1987, 31, (4) 180 attention as a matter of urgency. These are: Research Programme in tackling the problems The function of co-catalysts (such as outlined above will lead to the development of bimetallic catalysts) more cost-effective direct methanol fuel cells. Exploration of alternative electrolytes Optimisation of porous electrode structure. Acknowledgement In conclusion, it is hod that the broad We wish to thank the Commission of the European approach taken by the participants of the CEC Communities for their support of part of this work.

References I D. S. Cameron, Platinurn Metals Rev., 1978, 22, 14 J. E. Wynn, Power Source Symp. Proc., 1970, (2), 38 24, 198 2 K. Kordesch and A. Marko, Oesterr. Chem. Ztg., 15 c. Sylwm, Energv Convers., 1977, 17, (2/3), 67 19519 52, 125 16 C. L. Sylwan, Energy Convers. Manage., 1980,20, 3 G. Ciprios, J. Batzold and M. Lieberman, (I), I “Advances in Energy Conversion Engineering”, 17 K. Tamura, New Muter. New Processes, 1983, 2, A.S.M.E., 1967, 357-364 317 4 K. R. Williams and D. P. Gregory, 3. Electro- 18 J. Yamaguchi, Automot. Eng., 1983, 91, (4), 65 chem. SOC., 1963, 110, 209 19 B. D. McNicol, in “Studies in Electrical and 5 R. W. Glazebrook,3. Power Sources, 1982,7, 215 Electronic Engineering 11-Power Sources for 6 R. W. Glazebrook, Electr. Veh. Dev., 1982, 7, 18 Electric Vehicles’’, (3.8, ed. B. D. McNicol and A. Rand, Amsterdam> Ig84 7 N. A. Hampson, M. J. Wfilars and B. D. D* J. ~~~i~~l,3. power sources, 1979, 4, (D, 191 20 M. W. Breiter, “Electrochemical Processes in 8 p, A. Attwd, A. G. Dion, A. C. Houston and ce11s”3 Springer Verlag> ‘969 R. T. Short, 3. Chem. Tech. Biotechnol., 1984, 21 B. Beden, c. Lamy, A. Bewick and K. Kunimat- Elecrroanal. Chem., 1981, 121, 343 34, (I), 10 su, 3. 9 B. D. McNicol, Roc. of the Workshop on 22 K. Kunimatsu, 3. Electron Spectrosc. Relat. Electrocatalysis of Fuel Cell Reactions, Electro- PhenOm.3 1983, 3% 215 &em. Sot., 1979, 79, 93 23 A. Wieckowski, J. Sobrowski and A. Jablonska, 10 K. J. Cathro and C. H. Weeks, Energy Convers., 3. Electroanal. Chem., 1974, 55, 383 1971, 11, I43 24 T. Biegler and D. F. A. Koch, J. Electrochem. 11 W. Vielstich, Fourth Int. Symp. Batteries, SOC., 1967, 1143 904 Brighton, England, 1964, Pergamon, p. 271 25 B. Beden, F. Kadirgan, C. Lamy and J. M. 12 S. S. Kurpit, Intersoc. Energy Convers. Eng. kW,3. Eleczroanal. Chem., 1981, 127, (1-3), 75 Conf., 1975, 222 26 K. J. Cathro,J. Electrochem. SOC.,1969,116,1608 13 J. Perry, Power Source Symp. Proc., 1974, 26, 27 J. T. Glass, G. L. Cahen, G. E. Stoner and E. J. 171 Taylor, 3. Electrochem. Soc., 1987, 134, (I), 58 Fabricating Platinum Disc Microelectrodes A variety of electrochemical studies depend I, by weight) held at a temperature of upon the use of microelectrodes, and if an elec- 32o+1o0C; this being contained in a platinum trode disc of sub-micron proportions is used crucible which served as a counter electrode ohmic distortion is virtually eliminated. Disc while a platinum wire with a diameter of 65pm microelectrodes have been produced by encap- was dipped in the melt and anodically polarised sulating a fine Wollaston wire in glass and also by a periodic square wave, the amplitude of by vapour deposition, but an easier method has which affected both the shape of the pointed tip now been reported by K. Itaya, T. Abe and I. and the smoothness of the surface. Uchida of Tohoku University, Japan u.Elec- Tapered platinum wires with radii 10onm trochem. soc., 1987,134, (5), 1191-1193). have been produced relatively easily; such tips Anodic electropolishing is used widely to are then encapsulated in epoxy resin, or a prepare sharp points on needle-like metal similar sealing material, and the electrode sur- specimens that are to be examined by field ion face exposed by cutting through the composite microscopy, and this technique has been with a diamond knife attached to an adapted to produce microelectrodes. The ultramicrotome. It is suggested that this smoothest surface was obtained using a molten method could be extended to iridium and gold, salt of sodium nitrate and sodium chloride (4 to and even to carbon, using an alkali solution.

Platinum Metals Rev., 1987, 31, (4) 181 An Exchange of Ideas on Catalysis Homogeneous and Heterogeneous Catalysis EDITEDBY YU. YERMAKOV AND V. LIKHOLOBOV, VNU Science Press, Utrecht, 1986, 1169 pages, DM 270/$130 When catalyst scientists gather together the analogy in opening up new lines of thought and platinum group metals are generally a promi- enquiry becomes most evident. nent feature of their discussions. The “Fifth One of the visions of the future, probably International Symposium on Relations between held by all who work with catalysts, is the Homogeneous and Heterogeneous Catalysis”, possibility of being able to duplicate or even held at Novosibirsk in July of last year, proved simulate the activity and selectivity of biological to be no exception. enzyme systems. Several papers obviously had The recently published proceedings of this this as their theme, notably a paper by A. E. important meeting contain the full collection of Shilov of the Institute of Chemical Physics, some 39 invited guest lectures and a represen- U.S.S.R. Academy of Sciences, on organised tative 27 of the 267 poster communications molecular assemblies in catalysis. This included which were also presented. Since most of the results using micelles, microemulsions and invited speakers reviewed their own areas of ex- lipid vesicles. pertise, the information in this volume is very Another of the themes of much current work concentrated, giving an in-depth and up-to- is the nature of the active site itself, in par- date picture of practically the whole of ticular the nuclearity and effects of the localised catalysis, viewed from the aspect of organo- charge distribution. metallic surface intermediates. Earlier symposia had discussed catalytic and The rationale behind this particular series of chemical properties of metals quenched in a meetings was aptly expressed earlier in the matrix. Such studies have now been extended series when it was noted that “new departures into the gas phase. The low temperature oxi- in science and technology often originate at the dative addition of various hydrocarbons to boundaries between separate but related areas transition metal atoms and ions leads to the for- of enquiry”. This point of view is reiterated in mation of organometallic intermediates. Thus the foreword to this volume which lists “one of the reaction of Rh’ with hydrocarbons in a the main tasks of these symposia-to create an mass spectrometer results in all the reactions opportunity of a meeting of specialists from dif- and products more normally associated with ferent areas of catalysis for an exchange of ideas metallic surfaces, and which are usually inter- and a redistribution of experience from some preted by multicentre mechanisms. In the same areas of research into others”. In keeping with paper, by B. A. Dolgoplosk and I. A. Oreshlin these overall objectives, it is particularly useful of the A. V. Topchiev Institute of Petro- that this volume should begin by listing the chemical Synthesis, Moscow, interesting infor- subjects and titles of presentations given at mation resulting from the decomposition of the earlier symposia in this series. This serves to organometallic compounds produced by the re- put into historic perspective how far the subject action of CH,Li with platinum group metal has progressed since the first symposium was halides is given. held in Brussels in 1974. Another paper which seemed to embody the Here the presentations are considered in essence of the series was entitled “Multiple three roughly equal sections. Roles of Palladium in Liquid Phase Oxidation” The first section emphasises the relationships by J. E. Lyons, G. Suld and C.-Y. Hsu of the between homogeneous and heterogeneous Sun Refining and Marketing Company. Homo- catalysis, and it is here that the power of geneous catalytic oxidations with palladium and

Plurinurn Metals Rev., 1987. 31, (4), 182-185 182 a copper co-catalyst (Wacker) are generally sitive to these oxidation potentials and shows a associated with the vinylic oxidation of olefinic marked optimum at an intermediate level substrates, which arises from nucleophilic which is pH dependent. They went on to study attack on a palladium(I1) olefinic *-complex. silica, alumina and titania supported catalysts The authors point out however that olefms can with palladium and the same series of heteropo- also co-ordinate with metals (or palladium(I1) ly metal complexes. with electrophilic ligands) to form ?r-allylic This section of the symposium was concluded complexes. They show that these can then by a paper from the University of Utrecht undergo nucleophilic attack giving allylic pro- which illustrates yet another variant of the ducts. These types of catalytic systems have homogeneous-heterogeneous theme. Epoxi- been operated homogeneously and hetero- dation of cyclohexene by oxygen was the re- geneously-thus the commercially important action studied, and this time the oxidation oxidation of ethylene to acetaldehyde was co-catalyst was a heterogeneous platinum on initially carried out with a heterogeneous silica catalyst-or preferably a platinum-silver catalyst and is now practised in a homogeneous alloy catalyst-operated in conjunction with a system, whereas the equally important oxi- homogeneous manganese tetraphenylporphyrin dation of ethylene to vinyl acetate was fmt oxidation catalyst. Silver was added to inhibit practised in a homogeneous system but now the direct hydrogedoxygen reaction and there- uses a supported catalyst. by increase the oxygen conversion efficiency. This paper also shows how one may control allylic/vinylic oxidation, as in the case of pro- Immobilised Metal Complexes pylene, and discusses the palladium catalysed Much of the second section was taken up acetoxylation of aromatics. This reaction yields with discussions of Ziegler-Natta and nickel phenylene diacetates and diacetoxy biphenyls, catalysed polymerisation reactions, and olefin and these provide a route to dihydroxy aro- metathesis reactions using base metal catalyst matics of commercial importance. systems. Any hopes that the reader may find Palladium catalysed oxidation of a somewhat here the answer to the problem of catalyst different kind, carbon monoxide to carbon stability and leaching of conventionally dioxide with oxygen at low temperatures, was anchored homogeneous catalysts are not to be given in a paper by a large group of workers satisfied. Indeed there seems to be a growing from the Novosibirsk Institute of Catalysis. awareness that the essential lability of con- This reaction is catalysed by conventional ventional soft ligands to hydrolytic and thermal homogeneous PdCl, + CuCl, (Wacker) degradation may mean that the problem has no catalytic systems but the problems associated solution when attempted along these lines, and with the corrosivity and volatility of HCl led alternative approaches are now being explored. them to try other co-oxidants and also attempt One of these is the use of ligands with more to heterogenise the catalyst. One advantage of polar bonding and the use of polydentate the palladium catalyst, in contrast to the well- ligands. M. hpka from the Czechoslovak known low temperature Hopcalite catalyst, is Academy of Sciences studied neutral its water tolerance. The catalytic system was rhodium(1) complexes with bi-dentate varied, by varying the co-oxidant used. For this phosphines and cationic rhodium(1) complexes purpose a wide range of mixed metal with monodentate phosphines, both bonded to heteropolyphosphorus complexes based upon silica gel. Catalysts were characterised with molybdenum, vanadium and tungsten were regard to selectivity and stability in the prepared and characterised. With such com- hydrogenation of cyclooctadiene, I-heptyne pounds the redox potential of the co-oxidant and I-heptene. Much better results are obtain- could be systematically varied. The rate of car- ed by a procedure which entails forming the bon monoxide oxidation proves to be very sen- rhodium complex in solution using a silyl

Platinum Metals Rev., 1987, 31, (4) 183 substituted alkyl-diphenyl-phosphineand graf- characterised them by using a combination of ting this onto the silica rather than the more EXAFS, HREM and Mossbauer spectroscopy. conventional approach of first functionalising Work at Bristol University on chemical trans- the silica with the phosphinated anchoring formations associated with a tri-ruthenium car- ligand. Better results than when using the bonyl cluster is discussed by s. A. R. Knox, homogeneous catalyst alone are claimed. and osmium carbonyl clusters also come in for Another approach to heterogenising catalysts their share of attention from P. B. Wells of Hull is to use supported liquid phase systems having University and D. K. Chakrabarty and co- low volatility. J. Hjortkjaer from the Technical workers at the Indian Institute of Technology, University of Denmark has been using solu- among others. tions of HRh(CO)(PPh 1) in phenyl-dibenzo- French workers report some rather dramatic phosphole supported on silica for propylene effects on the selectivity for syngas conversion hydroformylation. However the results would to methanol for platinum on silica catalysts to appear to be inferior to the more conventional which chromia and molybdena have been homogeneous catalytic system. added. Possibly related effects on modified Carbon supported platinum group metals are rhodium on silica catalysts used for C, oxy- being used at the University of Tokyo for the genate formation are discussed by H. Knoz- carbonylation of methanol. The order of inger of the University of Munich in a general activity for the supported metals was Rh > Ir > discussion of the analogies between metal car- Ni > Pd > Co > Ru > Fe. Methyl iodide is used bonyls and surface chemisorbed carbon mon- as promoter in a vapour phase reaction at oxide. around 300OC. The use of nickel is somewhat Strong metal support interactions (SMSI), a surprising in view of the known methanation favourite topic at present for workers with activity of nickel catalysts, as indeed was found heterogeneous catalysts, did not receive much to be the case here when nickel was used on attention at this conference. One notable silica or alumina supports. exception was the paper by Yu. I. Yermakov Several papers also deal with novel ligand and Yu. A. Ryndin which discussed the effects systems including organic azo dyes at the of supports and metal promoters on platinum. Bulgarian Academy of Sciences and macro- This discussion included not only conventional cyclic ligands prepared in situ in conjunction supports but also the surprisingly large dif- with alumino-silica supports at the I. M. ferences which were found among the rare Gubkin Institute of the Petrochemical and Gas earth oxide supports. They conclude, after Industry in Moscow. discussing the possible reasons for the chemical effects associated with SMSI, which they also Catalysis by Metal Clusters define, that there can be significant catalytic ef- and Dispersed Metal Particles fects due to interaction between the active Much of this section is concerned with the metal and the promoter in an ionic form. use of organometallic and carbonyl cluster com- Perhaps the final say on the subject of metal pounds in the preparation of supported cata- clusters and dispersed metal particles should lysts. The potential advantage of these systems have been given to P. Gallezot at the French arises from the fact that in principle the CNRS catalyst laboratories who demonstrated catalytic site is well defined, and that analogous that he can reversibly interchange platinum car- polymetallic species can also be prepared whose bonyl clusters of high nuclearity and platinum structure can be well characterised. crystal aggregates, all when contained within M. Ichikawa from the Research Institute for the cages of a zeolite support. He showed that Catalysis at Hokkaido University has studied oxidation destroyed the metal-metal bonds but rhodium-cobalt and rhodium-iron bimetallic did not change the nuclearity, and this con- cluster catalysts for hydroformylation and has version is reversible. He extended this work to

Platinum Metals Rev., 1987, 31, (4) 184 supported rhodium aggregates but here car- research. All papers are of a very high standard, bonylation led to a break-up of the aggregate and the comprehensiveness makes this a and the formation of mobile mono-nuclear car- valuable source of up-to-date reference bony1 species. material. After five conferences in this series on homo- Conclusions geneous and heterogeneous catalysis it is clear Here it has only been possible to cover a small that the discussions engendered are very fruit- part of the work reported which, as remarked ful. This area of study is still expanding and on earlier, is very concentrated. Many of the developing, but there is clearly a long way to go other papers are interesting inasmuch as they before man can even start to approach nature’s suggest new techniques, and by analogy, new enzymes in their efficiency and selectivity. possibilities for following new directions in J.W.J.

Corrosion in Nitric Acid Plants The use of stainless steels for the heat ex- dramatic increase in the rate of corrosion. changers in nitric acid plants is widespread, However, these latter results are calculated on although nickel based alloys are finding ap- the basis of only 24 hours exposure and thus plication in the newer plants. These steels are may give a distorted picture. subject to corrosion by the reaction products, Anodic polarisation curves in 42 vol. per cent mainly nitric acid, which are produced during nitric acid measured on AISI 304L steel the oxidation of ammonia over platinum- samples taken from damaged tube elbows, rhodium catalyst gauzes. Such corrosion can which have a surface deposit containing about lead to premature failure of components, ~wt.per cent platinum, show corrosion poten- resulting in unscheduled plant shut down and tials in the range 1200-1700mV, approximately reduced production of nitric acid. 300-800mV higher than the same steel before In practice, this corrosion is particularly service exposure. The corrosion potential of the prevalent on parts subjected to tensional latter, typically goomV, lies within the passive stresses and, in an attempt to understand the region of the anodic polarisation curve, while factors tbat contribute to this enhanced corro- that of the “damaged” steel lies in the sion, S. Z. Kostii of Hemijska Industrija Pan- transpassive region of the curve. KostiC at- Cevo, Yugoslavia, has examined the behaviour tributes the nobler electrode potential to the of two typical stainless steels in boiling nitric establishment of a mixed potential between the acid; in particular the influence of cold work steel and platinum-rhodium in the surface and of galvanic coupling on the corrosion rate deposit. Metallographic examination of (Br. Corms. J., 1987, 22, (I), 53-55). “damaged” components and laboratory KostiC believes that galvanic coupling can samples shows corrosion to be intercrystalline, result from the deposition of platinum-rhodium attack being concentrated at chromium car- particles from the catalyst gauzes onto the bides in the grain boundaries. stainless steel tubes. The loss of platinum from The implication of these results for commer- such catalysts during service is well known, of cial practice is that the deposition of platinum- course, and has a significant impact on the pro- rhodium particles onto such stainless steel sur- cess economics. faces should be avoided, if possible, in order to Samples of two steels, AISI 304L (I8G-8Ni) inhibit enhanced corrosion and premature and 2RE10 (25Cr-zoNi), in strained and failufe. Clearly the use of catchment systems unstrained conditions, some in contact with would be beneficial here, since their prime pur- platinum-rhodium, were exposed to boiling pose is to trap much of the platinum emitted nitric acid (4245% vol.), and corrosion rates from the catalyst during service, primarily to and electrochemical corrosion potentials improve process economics. Such catchment measured. The results for the 2RFllO steel in- systems have been shown to be very effective dicate that the corrosion rate after 240 hours ex- (see, for example, A. E. Heywood, Platinum posure is substantially increased when the steels Metals Rev., 1982, 26, (I), 28-32) and are be- are in the strained condition, and that galvanic ing increasingly specified by major nitric acid coupling with platinum-rhodium leads to a producers. C.W.C.

Platinum Metals Rev., 1987, 31, (4) 185 The Chemistry of the Platinum Group Metals A REVIEW OF THE THIRD INTERNATIONAL CONFERENCE

Sponsored by the Dalton Division of the Royal Society of Chemistry, the Third International Conference on the Chemistry of the Platinum Group Metals, was held at Sheffceld University in July 1987. The first meeting in this series was held at Bristol in 1981 and the second in Edinburgh in 1984. Over three hundred and fifty delegates from academia and in- dustry attended with more than half from abroad and with over twenty countries represented. During the week forty-five lectures were presented along with over one hundred and seventy posters.

The conference opened with the Dalton sodium hydroxide at 12oOC catalyses the latter Presidential Address given by Professor P. M. reaction, through a combination of alcohol Maitlis from the University of Sheffeld who dehydrogenation, aldehyde decarbonylation described an interesting new area of platinum and the water-gas shift reaction. group metal chemistry in his talk on metal- containing liquid crystals. The inclusion of Clusters and Dinuclear Complexes metals in these systems may give rise to new The synthesis of metal chain compounds was magnetic and electrical properties, as well as described by Professor F. G. A. Stone from non-linear optical effects. The first compounds Bristol University. Chains are constructed by prepared contained platinum or palladium complexation of two metal atoms (nickel(0) or complexed by biphenyl nitrile ligands and the platinum(0)) to tungsten or molybdenum car- work has been extended to gold and palladium byne compounds where the carbyne ligand complexes with liquid crystal-forming pyridine bridges two metal atoms. Up to eleven metal derivatives and palladium dithiocarboxylic acid atoms have been joined together in this man- complexes. ner. Professor H. D. Kaesz from U.C.L.A. The T. A. Stephenson Memorial Lecture was presented some reactions of acetylenes with given by one of his former students Professor edge double-bridged trinuclear ruthenium and D. J. Cole-Hamilton of the University of St. osmium clusters, and Professor R. UsBn from Andrews, who described some recent work on the University of Zaragoza, Spain, described the production of hydrogen from alcohols. the preparation of unusual platinum com- Hydrogen is an important raw material in the pounds starting from binuclear anions of the chemical industry, used mainly for production type [Pt(p-X)(C,X’,)I:-, where X = CI, Br; of methanol and ammonia, and is usually pro- X’ = F, C1. Complexes with Pt-Pt bonds with duced by steam reforming of natural gas. An no bridging ligands were illustrated and reac- alternative route would be from renewable tion with silver salts gave platinum-silver fermentation products such as ethanol. The clusters with bridging silver atoms. known homogeneous catalysts for ethanol Many attempts have been made to use cluster dehydrogenation give hydrogen and compounds as homogeneous catalysts, but they acetaldehyde, and not the thermodynamically are usually unstable under the reaction condi- favoured products from ethanol and water tions and catalysis is by monomeric species. A which are alkane, carbon dioxide and new approach where clusters were stabilised by

hydrogen. However [Rh(bipyridyl) I + with a central carbon atom was described by H.

Platinum Metals Rev., 1987, 31, (4), 186-193 186 Yamazaki, of the Institute of Physical and with alcohols. Professor E. Singleton from Chemical Research, Japan. Thus the well- C.S.I.R., South Africa also described some new known cluster anion [Ru C(C0) I 6 1 - gave ruthenium chemistry using versatile, reactive [Ru,C(CO), ,Me] - on treatment with methyl intermediates, including [RuH(cycloocta- iodide at 13oOC. The alkyl, on treatment with x,5-diene)(H2NNMe,)1+.A number of routes hydrogen at 100 atm and IOOOC gave the to new compounds were shown involving hydride [Ru,C(CO),,Hl-, which was shown displacement of labile ligands, as well as an im- to be a catalyst for the hydrogenation of olefins proved synthesis of ruthenocene by reaction of at I atm H, and room temperature with no [RuCl,(COD)], with acetonitrile to give apparent dissociation of the cluster. Unusual [ RuCl ,(COD)(MeCN) ,I which with TlCp gave cluster compounds of main group elements and [RuCp,l in more than 90 per cent yield. platinum group metals was the subject of the lecture by P. Stoppioni of the University of Hydrides and Hydrogenation Florence, Italy. As an example Vaska’s com- The first two papers of this session described plex [IrCl(CO)(PPh,),l with P,S, gave a di- the use of NMR to study dihydrogen ligands. iridium species with each iridium co-ordinated Professor R. H. Crabtree from Yale University by a P, S ligand, and one phosphorus atom in discussed the chemistry of non-classical H , each ligand bridging to the other iridium bonding. Detection of dihydrogen complexa- atom. tion in metal polyhydride species is pro- Professor F. A. Cotton from Texas A&M blematic, for example their structures in University has worked with binuclear com- solution and in the solid state may be different plexes for many years. He pointed out that and their fluxionality gives rise to only one I H although binuclear rhodium complexes of the NMR resonance. However it has been found type exemplified by [Rh, (CH COO) ,1 are well that the temperature dependence of the relaxa- known, attempts to make iridium analogues by tion time TI can be used to identify structures the same methods invariably fail. His group has and obtain H-H distances. Correction for recently been investigating formamide ligands, temperature is carried out by taking of the type tolNCHNtol, (to1 = 4-methyl measurements at the minimum of the T , versus phenyl) from which [Ir,(tolNCHNtol),l can be temperature curve. These non-classical prepared. This is the first binuclear iridium polyhydrides are mainly found for d6 metal complex directly analogous to the binuclear ions and a high oxidation state is required. One rhodium complexes. With other metals the possible industrial application is for the ligand gives [M,(tolNCHNto1) I 1 ,M = Co with preparation of heavy water via H/D exchange. the shortest Co-Co bond length ever observed, Professor R. H. Morris of the University of and [M,(tolNCHNtol),I+, M = Ni, Pd. Toronto has looked at analogies between N , and There is a weak metal-metal bond in the nickel H, chemistry using NMR and labelling complex but not in the palladium complex. experiments. Dihydrogen complexes such Professor P. H. Dixneuf from the University as t-[M(q2-H,)(H)(PEt,CH,CH,PEt,),IBPh, of Rennes discussed his approach to the incor- where M = FeyRu, 0shave been prepared and poration of carbon dioxide into an organic the half-life for incorporation of deuterium in substrate. Vinylcarbamates are usually prepared acetone-d6 solutions has been measured in con- using phosgene but a number of ruthenium com- junction with NMR spectra. The H/D inter- plexes catalyse the reaction of acetylenes with change mechanism appears to have a number of secondary amines and carbon dioxide to give possibilities and a typical value for the free these synthetically useful intermediates. For energy of transfer of H between a dihydrogen catalyst precursors of the type [ RuCl ,(7 - and a classical hydride ligand on an osmium aryl)PR, 1 , ruthenium vinylidene complexes are complex is of the order of 50-55kJ/rnol at intermediates as shown by trapping experiments a temperature of 3ooK.

Platinum Metals Rev., 1987, 31, (4) 187 The use of H,/O, mixtures for oxidations hydrogenation. Interestingly no C, or C, catalysed by rhodium complexes was described species have been detected during these by Professor B. R. James, University of British reactions. Columbia. The selective oxidation of Hydrogenation reactions using binuclear dimethylsulphoxide (dmso) to the sulphone us- rhodium complexes were discussed by Pro- ing [RhCI] (dmso) ] 1 and of cyclooctene using fessor R. Eisenberg from the University of an iridium(II1) system were given as examples. Rochester, New York. NMR has been used to In each case the stoichiometry corresponds assign structures to these species and detect the to: presence of a radical pair mechanism, and the Substrate(X) + 0, + H, = X(0) + H,O use of deuterated substrates provides additional and the driving force for the reaction is the for- data. The results originally suggested that for mation of water. styrene hydrogenation a radical pair mechanism The mechanism of this type of reaction does was involved with a metal-based radical pair. not involve the formation of free radicals. However, a more extensive analysis showed When dimethylacetamide (dma) is used as a sol- that the chemically induced dynamic nuclear vent, the dma is selectively oxidised at so°C to polarisation effects observed were due to pro- the hydroperoxide. Spectroscopic and kinetic ducts from reaction of para-hydrogen with the data indicate oxygen transfer via a olefin, where the ortho/para equilibrium was rhodium(II1)peroxide intermediate and shifted in favour of the para-form by storage at dihydrogen is required to reduce rhodium(II1) liquid nitrogen temperatures. to rhodium(1). Use of the RhCl -methyltrioctylammonium Professor J. L. Spencer’s lecture was con- chloride ion pair as a hydrogenation catalyst cerned with work at the University of Salford was discussed by Professor J. Blum of the on electron deficient platinum clusters such as Hebrew University, Jerusalem. This system [Pt,H,(PBut,),l+ (x = 3,7). The metallic core was reported to hydrogenate aromatics at am- is stabilised by co-ordination to tri-t- bient temperatures and pressures, and also pro- butylphosphine but small molecules such as ved potentially useful in selectively dihydrogen react rapidly and reversibly, hydrogenating double and triple bonds and regenerating the polyhydrido clusters. aromatics in preference to vulnerable groups Characterisation of these species has been car- such as nitro and carbonyl derivatives. B. F. G. ried out using a variety of techniques including Johnson of the University of Cambridge X-ray diffraction, I1Pand 19sPtNMR, fast- described the formation of large osmium atom bombardment mass spectroscopy and clusters of ten metal atoms and beyond. These cyclic voltammetry. complex systems are influenced by the degree The use of so-ordinatively unsaturated of protonation, with the hydrogen located in clusters as models for chemisorption and tetrahedral and octahedral structures raising catalysis on platinum surfaces was discussed by the overall cohesive energy. Professor R. J. Puddephatt, University of The presentation of the recent work on Western Ontario. To mimic a surface using clusters at Cambridge was continued by P. P. clusters one requires systems that are co- Edwards who considered these species to be a ordinatively unsaturated, can accept extra potential link between microscopic and ligands and be capable of regeneration. Thus macroscopic regimes and that successful ex- for example the clusters [Pt, (JA -CO)(p- perimental probing could allow monitoring of

dppm) ,1 + and [Pt (p -H)(p-dppm) 1 + where the evolution of bulk properties from the dppm = Ph,PCH,PPh, serve as models for atomic and molecular level. reactions at the 3-fold sites on a platinum{ I I I} J. F. Stoddart of the University of Sheffield surface. Special attention has been given to the discussed the nature of the bonding between reactions of acetylene on platinum, such as outer sphere ligands such as crown-ethers or

Plarinum Metals Rev., 1987, 31, (4) 188 X-0.N cyclodextrins and a variety of platinum group investigation into palladium catalysed carbon- metal complexes including cis-[PtCl,(NH,) ,I. carbon bond formation from alkyl and aryl This second sphere co-ordination was inter- halides and Grignard reagents. Possible in- preted as a molecular recognition phenomenon termediates were prepared and their reactions and bonding is believed to be non-covalent with to give organic products were discussed. The stable molecular adducts being observed in syntheses of bicyclic and tricyclic systems were solution as well as in the solid state. This expan- illustrated by Professor G. P. Chiusoli from the ding area of extra-molecular chemistry offers University of Parma, Italy. In a versatile potential applications in drug delivery of method, palladium complexes were used to platinum anti-tumour agents and also to novel catalyse the co-cyclisation of terminal olefins catalytic systems. M. Schroder presented work with alkenes, alkynes, nitriles or carbon mon- recently carried out at the University of Edin- oxide, giving cyclic systems in high yield. burgh aimed towards applying the chemistry of Professor J.-E.Backvall from the University macrocyclic complexes of the platinum group of Uppsala, Sweden presented a fairly general metals towards homogeneous and electro- method for the highly specific I ,4 functionalisa- catalysis. The structures of octahedral tetra-aza tion of 1,4-dienes. In this reaction the complexes were discussed and it was shown palladium(I1) acetate catalyst is reduced to that square planar complexes of palladium(I1) palladium(O), but as shown in the Scheme, for could be reduced electrochemically to produce catalysis to take place oxygen acts as an oxidant highly reactive palladium(1) species. A range of via cobalt complexes which oxidise hydro- homoleptic hexathia complexes were described quinone, which in turn re-oxidises the and it was shown that the ability of the polythia palladium. This type of triple catalysis is com- crown ligands to stabilise mononuclear mon in biological reactions and may be ex- platinum(III), palladium(II1) and rhodium(I1) pected to be more widely used in homogeneous species was related to the stereochemical and catalysis over the next few years. Asymmetric electronic properties of these products. Wacker reactions, giving chiral products, have not yet reached the almost perfect enantioselec- Palladium Compounds in tivity encountered in rhodium-catalysed asym- Organic Synthesis metric hydrogenations and, as explained by T. Organic chemists are increasingly turning to Hosokawa of Osaka University, optical yields palladium compounds to give high yield, selec- are rarely more than 20 per cent. In his work, tive syntheses under mild conditions. A half palladium *-ally1 complexes derived from day session was devoted to this important area /3-pinene were used to cyclise derivatives of ally1 of palladium chemistry. Professor A. phenol with excellent chemical yield but Yamamoto from the Tokyo Institute of moderate optical yields. Technology presented results of a mechanistic W. P. Griffith from Imperial College has

Platinum Metals Rev., 1987, 31, (4) 189 recently been investigating the application of technique was originally used to study protein high oxidation state ruthenium complexes in electrochemistry but now finds a place in sensor organic synthesis. One novel, particularly selec- electrodes such as the recently launched blood tive system is (Pr4N)[Ru0,I/4- glucose monitor intended for use by diabetics. methylmorpholine N-oxide in dichloro- methane. This is simple to prepare from Surfaces and Catalysis ruthenium trichloride and oxidises primary Professor D. A. King of Liverpool University alcohols to aldehydes and secondary alcohols to reported on chemisorption studies on Pt{ I IO}, ketones, leaving sensitive groups such as epox- Pd{I I o} and Cu{ I IO} surfaces. Relatively sim- ides, olefins and silyl ethers unaffected. ple, well-understood systems such as those formed by carbon monoxide adsorption were Platinum in Biology investigated initially and formed a basis for Professor B. Lippert from the University of understanding more complex processes such as Freiburg began his lecture on platinum- the adsorption and decomposition of HNCO nucleobase interactions with a brief description and CH,NCO. A range of techniques were of what is known of the mechanism of action of employed for this work, mainly based on parti- the anti-tumour drug Cisplatin and its binding cle spectroscopy, which included vibrational to DNA and then showed examples of a spectroscopy, thermal desorption spectroscopy number of different types of platinum and angle-resolved ultraviolet photoelectron nucleobase complexes prepared in his spectroscopy; the latter being used to prove an laboratory. M. J. Cleare from the Johnson Mat- angular surface positional configuration of car- they Technology Centre was the first person to bon monoxide on P~{IIo}.The work has also prepare Carboplatin [diammine(cyclobutane- shown that considerable reconstruction of a I, I-dicarboxylato)platinum(II)l which has metal surface can take place following adsorp- recently been launched in the U.K. and else- tion which depends on the chemical properties where as a second generation platinum anti- of both the metal and adsorbate. Co-adsorption tumour drug. He gave the rationale for its selec- of potassium with other adsorbates onto several tion and illustrated its much reduced toxicity metal surfaces was also described and it was when compared with Cisplatin. Recent clinical shown that, in some cases, for instance with data was also discussed particularly on the use CU{IIO}stable salt formation can occur, of Carboplatin against ovarian and small cell whereas with Pd{ I IO} a more complex system lung cancer. evolves. This may have a bearing on the ap- The kinetics of reaction of platinum anti- plication of these metals to certain processes tumour complexes with typical nucleophiles such as Fischer-Tropsch catalysis. Professor P. found in biological systems have been studied B. Wells of the University of Hull described by I. A. G. Roos of the Peter MacCallum collaborative work carried out between the Cancer Institute, Melbourne, Australia who Chemistry and Physics Departments of Hull found that the conversion of Carboplatin to University and I.C.I. Chemical and Polymers Cisplatin by chloride ion was pH dependant. F. Group on the structure and catalytic chemistry Jo6 from the Hungarian Academy of Sciences of osmium clusters at oxide and sulphide sur- described his use of water soluble platinum faces. The eventual goal is that as metal clusters group metal complexes as hydrogenation can be highly characterised, catalytic site catalysts for double bonds in intact biological fabrication via metal clusters may lead to well membranes, and the effects of such hydrogena- understood catalyst systems which can perhaps tions. H. A. 0. Hill from the University of Ox- be easily optimised towards site configuration ford discussed the modification of gold and of a desired activity and/or selectivity. platinum electrodes with various ligands which Although that goal remains distant, carbonyl facilitate electron transfer to proteins. This clusters of osmium with nuclearity 3,4,6 and 10

Platinum Metals Rev., 1987, 31, (4) 190 have been impregnated from non-aqueous solu- information obtained was consistent with that tions onto a variety of oxide or sulphide sup- expected for this anion. This contrasted with a ports, and then rendered catalytically active by similar treatment of a gold cluster heating to 523K in helium to give an even [Au,,(PPh,),,Cl,l which readily lost all distribution of osmium on the surfaces. The ligands on electron impact. The mode of work has shown that for a relatively demanding destruction of the nickel-platinum cluster process, such as ethane hydrogenolysis where a following AEM at higher beam intensities was multi-nuclear site is required, cluster catalysts then described and involves agglomeration to are more active than conventional catalysts and give uniform size spots of approximately 4oA their performance is remarkably reproducible. followed by loss of carbon monoxide with con- The specific catalytic activities of the supported comitant formation of a graphite skin around a osmium clusters for ethene hydrogenation and nickel-platinum alloy. for ethane hydrogenolysis were found to vary The session was completed by D. S. Cameron by more than two orders of magnitude depen- of the Johnson Matthey Technology Centre ding upon the support and this was interpreted who reported on new developments in platinum as an electronic effect resulting from direct alloy catalysts for fuel cells. Fuel cell power chemical interaction between support and generators are capable of converting chemical cluster. Structural evidence was presented for energy directly to electrical energy and this is such an interaction between 0s-Al in the effected by reaction of hydrogen with oxygen osmium-alumina system. over electrodes comprising platinum or The topic of cluster chemistry was continued platinum alloy catalysts. The units are com- by Professor A. Ceriotti of the University of pact, highly efficient, non-polluting and they Milan, Italy who described investigations into a require little maintenance. Their cost can be new high nuclearity anion [Ni Pt ,(CO),] ,-. a disadvantage and to minimise this, much This cluster structure was found to be a Pt,- effort has been expended on improving the effi- tetrahedron fully encapsulated in a nickel atom ciency, activity and durability of the carbon skin and confirmed the theory that such supported electrode catalysts. The use of cer- clusters mimic the structure found in small tain platinum alloys as opposed to bimetallic particles where, under certain condi- monometallic platinum as the active centres on tions, the phase with lower surface energy will the oxygen reduction electrode has resulted in envelop the other phase giving rise to the so- improved activity and also minimises sintering called “Cherry” model. This led to conclusions and consequently this increases catalyst similar to those of Professor Wells, and it was lifetimes. These improvements should result in proposed that metal clusters may be useful commercially available fuel cell systems in the models for metal crystallites, and that investiga- near future. tions of their properties should lead to an im- proved understanding of the role played by Clusters and Catalysis metal particles in heterogeneous catalysis. The Professor B. C. Gates from the University of topic of high nuclearity carbonyl clusters was Delaware discussed molecular organometallic also discussed by Professor B. T. Heaton of chemistry on surfaces with reference to the Liverpool University. In this talk, some of the reactivity of metal carbonyls of osmium, problems in characterising these species were ruthenium and rhodium on silica, magnesia and covered, in particular beam damage following alumina. The reactions of these organometallic examination by analytical electron microscopy compounds on surfaces are strikingly similar to (AEM). A large nickel-platinum cluster their solution chemistry. The main goal of this [Ni,,Pt,(CO),,HI ’- however suffered little research is to prepare catalytic sites with metal damage following a low beam intensity carbonyl clusters of controlled nuclearity. Reac- examination, and the structural and elemental tions of surface-bound metal carbonyls include

Platinum Metals Rev., 1987, 31, (4) 191 oxidative fragmentation, giving ensembles of has recently been identified and is the subject of mononuclear complexes, and reductive car- a patent application. bonylation of metal ions to generate surface- bound metal carbonyl clusters. Novel Organometallic and Professor M. Ichikawa of Hokkaido Univer- Co-ordination Chemistry sity reported on the problems of improving Some aspects of conjugated diene complexes selectivity in the Syngas reaction. Rhodium is including their co-ordination geometry and the well-known as a good catalyst for this reaction nature of the bonding were described by Pro- and it has been shown that the addition of tran- fessor A. Nakamura of Osaka University. Ac- sition metals such as titanium, zirconium and cording to a structural and theoretical analysis, manganese have a marked promotional effect the chemical properties of the diene complexes on CO + H, conversion. However, selec- of electron-rich platinum group metals contrast tivities alter dramatically on changing from for markedly with those of electron-deficient early instance, rhodium-molybdenum to rhodium- transition metals and of actinides. M. A. Ben- iron and a wide range of techniques including nett from the Australian National University EXAFS, Mossbauer and i.r. spectroscopy have reported research carried out into the chemistry been used to understand this behaviour. The of diplatinum complexes containing bridging rhodium-iron system was carefully investigated orthometallated aryl phosphine ligands. The since it was found that almost complete conver- synthesis of mono-oxo and di-oxo alkyl com- sion of carbon monoxide and hydrogen to plexes of osmium(V1) has been investigated by ethanol could be achieved under certain condi- Professor P. Shapley from the University of tions. Clusters such as IFe,Rh,(CO),,l~- give Illinois at Urbana Champaign. The reaction of good efficiencies for ethanol formation while trans-[Os(O)2 C1, 1 [ PPh, 1 , with R, Mg or the cluster [Pt , ,(CO) I - gives 100 per cent RMgX (where R = CHI, CH, SiMe, , conversion. For the platinum-rhodium-iron CH,C,H, orC,H, andX = Bror1)produces system, iron exists as both Fe(0) and Fe(II1). [Os(O)R,l in yields of approximately 50 per The iron seems to act as a breaker to divide cent depending on R. These 0x0 alkyl com- rhodium and platinum clusters, and provides plexes of osmium(V1) are remarkably stable to active bifunctional sites for acid-promoted CO ligand loss and substitution and only react insertion. B. D. Dombek talked about Union under extreme conditions. Carbide’s recent work on the Syngas conver- J. G. Jeffrey from Oxford University describ- sion. Useful products from this reaction include ed the synthesis and some chemistry of ethylene glycol, ethanol, higher alcohols and trifluoromethyl and difluorocarbene acetic acid. For this reaction ruthenium mononuclear complexes of osmium, ruthenium catalysts give two types of reaction: the produc- and rhodium. D. Milstein from E.I. du Pont de tion of methanol in non-basic solvents, and the Nemours & Co.gave a lecture entitled “Activa- formation of methanol, ethylene glycol and tion of 0-H and N-H Bonds by Ir(1)”. The other alcohols in the presence of basic pro- reaction of [IrL,lX with water, where moters. In an effort to produce a catalytic L = PMe,, proceeds readily even at low system with high selectivity for ethylene glycol temperatures to give the hydroxy complex (I) formation with high conversion rates, model (X = PF,-, Clk): compounds such as [HRu(CO),l- were in- vestigated in the presence of basic promoters OH PMe , such as iodide using spectroscopic and kinetic Me,P 1 PMe, I ‘If studies. The addition of rhodium complexes to Me,P - Ir - PMe the ruthenium catalyst substantially enhances I Me P’ 1 ‘PMe , the selectivity to ethylene glycol. A novel PMe H system for methanol homologation to ethanol

Platinum Metals Rev., 1987, 31, (4) 192 The mechanism of this oxidative addition was produces an ammine-bridged bi-iridium com- followed by 31PNMR which shows that the plex, with the release of C1, and ethene. trans OH species is formed first and then re- arranges to form the more thermodynamically The Fourth Conference stable cis complex. There is a very strong trans During the week the oral presentations gave effect which follows the order an insight into the current state of research on H>P>SH>OCH,>OH. The cis Ir-0-H angle the chemistry of the platinum group metals. is unusually small (91"). The reaction with Some of the most recent work was presented in methanol is different from that for water and the poster sessions which gave an opportunity the end product is the protonated complex for informal discussion. The continued high [IrH, L,l+ and formaldehyde, although the level of academic interest in this area may well products do depend on the initial concentration result in new opportunities for commercial of the reactants. The addition of ammonia to developments, and can be expected to lead to alkenes would be a useful reaction and thus further useful discussions at the fourth con- analogies with the above reactions have been ference in the series, which is to be held in sought. The reaction of ammonia with the com- Cambridge in 1990. B.A.M. plex [Ir(PEt,),(C,H,),ICl in THF at 25OC G.G.F., R.J.P.

Weldabilitv.' Test for Thin Iridium Sheet The use of iridium alloys doped with thorium successfully determine hot cracking suscep- to encapsulate the *3sPu0,radioactive heat tibility (4). sources used in thermoelectric generators Sheet specimens 50 mm in diameter and 0.63 which provide stable electrical power during mm thick are held in a test fixture which is outer planetary missions has been reported here designed to restrain them at the centre and the previously (I , 2). These iridium alloys possess periphery. Using a gas tungsten arc welding high melting point, good high temperature procedure under an inert atmosphere, two cir- strength, resistance to oxidation, and are com- cular concentric autogenous welds are made, patible with both the fuel and the surrounding then the disc is removed, turned over, replaced, insulation materials. The thorium serves as a and the procedure repeated. The first weld is 35 grain boundary strengthener, segregating to the mm in diameter and the other 22.3 mm; after grain boundaries and inhibiting intergranular inversion the welds are repeated in the same fracture. order. A container is formed by joining together two The first welding sequence produces a hemispherical cups and, because of the applica- microstructure which is susceptible to cracking tion, the equatorial weld is required to be total- and it also increases the stress in the specimen. ly reliable. An improved method of welding has If cracking does not occur, the disc is then in- been developed for this purpose (3). verted and the process repeated. After the se- Iridium alloys may suffer from hot cracking cond sequence, a lack of evidence of cracking in during welding, and experience indicates that either of the two circular welds is taken to in- even when approved specifications and welding dicate a weldable alloy. If the smaller but not procedures are followed variations in weld the larger diameter weld shows cracking the quality can occur. Clearly defective welds material is regarded as being susceptible to represent a waste of both materials and fabrica- cracking, but if both welds are cracked the tion costs. Thus if the weldability of a material material is classified as highly susceptible to can be established prior to or early in the cracking. manufacturing process, significant savings will result. Standard tests to determine the hot cracking References tendency of metals and alloys do exist, but I Platinum Metals Rev., 1979, 23, (I), 16 these are most suitable for sections thicker than 2 H. Inouye, Platinum Metals Rev., 1979, 23, (3), I00 2.5 mm. Now, however, workers at the Oak 3 Platinum Metals Rev., 1985, 29, (I), 11 Ridge National Laboratory have developed a 4 S. A. David and J. J. Woodhouse, Weld. J., 1987, simple modified circular plate test which will 66, (51, 129s

Platinum Metals Rev., 1987, 31, (4) 193 Exhaust Gas Pollution Control Catalysis and Automotive Pollution Control, Studies in Surface Science and Catalysis

EDITED BY A. CRUCQ AND A. FRENNET, Elsevier, Amsterdam, 1987, 520 pages, Dfl.255.00/$124.50

The application of platinum group metal primary catalytic elements, usually platinum catalysts to control the emission of potentially group metals either singly or in combination. harmful components in the exhaust gases of The functional roles of these components and gasoline fuelled cars is now well established, their interactions are very complex, but impor- particularly in the U.S.A. tant in establishing the desirable performance In western Europe a growing awareness of and durability of the catalyst. The process for the detrimental effects of pollution on the en- the manufacture of autocatalysts has to be vironment, fuelled by the acid rain debate, led developed with these factors firmly in view, and to new standards being proposed by the EEC a paper by B. J. Cooper, W. D. J. Evans and Commission in 1984. These were approved by B. Harrison of Johnson Matthey illustrated not the Ministers of the Environment the following only the intricacies arising from the interac- year. The importance of catalysis to the tions, but also the inevitable compromises re- achievement of the European standards was quired by the sometimes opposing recognised at the First International Sym- requirements caused by the highly dynamic posium on Catalysis and Automotive Pollution operating environment. Control (CAPOC I) held in Brussels during In the period since catalysts were first fitted September 1986. The proceedings of this sym- to production vehicles substantial im- posium have now been published in the series provements have been achieved both in the per- Studies in Surface Science and Catalysis, a formance of the catalysts and in our selection of the papers is reviewed here. understanding of the relationship between the Possible effects of pollutants on health and on catalyst parameters and the duties they have to the environment, the viewpoints of the perform. This in turn reflects extensive invest- automotive and petroleum refining industries, ment in research and development, and the and the complexities of the differing pollution general improvement in the understanding of control standards now established or proposed catalytic and surface science. Nevertheless the in various parts of the world are all examined in environment in which autocatalysts perform is the first section, which consists of seven papers one of the most complex that any catalyst ex- aimed at providing a general introduction to the periences and much remains to be done to problem of automotive exhaust gas pollution. unravel the interactions involved. E. Kober- After reviewing the regulatory and test pro- stein and G. Wannemacher, Degussa A.G., cedure situation in some detail, K. C. Taylor reported on kinetic measurements, infrared from the General Motors Corporation sum- surface investigations under reaction condi- marised the key features which enabled the use tions, and model calculations for some of the of catalytic converters to meet the requirements reactions involving carbon monoxide, nitric ox- of the U.S. emission control limits from 1975 ide and oxygen on noble metal catalysts in an model year vehicles, pointing out that it is the attempt to understand the factors determining only technology available for meeting the most the width of air:fuel ratio windows in three-way stringent standards. catalysts. At low temperatures they observed The principle components of modern exhaust poisoning of the noble metal surface by adsorb- emission control catalysts comprise [il a ed reactants. As the temperature increased ceramic based substrate, [iil a high surface area regions corresponding to chemical reaction con- washcoat, [iiil base metal additives acting as trol, washcoat pore diffusion control and boun- stabilisers and/or promoters, and [ivl the dary layer diffusion control could also be seen

Platinum Metals Rev., 1987, 31, (4), 194-195 194 within the temperature range of normal auto- hence the surface area) of the platinum in- catalyst operation. creases. Thus additives deliberately included The reaction of carbon monoxide with air and to, inter alia, stabilise the platinum dispersion with nitric oxide on platinum and rhodium, and inhibit its agglomeration-ceria is perhaps respectively, was also report by G. B. Fischer the most common-may result in poorer activi- (General Motors) and a team of academic and ty for the oxidation of saturated hydrocarbons industrial colleagues. Although the than with the “unstabilised” catalyst. measurements were made under ultra high vacuum, the authors show that from the data The Effect of produced they could accurately predict results at Sulphur Oxides and Lead higher pressures. W. C. Hecker and R. B. Structural sensitivity may, however, be put to Breneman of Brigham Young University con- good use in inhibiting another unwanted reac- clude that the low activation energyhigh activity tion, that is the oxidation of sulphur dioxide to of silica supported catalysts with high rhodium sulphur trioxide. In the U.S.A. the level of loadings, contrasted to the higher activation sulphur dioxide exhaust gas is typically energyflow activity observed with low rhodium zo ppm; the situation in Europe may be more loadings on the support, point to the reaction on variable depending on the sulphur content of this metal being structure sensitive. The com- the fuel in individual countries. Sulphur oxides plexity of this situation over rhodium is further play an interesting role in the exhaust gas situa- demonstrated by C. Z. Wan and J. C. Dettling tion. Gandhi and Shelef and also J. W. A. (Engelhard) who find that nitric oxide, carbon Sachtler, I. Onal and R. E. Marinangeli of monoxide and propane conversions over Allied-Signal presented evidence that the rhodium oxide are structure insensitive, but that presence of sulphur dioxide was capable of the same reactions over metal rhodates are struc- causing enhanced activity in the oxidation of ture sensitive. They relate this difference to the hydrocarbons on platinum. These authors also ease with which the rhodium species is reduced confirm that a further benefit of sulphur diox- to the metallic form. H. Shinjoh, H. Muraki and ide is to convert lead in the exhaust gas to lead Y. Fujitani of Toyota presented results on these sulphate when platinum is the catalyst, thus and some of the other possible reactions involv- making platinum the least sensitive of the nor- ing known components of exhaust gas streams mally used noble metals to poisoning by lead. on alumina supported platinum, palladium and As with sulphur, the levels of lead in “lead rhodium catalysts, using both static and cycling free” fuel in Europe is likely to vary quite wide- gas feedstreams to simulate engine exhaust gas ly for some years. M. A. Kilpin, A. Deakin and conditions. They conclude that differences in Gandhi (Ford) provided evidence from reaction kinetics between the two regimes are a laboratory, dynamometer and vehicle durabili- function of the adsorption of the reactants on the ty tests that, allowing for high temperature ex- catalyst surface. cursions, the maximum level of lead which The nature of structure sensitive reactions could be tolerated without ultimate deleterious was one of the subjects discussed in the paper effect on a three-way catalyst was in the region by H. S. Gandhi and M. Shelef of the Ford of 5 mgflitre of fuel. Motor Company. These authors point out that On the evidence of this symposium the com- certain reactions thought to be structure sen- plex catalysis which takes place in catalytic con- sitive, for example the oxidation of saturated verters is gradually being unravelled. Much hydrocarbons, do not proceed so readily on remains to be done and considerable effort is highly dispersed platinum catalysts, whereas being put into the subject by both academia and those reactions which are structure insensitive, industry. The organisers hope to hold CAPOC for example the oxidation of carbon monoxide, 11, a similar symposium, in two to three years proceed more readily as the dispersion (and time. D.E.W.

Platinum Metals Rev., 1987, 31, (4) 195 High Temperature Gas Thermometry and the Platinum Metals SOME ASPECTS OF NINETEENTH CENTURY DEVELOPMENTS By Ian E. Cottington The Johnson Matthey Group

The present day importance to both science and industry of resistance thermometers and thermocouples utilising the electrical and thermoelec- trical properties of the platinum metals is so well known that it has tend- ed to overshadow the use of these metals for crucial components in gas pyrometers. For perhaps one hundred and fifty years gas thermometers, mostly incorporating noble metal bulbs, have provided a most accurate means of determining high temperatures. This article gives a selective ac- count of early developments in temperature measurement involving gas thermometry and the platinum metals, one result of which was the adop- tion of the first internationally recognised standard scale of temperatures, in October 1887.

The origins of the platinum resistance ther- temperatures, particularly of enclosed furnaces, mometer and the work that led to it being used was by the use of cylindrical clay pieces devised in 1927 to define the temperature range - 190 by the English potter Josiah Wedgwood. These to 660OC on the first practical International made use of the fact that clay was believed to Temperature Scale has been admirably covered contract in proportion to the intensity of the in this journal previously (I). For a hundred heat to which it was subjected. Thus by years prior to this event the most accurate way measuring the permanent change in length of a of determining high temperatures was by standard clay piece removed from a furnace the means of gas thermometry. This relies upon the temperature to which it had been exposed could fact that for a suitable gas a quantitative rela- be determined. tionship exists between an increase in However, it was not easy to obtain clay pieces temperature of the gas, when expanding under of uniform composition, while an even greater either constant pressure or constant volume, disadvantage of this method was the discovery and the amount of heat required to produce that if such a piece were heated for a long time that temperature increase. Indeed the general at a low temperature the contraction produced acceptance of the platinum resistance ther- could be the same as that resulting from a mometer was due in part to the fact that it per- shorter time at a higher temperature. The pro- formed favourably when compared with a gas blem caused wide concern. In 1815 Samuel thermometer, which incorporated hydrogen in Parkes wrote: an iridium-platinum bulb. “The want of a good pyrometer is severely felt by In the early years of the nineteenth century the manufacturers of Birmingham. Cases daily oc- no satisfactory method of measuring high cur of losses sustained in consequence of their not temperatures existed, and as a result many knowing the precise degree of heat in high manufacturing processes could not be control- temperatures.”(2) led satisfactorily. For a long time the most The situation had not improved significantly popular means of monitoring high by 1821 when J. F. Daniell, introducing his

Platinum Metals Rev., 1987, 31, (4), 196-207 196 -- - --,_ -. . - 7--L/---: . 1, 7-I, -- 7-a- -.--__ ! , . ’i

. -,. . ---- .-. - .-..- - - - - . . . The illustration that accompanied the account of the Schmidt air pyrometer showed it to consist of the same fundamental parts as later gas thermometers. The platinum bulb was joined by a platinum tube “of as fine a bore as possible” to a water-fded vessel. When the bulb was placed in a heated furnace, the air expanded forcing water up the graduated tube. Once due allowance had been made for the temperature of the air prior to the experiment, the true expansion of the air could be used to indicate the relative temperature of the furnace new platinum expansion pyrometer, noted: body” and his pyrometer was based upon “It would be needless to preface much upon the moisture-free air contained in a vessel of utility of an instrument to measure the higher platinum. Whether or not such an apparatus degrees of heat, as nothing in science has been was ever made or used by Schmidt is not known more eagerly desired, and nothing, it is generally by this writer. However a treatise published in allowed, would tend more to the perfection of many of the arts.”(3) 1832 contained a description of his pyrometer, but commented: During this period many people had tried to find a solution to the problem, and not surpris- “It is so evidently a mere theoretical proposal, and is, besides, an expensive, clumsy, and pro- ingly platinum, the recently available high bably not very accurate mode of ascertaining high melting point metal, had featured in a number temperatures”.( 5) of the proposals. Indeed as early as 1805 None the less the book included a redrawn Nicholson’s Journal of Natural Philosophy, figure of the Schmidt pyrometer. Chemistry, and the Arts carried an account of a It seems to be generally accepted (6) that the platinum pyrometer said to be capable of in- first practical pyrometer utilising the expansion dicating the temperature of a furnace. This had of gases for the measurement of high been submitted by Mr. J. G. F. Schmidt of temperatures was due to James Prinsep, and Jassy, in Moldavia, and it included a drawing of described by him in the year 1827; but a foot- his apparatus (4). Having considered which note in his relevant paper tends to suggest that substances were “capable of regularly contrac- this may not have been the case. ting or expanding, without altering their Prinsep was a man of wide interests and great chemical properties, when subjected to elevated abilities; as a youth he had started to train as an temperatures” he concluded that “the per- architect but the close work damaged his manently elastic aeriform fluids appear to me to eyesight, so it was necessary for him to seek be superior in those respects to any other another profession. He attended the chemical

Platinum Metals Rev., 1987, 31, (4) 197 lectures of Dr. A. J. G. Marcet, at Guy’s pure silver, gold and platinum are determinate Hospital, and afterwards was entered as a fee and unchangeable these three points can form apprentice to Mr. Robert Bingley, the Assay the basis of a temperature scale, while in- Master of the Royal Mint, London from whom termediate points can be established from the he received a certificate of proficiency (7). In melting points of a series of binary alloys of dif- 1819 he was appointed as Assistant to Dr. H. ferent proportions. Between the melting points H. Wilson, Assay Master of the Calcutta Mint, of gold and platinum Prinsep proposed 100 and the following year he was nominated Assay degrees, each indicated by an alloy containing Master at the Benares Mint (Varanasi, India). an additional one per cent of platinum. He While he was resident at Benares he pursued found, however, that 45 per cent gold-55 per his- interest in science, to keep pace with cent platinum was the highest melting point developments in Europe, and it was during this alloy which could be fused in his forge. period that he prepared a paper on the measure- Before use the specimens were flattened and ment of high temperature which was com- individually identified, then to establish a municated to the Royal Society in London by relative temperature an appropriate selection of Dr. P. M. Roget, on 13 December 1827, and alloys was positioned where the temperature afterwards published in the Philosophical Tran- had to be determined. Any samples that sactions (8). became molten at that temperature were readily identified, and: Prinsep’s Pyrometric Alloys “the heat of any furnace may be expressed by the In the first part of this most interesting and alloy of least fusibility which it is capable of informative paper Prinsep explained his use of melting.” pyrometric alloys to indicate the relative inten- Although the melted alloys could easily be sity of different heats. As the melting points of reflattened for further use the silver and gold

James Prinsep 1799-1840 In addition to his ofFicial duties, Prinsep engaged in a wide range of pursuits. Having skilfully amended the plans for the new mint to be built at Benares he was subsequently involved in a number of major pubkc works. In contrast to this, he is also credited with making an assay balance capable of measuring to an ac- curacy of three thousand parts of a grain. Despite such technical contributions, Prinsep is remembered largely for his literary works and for his studies of the antiquities of India, especially numismatics and the deciphering of inscriptions carv- ed in rock and on pillars Reproduced by permrrian of the British Library

Platinum Metals Rev., 1987, 31, (4) 198 alloys lost weight during long exposure to heat, pyrometric alloys, its usefulness was limited by but Prinsrp observed that “the platina alloys the relatively low melting point of the gold. are very durable”. By themselves these alloys could not give ab- Pouillet’s Platinum Bulb solute temperature values, but with them Thermometer Prinsep was able to indicate relative heats. In- Prinsep was followed by several other deed, the use of such alloys for pyrometry con- workers all using thermometers based upon the tinued into the twentieth century (9). expansion of air at constant pressure, but none made any significant improvement to Prinsep’s The “Golden Bulb” Thermometer apparatus until 1836 when Professor Claude- Having explained his method of determining Servais-Mathias Pouillet ( I 790- I 868) reported the relative heat of his furnace Prinsep went on to the AcadCmie Royale des Sciences his to describe his determination of the melting research on the measurement of high point of pure silver using his gas thermometer. temperatures (10). At this time he was assistant Clearly he was most anxious to avoid any possibility of being charged with plagiarism for he noted that: “Dr. Ure has recommended an air thermometer made of platinum; but I cannot learn whether his plan has ever been carried into effect”. and this comment was qualifted by the footnote referred to previously which leaves open the possibility that Prinsep was not the first to use such a thermometer, for he recorded: “I find since, that the instruments have been made for sale; but I have seen no statements of ex- periments made with them.” His own thermometer used air as the gas, which was contained in a bulb of pure gold, nearly ten cubic inches in volume and weighing approximately 6500 grains troy. This was con- nected to a reservoir containing olive oil, and to a sensitive manometer so that the air could be maintained at a constant pressure; the absolute temperature being calculated from the weight of oil displaced as the air in the gold bulb ex- panded. Small bone ash cupels containing silver and silver-gold alloys were arranged in the furnace adjacent to the bulb to monitor that the furnace The Pouillet gas thermometer was a had in fact melted the pure silver, but that the relatively simple instrument consisting of an temperature had been insufficient to melt any ovoid platinum vessel and a U-shaped com- munication tube which enabled the volume of the gold-containing alloys. Prinsep found the of air expelled from the vessel, by expan- average figure for the melting point of silver to sion, to be determined. In 1888 Carl Barus, be 1830°, which compared with 2~33~as deter- a respected authority on pyrometry, noted that “to Pouillet the form of constant mined by Daniell, and 4717~by Wedgwood. pressure manometer is due very nearly as Although Prinsep used his air thermometer to it is to be used in pyrometric work today” establish the melting point of many of his

Platinum Metals Rev., 1987, 31, (4) 199 professor of physics at the Faculty of Science in pioneering contributions to the metallurgy of Paris and also administrator of the Conser- the platinum metals have been noted here vatoire des Arts et Metiers, and many of his lec- previously (13), and L. J. Troost (1825-1911) tures were regarded as important surveys of the worked to determine a number of constant state of the various branches of physics and of temperatures. Wishing to use a heavier gas than recent developments in them. A key compo- air in their gas thermometer they chose iodine. nent of his air thermometer was an ovoid In addition they rejected the use of platinum for shaped bulb, with a capacity of ~OCC,made the containment vessel because it “is generally from a single piece of platinum. This bulb was considered as having the property of condens- soldered with gold to a platinum capillary tube, ing on its surface the gases with which it comes which in turn was joined by a silver tube to a in contact” (14) and instead they used a bulb of manometer. The use of a platinum bulb enabl- porcelain. With this they measured the boiling ed him to measure higher temperatures than points of cadmium and zinc which they found previously, including the melting point of gold; to be 860° and 1040°, respectively. However indeed he is credited with establishing gas ther- disagreements arose in 1863, when Pouillet’s mometry on a sound footing (9). work using air as the expanding gas in a In this paper Pouillet also put forward the platinum bulb was continued by Edmond Bec- idea of a “magnetic pyrometer”. This was a querel(1820-1891). Remembered for his work crude iron-platinum thermocouple, the on the platinum-palladium thermocouple first platinum wire being enclosed in an iron gun proposed by his father Antoine Cesar Bec- barrel which served as the second metal of the querel, Edmond concluded that cadmium boil- junction and also shielded the platinum from ed at 746.3O and zinc at 932O. These figures the action of the furnace gases. The story of this were not accepted by Deville and Troost who amazing instrument has been reported briefly set out to discover why Becquerel’s results were in this journal previously (11). In addition so different from the ones they had obtained. Pouillet made other contributions to pyrometry, one being his anticipation of the The Great Platinum Controversy method of temperature measurement through Deville and Troost undertook a series of gas determinations of the specific heat of platinum. diffusion experiments, initially using a This idea was subsequently developed by Jules homogeneous tube drawn from a well-worked Violle (1841- 1923)who used a gas thermometer ingot of platinum prepared by the traditional to determine the specific heat of platinum at a process of consolidating spongy platinum by number of temperatures up to 12moC, then ex- hammering. However they were later able to trapolating with this constant he determined repeat their experiments with a cast platinum the melting points of palladium and platinum to tube having a wall thickness of 2mm made by be 1500 and 1775-1779OC, respectively. George Matthey and sent to them “for the Over the following years advances in gas ther- benefit of science”, and the results were exactly mometry continued. During his classic resear- the same:- at high temperatures the platinum ches on heat, Henri Victor Regnault tube was porous to hydrogen. Apparently this (I 8 10- I 878) made a number of improvements problem had been avoided by Pouillet who had to the constant pressure gas thermometer, his “heated his apparatus in an iron muffle very studies establishing the validity of the idea (12) nearly closed” (15). Thus, in the opinion of and it is believed that the first constant volume Deville and Troost, platinum was quite un- gas thermometer was devised by Silbermann suitable for the construction of gas pyrometers and Jacquelin in 1853 (9). However gas ther- that were “to come into contact with the reduc- mometry was soon to suffer a serious setback. ing gases, or with the hydrogen of a furnace”. Over a number of years from about 1857 This was the first announcement of the Henri Sainte-Claire Deville, whose major permeability of hot platinum by hydrogen (I 6).

Platinum Metals Rev., 1987, 31, (4) 200 It is not at all surprising that George Matthey contributed a cast platinum tube for Deville’s investigation of the diffusion of hydrogen through platinum, because a “great bond of sym- pathy” existed between the two men. Although the British patent for the French process of melting platinum in a lime crucible had been assigned to Johnson Matthey in 1857, several years of co-operation between the two parties were required before the operation was suc- cessfully achieved in London. In fact, Deville was present in Hatton Garden during March 1862 when a huge ingot measuring twelve by eight by six inches, and weighing 100 kilogram- mes, was cast; it was this ingot that was displayed at the Second International Exhibition of Industry, in London

A bitter controversy developed between Bec- bulb are both important considerations. Ideally querel on the one hand and Deville and Troost the expansion of the gas should vary con- on the other. Both sides continued their tinuously and uniformly with temperature temperature measurements, and obtained change. Although no strictly “perfect gas” has results which they claimed supported their been found, hydrogen is very close to this, earlier figures, and it was to be many years while the accuracy obtained with nitrogen, before the situation was resolved. In time very which can be used over a greater temperature precise experiments showed that platinum was range, is “of the order of magnitude of a single quite impermeable to all gases other than degree” at IIOOOC (20). It has already been hydrogen (I 7) which, although frequently pre- noted that the bulb must be made from a sent in flames due to incomplete combustion, material which has a sufficiently high melting could be avoided, for example by electrical point, and it must be impermeable to gases resistance heating. Also it was established that under pressure. In addition its coefficient of ex- iodine vapour does not obey the gas laws of pansion must be both small relative to that of Mariotte (Boyle) and of Gay-Lussac, the vapour the gas and also accurately known at the density decreasing as the temperature increases temperatures which are to be determined, in (18), a property that makes it unsuitable for use order that the unavoidable changes in the as the expanding medium in a pyrometer. volume of the bulb which occur with changes in However, at the time the unfortunate result of temperature can be allowed for. this dispute was that platinum bulbs were The selection of porcelain by Deville and discredited and porcelain substituted, a Troost was unfortunate because it was found to “backward step which was not retrieved for be porous unless it had been glazed. Also such more than thirty years” (19). a glazed surface coating could be incomplete, as Clearly, in gas thermometry the choice of a well as being susceptible to cracking after suitable gas and an appropriate material for the heating to about 10ooOC.In addition porcelain

Plarinum Metals Rev., 1987, 31, (4) 20 1 In the Chappuis hydrogen thermometer the gas containment vessel, seen in the middle of this illustra- tion, consists of a platinum-iridium tube just over one metre long arranged horizontally. This is con- nected to the manometer, on the left, by a platinum capillary tube. The complexity of the manometer and the amount of ancillary equipment perhaps give an indication of the efforts that had to be made to upgrade earlier gas thermometers into an instrument that could measure temperatures with an ac- curacy that was internationally acceptable dissolves some gases, including water vapour, adopted as their standard the Centigrade scale which can then readily pass through the con- of the hydrogen thermometer at Sevres, the so- tainer wall, while inconsistent results may also called Chappuis hydrogen thermometer. The arise due to variations in the coefficient of ex- official text of the resolution was in French pansion of different samples. As has been men- (21); an English translation reads: tioned earlier, their choice of gas was also a “The International Committee on Weights and mistake. However, despite the misunderstan- Measures adopts as the standard thermometric scale ding that resulted from the investigations of for the international service of weights and measures, Deville and Troost, work on gas thermometry the Centigrade scale of the hydrogen thermometer, was later revived. having for fixed points the temperature of melting ice (oo)and that of the vapour of boiling distilled water ( 100~)under standard atmospheric pressure; the Chappuis’ Hydrogen hydrogen being taken at an initial pressure of I m of Thermometer mercury, that is to say at 1ocd760 = 1.3158 of the standard atmospheric pressure”. (22) Accepting the need for an international agree- ment on an accurate and reproducible The constant-volume thermometer employed temperature scale, the Cornit&International des included two essential parts, a bulb to contain Poids et Mesures met in Paris exactly one hun- the gas and a manometer to measure its dred years ago to consider the advantages and pressure. The former was a platinum-iridium disadvantages of the various devices then tube I. 10metres long with an outer diameter of available for the measurement of temperatures. 0.036 metres, the volume being 1.03899 litres Having done so, on the 15th October 1887 they at the temperature of melting ice. In use the

Platinum Metals Rev., 1987, 31, (4) 202 Pierre E. Chappuis 1855- 1916 Born in Bremblems near Morges, in Switzerland, Chappuis studied first at the University in Basel and later in Leipzig, where he received a doctorate for his work on the solidification of gases on glass surfaces. Afler his move to Paris in 1882 he at first did further work in the same field but it then fell to him to carry out the principal work of research on thermometry, work that was still in- complete some twenty years later when he return- ed to Basel, for family reasons. However he built and equipped a private laboratory in the garden of his house, and there continued his scientific in- vestigations. In addition he made his considerable experience available to the Swiss scientific com- munity, and accepted a seat on the board of the Swiss Office for Weights and Measures CouncJy of the Trustees of the Science Museum, London

temperature scales can be learnt from an ac- count of his life and work written in 1916by the then Director of the Bureau (24) and from two Swiss obituaries (25), all of which emphasise bulb was contained in a bath held at the the painstaking care and precision of his temperature that had to be determined, the measurements; while further details of the so- bulb being connected to the manometer by a called “normal hydrogen scale”, and of more platinum capillary tube with a diameter of up-to-date gas thermometry, are contained in a 0.7 mm. The apparatus is reproduced here, recent publication (26). from Chappuis’ principal publication on gas thermometry (23). The Measurement of Higher At the Bureau International des Poids et Temperatures Mesures thermometry was an essential interest, Work to improve the techniques of related to one of its original objectives, namely temperature measurement did not stop with the the comparison of national prototypes of length adoption of this standard scale in 1887;indeed with the international prototype. To enable the it was continued with great ingenuity as scien- temperature of the standard metre bars and the tists in several countries sought to overcome the coefficient of expansion of the platinum- limitations of the hydrogen thermometer, in iridium from which they were fabricated to be particular the restricted temperature range over measured, two very accurate mercury-in-glass which it could be used and the accuracy of the thermometers were supplied with each national results. The year 1887also saw the publication prototype metre, and it was therefore necessary of the first of four now famous, but then con- to establish a uniform temperature scale against troversial papers by H. L. Callendar in which which these could be compared. For almost two he described the essential requirements for decades Chappuis devoted himself to this most precise resistance thermometry (27); and over exacting task and the extent of his major con- the next four decades much notable work was tributions to thermodynamic and practical done on various means of determining high

Platinum Metals Rev., 1987, 31, (4) 203 temperatures, and again the platinum metals alloyed with the platinum and allow of its being had important contributions to make. properly worked-about 20 per cent” (30). The Brief mention has already been made of early bulb which had a volume of about 208 cc and thermocouples, which resulted from an obser- a wall thickness of 0.5 mm was made from three vation of Thomas Johann Seebeck (I 770- 183 I) pieces of sheet welded together and the seams that if one of the junctions of two dissimilar were “afterwards protected by a thick layer of metals was heated by the warmth of his hand platinum, melted and dropped on to the hot then an electric current was generated in the bulb-it then proved and has since remained circuit. Following work by the Becquerels, Pro- perfectly tight”. The capillary stem that served fessor P. G. Tait and especially Professor H. Le to connect the bulb to the manometer was also Chatelier and Carl Barus, and others, the pro- made of platinum-iridium. The first 10 cm had cedure of measuring the electromotive force an iridium content of 20 per cent, but for the generated when a junction of two dissimilar remainder of the length only 5 per cent was platinum metals or alloys was heated developed employed, this alloy being less brittle and into an effective practical means of determining therefore more convenient to use. Later, to temperature, and after calibration against a gas avoid any possibility of the vessel being thermometer such a thermocouple could be us- distorted at the high pressures involved, a bulb ed in an intermediary role to measure other with walls I mm thick-was made, the material temperatures. Indeed in 1927 the temperature being platinum-Io per cent iridium, and this scale between 660 and 1063OC was defined by proved to be as satisfactory as the first (31). means of a 10 per cent rhodium-platinum Despite many difficulties the researchers at against pure platinum thermocouple (28). the Reichsanstalt renewed their efforts to ex- At the Physikalisch-Technische Reichsanstalt tend the gas scale from 1150Oc towards in Charlottenburg, an institute devoted both to 16ooOC. In fact using a pure iridium bulb with theoretical research and to finding solutions to a capacity of only 50 cc, which had been made industrial problems, Professor Ludwig specially for the purpose by Dr. W. C. Holborn (1860-1926) and his colleagues, who Heraeus, who took a great personal interest in included Wilhelm Wien and the American their high temperature research, Holborn and physicist Arthur Louis Day, pursued with his co-workers made several determinations of vigour the investigation of gas thermometry. temperatures as high as 168ooC, a magnificent For temperatures up to 550°C they employed a achievement for 1906 (32). borosilicate glass bulb and used hydrogen as the expanding gas, but to extend the range up to Work in the United States I IOOOCthey initially tried porcelain bulbs glaz- Work on gas thermometry and the measure- ed inside and out, and filled with either ment of high temperatures was not confined to hydrogen or atmospheric nitrogen. Later they Europe. In order to be able to study the condi- changed to platinum for the bulb material and tions of mineral and rock formation with employed nitrogen as the expanding gas, which greater accuracy than previously possible, Carl of course could not diffuse through the con- Barus of the U.S. Geological Survey undertook tainer wall (29). Their use of electrical a comprehensive investigation of high resistance heating overcame any possibility of temperature measurement (33). A literature contamination or diffusion by furnace gases, survey of previous work probably helped him and also increased the uniformity of the to appreciate the crucial importance of a temperature around the bulb. uniform temperature distribution around the As platinum was found to be too soft for this thermometer bulb, which he was able to purpose the famous firm of Heraeus, in Hanau, achieve by enclosing the bulb in an iron muffle made a bulb from a platinum-iridium alloy that was revolved rapidly inside a gas fired fur- which “contained as much iridium as could be nace. Thus every part of the bulb was protected

Platinum Metals Rev., 1987, 31, (4) 204 Arthur Louis Day 1869-1960 After receiving his doctorate in 1894, Day remain- ed at Yale as an Instructor in physics until he mov- ed to Charlottenburg in 1897. In the same year that he returned to the U.S.A. he married Helene, the daughter of Fricdrich Kohlrausch-who was President of the Physikalisch-Technische Reiehsanstalt between 1895 and 1905. While Director of the Geophysica! Laboratory, Day made extensive studies of lavas and volcanic gases in Hawaii, and Californian geysers and hotsprings; he also played a prominent part in establishing and advancing seismological investigations, particularly in California. In addition to his academic activities he was appointed a Vice President of the Corning Glass Works in 1919. Many honours were bestow- ed upon him including, in 1941, the Wollaston Medal of the Geological Society Councry of rhc Gmcgrc lnrrirutron of Washington

from direct exposure to any temperature ir- regularity in the furnace. This elaborate arrangement meant that ther- mocouples had to be used as intermediaries to After being exhibited in 19w at the Congres compare unknown temperatures with the gas Internationale de Physique in Paris, a thermometer, and for this reason Barus made platinum-10 per cent iridium bulb made by Dr. an extensive study of thermocouples, as a result Heraeus was loaned to the American in- of which he selected limbs of pure platinum and vestigators who used it in an initial attempt to 90 platinum-Io iridium for his work. eliminate or substantially reduce the errors that In 1892 Barus published his final memoir on had previously occurred in gas thermometry gas thermometry and thermoelements, and measurements (35). The instrument was turned his attention to other matters when he generally similar to that at the Reichsanstalt but moved to the U.S.Weather Bureau. However the entire furnace was enclosed in a gas tight some time later, in 19Arthur Day was recall- container, so that the gas containment bulb ed from Charlottenburg to the U.S. Geological could be filled with nitrogen and also surround- Survey to equip a laboratory where the methods ed by nitrogen at the same pressure. Thus there of physics and physical chemistry could be ap- was no tendency for gas to diffuse through the plied to the study of minerals, and when the walls of the bulb, or for the bulb to deform. new Geophysical Laboratory provided by the However when the gas containment bulb was Carnegie Institution of Washington was com- made from iridium, or an alloy containing even pleted in I907 he was appointed the first Direc- small amounts of iridium, a problem arose tor, and set out to establish petrology as a when a noble metal thermocouple, which had quantitative science. Indeed his own researches been standardised against the gas thermometer, were largely responsible for perfecting the was used for the actual temperature determina- methods of high temperature measurement and tion. Above about 9m°C the limbs of the ther- standardising the thermometric scale to cover mocouple became contaminated by vapour the whole range of mineral formation (34). from the iridium, thus changing the electrical

Platinum Metals Rev., 1987, 31, (4) 205 characteristics of the junction which then in- employed to compare temperatures with the gas dicated erroneous temperatures. thermometer, and their use has become To avoid this contamination U.S. workers widespread for scientific and industrial applica- later used an alloy of platinum-20 per cent tions. This part of the contribution of the rhodium. Although less rigid than platinum- platinum metals to temperature measurement is iridium at temperatures above IOOO~C,the already well known (39). platinum-rhodium bulb performed entirely Some of the investigations mentioned here satisfactorily up to I 550°C provided equal were carried out during the first ten years of pressure was maintained inside and outside (36). this century, and are therefore outside the stated period of this review. This work is in- Making the Standard Scale cluded because of the major role played by the Available platinum group metals, and because it was a It may be apparent from this review that gas logical sequence to the late nineteenth century thermometers are cumbersome and compli- work. cated precision instruments, and belong in the Gas thermometry is still an accepted method standards laboratory rather than in the factory. of relating absolute measurements of Indeed at many stages during their develop- temperature to thermodynamics, in accordance ment it must have seemed that the early with the definition of the unit of ther- criticism of Schmidt’s pyrometer was correct. modynamic temperature, the kelvin (40). Addi- Nevertheless the genuine limitations of gas tionally, in anticipation of a future need for an thermometers have not always been appre- updating of the International Practical ciated. In the early part of this century “a well- Temperature Scale a number of standards in- known engineer” asked Day what the cost of a stitutes are currently undertaking work which dozen gas thermometers would be. Day was may be relevant to such a revision (41).In the obliged to answer that he: last century when Holborn and Day were engaged in their investigations of gas ther- “knew of but one in this country, and this one had cost us upward of four thousand dollars to mometry at the Reichsanstalt they were date and might cost even more before we had hindered by the fact that few studies had been finished with it” (37). made of the expansion of materials at high However once it was accepted that gas ther- temperatures, and the results were not very ac- mometers could provide an accurate standard it curate. They therefore devised an improved was then possible to use them to calibrate other method of determining the expansion of intermediary devices which, being more prac- materials, and used it to study some platinum tical, fulfilled the needs identified in the early metals and alloys (42). It is therefore interesting nineteenth century by Parkes, Daniel1 and to note that a recent paper from the National others. Initially the Chappuis hydrogen ther- Bureau of Standards at Gaithersburg has mometer was made more generally available described a technique for the accurate measure- when it was used to calibrate a series of very ment of linear thermal expansions over the accurate mercury in verre dur thermometers temperature range -27 to 5s°C, and deter- made by Tonnelot, of Paris in the late I~OOS,a minations of the thermal expansion of platinum number of which are still preserved (38). Later and two platinum-rhodium alloys; this work other precision mercury-in-glass thermometers being carried out in support of the National made by Baudin, about 1900, were also Bureau of Standards Gas Thermometry Pro- calibrated in this way. At times these high- gram (43). precision mercury-in-glass thermometers were Thus the platinum metals continue to designated “primary standards”, but of course contribute to the usefulness of gas thermometry this was a misnomer. Later, platinum ther- for the most accurate determination of mocouples and resistance thermometers were temperature.

Platinum Metals Rev., 1987, 31, (4) 2 06 Acknowledgements as from “A History of Platinum and its Allied Metals” by D. McDonald and L. B. Hunt. Grateful The author has gained much information from thanks are due to Dr. J. A. Chaldecott of the Science three standard texts on the measurement of high Museum, London and to Dr. T. J. Quinn of the temperatures, these being “Bulletin No. 54, U.S. Bureau International des Poids et Mesures, Sevres for Geological Survey” by C. Barus, “The Measurement reading this manuscript and suggesting additions to of High Temperatures” by G. K. Burgess and H. Le the text, and to Mr. P. G. Smyrk for translating Chatelier, and “High Temperature Gas Ther- Chappuis’ obituaries. Thanks are due also to the mometry” by A. L. Day and R. B. Sosman, as well archivists who have contributed information.

References

I L. B. Hunt, Platinum Metals Rev., 1980, 24, (3), 24 Ch.-l?d. Guillaume, “Pierre Chappuis et le 104; see also R. Price, 1959, 3, (3), 78 Dkveloppement moderne de la Thermomktrie”, 2 S. Parkes, “Chemical Essays”, Baldwin, Cradock Extrait de la Revue Gnkrale des Sciences, Avril and Joy, London, 1815, p. 376 1916, 0. Doin et Fils, Editeurs, Paris 3 J. F. Daniell, Quart. J. Sci., 1821, XI, 309 25 A. Hagenbach, Verh. Naturforsch. Ges. Basel, 4 J. G. F. Schmidt, J. Nar. Phil., Chem. &Arts 1916, XXVII, 86-92; H. Zickendraht, Verh. (Nicholson), 1805, XI, 141 Schweiz. Naiurforsch. Ges., 1917, 1-7 26 T. J. “Temperatures”, Academic Press, 5 Thermometer and Pyrometer, in “Library of Quinn, Useful Knowledge, Natural Philosophy” Baldwin London, 1983 and Cradock, London, 1832, p. 31 27 H. L. Callendar, “On the Practical Measurement 6 For example, see A. L. Day and R. B. Sosman, ofTemperature”, Phil. Trans., 1887, 178, 160, as “High Temperature Gas Thermometry”, quoted in E. F. Mueller, “Precision Resistance Carnegie Inst. Washington, Washington D.C., Thermometry” in “Temperature Its Measure- 1911, P. 4 ment and Control in Science and Industry”, 7 H. T. Prinsep, “Memoir of the Author”, in Reinhold, New York, 1941, p. 162 “Essays on Indian Antiquities, Historic, 28 Op. cit., (Ref. 22), p. 118 Numismatic, and Palaeographic”, by the late 29 L. Holborn and A. L. Day, “On the Gas Ther- James Prinsep, ed. Edward Thomas, London, mometer at High Temperatures,” Am. J. Sci., John Murray, 1858, Vol. I, pp. i-xvi 1899, 4th Series, 8, (49, 165 8 J. Prinsep, Phil. Trans., 1828, 118, 79 30 Op. cit., (Ref. 29), p. 186 9 Op. cit., (Ref. 6), p. 5 31 Op. cit., (Ref. 17), p. 69 10 C. S. M. Pouillet, Comptes rendus, 1836, 3, 782 32 Op. cit., (Ref. 6), p. 12 I I L. B. Hunt, Platinum Metals Rev., 1964,8, (I),23 33 C. Barus, Bull. U.S. Geological Suruey, 1889, 54 12 R. C. Mackenzie, Thermochim. Acta, 1984, 73, 34 C. E. T., Proc. Geol. SOC.,(London), 1959-60, (3), 290 (1582), 130-132 13 J. C. Chaston, Platinum Metals Rev., 1981, 25, 35 Op. cit., (Ref. 6), p. 15 (3), 121; D. McDonald, 1958, 2, (2), 55; B. 36 Op. cit., (Ref. 6), p. 50 Swindells, 1975, 19, (3), 110 14 H. St.-C. Deville and L. J. Troost, Phil. Mag., 37 Op. cit., (Ref. zo), 258 1863, 26, 4, 336 38 J. A. Chaldecott, “Temperature Measurement & 15 Op. cit., (Ref. IS), 339 Control”, Science Museum, London, 1976, 2nd 16 W. W. Randall, Am. Chem. J., 1897, 19, 682 Edn., (II), p. 15, item 43 17 G. K. Burgess and H. Le Chatelier, “The 39 D. McDonald and L. B. Hunt, “A History of Measurement of High Temperatures”, 3rd Edn., Platinum and its Allied Metals”, Johnson Mat- 1912, Wiley, New York, p. 54 they, London, 1982 18 Op. cit., (Ref. 17), p. 85 40 “Le Systeme International d’Unites (SI)”, 5th 19 Op. cit., (Ref. 6), p. 6 Edn., (French and English texts), 1985, BIPM, p. I 06 20 A. L. Day, Metall. Chem. Eng., 1910,8, (5), 257 41 P. P. M. Steur and M. Durieux, “Constant- 21 Comite Intern. Poids et Mesures, Proces-Verbaux Volume Gas Thermometry between 4K and des SCances de 1887, 1888, 85 rooK”, Metrologia, 1986, 23, (I), I 22 J. A. Hall, The International Temperature Scale, in “Temperature Its Measurement and Control in 42 L. Holborn and A. L. Day, “On the Expansion Science and Industry”, Vol. 2, ed. H. C. Wolfe, of Certain Metals at High Temperatures”, Am. 3. IYI, Reinhold, New York, 1955, p. 115 Sci., Fourth Series, 11, (65), 374 23 P. Chappuis, “Etudes sur le thermometre a gaz et 43 R. E. Edsinger, M. L. Reillyand J. F. Schooley, comparaison des thermometres a mercure avec le “Thermal Expansion of Platinum and Rhodium- thermom2tre a gaz”, Trav. Mem. Bur. Int. Pods Platinum Alloys”, J. Res. Natl. Bur. Stand., Mes., 1888, VI 1986, 91, (6), 333

Platinum Metals Rev., 1987, 31, (4) 207 ABSTRACTS of current literature on the platinum metals and their alloys PROPERTIES Correlation of the Concentration Dependences of the Characteristics of In- Effect of Evolution of Gases by High terdiffusion and Heat Resistance of Temperature UHV Treatment of Rh, Pt, Platinum Metals Alloys and Nb on the Formation of Highly Active B. S. DRILENOK, C. M. KUZNETSOV and E. I. RITVIN, Surface Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., 1987, S. NISHIYAMA, K. YOSHIOKA, S. TSURUYA and M. MASAI, (2), 88-92 Vide, 1987, 42, (2361, 47-49 Studies were made of the coefficients of interdiffusion The UHV treatment of Rh metal powder ar;d D, and the values of the activation energies in the in- H,PtC1,.6HZO powder and Nb(V) compounds is terdiffusion process were calculated for platinum reported. The H PtCl .6H ,0 decomposed to alloys. The increased Rh concen_tration in Pt-Rh metallic Pt. Gases evolved during Rh treatment con- alloys resulted in a decrease in the D coefficient from sisted mostly of N,O. For the Pt compound the gases ~.~o-"to2.10-"cm'/s. In Pd-Rh alloys, an in- evolved were mainly H,O and HCI. XRD powder Lrease in Rh concentration resulted in a decrease of patterns were taken of the Rh and metallic Pt after D coefficient from 3.10-"' to 6.1o-~~cm'/~In the UHV treatment, and results for the H,-D, exchange Rh concentration range of 30-70at.Yo the D coeffi- reaction show low activation energies and indicate cient stays constant at 4.5 . ~o-"cm~/s. that the Pt and Rh surfaces were active for H, molecular dissociation. Study of the Surface Composition and Catalytic Properties of the System Synthesis and Study of Binary Actinoid Zr Pd-H and Lanthanoid Compounds. IX. Ther- E. N. ANISOCHKINA, V. V. LUNIN, P. A. ZHDAN, G. D. mal Decomposition of Intermetallides CHUKIN and I. I. SKARZOV, Kinet. Katal., 1987, 28, Pt,Sm, Pt,Gd and Pt,Am (2), 427-430 M. A. RYABININ, V. hi. RADCHENKO, A. G. SESEZNEV, L. The mechanism of the formation of the active surface S. LEBEDEVA, V. D. SHUSHAKOV and V. YA. VASIL'EV, system Zr, Pd-H was studied spectroscopically. The Radiokhirniya, 1987, 19, (3), 276-279 results showed that the presence of Pdo on the surface Studies of the thermal decomposition of in- of the catalyst was due to the catalytic activity of the termetallides Pt,Sm, Pt,Gd and Pt,Am in vacuum initial Zr ,PdH ,., during hydrocarbon conversion. showed that they had high thermal stability in The increase in catalytic activity and selectivity of vacuum below the melting temperatures, but were Zr PdH, after oxidation-reduction treatment is quickly split up in liquid solutions. The high melting associated with Pd segregation in the near surface temperatures of the intermetallides studied makes it layer. The H dissolved in the crystal lattice of difficult to obtain pure lanthanoid and actinoid Zr,PdH, was found to affect the formation of the metals from intermetallides by thermal decomposi- structure and composition of the surfaces. tion methods. Phase Equilibria in the Ternary System Intergranular Embrittlement of Pt-Rh Cu-Ni-Ru at 770K Alloys I. E. YANSON, M. v. RAEVSKAYA and A. L. TATARKINA, YU. P. DENISOV, A. S. DRACHINSKII, YU. N. Vestn. Mosk. Univ., Ser. II. Khim., 1987, 28, (2), IVASHCHENKO, A. V. KRAINIKOV, A. V. PRONIN, N. I. 195-197 TIMOFEEV and S. A. FIRSTOV, Fiz. Met. Metalloved., Phase equilibria in the ternary system Cu-Ni-Ru were 1987, 63, (3), 604-609 studied by microstructural and X-ray analaysis, and Studies of the effect of aggressive media on the com- by measuring hardness and microhardness of the position and structure of surface embrittled alloys at 77oK. The isothermal section adjoining Cu- 13-18at.Yo Pt-Rh alloys were performed in molten Ni showed a wide layer of solid solution u, which glass at 14m0C. Continuous tempering resulted in became narrower with increased Cu content. In view brittle intergranular disintegration. Selective dissolu- of the absence of visible dissolution of Cu in Ru solid tion of Pt occurred along the grain boundaries due to solution, Ru base phase E was practically unobserved electrochemical reduction. Corrosion results showed in the ternary system and was badly attached to the 2-3 times lower Pt content on grain boundaries in Ru-Ni side up to 7at.%Ni. The biggest part of the relation to Rh, while grain boundaries became enrich- isothermal section in the Cu-Ni-Ru system was taken ed by O,, H,, Al, Si and Mg. The depth of the layer up by binary phase section a + E. A special feature of of the chemical heterogeneity depended on the degree this section appears to be penetration of a dome of im- of proceeding of the reaction and is estimated to be miscibility of complexes on the Cu-Ruside in the cen- several tenths of intermetallic spacing. tre of concentrations, up to 45at.%Ni.

Platinum Metals Rev., 1987, 31, (4), 208-214 208 CHEMICAL COMPOUNDS Synthetic, Electrochemical, Optical, and Conductivity Studies of Coordination A General Synthetic Route for Platinum Polymers of Iron, Ruthenium and Cluster Compounds Containing Carbonyl Osmium Octa-ethylporphyrin and Tertiary Phosphine Ligands and a J. P. COLLMAN, J. T. MCDEVITT, C. R. LEIDNER, G. T. Study of Their Reactions with Un- YEE, J. B. TORRANCE and w. A. LITTLE, 3. Am. Chem. saturated Inorganic Molecules SOC.,1987, 109, (Is), 4606-4614 D. G. EVANS, M. F. HALLAM, D. M. P. MINGOS and R. The synthesis and characterisation of a series of w. M. WARDLE, 3. Chem. soc., Dalton Trans., 1987, ligand-bridged metalloporphyrin polymers (8), 1889-1895 [M(OEP)L-L)],, where M=Ru, Os, Fe, L-L= The reduction of cis-[PtCI,(CO) (PR,)] where R is a pyrazines, 4,4 I -bipyridine, I ,4-diazabicyclo[z.2.2. I variety of alkyl or aryl groups, by Zn dust or by Na octane, are reported. The polymers are highly tetrahydroborate under a CO atmosphere is an effi- conductive when partially oxidised; their conduc- cient high yield method for the formation of tri-, tivity depends on the doping, the nature of the central tetra-, and penta-nuclear clusters. The method gives transition metal and the bridging ligand. superior yields, greater convenience and has more generality than other methods. ELECTROCHEMISTRY Platinocyclobutane Chemistry: Platina- Electrochemistry at Pt Band Electrodes cyclobutanes from Bicyclo[X.1 .Ol Hydro- of Width Approaching Molecular Dimen- carbons sions. Breakdown of Transport Equations E. J. PARSONS and P. w. JENNINGS, 3. Am. Chem. soc., at Very Small Electrodes 1987, 109, (131, 3973-3977 R. B. MORRIS,D. J. FRANTA and H. s. WHITE, 3. Phys. A method for the preparation, isolation and Chem., 1987, (131, 3559-3564 characterisation of platinacyclobutane complexes 91, from substrates such as bicyclo[X.~.ol alkanes and Pt and Au band electrodes, o.g-Icm long and alkenes (X=4, 6) is presented. In the absence of 20-sooi wide were constructed by evaporation strongly co-ordinating solvents the 8 membered ring techniques and their electrochemical behaviours complex rearranges to a hydrocarbon containing observed. The qualitative behaviour of these elec- I-methylcyclooctene, the exocyclic methylene trodes in voltammetric experiments with ferrocene in derivative, and cyclononene. Finally the acetonitrile and ferrocyanide in water was similar to platinacyclobutane from bicyclo[6.1.olnonane re- that of larger microelectrodes. arranges to methylidynylcyclooctane via an initial u- Ohmic Resistance of Polypyrrole- hydride transfer mechanism. Modified Electrodes with Incorporated Pt Particles Complexes of Iridium and Platinum Con- taining 5-Coordinated Phosphorus F. T. A. VORK, L. J. J. JANSSEN and E. BARENDRECHT, Electrochim. Acta, 1987, 32, (8), 1187-1190 A. J. BLAKE, R. W. COCKMAN, E. A. V. EBSWORTH, S. G. The ohmic resistance of polypyrrole modified elec- D. HENDERSON, J. H. HOLLOWAY, N. J. PILKINGTON trodes was studied as a function of the potential by and D. H. RANKIN, Phosphorus sulfur, 1987, 30, w. the a.c. impedance method. When the potential was (I-z), 143-146 decreased from -0.2 to -0.3V the ohmic resistance Complex Ir(CO)CI,(PEt 1) ,(P' F,) has been prepared showed a sharp increase. The electrodeposition of Pt in high yield from XeF, and particles in the fdm did not change the resistance at Ir(CO)CI,(PEt,),(P'F,) and characterised by high potentials but decreased the rise in ohmic various techniques. Related species Ir(C0)BrH resistance at low potentials. This decrease depends on (PEt 3) ,(PI F, H,) and PtCI-(PEt ,),(PI F,) which the current density used for the deposition. were also formed by reactions of XeF, are reported. Oxygen Evolution Reaction on Thermally Half-Sandwich Chiral Ruthenium Com- Treated Iridium Oxide Films plexes M. WKOVIC, 3. Appl. Electrochem., 1987, 17, (4), G. CONSIGLIO and F. MORANDINI, Chem. Rev., 1987, 737-745 87, (4, 761-778 The properties of electrochemically grown and ther- A summary of studies of the stereochemical course of mally treated oxide fdms on Ir were examined by selected metallorganic reactions, and the cyclic voltammetry and potentiostatic polarisation at diastereomeric equilibria of compounds containing 0, evolution potentials in o.gmol/dm' H,SO,. The prochiral ligands is presented for reactions using half- oxide was grown by square wave pulses from -0.25 sandwich chiral Ru complexes. Among reactions to + 1.z5V S.C.E., which is much faster than poten- studied are alkylations, hydrido complex formation, tiodynamic activation at the same frequency. The ac- halide ligand substitution reactions and acetonitrile tivated electrode, with low corrosion resistance complex substitution; olefm and alkylidenecar- during 0, evolution, was then stabilised by heat bene complexes are discussed (125 Refs.) treatment. Optimal conditions are at 200-300°C.

Platinum Metals Rev., 1987, 31, (4) 209 The Oxidation of Chloride Ions and Photoassisted Hydrogen Generation: Pt Bromide Ions on Ruthenium Dioxide and CdS Supported on Separate Particles Electrodes A. SOBCZYNSKI, A. J. BARD, A. CAMPION, M. A. FOX, T. J. A. HARRISON and s. D. HERMIJANTO, 3. Electroanal. MALLOUK, S. E. WEBBER and J. M. WHITE, 3. PhYS. Chem. Interfacial Electrochem., 1987, 225, ( I/z), Chem., 1987, 91,(I& 3316-3320 159-1 75 A comparison between the catalytic properties of The oxidation of solutions containing chloride ions at platinised TiO,, ZnO, SnO, and WO, all on SiO, RuO,/TiO, electrodes was studied using steady mixed CdS/SiO, was performed for visible light current-potential and impedance-potential photoassisted HI production from methanol-water measurements as a function of the chloride ion con- solutions. Activity is higher for separately supported centration. At chloride ion concentrations >o. IM, a particles than for samples prepared by depositing the 40 mV Tafel slope was observed at low potentials active materials on the SO, particles. which increased at the higher potentials. At the lower chloride concentration of o.xM, where the 0, evolu- Photohydrogenation of Acetylenes in tion reaction is significant, the Tafel slope for the CI Water-Oil Two-Phase Systems: Applica- evolution reaction appears to increase to 7omV. tion of Novel Metal Colloids and Mechanistic Aspects of the Process D. MANDLER and I. WILLNER, 3. Phys. Chem., 1987, PHOTOCONVERSION 91, (ID, 3600-36’35 Photohydrogenation of phenylacetylene and Colloidal Platinum Catalyst Protected by methylphenylacetylene was accomplished in a water- Nonionic Monomeric and Polymerized cyclohexane system using Ru(bpy):+ as a photosen- Micelle for Photochemical Hydrogen sitiser, a charge relay, Na,EDTA as a sacrificial elec- Generation from Water tron donor in the photosystem, and a Pt or Pd colloid N. TOSHIMA, T. TAKAMASHI and H. HIRAI, Chem. Lett. stabilised in the organic phase as a hydrogenation 3Pn., 1987, (6), 1031-1034 catalyst. Pt is a superior catalyst to Pd in the genera- A colloidal dispersion of Pt protected by nonionic tion of metal-bound H atoms, but Pd is better than polymerised micelles was prepared by visible light ir- Pt in activating the substrate for hydrogenation. radiation followed by y-ray polymerisation of an Methanation and Photo-Methanation of aqueous solution of H,PtCI, and polyethylene glycol undecenoate. The colloidal Pt obtained showed Carbon Dioxide at Room Temperature higher catalytic activity in photochemical H, genera- and Atmospheric Pressure tion than when protected by the corresponding K. R. THAMPI, J. KIWI and M. CMTZEL, Nature, 1987, anionic polymerised micelle. 327, (6122), 506-508 The selective conversion of CO, to CH, at room Photocatalytic Production of Hydrogen temperature and atmospheric pressure has been per- from H2SSolutions over CdS/Pt Colloids formed using a catalyst of highly dispersed Ru/RuO, N. Z. MURADOV, M. I. RUSTAMOV, A. D. CUSEINOVA and loaded onto TiO,. If the support TiO, powder is Yu. V. BAZHUTIN, React. Kinet. catal. Lett., 1987, 33, photoexcited the reaction rate is sharply enhanced. A (a,279-283 turnover number of 28 with respect to the surface Ru Photocatalytic decomposition of H, S over Pt/CdS atoms was produced without a decline in activity. was studied on the catalysts prepared by CdS decom- position from CdSO, and Na,S solutions in the presence of Pt colloid obtained from H ,PtC1, reduc- ELECTRODEPOSITION AND tion by NaBH, in poly(viny1 alcohol). The CdS/Pt SURFACE COATING colloids sensitised the photodecomposition of H, S in- to H, and S in aqueous solutions under visible light. Layer-Selective Metallising of Paper by Electroless Plating Using Surfactant- Photocatalytic Reduction of NO; to Stabilized Palladium Sols Form NH, over Pt-TiO, Y. NAKAO, T. IMAI and K. KAERIYAMA, 3. POlp. sci. A. KUDO, K. DOMEN, K.-I. MARWA and T. ONISHI, c, 19879 25, (71, 293-295 Chem. Lett. Jpn., 1987, (6), 1019-1022 Layer-selective metallising of paper was carried out Photocatalytic reduction of NO to form NH, and by electroless plating using three types of surfactant- the simultaneous evolution of 0, were observed over stabilised Pd sols Pd-SC, Pd-SD and Pd-PN, in the 0.3wt.% Pt-TiO, in aqueous HNO, and Na nitrate presence of surfactants stearyltrimethylammonium solutions. The amounts of NH, and 0, produced in- choloride (SC), sodium dodecylbenzene sulphonate creased proportionally to the irradiation. The rate of (SD) and polyethylene glycol mono-p-nonylphenyl NH, formation increased with the increase of HNO , ether (PN), respectively. The surfactant-stabilised concentration. The reaction also occurred over Ti0 sols which were nearly neutral, could be applied to loaded with Rh and Pd. A small amount of H, electroless plating without an acceleration treatment (o.o5pmol/h) was evolved on the 0.3wt.% Pd-TiO,. thus outer or middle layers were metallised.

Platinum Metals Rev., 1987, 31, (4) 210 LABORATORY APPARATUS Pt-Sn/Alz0 Bimetallic Catalysts AND TECHNIQUE Prepared by Solvated Metal Atom Dispersion (SMAD) Synthesis and Antimony-Doped Stannic Oxide-Based Catalytic Performance Thick-Film Gas Sensors Y. -x. L1 and K. J. KLABUNDE, Langmuir, 1987, 3, (4), L. N. YANNOPOULOS, Sens. Actuators, 1987, 12, (I), 558-562 77-89 Conventional Pt/Al ,0 catalysts were doped with Sn The use of stannic oxide thick fims doped with Sb by using low-termperature organic solutions of Sn for detecting combustible gases in oxidising and atoms/clusters in THF or toluene (solvated metal water vapour containing atmospheres is described. atom dispersion, SMAD). The resultant SMAD Pt- The H, and CO responses were recorded. The Sn/Al 0 , catalysts showed unusual behaviour in HC reliability and accuracy of the gas response was en- conversions. Dehydrocyclisation activities were high sured by the addition of 5wt.% Pd catalyst and/or when hydrogenolysis (multiple C-C bond cleavages) other diluents, such as Mg oxide and Ni silicide. Data activities were low. Resistance to S poisoning was were obtained at 250-500°c. good. Alloy formation of Pt-Sn appears to be im- portant. Ultrahigh Vacuum Studies of Pd Metal/Insulator/SemiconductorDiode Hz On the Selectivity of Bimetallic Catalysts Sensors Based on Platinum and Nickel R. R. RYE and A. J. RICCO,J. Appl. Phys., 1987,62, KH. SH. TKHOANG, KH. D. LAN and I. FEL’TER, Kinet. (9, 1084-1092 Katal., 1987, 28, (I), 137-151 Steady state and kinetic results for diodes with clean Bimetallic Pt based catalysts Pt-M/Al,O, and Ni- Pd surfaces have been obtained for H, detection at M/Al,O, (M=Sn, Sb, Bi or Pb) containing 0.3wt.Oh H, pressures from 10- to 10-’ torr. This sensitivi- Pt and ratio M: Pt of 0.5-5 were studied during ty limit is at least seven orders of magnitude greater cyclohexane dehydrogenation at 1o0-700~C. The than that obtained for devices with contaminated sur- results showed the stabilising effect of the addition of faces. Analysis of the results for clean Pd surfaces in- Sn, Pb, Sb, Bi to Pt base catalysts at 45o-5oooC. The dicates that at least two binding states are required for effect of the second metal on the activity and selectivi- H at the Pd/SiO, interface. ty of the catalyst depends on the nature and character of “metal-metal” and “metal-support” interactions. The explanation of a “bimetallic” effect as the HETEROGENEOUS CATALYSIS dynamic factor in the reaction, being a regulator and stabiliser of the selectivity in the reaction, is given. A Pt/Alumina Catalyst Coated on Aluminum Thin Plate for Oxidation Reac- Activity, Selectivity and Stability of tion on Heat Transfer Surface Bimetallic Catalysts in n-Paraffin and T. HASHIOKA, S. KOSEDO, M. ITOH, K. YAMAMOTO, Cyclopentane Reforming H. KAMEYAMA and T. KABE, Chem. Lett. Jpn., 1987, 1. M. PARERA, c. A. QUERINI,1. N. BELTRAMINI and N. (6), 1067-1070 S. FIGOLI, Appl.Catal., 1987, 32, (I-z), 117-132 Pt/A 0, catalysts were prepared by treatment of Al Catalytic activity, selectivity and stability under com- foil by anodic oxidisation of the y- Al ,0 coating and mercial conditions for reforming nC,-nC I paraffins, by Pt impregnation which was performed in a 0.I Yo cyclopentane and methylcyclopentane were studied chloroplatinic acid solution whose pH was controlled for Pt/Al,O, (I) (30kg/cm2),Pt-Re-S/Al,O, (2) and by addition of NH,OH. Prepared catalysts showed Pt-Ge/Al,O, (3)(15kg/cm’). For n-paraffin transfor- high activity during the oxidation of acetone. mation the order of activity was (1)>(2)>(3); (I) is most active for hydrocracking, (2) for aromatisation Low-Concentration Supported Precious and (3) for isomerisation. (I) has a minimum in coke Metal Catalysts Prepared by Thermal formation and deactivation with n-heptane as feed, Transport but on (2) and (3) coke formation and deactivation in- crease from with increase in paraffin length. Y. -F. YU-YAO and 1. T. KUMMER, 3. Catal., 1987,106, n-C, (I), 313-317 Promotion of Platinum-Based Catalysts The thermal transport of metal from a sheet of Pt, for Methanol Synthesis from syngas Pd, or Rh onto an Al,O, support surface was per- formed by heating both together in air, to prepare P. MERIAUDEAU, K. ALBANO and C. NACCACHE, J. catalysts. The catalytic activity of the Al,O, powder Chem. soC.3 FaradaY T~u.I, 19879 83, (7)> was ;hen evaluatedby CO oxidation. The meial con- 2113-2118 centration was very low and highly dispersed. The ef- Addition of Mo compounds to SiO, -promoted Pt fects of support additives, GO,, temperature and catalysts resulted in an increase in their activity for preparation methods on the catalytic activities were methanol formation. The Mo oxide promotion was assessed. GO, ereatlv enhances the transfer from the found to partly cover the Pt surface. The respective Pt and Rh sheets to ;he support surface. roles of and Mo are discussed.

Platinum Metals Rev., 1987, 31, (4) 211 Hydroconversion and Diffusion of n- Methanol from Synthesis Gas over Iron- Heptane on Mordenite Catalysts Rich Iron-Iridium on Silica Catalysts A. K. ABOUL-CHEIT, M. F. MENOUFY, A. K. EL-MORSI and D. C. KONINGSBERGER, C. P. J. H. BORGMANS, A. M. 1. S. M. ABDEL-HAMID, zeolites, 1987, 7, (4), 353-359 VAN ELDEREN, B. J. KIP and 1. W. NIEMANTSVERDRIET, Hydroconversion of n-heptane was carried out in a 3. Chem. SOC.,Chem. Commun., 1987,(12), 892-894 high-pressure continuous plug-flow reactor system over Under steady state conditions Fe-Ir/SiO, catalysts with Pt/HM, Re/HM, Pt-Re/HM and Pt-Th/HM catalysts Fe: Ir=o.I-5 produce methanol from C0+3H, at containing hydrogen mordenite (HM). PtIHM was 542k and q.oMPa, with selectivities of 75% and higher. most selective for n-heptane isomerisation, whereas Pt- Re/HM and Pt-ThiHM had comparable intrinsic Hydroprocessing of Shale Oil Using isomerisation activities and excellent centric Ruthenium-Based Catalysts hydrocracking selectivities. Pt-Th/HM gave the highest T. G. HARVEY, T. w. MATHESON, K. c. PRATT and M. i-C, : n-C, ratio. S. STANBOROUGH, Fuel, 1987, 66, (6), 766-770 Silica-Supported Bis(trialky1phosphine)- Retorted shale oils from the Rundle (Queensland) deposit were hydrotreated in both batch and continuous platinum Oxalates. Photogenerated modes. Two catalysts, a commercial Ni-Mo/Al,O, and Catalysts for Hydrosilation of Olefins a novel 3.3wt.%RuN zeolite catalyst, were used. The A. L. PRIGNANO and w. c. TROGLER, 3. Am. Chem. soc., new Ru catalyst displayed N removal and its 1987, 109, (12), 396-3595 hydrocracking abilities were far in excess of the com- A heterogeneous hydrosilation catalyst has been mercial system. prepared by linking a photoactive Pt(C,O,)L complex to SiO, using the functionalised ligand L=(OMe),Si(CH,),PEt,, and characterised. The HOMOGENEOUS CATALYSIS catalyst differs from hydrosilation catalysts in its sen- sitivity to O,, lack of an induction period and inhibi- Platinum Complex-Catalysed Carbonyla- tion by co-ordinating solvents or excess olefin. The tion of Acetylenic Compounds catalyst precursor is thermally stable up to 18oOc and Y. TSUJI, T. KONW and Y. WATANABE, 3. Mol. Caral., can be stored for months. 1987, 40, (3), 295-304 The carbonylation of acetylenic compounds is effec- Hydrogenation of Unsaturated Hydrocar- tively catalysed by homogeneous Pt catalysts bons in the Presence of Palladium Com- PtCl,(PPh,),, PtH(SnCI,)(PPh,), and Pt(PPh,), and plexes Fixed on Polymeric Support Sn(I1) (or Sn(1V)) chloride in alcoholic media. Dur- L. I. GVINTER, V. M. ICNATOV, L. N. SUVOROVA and V. ing the carbonylation of propargyl alcohol, z. SHARF, Nejiekhimiya, 1987, 27, (3), 348-351 ethyl-2-methylene-3-hydroxypropanoatewas obtained in 68% yield at IOOOC under 8okg/cm2 of initial CO New metallocomplex Pd catalysts of Na ,PdCl 1, pressure. 3-Butyn-1-01 was selectively cyclocar- PdCl I (PPh ,) , and PdCl , fued on polymeric supports were studied during hydrogenation of unsaturated bonylated to a-methylene-y-butyrolactone. hydrocarbons at 25OC and atmospheric pressure. The catalysts were highly active and stable during the reac- A Novel Palladium-Catalyzed Reductive tion and did not require additional activation by Cyclization NaBH, . Activity of the catalyst depended on the nature B. M. TROST and R. WALCHLI,~. Am. Chem. soc., 1987, and composition of the solution. In mixed solutions 109, (1 I), 3487-3488 of benzene-methanol, the reaction rate was higher than A novel chemoselective reductive cyclisation catalys- in pure benzene. ed by Pd is reported. The substrate was readily prepared from cyclohexanone and when treated with Heterogeneous Olefin Hydrogenation I equivalent of (tri-n-butylstannyl)diethylalane, Catalysis of Metal Cluster Compounds Con- romol% of Pd(o) catalyst and 4-6 equivalents of Ph ,P sisting of Rhodium-Boron Cluster Anion per I'd in THF, at room temperature, then 6o°C and and Rare Earth Cations finally at IWOC the desired cyclisation product was achieved, at 60% yield. K. SAITO, A. NAKAMURA, H. TAKEI and B. WANG, 3. catal., 1987, 106, (I), 292-294 The Direct Conversion of Synthesis Gas in- Hydrogenation catalysts with much increased activity to Ethylene Glycol Catalysed by and prolonged life have been made by H , absorption RhX(CO)L, =Anioni,c Ligand, onto single crystals of LnIRh,B,I, LnIRh,Bl and [X L = P(cycl0-C HI,) or PPr LnIRh,B,I, where Ln= lanthanoid elements in the 3'1 3 + state. The preparation of the crystals is described, Y. OHGOMORI, S. -I. YOSHIDA and Y. WATANABE, and it was found that they are unique in their poten- 3. Chem.Soc., Chem. Commun., 1987, (I I), 829-831 tial for activation by H, at ambient temperature and Higher catalytic activities for the direct conversion of atmospheric H, pressure. The crystals act under mild syngas into ethylene glycol have been found for conditions with substrate selectivity. RhX(CO)L, complexes.

Platinum Metals Rev., 1987, 31, (4) 212 Mechanism of Deactivation of Phosphine- The Selective Oxidation of Primary Modified Rhodium-Catalysed Hydrofor- Alcohols to Aldehydes by 0 Employing a mylation: A CIR-FTIR Study Trinuclear Ruthenium Carboxylate w. R. MOSER, c. J. PAPILE and s. 1. WEININGER, 3. Catalyst Mol. Catal., 1987, 41, (3), 293-302 c. BILGRIEN, s. DAVIS and R. s. DRAW, 3. Am. Chem. The deactivation mechanism for the hydroformyla- SOC.,1987, 109, (I2), 3786-3787 tion of I-hexene was studied by cylindrical internal Ru,O(O,CR),L:, (where R=CH, or C,H,, reflectance i.r. spectroscopy (CIR-FTIR) under L=H,O or PPh, and n=o or +I) was found to be autogenous conditions. The initial deactivation was an efficient catalyst for the selective oxidation of found to involve the conversion of the most active primary alcohols to aldehydes and of secondary catalytic intermediate, RhH(CO,)(PR,) to a less ac- alcohols to ketones by 0, under mild conditions. tive orange dimer [Rh(CO)(PR,),l, which was Primary alcohol, can be oxidised more rapidly than followed by the formation of a totally inactive secondary, but tertiary alcohols were unreactive. binuclear complex with a bridged phosphido ligand. A series of hydroformylation reactions was perform- ed, in which the triphenylphosphine ligands carried a FUEL CELLS variety of para-substituents on the phenyl rings. Sputtered Fuel Cell Electrodes Hydroformylation of Formaldehyde to M. F. WEBER, S. MAMICHE-AFARA, AM. J. DIGNAM, L. Give Glycolaldehyde with Halide- PATAKI and R. D. VENTER, 3. Electrochem. soc., 1987, Promoted Rh, (CO) ,* 134, (6), 1416-1419 M. MARCHIONNA and G. LONGONI, 3. Chem. SOC., H and 0 fuel cell electrodes were fabricated by sput- Chem. Commun., 1987, (14), 1097-1098 tering Pt onto wet-proofed porous C and Ni Hydroformylation of paraformaldehyde and 37% substrates. The H electrodes were diffusion limited at aqueous formaldehyde to give glycolaldehyde with 5-20mA/cmz, but the 0 electrodes performed to selectivity up to - 90% was carried out in acetone at SoomA/cmz at potentials above o.7VH,,,. Data in- 90-14ooC and 100-140 atm CO-H? using Rh, (CO) ,? dicate that at current densities >xoomA/cm’ the reac- promoted with halide as the catalyst precursor. tion was catalysed partly by the high surface area C. Chemo-Selectivity of Group-VIII Metal The Catalytic Activity of Tungsten Car- Catalysts in Hydrogenation of Noncon- bide Modified by Ion Implantation and jugated Enones Ion Beam Mixing J.-I. ISHIYAMA, S. MEDA, K. TAKAHASHI, Y. SENDA and G. K. WOLF, R. SPIEGEL and K. ZUCHOLL, NUCl. In- S. IMAIZUMI, Bull. Chem. SOC.Jpn., 1987, 60, (s), strum. Methods Phys. Res., 1987, Bxglso, (II), 1721-1726 1030-1033 The chemo-selectivity of Group VIII metal catalysts Ion implantation and ion beam mixing were used to was studied during hydrogenation of non-conjugated dope WC substrates with finely dispersed Pt in an at- enones at ambient temperature and atmospheric H, tempt to produce active catalysts for fuel cell elec- pressure. 0s showed the highest selectivity among trodes. The catalysts produced were tested for their the platinum metal catalysts for the reduction of the activity for the electrochemical H redox reaction and carbonyl bond in the hydrogenation of trialkylated the oxidation of formic acid and methanol. Results in- olefinic ketones. The hydrogenation of 4-methylene- dicate that the implanted substrate catalysts were and 4-ethylidenecyclohexanonewas accompanied by much more active than untreated ones, and above a the formation of diethyl acetals over Ru, Rh and Pd dose of ~o’~Pt+/cm’the activity even exceeds that of black catalysts in an ethanol solvent. smooth Pt metal. Ion beam mixing was less effective. Homogeneous Catalysis by Metal Preparation and Characterisation of Clusters. 2. Tetranuclear Osmium Com- Carbon-Based Fuel-Cell Electrodes with plexes as Catalyst Precursors in the Platinum-Group Bimetallic Catalysts Hydrogenation of Styrene K. V. RAMESHI, P. R. SARODE, S. VASULDEVAN and A. K. R. A. SANCHEZ-DELGAW, A. ANDRIOLLO, J. PUGA and SHUKLA, J. Electroanal. Chem. Interfacial Elec- G. MARTI”, Inorg. Chem., 1987, 26, (Iz), 1867-1870 trochem., 1987, 223, (1/2), 91-106 Styrene was efficiently hydrogenated by osmium Electrochemical activities for H, oxidation on porous complexes HjOs,(CO) i,(I), H,Os,(CO) ,,, C electrodes with platinum group bimetallic catalysts [H, Os, (CO) ,,(I)] - and [H,Os,(CO) 1 - in decalin Pt+ Ru, Pt+Pd and Pd+Ru in acid and alkali elec- solution at 14oOC and 800 torr of H,. The reaction trolytes were measured as a function of composition. rate is dependent on the structure of the cluster and Carbon electrodes containing 4wt.%Pt + 6wt.%Ru is first order with respect to styrene and hydrogen showed the maximum activity, which is also higher concentrations. However turnover frequency in- than that for the individual metal catalysts. This creases with decreasing cluster concentration. The catalyst was also active for the indirect oxidation of results are interpreted by cluster fragmentation. NH as well as for the reduction of 0,.

Platinum Meials Rev., 1987, 31, (4) 213 ELECTRICAL AND ELECTRONIC Characterization of Reactively Sputtered ENGINEERING Ruthenium Dioxide for Very Large Scale Integrated Metallization In Situ Examination of Segregation and L. KRUSIN-ELBAUM, M. WIlTMER and D. S. YEE, Appl. Wear Processes of Precious Metal Elec- Phys. Len., 1987, 50, (26), 1879-1881 trical Contact Alloys Reactively sputtered films of RuO, have been ex- L. E. POPE and D. E. PEEBLES, IEEE Trans. Com- amined for use in VLSI circuits. Sputtering yields ponents, Hybrids, Manuf: Technol., 1987, CHMT-10, stoichiometric RuO, in a large window of 0, 47-55 pressures and the films are reasonably low stressed in An UHV pin-on-plate device was assembled to the 10’ dyn/cm* range. The resistivity of as- measure simultaneously and continuously the friction deposited films is 4opQcm. The films are excellent coefficient and the electrical contact resistance of a Pd barriers against interdiffusion of Si and Al. based alloy pin sliding on a Au-based alloy plate, by scanning Auger microscopy. The wear process was of adhesive wear. Initially a prow formed on the pin and TEMPERATURE subsequently debris was transferred back and forth MEASUREMENT between pin and plate. Platinum Resistance Thermometers for Metallographic Research on Extruded Industrial Applications Copper/Palladium Composite Materials H. 1. A. KLAPPE, Tech. Mess., 1987, 54, (4, 130-140 D. STkKEL, K. MOLLER and H. CLAWS, Metall, 1987, The stability, precision and range of uses of commer- 419 (713 702-706 cially available Pt resistance thermometers are Using CuPd composite materials instead of Cu-Pd discussed. Such thermometers can measure alloys improves the performance of electrical contacts temperatures from -2ooOC to 85oOC. Thin film and reduces their costs. However, the formation of technology for manufacturing the thermometers has solid solutions at the CuPd interface during com- improved the reaction times and reduced the cost. posite production must be avoided. The best com- For example, thin films of resistance I~Qat o°C posite is made by indirect extrusion of a billet formed can be used in the car and the heating industries. by rolling together Cu and Pd strips. Mechanical pro- perties, methods of production, recrystallisations, Temperature Coefficients of Resistivity of electrical properties, crystal structure are studied. Rh-Fe Thin Films for Cryogenic Ther- 0s-Coated Cathode for Very High mometer Use Emission-Density Applications 0. TAMURA and H. SAKURAI, 3pn. 3. Appl. Phys., part 2. Lett., 1987, 26, L947-Lg50 A. SHIH, A. BERRY, C. R. K. MARRIAN and C. A. HAAS, IEEE Trans. Electron Devices, 1987, ED-34,(s), The temperature coefficients of electrical resistivity 1193-1200 were measured on Rh-Fe thin films sputter deposited 0s-coated cathodes were prepared by coating “B” onto sapphire substrates from a Rh-o.gat.%Fe target, type W dispenser cathodes by thermal decomposition at temperatures from 4.2K to room temperature, to estimate their thermodynamic sensitivity. The of Os(CO), onto cathodes held at 205OC using CVD. The coatings had good adhesion and rapid activation. temperature coefficients are close to those of high The activation process involves the formation of a purity well annealed Rh-o.gat.%Fe wires, although the resistivity is higher than that of the wires. The BaO surface layer and also the formation of an op- dilute Fe in the films is as effective as in wires. timum surface alloy of 50%oS-50%w.The cathodes had excellent emission capabilities and at 1085OC~a zero-field emission density near SoAlcm’ was obtain- ed. At 1o85OC~an emission level of 4o-5oA/cm2 for MEDICAL USES over looh of life is obtainable. The pulsed emission density and surface composition were monitored. Radiosensitizers Targeted to DNA Using Platinum. Synthesis, Characterisation, Effects of Surface Modification on n- and DNA Binding of cis-[PtCl,(NH,) CdTe Photoelectrochemical Solar Cells (Nitroimidazole)] K. C. MANDAL, S. BASU and D. N. BOSE, 3. Phys. Chem., N. FARRELL and K. A. SKOV, 3. Chem. soc., Chem. 1987, 91, (IS), 4011-4013 Commun., 1987, (13), 1043-1044 When Ru was used to modify large grain n-CdTe the The preparation and characterisation of cis- properties of the n-CdTe photoelectrochemical solar IPtCI,(NH,)(misonidazole)l and cis-[PtCI,(NH ,)- cells were improved. The dark I-V characteristic (metronidazo1e)l are reported. These complexes bind decreasedfor J, from8.6~10-*to 4.2~10-~A/cm’ to DNA and radiosensitise more efficiently than their and in ideality factor n from 2.12 to I. 16. Under AM1 analogues containing two nitroimidazole groups, and illumination V, increased from 0.52 to 0.78V the results confirm the possibility of targeting vs.S.C.E., J(short-circuit current density) increased radiosensitising ligands to DNA by complexation from 3.4 to ~.zmA/cm*. with Pt.

Platinum Metals Rev., 1987, 31, (4) 214 NEW PA TENTS METALS AND ALLOYS ELECTRODEPOSITION AND SURFACE COATINGS Metal Powder Production Aluminium Coated Carbon Fibres OCCIDENTAL RES. CORP. U.S.Patent 4,655,825 Metal and alloy powders and particulates, especially NIPPON OIL K.K. Japanese Publ. Appl. 6214,845 of Rh, Pt, Pd, Ag, Au and others, are produced by Pd complex compounds are deposited on the surface distilling Zn from an alloy of Zn with the required of C-fibres, which deposit metallic Pd on heating, metal($. The powders can be produced in very pure these are then covered with Al metal by contact with form and need no further size reduction. organic Al compounds, during or after heat treat- ment. A C-fibre reinforced Al composite is obtained having good adherence, high strength, and without CHEMICAL COMPOUNDS producing Al carbide. Palladium Complexes Platinum-Containing Polishing Agent CIBA GEIGY A.G. European Appl. 214,og7A SHINETSU CHEM. IND. K.K. A mixture containing one or more dibenzalacetone- Japanese Publ. Appl. 62110,178 Pd complexes and one or more olefinic compounds is A new solid silicone type polishing agent consists of useful for electroless metallisation of mouldings, self- an organosiloxane composition containing Pt or Pt supporting films, hardened products. compounds, a liquid diorganosiloxane, and an organic solvent. It is used for car polish; providing a Stable Organopolysiloxane Compositions transparent coated fim with good glaze, water GENERAL ELECTRIC CO. U.S.Patent 4,645,815 repellency and dirt repellency. Compositions containing a cyclic Pt phosphite com- plex catalyst, an olefmically unsaturated LABORATORY APPARATUS organopolysiloxane and an organo hydrogen polysiloxane, provide inhibitor-free, one-package AND TECHNIQUE compositions with superior shelf life. Platinum Sensing Elements HITACHI K.K. European Appl. 218,232A ELECTROCHEMISTRY An exothermic resistor has a coiled Pt wire, coated with an inorganic glass material. Two such resistive Photo-Electrolysis Apparatus sensing elements are included in a device located in R. GORWN U.S. Patent 4,650,554 an engine intake air by-pass duct, for air flow velocity A photo-electrolysis apparatus has a conductive and temperature measurements. porous barrier layer sandwiched between Electrochemical Sensor with Rhodium photovoltaic and catalyst layers. The apparatus is us- ed for solar production of H, and 0, from water, and Cathode has a layer of Ru oxide for 0, evolution, and a BECKMAN IND. CORP. World Patent Appl. 8712,461A transparent catalyst coating of Pt, Pd, Ir, Os, Rh, Ru An electrochemical sensor for a fluid sample has a or their alloys for H, evolution. cathode formed of a Rh disc fused in a glass sheath, an anode, and a selective membrane. The cathode has Platinum Cathode for Electrolysis high resistance to thermal shock and an extended life. MITSUBISHI HEAW IND. K.K. Japanese Publ. Appl. 6217,887 Gas Sensor A cathode consists of a Pt layer ion plated onto the NIPPON PIONIX K.K. Japanese Publ. Appl. 62122,062 surface of a cleaned Ni or Ni alloy substrate. It is A gas sensor is composed of a mixture of a Pd salt and suitable for use in the electrolysis of sea water. a cupric salt of an inorganic or organic acid, usually impregnated into a support. The gas sensor has ex- Ruthenium Complex Film for Water cellent sensitivity to harmful gases. Photoly sis RIKAGAKU KENKYUSHO Alkaloid Analysis Japanese Publ. Appl. 62156,588 SHIhlADZU SEISAKUSHO K.K. The surface of a visible range n-type semiconductor Japanese Publ. Appl. 62125,261 electrode is modified by coating with a complex A heated metal solid composed of Pt, Ir, Re or Mo, polymer fim containing tris(2, 2'-bipyridine)Ru(II) their oxides, or a mixture of these, is contacted with complex, or a Group VIII metal or its oxide. Simple separated alkaloid gases, and the ionisation current of photolysis of water to 0, and H, is possible by visible the decomposed gases is measured. Stable, quick and irradiation of the electrode, in electrolytic solution. accurate analysis can be achieved.

Platinum Metals Rev., 1987, 31, (4), 215-219 215 Protein or Nucleic Acid Detection Measuring Organic Impurities in Water KONISHIROKU PHOTO K.K. ELECTROCHEM. INST. Russian Patent 1,250,928 Japanese Publ. Appl. 62135,262 A dynamic potential method for the determination of Metal staining with Pt, Pd, Ir, Ag or Au is used to organic impurities in water involves using an elec- dye protein or nucleic acids in a carrier, after separa- trochemical cell containing a sensing Pt electrode fed tion by electrophoresis. The resulting metal nuclei with square and sawtooth pulses of controlled dura- are treated with an intensifier and a dye-forming com- tion. The method lowers the detection limit to 0.05 pound. In this way, proteins or nucleic acids are mgA which is less than other known methods. detected with high sensitivity by adding the simple operation of dye formation to metal staining. JOINING Gas Detecting Element NOHMI BOSAI KOGYO K.K. Brazing Alloy for Abrasive Tool Japanese Publ. Appl. 62/67,437 GENERAL ELECTRIC CO. European Appl. 213,300A A gas detecting element consists of a Pt and Pd An alloy of Pd, Cr, B and Ni is used for brazing an catalyst, a metal oxide semiconductor mainly con- abrasive compact support to a substrate. The brazed sisting of stannic oxide, an Sb compound as stabiliser, bond has high strength, heat resistance, reliability and a means of heating the semiconductor. The ele- and reproducibility. The implement is used as a drill- ment selectively detects gas such as silane with high ing or cutting tool, for oil exploration. response speed, exhibits high SIN ratio, and can detect low gas concentrations. Effective Bonding to Platinum Metals NIPPON ABIONICS K.K. Extensometer Strip with Platinum Alloy Japanese Publ. Appl. 62/22,878 Layer A metal workpiece of Pt, Pd, Rh, Os, Au, Ag or other DEGUSSA A.C. German Offen. 3,532,328 metals can be bonded to another metal or non-metal An extensometer strip has a resistance layer of a workpiece by base metal electrodeposition on the binary Pt alloy containing Ir or Ru, on an electrically metal body, expelling H2from the deposited layer, insulating carrier. It is used for measuring mechanical and coating both workpieces with an adhesive. This deformation by changes in electrical resistance of the is especially effective for Pd, and degradation of the alloy layer. An advantage is that the resistance layer adhesive is eliminated. contains no Pd. Pressure-Force Measurement Sensor HETEROGENEOUS CATALYSIS DEGUSSA A.G. German Offen. 3,532,333 Ruthenium Fischer-Tropsch Catalysts An electrical sensor has a circular elastic membrane with a circular array of extensometer strips, BRITISH PETROLEUM P.L.C. British Appl. 2,178,334A preferably made of a Pt-Ru alloy or a binary Ir alloy Fischer-Tropsch catalyst precursors are prepared by containing Pt, Ru, Re, Mo, W or Cr. The sensor is impregnating Ce02 with a non aqueous solution of a used for pressure and force measurement, and has ex- thermally decomposable Ru compound (other than a tremely low temperature sensitivity without needing carbonyl). After reductive activation, the catalysts, separate temperature sensors. optionally in combination with a zeolite, have high selectivity for production of gasoline range hydrocar- Ionic Activity Measuring Device bons from synthesis gas, especially at a temperature UNIVERSITY PATENTS INC. Canadian Patent 1,219,632 of z50-350°C and a pressure of 10-50 bar. A device for measuring ionic activity especially H ion Selective Diolefm Hydrogenation concentration, has an electrode of an amorphous ox- Catalyst ide of a platinum or rhenium group metal, preferably sputtered Ir oxide, and a means for measuring the PHILLIPS PETROLEUM CO. European Appl. 21 1,381A potential developed in use. The electrode has ex- A supported catalyst containing a Group VIII metal, cellent stability, low impedance, good response and such as Pt, and Pb, Sn and/or Ge, is used for the may be very small. selective hydrogenation of diolefin impurities in a hydrocarbon stream containing other unsaturated Heated Platinum Filament for Polymer hydrocarbons, which are left unchanged. Molecular Weight Determinations O.V. SIGOV Russian Parent 1,242,799 Alkane Dehydrogenation Catalyst Testing the characteristics of liquid media involves BRITISH PETROLEUM P.L.C. European Appl. 212,850A using an electrically heated Pt filament and measur- The catalyst preferably contains Pt, Ru, Ir, Rh or Pd ing the imbalance of a measuring bridge containing on a silicalite support, and is especially useful for sample and comparison cells. Using this method, dehydrogenation of 3 - 6C paraffins to the correspon- quicker thermophysical determination of polymer ding olefins. The catalyst has high activity and selec- mean molecular mass is achieved. tivity for dehydrogenation, and improved stability.

Platinum Metals Rev., 1987, 31, (4) 216 Noble Metal Absorbent for SO2 Removal Palladium Packaging Material INST. FRANCAIS DU PETROLE TORAY IND. INC. Japanese Publ. Appl. 611293,846 European Appl. 21 5,709A A packaging material consists of a base, a thin layer SO, is removed from gases by contact with an of catalytic Pd formed on it by vacuum deposition, Al ,0, based absorbent, containing one or more and a layer of a gas-selective permeable substance. It Group VIII noble metals, preferably Pt and/or Pd, can prevent modification of packaged articles, and is and MgO, in the presence of 0,. The absorbent is useful for foodstuffs, drugs, electric contacts and then contacted with an H,S containing gas. Group precision or measuring devices. A gas(H) capable of VIII noble metals catalyse SO, fixation by conversion reacting with an ambient harmful gas (0)is sealed in of MgSO, ,and reduction of MgSO, to MgO by H, S. the packaging, and when H and 0 reach the Pd they react to form H,O. Hydrogen Production from Methanol JOHNSON MATTHEY P.L.C. European Appl. 217,532A Ruthenium Catalyst for Hydrocarbon A reactor having a downstream supported catalyst of Production Cu with Pt and/or Pd, and an upstream catalyst of KAIHATSU GIJUTSU K.K. supported Cu, is used for H, production by catalytic Japanese Publ. Appl. 621 I ,783 oxidation of CH,OH with 0,.After initiation, oxida- A catalyst composition containing Ru, Mn oxide, an tion moves away from the Cu-Pt-Pd catalyst zone alkali metal, S, and a crystalline zeolite is used for which minimises catalyst loss and CO formation. The hydrocarbon production from a mixture of CO and Pt-Pd catalyst converts unreacted 0, to H,O. H, . A hydrocarbon usable as gasoline is produced in Hydride Storage Powder one stage from the synthesis gas, with high selec- tivity. MAX PLANCK GES. WISSENSCH. World Patent Appl. 87/2,o22A Tertiary Amine Production A hydride storage powder contains a hydrogena- KAO CORP. Japanese Publ. Appl. 62110,047 tion/dehydrogenation catalyst powder, preferably a A Pd or Pt catalyst supported on N,O, or Si0,- platinum group metal but especially Pd andlor its ox- Al ,0, is used in the preparation of tertiary amines, ides. The catalyst is in the form of a coated substrate, by reacting primary or secondary amines with for- preferably Pd, Pd/Al,O, andlor Pd-coated Cu. The maldehyde and H l. High purity tertiary amines are powder is used for H, storage, is easily produced, obtained in high yield, and the catalyst can be easily and is not contaminated/deactivated by air. recovered and used repeatedly. Palladium, Platinum Catalyst Activation Catalyst for Fluorobenzene Production NAT. AERO &! SPACE ADMIN. U.S. Patent Appl. 061874,320 ASAHI CHEMICAL IND. K.K. Japanese Publ. Appl. 62/19,541 Pd andlor on SnO, catalysts for recombining CO Pt Fluorobenzene can be prepared in higher yield than and 0, in a closed-cycle, high-energy pulsed laser, by any other process by dehydration of r-fluoro- can be activated simply and quickly by exposing to a cyclohexene over a supported platinum group metal reducing gas in an inert carrier, at a temperature catalyst, especially Pd, or Ru. The reaction can be above the operating temperature, followed by inert Pt carried out in the vapour or liquid phase. carrier alone, and cooling. Reactivation only requires the heating stage. Osmium Catalyst for Oxalic Acid Ruthenium Catalyst Pretreatment Preparation EXXON RES. & ENG. CO. U.S. Patent 4,647,592 IDEMITSU KOSAN K.K. Japanese Publ. Appl. 62/56,450 A Ru/TiO, catalyst useful for the production of hydrocarbons from synthesis gas is pretreated with a Oxalic acid is prepared by oxidation of propylene mixture of steamkarrier gas or steamM, at about with 0, over a supported OsO, or Os0,-Cu halide 2oo-550°C to produce larger Ru agglomerates. The catalyst. High yield and selectivity are obtained in a increase in Ru particle size moderates the catalytic ac- single step reaction, with the Cu halide-containing tivity and reduces the CH, selectivity, in a much catalyst giving superior results. shorter time than previously. Exhaust Catalyst with Separate Platinum Lead-Tolerant Catalyst for Exhaust Gas Group Metal Layers Purification TOYOTA JIWSHA K.K. ALLIED CORP. U.S. Patent 4,650,782 Japanese Publ. Appl. 62157,651 A Pb-tolerant catalytic composite comprises one of Ir, A monolith catalyst with high activity for exhaust gas Rh, Pd, Ag, Au or especially Pt deposited on an in- purification has three catalytic Al,O, layers: a lower organic refractory oxide support, with a protective layer of Pd with Nd or Sm, a middle layer of Rh with coating of TiO, to enhance the Pb tolerance. It is us- La, Y or Sc, and a top layer containing Pt and Ce. ed for treating automobile and other Pb-containing Separation of the platinum metals prevents alloy for- exhaust gases and can be used in the presence of SO,. mation, thus catalyst deterioration is avoided.

Platinum Metals Rev., 1987, 31, (4) 217 Absorbent for Waste Water Components Carbonate Ester Preparation MITSUBISHI CHEM. IND. K.K. BRITISH PETROLEUM P.L.C. Japanese Publ. Appl. 62179,289 Eumpean Appl. 220,863A Sulphides of Ru, Rh, Pd, Pt, Au, Ag or other com- A catalyst containing a platinum group metal and a pounds, are supported on a spherical or granular car- Cu compound is used in the preparation of a car- bonaceous mesophase material prepared from coal tar bonate ester from an alcohol and CO, in the presence pitch, naphtha tar pitch or resin. The product is used of a dihydrocarbyl peroxide. The ester is obtained in to absorb trace amounts of radioactive constituents in high yield under mild conditions. waste water, such as I, and as a catalyst for various reactions. Rhodium Dimerisation Catalyst SHELL OIL CO. U.S. Patent 5,638,084 NOx Removal from Flue Gas A dimerisation catalyst is prepared by reacting KRAFTWERK UNION A.G. German Offen. 3,534,845 chlorobis(ethylene)Rh(I) dimer with Ag tetra- A catalyst having one or more of Pt, Rh, CuO, COO fluoroborate in the presence of an olefin. It is used for or V,O, supported on SiO,, Al,O, and/or TiO,, is the dimerisation of alkyl acrylates or methacrylate, used for reduction of NOx in the flue gas stream of and the catalyst produces unbranched dimers with a steam generator fed with fossil fuel. Reaction is high selectivity. characterised by use of CO and/or H, as the reducing gas. The process is useful in power stations because Self Emulsifying Silicon Composition the CO and H, can be produced on site. SHINETSU CHEM. IND. K.K. Japanese Publ. Appl. 6217,438 Catalysts for Phenol Hydrogenation The composition consists of a Pt catalyst, methyl BAYER A.G. German Offen. 3,538,129 hydrodiene polysiloxane, an oxyalkylene compound, Supported Pd catalysts useful in the hydrogenation of an unsaturated hydrocarbon having a vinyl group, phenols to cyclohexanols are prepared from an inert and an antifoaming agent. This self-emulsifying Si support material, a Pd salt solution, and a base, in composition has improved high temperature and such a way that the base is retained after reduction. mechanical stability. The catalysts have high long-term stability. Palladium Catalyst for Cyclic Ketone Carboxylic Acid Ester Preparation Production BRITISH PETROLEUM P.L.C. AGENCY OF IND. SCI. TECH. Australian Appl. 86/62,013 Japanese Publ. Appl. 62/26,244 A Pd-Cu catalyst is used in the preparation of carbox- Cyclic ketones are prepared in the liquid phase from ylic acid esters, by reaction of an olefinic hydrocarbon cyclic olefins by oxidation with molecular 0, in the with a formate ester and a CO/O, mixture, in the presence of a catalyst consisting of a Pd compound presence of H,O and H+.This catalyst together and an organic base. Cyclic ketones can be simply with a source of aqueous acid allows the use of much prepared in high yields with high selectivity. milder conditions, without the corrosion and separa- tion problems of halide promoters. New Preparation of Aromatic Carboxylic Acids ASAHI CHEMICAL IND. K.K. HOMOGENEOUS CATALYSIS Japanese Pu bl. Appl. 62/53,9 5 5 Catalyst for Diester Preparation A catalyst having at least one platinum metal (preferably Pd and/or Rh) and at least one of Br or I, SHELL INT. RES. B.V. European Appl' 212,729A is used in the preparation of aromatic alkoxycar- A noble metal catalyst, Preferably pd Or a bamoyl carboxylic acids. This new preparation is sim- pound, is combined with a cupric salt and used for ple, gives high yield and selectivity by reaction of the reaction of a dihydrocarbyl peroxide, co and OP- aromatic amino carboxylic acids with alcohol and CO, tionally an alpha-ethylenically unsaturated Corn- and does not use phosgene. wund. This method of DreDaration of diesters of Hlkanedioic acids can be abatch, semi-continuous or continuous process. CHEMICAL TECHNOLOGY Rhodium Hydroformylation Catalyst Platinum Wires for Crystal Manufacture RUHRCHEMIE A.G. European Appl. 216,315A AKAD . WISSENSCHAFT D .D .R . Aldehydes are produced by the reaction of olefins East German Patent 240,821 with CO and H, in the presence of a catalyst contain- Two platinum wires are tensioned slightly above the ing Rh and the amine salt of a sulphonated or carbox- surface of a melt, and are used to form profded ylated triarylphosphine. Hydroformylation of the crystals - specially rectangular crystal bands - from oIefin occurs in high yield, and the method allows the liquid phase. This method creates a continuous separation of the catalyst for recycling. process over a long period, at reduced cost.

Platinum Metals Rev., 1987, 31, (4) 218 ELECTRICAL AND ELECTRONIC Platinum or Rhodium Layer for Gas ENGINEERING Turbine Blades BBC A.G. BROWN BOVERI CIE swiss Patent 660,200 Optical Fibre Fracture An intermediate layer of Pt or Rh acts as a diffusion TELEPHONE CABLES LTD. British 2,179,341A barrier between an Fe, Co or Ni superalloy base and A hot Pt or Ir metal wire, heated to >10ooOC is used its corrosion protection layer. Interdiffusion and to sever optical fibres and strip off plastic coatings building of brittle phases between the body and the from optical fibre ribbon. The advantage of this corrosion protection layer are prevented, thereby method is that fibres are severed cleanly in the same avoiding flaking. This is useful for turbine blades. transverse plane, to enable coupling to a second ribbon. MEDICAL USES Optical Fibre Protection Catalyst for Eye Surgery Material CAVI PIRELLI S.P.A. European Appl. 217,066A MOSC. EYE MICROSURGE British Appl. 2,179,667A An optical fibre telecommunication cable consists of at least one optical fibre embedded in a mixture of a A catalyst based on compounds of platinum group Pd or Pt catalyst and Mo trioxide, enclosed by a metals is used in the vulcanisation of a mixture of sheath. The mixture protects the fibre from degrada- siloxane derivatives. The fmal cured composition is tion by H2over its useful life. an elastic material of low density, good mechanical and high optical properties, and is biologically inert. Resistive Material for Semiconductor It is especially used in eye surgery as part of, or in Chip Housing support of, prosthetic crystalline lenses or lenticuli. MO VALVE co. ~m.World Patent Appl. 87/1,24oA New Complexes for Imaging Ru oxide may be used to coat the inner lid surface of a sealed housing for a semiconductor chip. It forms HARVARD COLLEGE European Appl. 213,945A a layer of resistive material having a permittivity New co-ordination complexes consist of lower alkyl similar to that of free space, and prevents perfor- isonitrile ligands and a radioactive isotope of Ru, Pt, mance being disturbed by reflection of microwave Re or others. The complexes are useful in imaging of energy from the housing lid. body tissues, giving high liver and lung clearance, and high contrast. Electrochromic Display Element ALPS ELECTRIC K.K. Anti-Tumour Platinum Compounds Japanese Pubi. Appl. 62/3o,r84 JOHNSON MAlTHEY P.L.C. European Appl. 222,522A Ag and/or Ru or 0s may be contained in a New anti-tumour Pt complex compounds are claimed polynuclear transition metal cyanide used to prepare with amino containing dioxolane groups, useful for an electrochromic substance, which is coated on the treating cancer in humans and animals. An in- display electrode of an electrochromic display ele- termediate based on an isopropylidene threitol com- ment. The technique enables a better variety of col- pound is also new. ours to be displayed, and an element with a rapid response is obtained. Biomedical Iridium Isotope Generator Gel Composition for Optical Joint U.S. DEFT. OF ENERGY U.S. Patent Appl. 061769,519 TOSHIBA SILICONE K.K. An Os-~g~Ar-~ymisotope generator comprises an Japanese Publ. Appl. 62/39,660 activated C adsorbent loaded with a compound con- A Pt, Pd or Rh catalyst with a polyorganosiloxane and taining 0s- 191, preferably K hexachloro-osmate(1V)). a siloxane, forms a gel composition which has ex- Physiologically compatible saline is used to elute cellent adhesion, and does not discolour or change at Ir-191m. The generator has good yield of Ir-191m, high temperature. It is used for electric or electronic low breakthrough of 0s-191 and is used for parts, especially for optical coupling pads, which biomedical applications. need optical transparency, and in the manufacture of human body models. Platinum Complexes for Inducing Cancer Regression Conductive Organic Material AMERICAN CYANAMID co. U.S. Patent 4,665,210 TORAY IND. INC. Japanese Publ. Appl. 62158,508 New Pt complexes with tricarboxylic acids are used A conductive organic material contains conductive in- for inducing the regression and/or palliation of organic particles preferably of Pt, Pd, Au, Ag or leukaemia and related cancers. The dose is preferably others, physically or chemically adsorbed on the sur- 1-50 mg/mz of body surface area. face of spherical particles made from an organic polymer. The material is reliable, and is used for making conductive paste, conductive adhesives and The New Patents abstracts have been prepared from pressure sensitive rubber. material published by Dement Publications Limited.

Platinum Metals Rev., 1987, 31, (4) 219 AUTHOR INDEX TO VOLUME 31

Puge Pug1. Pug1, fuge Abdel-Hamid, S. M. 212 Borgarello, E. I03 Craft, A. P. 147 Frennet, A. I94 Abe, T. 181 Borgmans, Crucq, A. I94 Friedrich, F. 104 Aboul-Gheit, A. K. 212 C. P. J. H. 212 Frindt, R. F. I46 Adachi, G.-Y. I46 Bose, D. N. 2 I4 Damjanovic, A. 102 Fujimoto, K. I06 AkhavanLeilabady,P. 150 Bournonville, J. P. 152 Das, D. 47 Fujishima, A. I49 Ako, C. T. 105 Boutonnet, M. I05 Datars, W. R. 147 Fujitani, Y. 44 Albano, K. 21 I Bown, M. 148 Daube, K. A. I48 Fujita, Y. I05 Ali, N. I47 Brenner, S. S. I36 Dauns, H. 151 Fukamichi, K. 43 Andriollo, A. 213 Brotzen, F. R. I46 David, S. A. I93 Ang, K. P. I04 Brown, D. B. I07 Davis, S. 213 Anisochkina, E. N. 208 Brown, J. M. I37 De Croot, D. G. 147 Galieva, S. G. 104 Gallagher, K. 107 Anson, F. C. I53 Bruce, M. I. I48 De Jonge, W. J. M. 146 P. Antler, M. 13 Brydson, R. D. 45 De Visser, A. 42. 146 Gallezot, P. 24 Galus, 2. 149 Antropov, V. P. I01 Budhani, R. C. 101 Deb, P. 104 Appelbaum, A. I07 Buffle, J. 103 Deem, M. L. I06 Gandhi, H. S. 42 Appleby, A. J. 43 Bunshah, R. F. 101 Degani, Y. I48 Garcia, N. 42 Arafawa, H. I52 Burch, R. 46 Den Broeder, F. J. A.146 GarciadelaBanda. J. F.45 Gasnikova, G. 101 Arajs, S. 101 Burger, J. P. I47 Denisov, Yu. P. 208 P. Arakawa, H. 46 Burke, L. D. I49 Dhar, H. P. 47 Gipson, S. L. 153 Aramata, A. I49 Burke, M. G. I36 Dignam, M. J. 213 Glaunsinger, W. S. 151 Arapa, P. E. 45 Burnett, J. 41 Diosady, I,. L. 45 Glinski, M. I06 Arimoto, H. 147 Butkova, E. I. 62 Disdier, J. 24. 44 Golas, J. I49 Goldberg, Y. Sh. 106 Arjavalingam, G. 144 Butochnikova, L. F. 105 Doi, Y. 152 Armgarth, M. 105, 150 Domen, K. 210 Gomez, J. 42 Arvia, A. J. 42 Donaldson, E. K. 2 Gonzalez, I. I02 P. Goodrich, G. 47 Asami, K. 101 Cameron, D. S. 173 Doran, S. L. I07 R. Gorton, L. 44 Asbury, D. A. 101 Campbell, C. T. 148 Dorofeyev, Yu. A. 101 Aspnes, D. E. I48 Campion, A. 44. 210 Douglas, K. D. I54 Gottesfeld, S. I48 Augustine, R. L. 45 Candy, J. P. I52 Doyle, M. 147 Gratzel, M. 2 10 Carlsen, P. H. J. 154 Draaisma, H. J. G. 146 Graff, J. L. I53 Cesarotti, E. I53 Drachinskii, A. S. 208 Graydon, N. F. 45 Greenwood, N. 148 Baba, K. 147 Chaldecott, J. A. 91 Drago, R. S. 213 N. Baba, R. I49 Chaloner, A. 43 Drilenok, 9. S. 208 Griessen, R. 147 P. Gross, M. E. I07 Badcock, G. C. 8 Chandrasekharaiah, Droguett, S. E. 45 Badilla-Ohlbaum, R. 45 M. S. 47 Dumesic, J. A. 45 Gulari, E. I06 Baiker, A. I06 Chang, C.-A. 101. 146 Durieux, M. I07 Gunasingham, H. 104 Guseinova, A. D. 210 Baker, R. T. K. 45 Chen, S.-Y. 151 Dust, M. 104 Bankston, C. P. 154 Cheryukanov, A. S. 104 Gvinter. L. 1. 212 Bar, G. 104 Chevalier, 9. I48 Ebel, M. F. 101 Barbier, J. 102 Chida, E. 104 Ebsworth, E. A. V. 209 Haas, G. A. 2 14 Bard, A. J. 44. 210 Chiesa, A. I53 Edsinger, R. E. I32 Haase, D. G. 47 Bardin, T. T. 101 Chikanari, K. I54 Ekimoto, T. 147 Hacker, M. P. I07 Barendrecht, E. 209 Chikyow, T. 42 El-Morsi, A. K. 212 Hageni, M. 104 Baris, H. I06 Chin, D.-T. I07 Emo, G. I03 Hagenmuller, P. I48 Barnard, C. F. J. 23 Chludzinski, J. J. 45 Enquist, F. I05 Hallam, M. F. 209 Baro, A. M. 42 Choi, S.-Y. 44 Enyo, M. 146, 149 Haller, G. L. 24 Barshad, Y. I06 Chopiin, A. 105 Esashi, M. 44 Halpern, J. I07 Basset, J. M. 102. 152 Chou, I.-M. 71 Etourneau, J. I48 Harada, A. I06 Basu, s. 214 Christner, L. G. 47 Evans, D. G. 209 Hards, G. A. I73 Bayuzick, R. J. 62 Chuang, K. T. 151 Harman, W. D. 148 Bazhutin, Yu. V. 210 Chukin, G. D. 208 Farahi, F. I50 Harriman, A. 45. 125 Beaupere, D. 46 Claus, H. 42, 214 Farrell, N. 214 Harris, I. R. I47 Becker, E. R. I62 Cleare, M. J. 23 Feenstra, R. 147 Harris, P. J. F. 44 Beltramini, J. N. 2 I I Cockman, R. W. 209 Fel’ter, I. 21 I Harris, R. I03 Berezkina, N. Yu. 104 Cole, T. I54 Fenoglio, R. J. 24 Harrison, 9. I73 Bernas, H. I46 Cole-Hamilton, D. J. 107 Ferretti, 0. I52 Harrison, J. A. 2 10 Berry, A. 214 Collins, T. J. I53 Ferrier, G. G. 186 Haruyama, T. 47 Berube, M. N. 152 Collman, J. P. 209 Figoli, N. S. 21 I Harvey, T. G. 2 12 Bhattacharya, R. S. 150 Colombo, L. I53 Firstov, S. A. 208 Hashimoto, H. I47 Bhattacharya, S. 153 Conrad, H. 42 Flanagan, T. B. I47 Hashimoto, K. 101 Bilgrien, C. 213 Consiglio, G. 209 Fontaine, X. L. R. I48 Hashioka, T. 211 Birss, V. I. I02 Corma, A. 45 Fontal, 9. I02 Hattori, T. 25 Blake, A. J. 209 Corti, C. W.71. 132. 185 Foulds, G. A. I 02 Hawk, R. I 03 Blomen, L. J. M. J. 63 Cottington, I. E. 23. 73, Fox, M. A. 44, 210 Hayashi, T. I53 Bond, G. C. 25. 46, 106 114. 123. 136. 144, 181. Franse, J. J. M. 42. I46 Haynes, R. D. I44 Boone, D. H. 104 193. 196 Franta, D. J. 209 Heller, A. I48

Platinum Metals Rev., 1987, 31, (4), 220-222 220 Page Puge Puge Pug0 Henderson, S. G. D. 209 Kazantsev, V. A. 101 Lundstrom, I. 105. 150 Miyauchi, E. I47 Hendriks, A. H. C. 47 Kennedy, J. D. 148 Lunin, V. V. 208 Moen, V. A. 146 Hermijanto, S. D. 210 Khokhar, A. R. 107 Lunstrom, 1. I50 Morandini, F. 209 Herrmann, J.-M. 24. 44 Kholopov, G. K. 104 Lyons, M. E. G. 149 Moriyama, Y. 46 Heyne, H. 104 Khoo, S. B. 104 Morris, R. B. 209 Hidai, M. 154 Kidani, Y. 47 Morrison, S. R. I46 Higuchi, T. I54 Kijenski, J. 106 Mabillon, G. 152 Morton, D. I07 Hirai, H. 152. 210 Kiji, J. 46 Machida, K.4. 146 Moser, W. R. 213 Hirai, H. F. 46 Kimura, H. M. 147 Macintyre, J. E. 73 Motkin, E. S. 44 HoRund, G. B. 101 Kimura, K. I52 MacKinnon, P. I48 Moyes, R. B. 46. 153 Hofmeister, W. H. 62 Kimura, S. 154 Maeda, A. I52 Miiller, K. 147. 214 Holloway, J. H. 209 Kip, B. J. 212 Maeda, S. 213 Mukaida, M. 43 Honda, K. I49 Kiso, Y. I53 Mague, J. T. 148 Muradov, N. Z. 210 Howard, P. D. I07 Kiwi, J. 210 Maidan, R. 103 Murahashi, S.4. 107 Howell, F. S. 43 Kizling, J. I05 Maire, G. I 05 Muraki, H. 44 Hsu, N. 45 Klabunde, K. J. 21 I Makino, Y. 151 Muroi, N. I03 Hu, Y. 106 Klappe, H. J. A. 214 Mallouk, T. 44, 210 Murrer, B. A. I86 Hukkanen, H. 44 Kobayashi, T. I47 Mamiche-Afara, S. 2 I3 Muto, T. I05 Hunt, L. B. 11, 32 Koda, Y. 43 Mandal, K. C. 2 I4 Hurd, T. J. 26 Kolawa, E. I54 Mandler, D. 210 Hutchings, G. J. 105 Komatsuzaki, S. 46 Marchionna, M. 213 Naccache, C. 21 I Hydes, P. C. 23 Komiyama, M. I52 Margitfalvi, J. 24 Nagano, S. 151 Hydes, P. C. S. 25 Kondo, T. 212 Marrian, C. R. K. 214 Nagao, H. 43 Hyer, G. N. 144 Kong, P. C. 102 Martin, G. 213 Nagy, Z. I02 Koningsberger, D. C. 2 I2 Maruya, K.4. 210 Naito, S. 103 Ignatov, V. M. 212 Konishi, H. 46 Maru, H. C. 47 Nakabayashi, S. 149 Ijdo, D. J. I48 Koon, N. C. 42 Marvel, C. S. I05 Nakajo, T. 46. 152 W. Nakamura, A. Imaizumi, S. 213 Kordesch, M. E. 42 Masai, M. 208 212 Imai, T. 210 Kosedo, S.. 211 Masel, R. I. 42 Nakamura, €3. I05 Inagaki, K. 47 Kostic, S. Z. 185 Massoui, M. 46 Nakao, Y. 210 Inoue, A. 147 Koszta, J. 46 Masumoto, T. I47 Naota, T. I07 Neuburg, H. J. Inui, T. 151 Kounaves, S. P. 103 Masumoto, Y. 147 45 Iovel, 1. G. Kotz, R. 43 Matheson, T. W. 212 Nicolet, M.-A. I54 106 Nidola, A. Irvine, D. J. 25 Koyasu, Y. I54 Matsuhira, S. 46, 152 I49 Niemantsverdriet Ishida, H. I03 Krafft, T. E. I53 Matsumoto, N. I03 Ishii, 0. Krainikov, A. V. 208 Matsumoto, Y. I03 J. W. 44, 212 I50 Nishihara, Y. Ishiyama, J.-I. 213 Krasil’nikov, A. N. 105 Matsuo, T. 44 43 Itaya, K. Krusin-Elbaum, L. 2 14 Matveev, A. G. 104 Nishiyama, S. 208 181 Notton, J. H. F. Itoh, M. 21 I Kudo, A. 210 McCabe, R. W. 45, 106 133 Nozaki, F. I52 Ivashchenko, Yu. N. 208 Kuji, T. I47 McCoy, B. J. 151 Iwahara, H. I02 Kumagai, N. 101 McDevitt, J. T. 209 Kummer, J. 21 I T. 44. McGill, I. R. 62, 74. 172 Ohdomari, I. 42 Kunimatsu, K. I49 McGrath, R. B. 8 Ohgomori, Y. 212 Jablonski, A. 101 Kunimori, K. I52 McKelvy, M. J. 151 Ohtaki, M. I52 Jackson, D. A. I50 Kunugi, T. I06 McLellan, R. B. 146 Okano, 46 Jackson, S. D. 46, 153 Kush, A. K. 47 T. Janssen, L. J. J. 209 Meas, Y. I02 Okazumi, F. 151 Kuznetsov, G. M. 208 Medzhinskii, V. L. 105 Jefferson, D. A. 45 Onishi, T. 210 Melo, V. 45 Jeffries-Nakamura, B. 154 F. Ono, K. 147 Memovski, A. 147 Orlewski, J. I02 Jenkins, J. W. I82 Lamy-Pitara, E. I02 Menoufy, M. F. 212 Jennings, P. W. 209 Orna, M. V. 41 Lan, Kh. D. 21 1 Menovsky, A. 42. 146 Jensen, W. B. 41 Osteryoung, J. I49 Laule, S. 103 Menshikov, A. Z. 101 Jen, S. U. 146 Otsuka, K. 43 Lebedeva, L. S. 208 Meriaudeau, P. 21 1 Ott, D. Jiwan, L. 45 Leclercq, C. 64 24 Michaels, A. S. 43 Ouchi. I54 Jonsson, G. 44 Leidner, C. R. 209 Y. Johnson, B. F. G. 102 Michel, J. B. 105 Lewis, J. I02 Mikhina, G. F. 47 Jones, G. A. 105 Likholobov, V. I82 Miller, D. 103 Paffett, M. Jones, J. D. C. 150 T. I48 Lin, Y.J. 24 Miller, M. K. 136 Pakkanen, T. T. Josel, H.-P. 149 44 Little, W. A. 209 Mills, A. I49 Joshi, B. M. 42 Patczewska, V. 101 Li, Q. 47 Millward, G. 45 Pan, E. T.4. Jung, H. J. 162 R. I54 Li, Y.-X. 21 I Minero, C. I03 Papile, C. J. 213 Logvinenko, S. P. 47 Mingos, D. M. P. 209 Parera, J. M. 21 I Kabayashi, K. I54 Longoni, G. 213 Mintsa-Eya, V. 105 Parlar, H. I49 Kabe, T. 21 I Lossew, w. w. I49 Miremadi, B. K. 146 Parsons, E. J. 209 Kadowaki, K. I46 Loveland, M. E. I54 Mitchell, P. J. 45. 106 Pataki, L. 213 Kaeriyama, K. 210 Luengo, M. A. M. 24 Miura, N. I50 Peebles, D. E. 214 Kakihana, K. 43 Luft, G. 45 Miyake, H. I52 Pelizzetti, E. I03 Kameyama, H. 21 I Lukefahr, H. 47 Miyake, N. I47 Perdriel, C. L. 42 Kamikubo, F. I I5 Lukevics, E. I06 Miyamoto, A. 151 Philpott, J. E. 63

Platinum Metals Rev., 1987, 31, (4) 22 1 Page Puge Puge Ptrge Piazza, S. I50 Sanchez-Delgado,R.A2 I3 Takahashi, K. 44,2 I3 Vork, F. T. A. 209 Pichat, P. 24. 44 Sano, K.4. 46. 152 Takahashi, S. I06 Vukovii., M. 209 Pilkington, N. J. 209 Santini, C. C. I02 Takamashi, T. 210 Pogrebiskii, D. M. 62 Sarode, P. R. 213 Takeda, K. 43 Wakabayashi, H. 147 Pollard, D. 63 Satoh, H. I I5 Takei, H. 212 Walchli, R. 212 Pope, L. E. 214 Satoh, S. I52 Tamura, H. 103 Wang, B. 212 Porter, J. D. 148 Sato, E. 104 Tamura, 0. 214 Wang, S.-H. 46. 213 Potapenko, L. A. 62 Sato, E.-I. I03 Tanaka, K. 103 Wardle, R. W. M. 209 Poteiko, P. A. 104 Sato, Y. I47 Tanaka, M. 102. 153 Ware, M. J. I24 Potter, R. J. 173. 186 Schira, R. I49 Tanaka, T. 103 Watanabe, Y. 212 Prati, L. 153 Schmidt, L. D. 25, 151 Tandon, J. L. I54 Watson, C. H. 47 Pratt, K. C. 212 Schoenmaker-Stolk, Tatarkina, A. L. 208 Webber, S. E. 44. 210 Prignano, A. L. 212 M. C. I52 Tatlock, G. J. 26 Webb, B. C. 107 Pronin, A. V. 208 Scholten, J. J. F. IS2 Taube, H. 148 Weber, M. F. 213 Pronko, J. G. 101 Schooley, J. F. 132 Tay, B. T. I04 Webster, D. E. 124. 194 Pszonicka, M. 101 Schuhmann, W. 149 Tazawa, T. 103 Weinberg, W. H. 151 Puga, J. 213 Schwartz, S. B. 151 Terada, A. 150 Weininger, S. J. 213 Puissant, L. J. 151 Schwarz, J. A. 24 Thackeray, J. W. 104 Weitkamp, J. 151 Punni, J. S. 26 Sears, W. M. I46 Thampi, K. R. 210 Wells, P. B. 25. 46, 153 Segmiiller, R. 101 Thatcher, D. R. P. 151 Wheeler, B. L. IS4 Senda, Y. 213 Thomas, J. M. 45 White, H. S. 209 Qiu, R.-Z. 47 Sermon, P. A. 24 Thompson, D. T. 12. 171 White, J. M. 44. 210 Quaiatti, R. J. 151 Serpone, N. I03 Thomson, A. I. 151 Whyman, R. 46. 153 Querini, C. A. 21 I Seseznev, A. G. 208 Thornton-Pett, M. 148 Wileman, R. C. J. 147 Quiroz, M. A. I02 Shankar, S. 104 Timofeev, N. 1. 208 Williams, G. I49 Shapley, P. A. I02 Tkhoang, Kh.Sh. 21 I Williams, R. M. 154 Sharf, V. 2. 212 Tokumoto, M. 43 Willner, 1. 2 10 Radchenko, V. M. 208 Shelef, M. 42 Tombacz, 1. 46 Willner, J. I03 Raevskaya, M. V. 208 Sheng, T. T. 148 Tong, H. M. 144 Winquist, F. I50 Rajaram, R. R. 46 Shih, A. 214 Torrance, J. B. 209 Winterbottom, J. M. 151 Ralainirina, R. 46 Shimizu, K. 43 Toshima, N. 46,2 I0 Wittmer, M. 214 Rameshi, K. V. 154, 213 Shimogori, K. I15 Touroude, R. I05 Witt, J. I47 Rankin, D. W. H. 209 Shiokawa, J. I46 Traverse, A. I46 Wokaun, A. I06 Rao, K. V. 101 Shirotani, I. 20 Triaca, W. E. 42 Wolf, G. K. 213 Raoufi, A. 101 Shnaider, B. I. 62 Tributsh, H. I50 Woodhouse, J. J. 193 Raub, Ch. J. 64, 104 Shukla, A. K. 154. 213 Trogler, W. C. 212 Worrell, W. L. I so Reilly, M. L. I32 Shushakov, V. D. 208 Trost, B. M. 212 Wrighton, M. S. 104 Resaseo, D. E. 24 Shymanska, M. V. 106 Trumbo, D. L. I05 Wright, J. C. 43 Reynolds, B. J. I33 Simpson, J. H. I53 Tsujikawa, I. 102 Wyatt, B. S. 25 Ricco, A. J. 21 I Singh, R. N. 43 Tsuji, Y. 212 Richard, D. 24 Sing, K. S. W. 24 Tsuno, K. 45 Yamaguchi, Y. 43 Richards, D. C. I06 Skarzov, 1. 1. 208 Tsuruya, S. 208 Yamamoto, 1;. 21 I Richardson, J. T. 25 Skov, K. A. 214 Yamanaka, H. I47 Ridden, J. M.C. 47 Smith, J. M. 151 Yamanaka, 1. 43 Riemenma, A. J. 42 Smiyan, 0. D. 62 Uchida, H. I02 Yamasaki, I. I02 Ritsko, J. J. 144 Sobczynski, A. 103. 210 Uchida, 1. 181 Yamazaki, T. I49 Ritter, G. 45 Sodesawa, T. 152 Uchida, Y. 154 Yang, Y. 24 Ritvin, E. I. 208 Soga, K. I52 Uchijima, T. 152 Yannopoulos, I,. N. 211 Robinson, H. B. 62 Solymosi, F. 46 Underhill, A. E. 72 Yanson, I. E. 208 Robins, 1. I07 Sorrell, R. M. I02 Uzan, R. 46 Yao, Y. D. I46 Rochon, F. D. I02 So, F. C. T. I54 Yee, D. S. 2 I4 Romanelli, M. G. I53 Spetz, A. I50 Yee, G. T. 209 Ross, J. F. I07 Spiegel, R. 213 Vajo, J. J. 151 Yermakov, Yu. I82 Rubel, M. 101 Srinivasan, V. I50 Van den Broeek, H. 63 Yonco, R. M. I02 Rubin, L. J. 45 Stanborough, M. S. 212 Van Elderen, A. M. J.212 Yoneyama, H. I03 Riihlicke, D. 104 Stenius, P. I05 Van Langeveld, A. D. 44 Yoshida, S.4. 212 Russell, M. J. H. I45 Stenzel, W. 42 Van Rheenen, P. R. 151 Yoshihara, M. I46 Rustamov, M. 1. 210 Steur, P. P. M. 107 Van Sprang, M. 146 Yoshimura, F. 150 Ryabinin, M. A. 208 Stille, J. K. I53 Vannice M. A. I52 Yoshimura, S. 104 Rye, R. R. 21 I Stock, J. T. 41 Vasil'ev V.Ya. 208 Yoshioka, K. 208 Stock, L. M. 46. 213 Vasuldevan, S. 213 Yoshizaki, R. 47 Stiickel, D. 214 Vazquez, L. 42 Yu-Yao, Y.-F. 21 I Saeki, K. I53 Stokes, J. 54 Veillard, A. 12 Saha, C. R. 153 Stucki, S. 43. 63 Venter, R. D. 213 Zandbergen, H. W. 148 Saito, E. I07 Sung, B. I52 Veprek, J. I54 Zharkov, B. B. I05 Saito, K. 212 Sun, Y. K. 151 Verdoes, D. I48 Zhdan, P. A. 208 Sakakura, T. 153 Susu, A. A. 10s Verhoef, R. 42 Zhong, W. X. I48 Sakamoto, Y. 147 Suvorova, L. N. 212 Verwijs, J. W. I52 Ziemecki, S. B. 105 Sakurai, H. 214 Suzuki, S. 42 Volkov, Yu. L. 104 Zucholl, K. 213

Platinum Metals Rev., 1987, 31, (4) 222 SUBJECT INDEX TO VOLUME 31 a =abstract Page Carbon Oxides, CO (conrd.) Page Acetaldehyde, production from esters, a 153 methanation to CH, , a 210 Acetic Acid, dehydration to ketene. a 151 CO,CO,, hydrogenations, a 46, 153 synthesis, from syngas, a 46, 152 CO,, hydrogenations, a I52 Acetic Anhydride, synthesis. a 45 oxidation on Pd/, Pd-Agly-Al ,O, , Acetone, oxidation, on Pt/AI,O,/AI thin plate, a 211 synergisms, a I 06 Acetylenes, carbonylation, by Pt complexes, a 212 photoproduction, from CH ,OH+HIO, on Alcohols, dehydrogenation, for H, production, a 107 Na +Pdl,Na+Rh/TiO,, a I03 detectors, review, a I50 photoreduction to CH,, by Ru, a I03 electro-oxidation, by trans-Os(q'-CHBA-Et)-(py),, production from isobutylaldehyde, over to a1dehydes.a 153 Pd+Na,S/support, a 106 ethyl, formation from syngas, a 106 reduction to HCOO-, a I03 methyl, electro-oxidation on Ir in acids, a 149 Carbonylation, acetylenic compounds, a 212 for H, photoproduction, benzene and cyclohexane, a I53 on PtlCr,O,-TiO,, a I03 esters, a I53 for syntheses, by Pt/SPE, a 43 Carbon, deposits, on platinum metal catalysts, a 44 formation from syngas, a 212 Carboxylic Acids, production from coal, a 46 oxidation, for exhaust catalysts, a 45, 106 Carola Oil, hydrogenation over Pd/C,Pd black, a 45 photoreaction with H,O, a 103, 210 Catalysis, asymmetric I37 oxidation, by RhH(PPh ,), , a 46 automotive, European symposium I94 primary, oxidation, to aldehydes, a 213 heterogeneous & homogeneous, conference I82 production from ethyl acetate, on Rh-Sn/SiO,, a 152 heterogeneous, a 44, 45, 46, 105, 106. 151, 152, propargyl, carbonylation, a 212 153. 211 reactions with CO, olefins, a 154 homogeneous. a 46, 106, 107,'k3, tertiary. production from alkane oxidation, a 154 154... 212. 213 Aldehydes, ppduction, from alcohols, a 153, 213 homogeneous, alkane C-H bond cleavage, a 106 Aliphatic Acids, production, from coal, a 46 phase transfer, a I06 Alkanes, C-H bond cleavage, a 106 platinum metals. coke formation on, hydrogenolysis, a 46 study of, a 44 oxidation, to alcohols, ketones, u I54 Catalysts, automotive, review, a 44 production, from isobutylaldehyde, a I06 heterogeneous, preparation of, conference 24 Ally1 Acetates, Chlorides, reduction, a 46 in fuel cells, a I54 Amides, synthesis, from nitriles and amines, a 107 Ir-FelSiO, , for methanol production, a 212 Ammonia, detection, a 150 Ir"'+NH, chlorometallate, bifunctional, a 106 MOSFET sensitivity to, a 107 Osmium, for CO bond reduction, a 213 photoproduction, from NO;, on PtlTiO,, a 210 Osmium Complexes, H ,Os, (CO) ,,, for styrene synthesis, in fixed bed reactor, a I06 hydrogenation, a 213 Ammonium Chlorometallates, +Pt", +Ir"', trans-O~(q'-CHBA-Et)-(py)~,systems, a 153 bifunctional, in hydrosilylations, a 106 Osmium clusterslinorganic oxides, activity, a 46 Anilines, production, from nitroaromatics, a 153 Palladium, black, carola oil hydrogenation, a 45 Arenes, metallation of, by Ru complex catalysts, a 107 colloids, + Ru(bpy) , +,for Aromatisation, selective, of light paraffins, a 151 photohydrogenation, a 210 Astronomy, history, Pt, Pd in 91 in Sn oxide combustible gas detectors, a 21 1 thin film electrocatalysts, a 148 Benzaldehyde, production from benzene, a 153 Zr,Pd-H, surface effects, a 208 reduction, by Pd(II), Pt(l1) polyvinylpyridine, a 153 Palladium Complexes, ally1 chloride, acetate, Benzene, hydrogenation, on Ru-CulSiO,, a 152 reduction, a 46 photo-carbonylation, to benzaldehyde, a 153 for asymmetric catalyses I37 Blackbody, construction, with Pt heater, a 104 Pd(I1)-bis(acetonitri1e) (dichloro), Book Reviews, Catalysis & Automotive Pollution for enynes production, a 153 Control I 94 Pd(l1)-polyvinylpyridine. for nitroaromatic Homogeneous and Heterogeneous Catalysis I82 reduction, a I53 Or anic Syntheses by Oxidation with Metal Pd(OAc),, for ester carbonylation, a I53 $om pounds 145 Pd complexes/polymeric support, for platinum in historical instruments 41 unsaturated hydrocarbon hydrogenation, a 2 12 Quantum Chemistry: The Challenge of Transiticin Pd single crystals/polyethylene, CH-monomer Metals and Coordination Chemistry 12 synthesis, a I05 Bronzes, DyPtX, DyPdX, synthesis, a 146 PdCI, -cyclodextrins, for olefin conversion, a 106 Butanes, hydrogenolysis. on pretreated RulTiO, , a 46 Pd(O), for reductive cyclisation, a 212 But-lsne, deuteration, isomerisation, a I05 Pd(colloidal)/chelate resin, for cyclopentadiene hydrogenation, a 46 Cancer, PI anti-tumour complexes, a I07 Pd+Na/TiO,, for H,O-CHIOH reaction, Pt complexes binding with DNA, a 47 to H,. methvl formate. CO,. a 103 review, platinum drugs 23 Pd+Na;S/support, for isobuiylaldehyde Capacitors, MOS with Pt, for NH, detection, a 150 decomposition, a I06 CAPOC I, conference I94 Pd-AglSiO,, Pd-NilSiO, , characterisation, Carbon Oxides, CO, for Fischer-Tropsch. a 106 activity for soya oil hydrogenation, a 151 for glycolaldehyde production, a 213 PdlAI,O ,, for a-methylstyrene hydrogenation, a151 for NO reduction, a 44 reparation by thermal transport, a 211 from gas turbines, catalytic cleaning 162 PdlC!, for carola oil hydrogenation, a 45 hydrogenations for S poisoning tests, a 152 PdlLaY, hydrogenating activity, a 151 hydrogenations, a 152 Pdlphasphinated inorganic oxides, a 45 reactions with olefins, alcohols, a I54 Pd/pumice, for but-I-ene reactions, a 105

Platinum Metals Rev., 1987, 31, (4), 223-228 223 Catalysts (conid.) Puge Catalysts (corrrd.) Page Pdlsupport, poisoning by H?S. a I52 Rh-Pt+La,O,/TiO,, for alcohol formations. a 106 Pdl, Pd-Agly-Al,O, , synergism. Rh-SnlSiO,, for ethyl acetate conversions. a 152 in CHIOH. CO, oxidations, a I06 RhlAI,O,, for chemisorption, a I52 Platinum, colloidal sols, atomic structure. a 45 heterogenised homogeneous, a 45 colloidal, for H, photogeneration, a 210 preparation by thermal transport, a 21 I colloidal, for H, production by U.V. I25 Rh/Cr,O,lAl,O,, homogeneous, a 45 colloids, +Ru(bpy),!+. for RhlNb,O,-CulSiO,, for CO,:H, reaction, a 152 photohydrogenation. a 210 Rhlpumice, for but-I-ene reactions, a I05 oscillations for NO+CO reaction. a 151 RhlTiO,, + W +,electrical properties of TiO, , polycrystalline wire. acetic acid during hydrogenation, a 46 dehydration, a 151 Ruthenium, colloid, for CO? photoreduction. a 103 Pt-Ni. Pt-Ti, graphite-steam reaction, a 45 RuO,, for coal oxidation. a 46 Platinum-Rhodium, for controlling gas turbine Ruthenium Complexes, chemistry, a I07 emissions I62 for alkane oxidation to alcohols, ketones, a 154 Platinised n-Si, for formic acid RuH,(PPh,),, for amide synthesis, a I07 photodecomposition. a I03 Ru,O(O,CR),L,". for alcohol oxidation, a 213 Platinum Complexes, in asymmetric catalyses I37 IRuJbpy),(CO,lz', for CO, reduction, a 103 PtCI,(PPh,),, acetylenic carbonylation. a 212 Ruthenium:Iodide, for olefin-CO-alcohol Pt(1l)-polyvinylpyridine, for nitroaromatic reaction, to esters, ketones, a I54 reduction, a I53 Ru+KlAI,O,, for NH, synthesis, a I06 Pt"+ NH, chorometallates. Ru-CulSiO,, for benzene hydrogenation. a I52 for hydrosilylations. a I06 Ru-Ni, graphite-steam reaction, a 45 Platinum Metalsla-Al,O ,, NO reduction by Ru/AI,O,, for Fischer-Tropsch, a 106 cycled CO, a 44 RulMgO+K, for NH, synthesis, a 106 Platinum Metalsly-Al,O ,, for methanol RulRuOJTiO,, for CO, conversion to CH,. a 210 oxidation, a 45 Rulsupport, for CO hydrogenation, a 152 bis(trialky1phosphine)Pt oxalate/SiO ,, RulTiO,, for hydrogenolysis. a 46 photogenerated, for olefin hydrosilation, a 2 12 Ru/Y zeolite, for shale oil hydroprocesssing. a 212 Pt,Pd,Cu,NilTiO,. for C,H, photohydro- Ruthenium clusterslinorganic oxides, activity, a 46 genation, a I49 Ru ,(CO) Ru,H, (CO) ,, clusterslsupport, Pt-lr/Al,O, for reforming, S effect, a I05 for hydrogenations, a 153 Pt-MolSiO,, for syngas conversion. a 21 1 Cathodic Protection, conference, 25 Pt-MIA1 ,O ,, for cyclohexane dehydrogenation, Cells, multielectrode, for water photolysis. a 44 effect of M. a 21 I Chemisorption, H, on Rh/AI,O,, a I52 Pt-M/AI,O,, for paraffins reforming, a 21 I Chloralkali, electrolytes, membrane cells, a I49 Pt/AI,O,, films, S induced faceting, a 44 Chlorine, evolution from chloralkali cell, a 149 for n-octane dehydrocyclisation. a I05 ions, oxidation at electrodes, a 210 for reforming, effect of sulphiding. a I05 Chloroplatinic Acid, reduction to PI particles, a 151 for wood liquefaction. a 45 Chromatography, liquid, with Pt microelectrode, a 104 preparation by thermal transport. a 21 1 Circuits, VLSI, RuO, films in. a 214 PtlAI,O,,+Sn, preparation and activity. a 21 I Claddings, Pt. Pt alloys, on Cu-. and Ni alloys 64 PtlAI,O,IAI thin plate, for acetone oxidation. a 21 I Coal, oxidation by RuO, , for carboxylic acid. a 46 Ptlberyl, for HCN production, a I05 Coatings, Ir on electron tube cathodes, a I54 PtlCdS, colloids, H,S photodecomposition. a 2 10 0s on W cathodes, for thermionic emission, a 214 for photo-oxidation of H,O. at pH>12, a 149 Pt aluminides, Cr modified, hot corrosion. a 104 PtlC, atomic structure by TEM. a 45 Pt on powder TiO,, photoassisted, a 44 wetproofed, for T removal, a 151 Colloids, production, for water photolysis I25 PtlGa silicate, for propane conversions, a I5 I Commodity Meeting, I lth, IMM II PtlH mordenite, n-heptane hydroconversion. a 2 12 Composites, extruded CulPd. electrical contacts. a 2 I4 Pt/metal oxide, CdSlSiO,, for H2 Conferences, 1st Int. Symp. on Catalysis & photoproduction, from CH ,OH-H,O. a 210 Automotive Pollution Control 194 PtlNaY zeolite, for methylcyclohexene CEC-Italian Fuel Cell Workshop I73 dehydrogenation, kinetics, a 45 Chemistry of the Platinum Group Metals, Ptlpumice, for but-I -ene reactions, a 105 3rd Int. Conf., Sheffield I86 PtlSiO,, wetproofed, for T removal, a 151 Fifth Int. Symp. Homogeneous & PtlTiO,, for NH, photoproduction, a 210 Heterogeneous Catalysis. Novosibirsk 182 Rhodium, LnIRh-BI-H crystals, for olefin fuel cells, Eureka initiative 63 hydrogenation, a 212 Preparation of Heterogeneous Catalysts, 4th Int. 24 thin film electrocatalysts. a I48 UK Corrosion '86 25 Rh colloidslpolyacrylamide gel, for olefin Constant Volume Gas Thermometer 107, 196 hydrogenation, a I52 Copper Alloys, clad with Pt, Pt alloys 64 Rhodium Complexes, asymmetric catalysis 137,153 Corrosion, conference 25 RhCI(CO)(PMe ,),, photo-carbonylations, a 153 crevice, in Ti materials I I5 RhH(CO,)(PR,),, for hydroformylation. a 213 hot, of Ni alloys, Pt additives for, 26 RhH(PPh ,), , for alcohol oxidation, a 46 in nitric acid plants 185 RhX(CO)L,, for syngas conversion, a 212 on Pd-Ag lead paths. by gases, a 47 Rh,(CO),,-halide promoted, for Pt-Rh alloys, in molten glass, a 208 glycolaldehyde, a 213 Creep, properties of platinum metal alloys 74, 172 + imidazole, ethylene glycol formation. a 153 Crystals, LnIRh-B1, for olefin hydrogenations, a 2 12 IRh(bipy),lCI. for HI production, a I07 RuS ,, growth and conductivity, a I50 Rh+La,O,/TiO,, for alcohol formation Cyanide, hydrogenation, on Pd( IOO),Pd( 11 I), a 42 from syngas, a 106 Cyclisation, by Pd(0) catalysts, a 212 Rh+NaiTiO,, for CHIOH-H,O reaction, a 103 Cyclohexane, dehydrogenation on Rh/AI,O,, a 152 Rh-Mn-Ir-Lil, Rh-Mn-Zr-Li/SiO, , for acetic on Pt-M/AI,,O,, effect of M on. a 21 I acid production, from syngas, a 46. 152 photo-carbonylation, to benzaldehyde. a 153

Platinum Metals Rev., 1987, 31, (4) 224 Page Electrodes (contd.) Page Cyclopentadiene, hydrogenation, a 46 Ru,lr, .xO,. for 0,evolution in acid, a 43 Cyclopentane, reforming, a 21 I Ru,Sn, -,O,, in alkaline solution, Cyclopentene, production, a 46 for 0,evolution, a I49 W-Pt, in thermoelectric converter, a 154 Dehydrocyclisation, of hydrocarbons, a 21 I Zn porphyrinate-Pt, in photosystem, a I49 Dehydrogenation, alcohols, for HI production, a 107 Electrolysis, steam, high temperature, a I02 cyclohexane. on Pt-M/AI,O,, a 152. 21 I Electroplating, Pd/Au, NilPdlAu, for connectors, a 104 methylcyclohexene, on PtlNaY zeolite, a 45 Emission Control, automotive exhaust, conference I94 Detectors, ammonia, a I50 catalysts, for gas turbines I62 amperometric. in liquid chromatography. a 104 exhaust gases from automobiles, a 45, 106 combustible gases, by stannic oxide films, a 2 I1 exhaust gases from industrial plants, a 122 gas sensitive semiconductors, review, a 150 Enones, non-conjugated, hydrogenations, a 213 glucose, with PdlAu modified C electrode. a 44 Enynes, conjugated, catalytic production, a 153 H,, by Pd-fibre optics, a I50 Esters, reductive carbonylation, by Pd(OAc), , a 153 HI. stabilisation, by Pt/Pd gate, a 44 synthesis, from olefin-CO-alcohols, a I54 H,. 0,.in solution, a 104 Ethane, hydrogenolysis, hydrogenation, a 46 H,. VHV response, by Pd MIS, a 211 Ethyl Acetate, hydrogenation to ethanol, a 152 organic vapour. on Pt hot wire, a I46 Ethylbenzene, dehydrocyclisation, Diodes, junction, RuO, thin films in, a 154 hydrogenation, a 105. 151 DNA, binding with Pt complexes. a 47. 214 Ethylene Glycol, production from syngas, a 153, 212 Drugs, Pt, review 23 Ethylene, detectors, review, a I50 photocatalytic hydrogenation, a I49 Electrical Conductivity, of Pt,(NH,),,CI,,X,, a 102 Eureka initiative on fuel cells, conference 63 TiO, support doped, effect on Rh catalyst, a 46 E.E.C., research on direct methanol fuel cell I73 Electrical Contacts, Pd based, development 13 Pd pin on Au alloy base plate, a 214 Fibre Optics, in gas sensors, a 150 PdlAu, NilPdlAu, plated, a 104 Films, composite, PdlAI gate MOS. a 105 Electrical Resistance, Pd-8at. %Y, a 147 Ir oxide, electrochemical studies on, a 209 Pd,Mn disordered, a I47 RuO,, for VLSl circuits, a 214

I ~~ Electrical Resistivity, Fe, _,Pt alloys, a 146 Fischer-Tropsch, forced cycling over RulAI ,O 11 Pd-Ag, Pd-Ag-Fe alloys, plastically deformed, a 101 for product modification. a I06 WPt I _,Pd,), , a 42 Formaldehyde, hydroformylation, Electrochemistry, a 43, 102, 103, 148, 149, 209, 210 to glycolaldehyde, a 213 Electrochromism, Ir oxide films, a I47 Formic Acid, photocatalytic decomposition, a I03 Electrodeposition, a 44, 104, 210 Fuel Cells, a 47, 107. 154, 213 Pd, pulsed current and DC, a 104 direct methanol I73 Electrodes, amorphous PdlPd-Rh-P-Si, active, a 101 glycollair, with Pd:Pt:Bi/C electrode, a 47 anodes, in cathodic protection 25 H,O, electrode production, a 213 IrO,/TiO,/Ti, for 0,evolution, a I03 industrial forum, Eureka initiative 63 Pt in phosphoric acid fuel cell, a 107 phosphoric acid, electrodes, a 47, 148 PtlC, porous, in fuel cell, CO poisoning, a 47 Pt-Rulporous C electrodes, activity, a 213 RuO,, for biphenyl destruction, a I03 Pt/WC electrodes for, a 213 RuO,, in chloralkali electrolytes, a I49 cathodes. Ir coated M-type, in electron tube, a 154 Gas Thermometry, history I96 0scoated. for themionic emission, a 214 Glass, industry, Pt in 54 Pt. for steam electrolysis, a I02 molten effects on Pt-Rh alloys, a 208 RuO,/Ni, in chloralkali cell, a I49 Glucose, sensor, a 44 classical H, of Pd-Ag, a I02 Glycloaldehyde, production, a 213 HglIr, preparation, a I03 Graphite, reaction with steam, a 45 Ir oxide films, 0, evolution on, a 209 Ir, in acids, for methanol electro-oxidation, a 149 n-Heptane, hydroconversion, a 212 Ir-based Hg, in electroanalysis, a 149 1 - Hexene, deactivation for hydroformylation, a 213 PdlAg membrane, for high temperaturdhigh History? gas thermometry 196 pressure measurements, a I02 iridium 32 PdlAu modified C. in glucose sensor, a 44 Pt, Pd, in astronomy and navigation 91 Pt band, construction and behaviour, a 209 Pt in early instruments 41 Pt disc microelectrodes, fabrication 181 Honeycat, air pollution control 122 Pt gate, in MOSFETS, a I07 Hunt, Dr. Leslie Bernard, obituary I14 PtCr, in phosphoric acid fuel cells, a 148 Hydrocarbons, C,,, production from CO,:H,, a 152 Pt+Ru,Pt+Pd,Pd+Rulporous C, fuel cells. a 213 emission from gas turbines, catalytic removal I62 Pt, for 0,evolution in alkali, a 102 formation by Fischer-Tropsch reaction, a I06 for Pt-Ru alloy formation, a 102 unsaturated, hydrogenation, by Pd ultramicroelectrode, in chromatography, a 104 complexeslpolymeric support, u 212 (100)-type, surface structure, a 42 Hydroconversion, n-heptane, a 212 Pt-PdlC, Pt-RulC, 0 reduction in fuel cell, a 154 Hydroformylation, reactions, a 213 Pt-polypyrrole. ohmic resistance, a 209 Hydrogen Cyanide, for CH, ammoxidation, a I05 PtlNafion, Ptlgraphite, in 0,separator cell, a 105 Hydrogen Sulphide, detectors, review, a I50 Pt/porous C, Ni, sputtered, H.0, fuel cells, a 213 photodecomposition, on PtlCdS colloids, a 210 PtlSPE. for methyl formate synthesis, a 43 poisoning Pd catalysts, in H,:CO reaction, a I52 PtlTiO,, photo, for H,O splitting, a 44 Hydrogenation, asymmetric, PtlWC, ion implanted, for fuel cells, a 213 by Rh aminophosphine-phosphinite,a 153 Pt:Pd:BilC, in glycollair fuel cell, a 47 benzene, on Ru-CulSiO, , a I52 RuO,. in alkaline solution, for 0, evolution, a 149 but-I-ene, on Ptl, Pdl. Rhlpumice catalysts, a I05 RuO,ITiO,, oxidation of CI ions at, a 210 carola oil, on Pd, a 45 Ru-Ti oxide, for urea electro-oxidation, a 43 CN, on Pd(100). Pd(1 I I), a 42

Platinum Metals Rev., 1987, 31, (4) 225 Hydrogenation Imird.) Pup Pugr CO. on Rulsupport. support effects. (I I52 Magnetism, antiferromagnetism. in U(Pt.Pd), . (I 146 CO.CO,. on RhlTiO, + Wb’, conductivity, (1 46 Cr-Ru. b.c.c.. u 43 on Ru ,(CO) ,, clusters/ support, a I53 LuRh,.,Sn,. a 147 CO!. to C,,, on RhlNb,O,-CulSiO!. a I52 Pd alloys, 0 effects on, a 42 cyclopentadiene. by colloidal Pdlchelate resin. a 46 (Fe, .,Mn,)Pt, phase diagram, (I 101 ethene. on 0s-.Ru clusterslinorganic oxides, a 46 Medical, anti-tumour Pt complexes 23. 107 ethyl acetate. conversion to ethanol. (I I52 binding with DNA. a 47 ethylbenzene. by PdlLaY. a 151 neurological prostheses 2 ethylene. photocatalytically. a I49 PI complexes for radiosensitising. a 214 u-methylstyrene, on PdlAl ,O,, a 151 Metallurgy, contact, for Pt-Si. a 101 non-conjugated enones, a 213 Methanation, CO,. to CH,. by RulRuO TiO,, a 210 olefins. a 45. 152. 212 Methane, for HCN production on PtlAl!b,. a 105 photo, acetylenes. a 210 photoproduction from CO, , a 103, 210 reactions. by Ru polyhydride complexes. a 107 Methanol, fuel cells I73 soya oil. by Pd-Nil. Pd-Ag/SiO,. a 151 synthesis, on Pt-MolSiO,. a 21 I styrene, by 0s complexes. a 213 Methyl Formate, photoproduction. a I03 unsaturated hydrocarbons. a 212 synthesis, from CH,OH, by PtlSPE electrode. a 43 Hydrogenolysis, ethane, propane, n-butane. a 46 Methylal, synthesis, a 43 Hydrogen, absorption, in Pd-Co. Pd-U alloys. a 147 Methylcyclohexene, dehydrogenation kinetics. a 45 chemisorption. on RhlAI,O,. a I52 Methylphenylacetylene, photohydrogenation. a 2 10 detectors, a 44. 104. 150 u-Methylstyrene, hydrogenation, a 151 effect on PtSi-Si Schottky diodes. a 101 Microgravity, for solidifying PI, Ir, Rh. Ru 62 evolution, from steam electrolysis. a I02 Monomers, CH-terminated, synthesis, a 105 permeation. at high pressure 71 MOSFETS, response to NHJ. a I07 photoproduction. a I49 by Ru (bipy),CI,,Rh cdrbonyls. a 44 Navigation, history. Pt. Pd in 91 by u.v., by Pt colloids and ketyl radicals 125 Nerve Stimulators, in implanted prostheses 2 from CH,OH-H,O, a 103. 210 Nickel Alloys, clad with Pt. Pt alloys 64 from HiO. by protected colloidal PI. u 210 Nickel Alloys, PI to control hot corrosion in 26 from H,S, by PtlCdS colloids, a 210 Nitric Acid Plants, corrosion in 185 production, from isobutylaldehyde, a 106 Nitric Acid,photoreduction to NH,. by Pt/TiO,, a 210 from alcohols, over [Rh(bipy),lCI, a I07 Nitroaromatrs, reduction to aniline, a 153 solubility. in Pd alloys, a I47 Nitrogen Oxides, NO, cycled reduction with CO. a 44 study using Pd-AI gate MOS. a I05 reduction on PI, a 42 Hydrosilation, olefins, a 212 Norbornane, oxidaton, a I54 Hydrosilylation, chlorometallates, bifunctional, a 106 Nuclear Waste, T, removal. a 151 Inst. of Mining and Metallurgy, I Ith Commodity Obituary, Dr. Leslie Bernard Hunt I14 Meeting, on platinum metals II n-Octane, conversion to 2-octene. a I06 Ion Beam Mixing, Pt with Ni superalloy. a 150 Octanes, dehydrocyclisation, on PtlAI,O ,. a I05 Ion Emission, from hot Pt wire. a I46 Olefins, catalysts for hydrogenation. a 212 from PdNiSiEkB liquid metal, a 147 hydrogenation. a I52 Iridium, coated cathodes, in electron tubes. a I54 hydrosilation, a 212 compounds, ZrIrGe. HflrGe. TiIrGe. structure, reaction with CO, alcohols, a I54 superconductivity, a I48 terminal, oxidation to ketones, a I06 history of 32 Optical Fibres, Pt coated. for gas detection. a 150 organometallics, annual survey for 1985. a 148 Osmium, additions to y-Fe,O?. grain size, a I50 solidification in microgravity 62 coated cathodes, fo: thermionic emission. a 214 surface microscopic observation, a I47 compounds,LOs(NH,),(~*-benzene)], a I48 Iridium Alloys, constitution and properties 74, 172 polymers, LOs(octa-ethylporphyrin)L-L)ln,a 209 weldability in sheet form, test 193 Osmium Alloys, constitution and properties 74. 172 Iridium Complexes, Ir(CO)CI,(PEt J),(P’F,). a 209 Osmium Complexes, annual survey, 1984, I02 Ir,(CO),L,, water-soluble, synthesis, a I02 Os,(CO),,L,, water-soluble, synthesis, a I02 Iridium Oxide, films. electrochemical studies on. a 209 ~N(PPh,),lIOs,M’(CO)I I. synthesis. a I02 electrochromism in, a I47 Osmium Tetroxide, with RuO,, B.P., a 43 Iron Oxide films, 0s effect on grain size, a I50 Oxidation, 4,4’-dichlorobiphenyl, at RuO, anode, a 103 Isobutylaldehyde, decomposition, a I06 acetone, by Pt/AI,O,/AI thin plate, a 211 alcohols, by RhH(PPh,),, a 46 Johnson Matthey, collaboration with Europe alcohols, primary, to aldehydes, a 213 on direct methanol fuel cell I73 CHJOH, CO,, on Pdl, Pd-Agly-Al,O,, a 106 Honeycat air pollution control unit I22 CI ions, at RuO,/TiO,electrodes, a 210 metal loan scheme 171 coals, by RuO, , benzene acid production. a 46 standard for impurity measurements in Pt I33 high temperature, Pd-Rh alloys. surface effects. a 42 ZGS platinum alloys, in glass making 54 Magnus’ green salt. to Pt,(NH,),,CI,,X,. a 102 ZGS Pt-596Rh alloy 8 methanol, on noble metally-Al,O,, a 45 “Platinum 1987”, commercial survey 123 Pd, Pt,,Rh: Pt-Rh, Pt-Pd-Rh, by 0, r.f. plasma, a101 Joining, a 150 Pt,Sn in air, a 101 Oxygen, detection, in aqueous solutions, a 104 Ketene, production from acetic acid, a 151 effect on magnetism of Pd alloys, a 42 Ketones, production a 106. 154 evolution, at Pt electrodes in alkali, a I02 at Ru electrodes, in alkaline solution, a 149 Laboratory Apparatus, a 44, 104, 105, 150, 21 I from chloralkali cell, a 149 Lasers, for Pd electrodeposition. a 104 on Ir oxide films, a 209 Liquefaction, of wood, a 45 on Ru,Ir, -xO, eletrode, a 43 Loans Scheme, Johnson Matthey, metals for research171 using IrO,/TiO,/Ti anode, a 103

Platinum Metals Rev., 1987, 31, (4) 226 Oxygen (contd.) Page Platinum (conrd.) Page reduction, at PI-RulC, electrodes, in fuel cell, a 154 electrodes, (IOO)-type, surface structure. a 42 separation, by ion-exchange membrane, a I05 faces, NO reduction on, models, a 42 heater in a blackbody, and thermometer, a 104 Palladiotype, photography, new work on I24 H,, permeability through 71 Palladium, amorphous Pd/Pd-Rh-P-Si cast alloy, in implanted prostheses 2 electrolytically active, a 101 in Ni alloys, for corrosion protection 26 compounds, DyPdX bronzes, synthesis, a I46 in optical pyrometer, a 47 Pd,Mn. H, solubility, electrical resistance, a147 ion mixed with Ni superalloy, a I50 CulPd extruded, for electrical contacts, a 214 platinised poly(3-methylthiophene), a 104 electrodeposition by pulsed current, a 104 powder, H,PtCI,.6H20, gas evolution on, a 208 in electrical contact materials 13 properties, for use in glass industry 54 in solar cells, a I54 purity of, analytical standard 133 in steel, distribution in I36 solidification in microgravity 62 laser-assisted deposition, a 104 synthesis of small particles, a 151 Mo/Pd/Si thin films, interactions, a 43 thin film, for dry solder wetting, a I50 Pd(lII), Pd(100). CN hydrogenation on, a 42 ultramicroelectrode, in chromatography cell, a 104 Pd(I1) chloride salts, photoreduction, a I03 wire hot. ion emission from I46 PdlAu modified C electrode, glucose sensor, a 44 ZGS, in glass making 54 Pd/Co,PdlFe thin film, magnetic anisotropy, a 146 Platinum Alloys, Fe, _,PI, ~1,ordered, a 146 Pd/Pt gate, in H, sensor, a 44 new data on thermal expansion coefficients 132 pin in electrical contact, wear, a 214 Platinum-S%Rhodium, ZGS 8 plating of printing tubes, a 104 Platinum-Cobalt, Platinum-Iridium, cladding 64 prevention of crevice corrosion, in Ti, Ti alloys 115 Platinum-Rhodium, corrosion in glass, a 208 single crystals, elastic properties, a I46 interdiffusion, a 208 sols, for metallising paper, a 210 new data on thermal expansion coefficients 132 thin film electrocatalysts, a 148 Platinum-Ruthenium, formation, a 102 Zr,Pd-H. surface studies, catalytic activity, a 208 Platinum-Silicon, contact metallurgy, a 101 Palladium Acetate, films, laser metallisation, a 107 Pt,Sn, oxidation in air, a 101 Palladium Alloys, amorphous for electrodes, a 101 ternary, quarternary, constitution 74. 172 amorphous spherical particles, Ni-Pd-P. a 147 weldability 62 Palladium-Cobalt, H, absorption in, a I47 (Fe, _,Mn,)Pt, magnetic phase diagram, a 101 Palladium-Gold, hydride formation. a I05 Platinum Aluminide, coatings, Cr modified, hot Palladium-Iron, 0 effect on magnetism. a 42 corrosion behaviour and structure, a 104 Palladium-Rhenium, hydride formation, a I05 Platinum Complexes, anti-tumour 23, 47, 107 Palladium-Rhodium, foils, after oxidation, a 42 for radiosensitising, a 2 I4 Palladium-Silver, electrical resistivity, a 101 co-ordination, literature review, 1983. a 43 H, permeability through 71 platinacyclobutanes, preparation. a 209 lead paths, gas corrosion in, a 47 PtCI(PEt ,) ,(PI F4), preparation. a 209 Palladium-Silver-Iron, plastically deformed, a 101 Pt,(NH,) ,,CI I ,X,, synthesis, a I02 Palladium-Uranium, H, absorption in, a 147 IPt(L)I, I, cis-[Pt(L)(L I )I ,I, a 101 Palladium-Yttrium, electrical resistance, a 147 Platinum Metals Alloys, properties 74. 172 Pd,,Ni,,Si,Ee,B,,, ion emission, a I47 Platinum Metals, chemistry of, conference report 186 ternary, quarternary, constitution 74, 172 reactivity rationalised, book review 12 Palladium Complexes, literature review, 1983, a 43 sources, uses, IMM Commodity Meeting II Pd(niox), pressure sensitive 20 Platinum Oxides, volatile, production. a 101 Palladium Hydrides, review, properties, a I46 Platinum Silicides, formation in presence of Al, a 146 Palladium Oxides, volatile, a 101 Poisoning, by S, on R/AI,O, films, faceting. a 44 Palladium Silicides, PdSi, Pd,Si. phase changes, a 41 of Pd catalysts by H,S, a I52 Paper, metallising, by electroless plating, a 210 S, resistance, by Pt-SnlAI20,, a 21 I Paraffins, aromatisation, a 151 Pollution Control, air, by Honeycat unit I22 reforming, on Pt-M/AI,O,, a 21 I automotive, European symposium 194 PdlAl gate MOS, for H study in, a I05 exhaust gases, a 45. 106 Permeability, H,. through PI. Pd-Ag, Au, Ag 71 gas turbine exhaust, by Pt-Rh catalyst I62 Phase Changes, PdSi to Pd,Si. kinetics, a 41 polychlorinated biphenyls, oxidation. a I03 Phase Diagrams, Cu-Ni-Ru, at 770K. a 208 T, from nuclear fusion experiments, a 151 platinum metals. ternary, quarternary alloys 74, 172 Polyamides, production from amines, a I07 U(Pt,Pd) 1. a 146 Polychlorinated Biphenyls, destruction, a I03 (Fe, -xMn,)Pt, magnetic, a 101 Polymers, IM(octa-ethy1porphyrin)L-L)],, a 209 Phenylacetylene, photohydrogenation, a 210 Powders, H,PtC1,.6H20, Rh metal, a 208 Phosphoric Acid Fuel Cell, poisoning of anode, a 107 Printing, Pd plated ink jet tubes, a 104 Photocatalysis, a 44, 103, 149, 150, 210 Propane, conversion to aromatics, a 151 of water, by u.v., colloidal Pt and ketyl radicals 125 hydrogenolysis, on pretreated RulTiO, , a 46 Photography, new technology for PI, Pd prints 124 Propene, production from isobutylaldehyde, a 106 Platinotype, new work on I24 Prostheses, neurological, implanted 2 “Platinum 1987” I23 Pyrometers, optical, a 47 Platinum, book review of early instruments 41 capsules, for high temperature heating. a 148 Reduction, ally1 chlorides, acetates, a 46 claddings, on Cu-, Ni alloys 64 CO,, by [Ru(bpy),(CO),lz+,a I03 cluster compounds, synthesis, a 209 NO with CO, cycled, on noble metal catalysts, a 44 compounds. DyPtX bronzes. synthesis. a 146 NO, on PI surfaces active site models, a 42 Pt,Sm, Pt,Gd, Pt,Am, a 208 photo, CO,. by Ru colloid catalyst, a I03 U(Pt,Pd),. superconductivity, a I46 photo, of nitrate to NH,, a 210 U(Pt, -xPdx)3.a 42 photo, Pd(II), Rh(lI1) chloride salts, a 103 contact metallurgy with Si. a 101 Reforming, n-paraffins, cyclopentanes. a 21 I deposition on TiO,, photoassisted. a 44 Pt catalysts, effect of sulphiding on, a I05

Platinum Metals Rev., 1987, 31, (4) 227 PUgC Page Resistance Thermometers, Pt, industrial. u 214 Structure, atomic, of catalysts, by TEM. u 45 Pt. automated, solidification of TNT. a 47 PtlAI,O, films, by TEM. (1 45 Pt. stability over 13-273 K, a I54 surface topography, (100)-type Pt. a 42 Pt. thin film. in high magnetic fields. at low Styrene, hydrogenation, by 0s complexes, u 213 temperatures, a 47 Sulphur Dioxide, in gas turbine exhaust I62 Rh-O.Sat.%Fe, a 41 Sulphur, effect on Pt reforming catalysts, u I05 Resistors, thick film, Bi,Ru,O,. a 47 poisoning, of AI,O, films. a 44 Reviews, anti-cancer Pt drugs 23 of methanol synthesis catalysts. u I53 catalysis for automotive exhaust, a 44 resistance of Pt catalysts to, a 211 cleavage of C-H bonds, a I06 Superalloys, Ni-base with Pt-AI-Cr coatings. a I04 gas sensitive semiconductor devices, a I50 Superconductivity, b.c.c. Cr-Ru. a 43 IMM Commodity Meeting II LuRh, ,Sn,.a 147 Ir. Rh organometallics, annual survey, a I48 U(Pt,Pd), system, a I46 literature, Pt, Pd co-ordination chemistry, ZrIrGe, HflrGe. TiIrGe, HfRhGe, a 148 1983, a 43 Synthesis Gas, for acetic acid production. a 46, 152 Pd. H implanted, low temperature properties, a 146 for alcohol production, a I06 Ru complexes, half-sandwich chiral, a 209 for aldehydes and acetic acid production. Ru, 0s organometallic complexes, 1984, a 102 by Pd(0Ac) ,, a 153 Rhodium, compounds HfRhGe, superconductivity, for ethylene glycol production, a 153, 212 structure, a 148 for methanol production, a 211. 212 Rh(II1) chloride salts, photoreduction, a 103 powder, gas evolution on, a 208 Temperature Measurement, u 47, 107. 154, 214 solidification in microgravity 62 Pt heater in blackbody, a 104 thin film electrocatalysts, a I48 by fast Pt-Ir thermocouple 144 Rhodium Alloys, Rhodium-Platinum, corrosion in gas thermometry, history I96 molten glass, a 208 Thermocouples, Pt-Ir, fast response 144 interdiffusion, a 208 Thermoelectric Converter, Pt-W electrodes in. a 154 ternary, quaternary, constitution, a 74. 172 Thermometers, low temperature, a 47 Rhodium Complexes, organometallics, annual Rh-Felsapphire, 4.2K to room temperature, a 214 survey for 1985, a I48 Thick Films, lead paths, Pd-Ag, gas corrosion of, a 47 Ru(bipy),CI,, for HI photoproduction, a 44 resistors, Bi,Ru,O,, as low temperature Rhodium Oxides, volatile, production, a 101 thermometers, in high magnetic fields, a 47 Royal Society of Chemistry, 3rd Int. Conf. on stannic oxide + Sb + Pd, gas detectors, a 21 I the Chemistry of the Platinum Group Metals I86 Thin Films, electrocatalysts, highly transparent, Ruthenium, compounds, carbonyls, H ,production. a 44 Pd,Rh,Pb,Re on InP, a 148 Ru,Ir, -xOz,anodic 0,evolution, a 43 MolPdlSi, interactions. a 43 for n-CdTe modification, of solar cell, a 214 Pd acetate, laser direct-write metallisation, a 107 polymers, [Ru(octa-ethylporphyrin)L-Lln,a 209 PdlCo, PdlFe, magnetic anisotropy, a 146 solidification in microgravity 62 PtSilSi, H, effect on, a 101 Ruthenium Alloys, Chromium-Ruthenium, Pt, for dry solder wetting, a I50 superconductivity, magnetism, a 43 Rh-Felsapphire, TCR, for cryogenic use, a 214 Ruthenium-Copper-Nickel, phase equilibria RuO,, diffusion barrier, in junction diodes, a 154 at 770K. a 208 Tin, alkynylstannanes for enynes synthesis, a 153 ternary, quaternary, constitution, a 74, 172 Titanium, Titanium Alloys, crevice corrosion in I15 Ruthenium Complexes, cluster carbonyls. Transistors, platinised poly(3-methylthiophene), substitution reactions of, a 148 as 0,, H, sensors. a 104 double cluster with B, a I48 Tritium, removal after nuclear fusion half-sandwich chiral, reactions, review, a 209 experiments, a I51 organometallic, annual survey, 1984 I02 Troughton, Edward, history, Pt, Pd in astronomy Ru,(CO),, -xLz, water-soluble, synthesis, a 102 and navigation 91 Ru,(CO),,, for substitution reactions, a 148 Turbines, gas, catalysts for emission control 162 IN(PPh,),l IRu,M'(CO),,l, synthesis, a 102 gas, Pt in blades 26 IRuX(N0,) (bpy),IY, synthesis, a 43 Ruthenium Dioxide, films, reactively sputtered, Urea, electro-oxidation, at Ru-Ti oxide elecrode. a 43 for VLSI circuits, a 214 Ruthenium Dioxide, thin film in junction diodes, a 154 Vehicles, methanol fuelled, Ruthenium Oxides, BaO-RuO ,-Fe 0 ,, a 148 catalyst development for, a 45, 106 Ruthenium Sulphide, crystals, Vinyl Iodides, coupling with alkynylstannanes, growth and conductivity, a I50 to give enynes, a 153 Ruthenium Tetroxide, B.P.. ideal solutions, a 43 Water, photochemical splitting, a 44 Schottky Diodes, PtSilSi, HI effect on, u 101 photoreduction, a 149, 210 Sextants, history, Pt, Pd in 91 photo-oxidation, to 0,.a I 49 Shale Oil, hydroprocessing, a 212 U.V. catalysed reduction, by colloidal Pt, Silicon, contact metallurgy with Pt, a 101 and ketyl radicals 125 Solar Cells,, photoelectrochemical, a 214 Welding, Ir sheet, hot cracking susceptibility I93 stable Si, at high temperature, a 154 platinum alloy, affect of variables 62 Solder, dry, Pt film for wetting, a 150 Wollaston, William Hyde, history, Pt, Pd in Solidification, Pt, Rh, Ir, Ru. in microgravity 62 astronomy, navigation 91 Soybean Oil, hydrogenation, a 151 Wood, catalytic liquefaction, a 45 Space, microgravity experiments 62 Stainless Steel, corrosion in nitric acid plants I85 Xylenes, dehydrocyclisation, on PtIAI,O, , a I05 Standard, Pt, for impurity levels in I33 Steam. electrolvsis. a I02 ZGS 5%Rhodium-Platinum. Drooerties 8 Steel, Pd distrihion in 136 ZGS Platinum, Platinum Alloys; in glass making 54

Platinum Metals Rev., 1987, 31, (4) 228