Studies in Uncatalysed and Catalysed Reactions Between Sodium

STUDIES IN UNCATALYSED AND CATALYSED REACTIONS BETWEEN SODIUM

CARBONATE AND METAL-OXIDE SYSTEMS IN THE SOLID STATE

A Thesis Presented for the Diploma

Membership of Imperial College by

K.C.Chen, B.Sc.(Amoy)

December 1950.

isp II UNOATgn1, ARB t ATAL/SED REAPT 0 *prom CARBONATE -OXIDE $XSTENs IN tm z ©L STATE. AMMO The pr eaen ork is an to reetite the reactions between metal -ox e ysteAs and sodium oar bona in the solid state nd theeffects of catalysts, particularly sodium flu ide, on these react ions. A beryl ore is decomposed with sodium erbte in the solid state. T .e reaction is etadied by X-ray r nalysis. A UAW ulna].t, is fo d the reaction. An empirical formula BeS tablished by synthesising this compound from beryllium oxide,ilica, and sodium carbonate. The presence of sodium, fluoride as catalyst has an exce ent effect in faeilitating the reaction. Chemical an .ysis shows that the beryllium and aluminium contents are ost completely converted into soluble beryllium and aluminium sulphites by concentrated sulphuric acid. The reactions between sodium carbonate and woiframite, mite, columbite, bauxite and fourteenmetal oxides in the solid state are investigated. The products of each

ref these reactions are tidied by X-ray analysis. The effects of sodium fluoride on each reaction are also inveatiated. Among these metal oxides nd oxide ores, sodium fluoride shows excellent effects on the solid actions between sodium carbonate and beryl,tungeten trioxide, and aluminium oxide. It also shows marked effects on the solid reactions between sodium carbon te with molybdenum trioxide, zirconium dioxide, titanium dioxide, chromic oxide and etannic oxide The reactions between sodium fluoride and these oxides in the solid state are then investigated. The purPose is to try to see whether intermediate compounds are produced by these oxides with the sodium fluoride catalyst in the reactions of metal oxides and sodium carbonate. No reaction is indicated between sodium fluoride and zirconium dioxide, titanium dioxide dhromic oxide, stannic oxide, and aluminium oxide under the experi. mental conditions. In the reactions between these metal oxides and sedium carbonate, sodium fluoride acts probably as a surface catalyst. Sodium fluoride reacts with tungsten trioxide and molybdenum trioxide in the maid state, and gives new compounds. The empirical formulae of these compounds are identified as Na and NaM00 With 2 WO3 P2 beryl in the solid state sodium fluoride gives a complicate& new compound. The empirical formula of this compound. is various catalysts the rea sti.on be een aodime carbonate and alnmillima amide in he aid state are also investigated. Calcium fluoride, magnesium fluoride, and sodium Chloride are just as effective as sodium fluoride. sodium borate gtyes a good effect at 760° and poorer result at 7004, as it molts at 740° This shows that the presence of a 14,44 phase accelerates the reaction. Paseo I INTRODUCTION 1 — 9

II RNAOTIONS QARBOI ATE AND BERYL IN TES STATE. Procesees for the de 4 omposition of natural beryl 10 — 12 b. Expwrim.ental methods 12 — 13 o. Uncatalysed reaction between beryl and sodium carbonate in the solid sta The reaction between beryl and sodium carbonate in the solid state with aodium fluoride as a catalyst 16 motions of the product with we te r oou.centroted sulphuric acid 16 17 Chemical, analysis of the beryl sample 17 — 20 Determination of the available beryllium and alumirivim contents in the concentryted, eulphurio acid extract . 20 22 thesis o,f the unknown compound in reaction product from the constituent xides of beryl and sodium carbonate 22 — 27

Suuunary and discussion. 28 29 CTIONS BETWEEN SODIUM CARBONATE WITH OLTIRAMITR, CHROMITE, COLUMBITR AND BAUXITE IN THE SOLID SVITE. The reaction between. wolframi e and. sodtam carbonate in the solid e. 30-33 The reaction between woiframite and sodium carbonate in the solid state with sodium fluoride as a catalyst 33 34 The reaction between e and sOdium carbonate in t state in a current of air. 34

Determination of t i ►n. in the wolframite ore. 35 7 tion of tungsten in the water extra to of the reaction products • 37 — 36 • The reaction between. chromite and sodium carbonate in. the solid state. 38-39 The reaction between chromate a carbonate in the solid state in a of air. 39 40 he reactionbeweex Ito a s um, carbonate in the ©L id ata e r sth sodium fluoride as a catalyst and of air 40 — 41

41 42 the water Sion products 42 k. Uncatalysed and catalysed reactionsbetween columbite and sodium carbonate in the solid state 43 46

1.. trncetalysed anad catalysed reactions between sodium carbonate and. a bauxite 47-49 Chemical analyeia of the bauxite ore. 49--51

Summary and discVA lion. 51--5 2 ,QNS B IB CARBONAT AND S OLID TATS. a . Alunti i um Oxide. 55 57 b. Titanium dioxide. 57 0. Zirconium dioxide. — 64 , 8tann.ic oxide. 64 67

Lead monoxide. 67 68 . Vanadium pentoxide. 69-74

Antimony trioxide. 74 77 h. Ohromic 78-79

1 bdenum trioxide. 79 85 . j, Tungsten trioxide. 85 87 k. Fczwric oxide, beryllium oxide, zinc oxide, azd bismuth trioxide. 87 90

ry and dUctuesion. 90 92

OF 'VARIOUS CATALYSTS 0 THE RRNACTIox Ai:um-cram OXIDE AND SOD= CARBONATE IN THS SOLID STATS.

,30dium u.oiidei 93 1- 95 Calcium fluoride. 96 — 97

•Ma gnee ium flu ©ride. 97 - 99 Sodium chloride. 99 Sodium, pyrophosphate. 100

Sodium borate. 101

Summary and disc o 42,-103 MECHANISMS OF SODIUM FLUORIDE N THE RRAOTIONS BETWEEN MBTAL OXIDE !STEMS AND SODIUM CARBONATE IN THE SOLID STATE . The reaction between al oxide and sodium fluoride. 05 The reaction between dio de and sodium fluoride a 105»106 The reaction between mircoolum dioxide and sodium fluoride at 570 106 reaction between a amnia oxide and um fluoride at 660 106.107 e. The reaction between chrc4 oxide and sodium fluoride at 570 107 The reaction between molybgen to oxide and sodium fluoride at 560 The reaction between sodium trioxygic fluomolybdate and sodium carbonate at 540 2 The reaction between tunic en trioxide and a odium nuorile at 560 . 112.114 on between sodium trioxylii- am4 sodium cwrbonate at 40%114-115 The reaction belween beryl and sodium fluoride at 76C 115 The synthesis of the unknown a°mounds produced in the reaetioms to en beryl and sodimm fluoride at 760 • 115-124 The reaction between the compoun 3 and Carbonate A120 #21300#3.510„, 2 #4Na sodium at 770w 124-125 125-127 VII EBNBRA1 DIS 0USSION. 128-3:34 (I) INTRODUCTION_.

The first recognition of the occurrence of solid reactions between two inorganic compounds is usually attributed to

Spring (Bull. Soc. Chia., Prance, 4495i- 4, who investigated the reaction of barium carbonate with sodium sulphate, and intensive investigations in this field have been done during the first half of this century. Reactions between alkaline earth oxides with sulphides, phosphides, carbides and silicates have been studied by Hedvall

(Hedvall and Norstron, Z. anorg. ailgem. Chem. 1926, 154,

1), and reactions between metal oxides have been studied by Jander and his co-workers (Z. anorg. allgea. Chem. 1928,

17.1 11). The thermodynamic relations have been elucidated by Tammann (Z. anorg. allgam. Chem. 1925, 142, 21). The criterion governing these reactions is that reactions in systems composed entirely of solids must be exothermic.

The course of the reactions in the solid state has been elucidated by Jander (Angew. Ohem. 1934, 47, 235). The vibration of the crystal lattice units (atoms iiIng or molecules) causes the initial contact between the two compounds, forming a molecular layer of the reaction prodnoit at the contact s e. Diffos,ion of one or both compounds through the reaotion layer propagates the reaction. Some solid reactionu are foAnd to be analogous to those in eo1ution, but some of them not obtained in solutions, usually because of insolubility of one or more reactants. The X-ray powder method has been widely applied to the investigation of solid reactions. The formation of many new compounds, which cannot be made in the wet way, has been established by this method Complicated compounds composed of four or more different kinds of stems have been synthesized by heating correct proportions of their constituents in the solid state; for instance, gohlenite has been synthesized by Jander and Petri (Z. Rlektroehem. 1938, hAtt 747) in this way and verified by the X-ray powder method. The work done on the studies of effects of catalysts on solid reactions is surprisingly small. The investigation of the effect of some metal oxides on the decomposition of potassium permanganate has been made (Roginsba, Ukra kat Zhurnal, 1928, 3, No 2, P ea. 177) It has been found by Nagai and his co-workers (J. soc. Chem. Ind. Japan (Supp ) 1934, )2 303B) that the presence of of calcium fluoride has a pronounced accelerating e feet on the thermal synthesis of calcium silicate from calcium carbonate and silica in the solid st-lte it has also been found that °alai= fluoride shows a. marked effect on accelerating the thermal eynthesio of calcium aluminate from calolum carbonate and alumina and the synthesis of calcium ferrite from calcium carbonate and ferric oxide (ibid, 1934, ALT, 693B; 1935, 35 3?4B) Studies on effects of various fluorides on thermal a thea of calcium silieate have also teen nadep and it has been found that Na AlF6 is most effective and the other fluorides are stated here in order of their effectivenese, Bar, Na2S136, 111021 CaP2 and Masi% (ibid, 1936, 12 30B). Ia these reactions the role played by the catalysts has not been investi ted. Sodium fluoride is an active compound which. forms omplex fluorides with many other fluorides. It reacts th some metal oxides to form complex fluorides; for

33.00 with magnesium oxide it forms sodium magnesium fluoride NaNg03. It has been found that in the preeence r dioxide and air, sodium fluoride gives cryolite with al 4Alum oxide and gives a complex oxyfluoride, robahlY t 'chromic oxide. has alse been found that on g siroon, niobite a beryl with sodium fluoride in the presence of sphur dioxide end air, zirconium, niobium and tentalmm and respectively, can be extracted ea double odium fluorid (Welch, j Roy Col. Sci., 1944, lb 17). The reactions between sodium carbonate with titanium dioxide and with silicon dioxide in the solid etate have been investigated (Barblan Schweiz Aline= Potroa. Mitt 1943, 23, 2951 HAttig. Bor. 1942, la, 73). Ezcep the oxides mentioned above, moat of Oxides show amphoiieric or acidic properties may also reactwtth sodium carbonate in the said state. The presence of sodium luoride may probably show distinct effects on accelerating those reactions. It was therefore decided to.investigate the effects of sodium fluoride on the reactions of sodium earbonate and amphoteric or acidic oxides. The rates of the reactions were determined by the evolution of carbon diexide. The products of both of the catalysed and ancatalys d reactions were examined by X—ray powder methods. Beryl is the only ore of beryllium available in considerable quantities It is difficult to attack Several methods of decomposing the ()relieve been developed, among these the siliootluoride prooese and sodtMm ferric fluoride process are better known industrial processes utilising complex. fluorides. In the former•process• sodium silicofluoride is employed-. The conversion of beryllia and alumina contents of beryl. into. sodium -beryllium fluoride and sodium aluminium fluoride may be probably attributed to the attack of the oxides by silicon tetrafluoride, which is produced by the dissociation of the reagent. In the latter process, sodium ferric fluoride is used •as the attacking agent. This reagent reacts preferentially with beryllium oxideand leaves alumina and silica umattocked.

In these two processes, a large amount of the attacking reagents is required. The high cost of the reagente seems to•render the processes Uneoonomio. Beryl may also be decomposed by fusing with sodium carbonate. The beryllium and aluminium contents in the ore may be converted into soluble sulphates by treating the fUsed maws with dilute sulphuric acid. The decomposition of the ore with sodium► carbonate in the solid state and the effect of sodium fluoride on accelerating the decomposition have not yet been reported. It woe therefore decided to attempt an investigation of the decomposition of beryl with sodium carbonate in the solid state using sodium fluoride s catalyst. The investigation of the decomposition of mineral ores with sodium carbonate in the solid state using sodium fluoride as catalyst had been extended to wolframite, Chromite, columbite and bauxite. These minerals Ure oomposed of simple Or mixed metal oxides and itvly be regarded as metal-oxide systems. In the investigation of the reactions between sodium carbonate and metal oxides or minerals by the X-ray powder method, the standard interplanar spacing data published by the American society of Testing Usterials are not au complete as they ought to be. It, therefore, appeared to bivriOooseary to work on the preparation and X issis of certain compounds, which they had failed to record, for the purpose of identifying products of some renctions. any explt.inations of catalysis have been given and it is not likely tht one will cover all the cruses. A theory which can be appliod to a large number of cases is the intermediate compound theory, proposed by Clement and Desermes in 1806. In such a ease, the catalyst reacts with one of the reactants forming an intermediate compound, which in turn reacte with another reactant yielding the final products and regenerating the catalyst. The intermediate compound permits the reaction t o take place in etges with low motivation energies, and hence accelerates the reaction. ,5ometimes the intermediate compound can be identified as a known compound. In other cases, however, the intermediate oompoun. mLy exist on a uurfc4ce or it may h,;ve a transitory existence only, so that it will not be identical with any known compound. In the reaction° between sodium carbonate with metal oxides and minerals, intermediate compounds sely probably be formed. Lo evidence of the existence of intermediate compounds in the re'totion mixtures cNn be obtained directly b. X-ray analypie, beaauae the quvntity of the catalyst used is so small that the weight of an intermediate compound is usually less than 5 per cent of that of the reaction product. -Ray analysis is usually not capable of detecting a constituent such a low percentage. The formation of intermediate compounds in these reactions is examined by an indirect method. The metal oxide or the mineral is heated with the catalyst, and the product to eubjected to A-ray amlysio. If compounds other than the reactants are found in this prodrAct, the product in then heated with sodium carbons e, The existence of an intermediate compound will be establiehed when the catalys t and the sodium oxyealt of the over-all reaction are found in the product of the reaction between the intermediate compound and sodium carbonate. New and complioated compounds have been found in the decomposition of beryl with sodium carbonate, in the reaction between beryl and sodium fluoride, in the reaction between molybdenum trioxide and sodium fluoride, and in the reaction between tungsten trioxide and sodium fluoride. ,For the purpose of forming clear picture of these resctions, it was attempted to synthesize these compounds from their constituent oxides and sodium fluoride By thermal synthesis these compounds were succeesfully synthesized and their empirical formulae estJblished by X-ray powder methods. The effect of sodium fluoride on the reactions of sodium carbonate with metni oxides and with minerals is studied in this thesiLt. For a better understanding of the effects of varioun ca,t lyets on the reaction between metal oxides and sodium eirbonate, an investigation of the effects of calcium fluoride, magnesium fluoride, sodium chloride, sodium pyrophosphate= and sodium borate was made on one of the reactions of sodium carbonate and metal oxides.

The reaction between aluminium oxide and sodium crirbonate was adopted for this purpose, as sodium fluoride showed an excellent effect on this reaction. 10

SQLID SWATH. (a) 2rooeasee for the Decomposition of ie tura1 Beryl. t years beryllium has become increasingly important, in particular in the preparation of alloys and in nuclear research. The extraction of this element is complicated by the difficulty of attacking beryl and the separatiOn of the beryllium from the accompanying aluminium. Beryl is the only beryllium care available in considerable quantities. It is an aluminosilicate of the empirical formula 3Be0, A1203, 6si02. Its detailed structure has been given by Wahl (Z int, 1927, 66 433). Beryl can be decomposed by fusing Lt in a 0-lined electric furnace at not leas than 1500-1600° The reaul.t in sass reacts read14 with concentrated sulphuric acid, beryllium and alumi ium being converted into partly hydrated sulphates. Sodium silico f ,uori de is used as an attacking reagent of beryl. The ore is fused at 850° entered at 650° with equal weight of sodium silicofluoride; beryllia is converted into sodium beryllium fluoride and alumina into artificial lite. Sodium beryllium fluoride is separated from the relatively insoluble _cryalite by exxtrsact with boiling water. Sodium ferric fluoride (Na 0) is also used as an attacking reagent of b In this process the ore is made into briquettes with the theoretical amount of sodium ferric fluoride required to convert the beryllium oxide content of the ore into sodium beryllium fluoride (Na 2l3 and heated for half an hour at 750°. The soluble sodium beryllium fluoride is leached fram the insoluble alumdma and silica of the ore and the ferric oxide formed as * reaction product. On fusing beryl with two parts by weight of sodium carbonate at 900-1200° and leaching the fused mass with dilute sulphuric acid, the beryllium and aluminium contents are converted into soluble sulphates. intering processes are usually preferred because: (a) the reaction vessels may be lined with a Cheap refractory like fire-clay instead of expensive graphite in the fusion processes; (b) the products are in the form of a friable mass and hence can be more easily treated. As no attempt has yet b en'made on the investigation of the sintered process between beryl and sodium carbonate, was decided to investigate whether sodium fluoride had 12

a good effect on the process ;o what extent would the eactiona proceed and what were the mechanisms of the reactions.

(b) 4XPerimental a eth The beryl ore used in the experiment was supplied by Gregory Bottles of Fulham. a white in colour and of very good quality. The sodi carbonate and sodium fluoride employed were the pure form supplied by Hopkin and Williams Ltd. The beryl was groand and dried in oven at 1400 and the carbonate was heated to 350 for three hours in order to remove the water of crystallization immediately before the preparation of mixtures. The mixtures were prepared by grinding the reactants in an agate mortar for twenty minutes ke sure that the reactants were thoroughly mixed. A Gallenkamp nichroms-wound furnace carrying a silica tube was employed for heating purpose, and it was supplied from the 230 volt A.O. mains through a transformer. The . temperature measurements were made with a chromel-alumel thermocouple connected to a Siemens pyrometer indicator. The end of the thermocouple ww a placed in the lower centre of the annular space between the furnace tube and the urnace. 13

gnesia boats were employed in theas experimenter it was found that they were unattaoked up to about 7600 by the sodium carbonate and sodium fluoride.

X-Ray analysie by the powder method was adopted in the

study of the reactions. A Metropolitan4riokers "Raymax" set was used for the prOduotion of X-rays. This was of the continuously evacuated type fitted with do-mountable anticathodes. A 9-cm. diameter powder camera of the type designed by Zradley, Lipson and 2etoh was used.

Specimen° were prepared by grinding the entire reaction miles to a fine powder in an agate mortar and filling in small Lindemann glass capillary tubes. The films were measured to the twentieth of a millimetre with a film measuring rule sUPPlied by Hilger and Watts Ltd. For the purpose of identification, the card index (published in 1946 by the Joint Committee of the American Society for X-ray and electron Diffraction and the American Society for Testing arz,terials) and the collection of 1000 patterns (published in 1938 by anawalt, Rinn and /travel) were usually consulted.

(a) U catalysed Reaction :between. Beryland Sodium Carbonate

in the Solid State

Equal portions by weight of beryl and anhydrous sodium carbonate were thoroughly mixed. The mdxture was placed in a magnesia boat and heated in electric furnace at 700-76e for three and a half to four and a half hours. It was then cooled and weighed. The heating was repeated until the constant weight was practically reached. The product was a white sintered mass with 19% lose of weight The details of the change in weight are tabulated below:

g. beryl 10.002 7.751 g. sodium carbona 10.002 7.751

Temperature Time Decrease ights (g) (hour) (1) (2)

700-740 3.5 1.218 0.937 700-740 4.0 0.354 0.256 700-740 4.0 0.253 0.217 700-735 4.5 0.290 0.210 700-745 4.5 0.287 0.232 700-745 4.5 0.216 0.198 700-740 4.5 0.211 0.158 700-745 4.5 0.183 0.129 700-740 4.5 0.147 0.130 700-740 4.5 0.143 o.106 700-760 4.5 0.147 0.129 700-760 4.5 0.106 0.086 700-760 4.3 0.101 0.095 700-755 _ 4.5 0.0$9 0.086 700-760 61.0 3.745 2.969

x-Ray analysis of this product showed the practically complete decomposition of beryl. The radiogram did not give any evidence of the presence of sodium aluminate,

sodium silicate, sodium aluintni silicate or any of the constituent oxides of beryl.The reaction produc might be a tare compound such as sodium alumirium beryll silicate, sodium beryllium silicate or sodium beryllium aluminatet or even a mixture of these compounds.

(_d) The Reaction betwepn. Beryl and din Carbonate in the Solid _State with Sodium Fluoride as a Cataltak. Mixtures were prepared by mixing equal portions by weight of the beryl and sodium crbonate and one tenth by weight of sodium fluoride. The mixtures were placed in magnesia boats and heated in an electric furnace at 700-745°. The boats were cooled and weighed after every three and a half hours heating. Constant weight was reached after the fourth heating. The produot was a white sintered was with a. 24 loss by weight. The details of the change in weight are shown below; beryl 7.751 7.752 sodium carbonate 7.752 7.752 sodium fluoride 0.775 0.775 Temperature Time Decrease(;.) in weights ( g . ) ( h01,119 700-745 3.5 2.852 2.789 700-745 3.5 0.349 0.432 700-740 3.5 0.163 0.133 7EE0215...... ----0.018 0.033 700-745 14.0 3.382 3.387 16

Th produ st gave a se radiogram as that of the uact lysed reaction, except some additional lines showing the presence of an excess of sodium fluoride.

(e) Extractions of the product'with Water and Oo

SulPhuricAl4d. A 1-g. sample of the product of the sintered reaction of beryl and sodium carbonate with fluoridecatalyst was leached with a 200-ml and a 100-ml. portions of water. The residue was dried at 1300, cooled and weighed. It was found to be TV. The extract was evaporated to dryness. By X-ray analysis it was found that sodium silicate and sodium fluoride were present in the extract. The residue gave a X-radiogram of the unknown compound and showed the absence of the sodium fluoride. A 1-g. portion of the product was moistened with 2 ml. of 1 1 conc. sulphuric acid. At first a pastes was formed, and it became a friable mass a little later. The mass was broken with a rod and leached with two 20-mi« portions of warm water. The residue wan separated, ignited and wed. a ed. It was foand to be W. The extract was evaporated to dryness, treated with water and filtered. The filtrate was evaporated again to dryness and ignited. photographs were taken of both residue and the solid recovered from the filtrate, InterPretation of these X -radiograms showed that the water-insoluble uliknown compound was completely destroyed, and silica in the form of ex eristobalite was the Only compound found in the reeidue. Sodium sulphate, beryllium oulPhete, and alumi,i1 sulphate were recovered fram the filtrate. These experiments indicate that the unknown compound, although insoluble or very slightly soluble in water may be converted into soluble beryllium and aluminium sulphates by conaentrat ed sulphuric aoid.

(f) Chemical Analysis of the Beryl sample. The previous experiment showed that the beryl sintered with sodium carbonate gave a water insoluble substance, which in turn might be converted into soluble beryllium and aluminium sulphates by cane sulphuric acid. It was decided to determine to wint extent the beryllium and aluminium content of the beryl might be converted into available sulphate . The first step was to analyze the beryl sample. In the determination of berylIia, alumina and silica contents in the beryl, the mineral. wee usually fused with 18 ten times of its weight of sodium rbona e, and the fused mass was dissolved lute hydrochloric acid. Silica was separated by dehydrating with hydrochloric a oid and determined by treating with hydrofluoric: acid. Aluminium and beryllium contents were precipitated together as drated oxides with ammonium hydroxide and then separated from each other by either 8 --12ydroxyguinoline method or sodium carbonate fusion. method. Owing to the feet that the eodiwa carbonatefusion o beryl gave variable extractions of beryllium QM the ore, a. H. Osborn (Analyst 1947, 72., 475) carried oat a fall investigation on the time, ratios and temperatures the factors which affected the sodium carbonate fusion of beryl. It was found that the ratio 2:1 gave reliable results over all ranges of temperature from 800 to 12000 and over all periods of heating. Higher ratios gave very variable results showing low beryllium extraction. iihe conoluaion was drawn that the excess alkali caused formation and precipitation of the a, hydroxide of beryllium, which, being insoluble in acid, was lost with the silica when it a removed by filtration. he use of hydrochloric acid for extracting the melt 19

and d drating the silk a was rejected. This reagent might e the formation of insoluble beryllium oxychloride which would be removed with the silica and thereby lost. Perehloric acid was adopted for this Purpose. 0.5g. of the sample was fused in a platinum crucible with lg. of "Amine sodium carbonate at 9000. The fUsed mass was dissolved in a dilute solution of perchloric acid. Silica wes dehydrated by evaporating the solution on a sand bath to dense white fumes. It was then filtered and washed. The silica content was determined by igniting

ai+d +ben treatiiir the filters „with cone. sulphuric acid and hydrofluoric acid in the usual way. Alt +- and beryllium hydroxides were precipitated from the filtrates by the addition of dilute ammonium hydroxide with phenol red es indicator. The precipitate was washed, dried and ignited. The mixed oxides were fused with 5 grams of sodium carbonate at 8700 for 3 hours and the fused mass was leached with water. The fusing and leaching ware repeated, and the beryllium oxide was ignited and weighed. To the filtrstes dilute nitric acid was added until the precipitete redissolved. The aluminium content was oipitated as hydroxide and determined as oxide. The results are listed as follows:—

g. beryl sample 0.5030 g. SiO2 0.3284 g. Do0 0.0701 g. AI2 03 0.0872 3/82 65.29 Be° 13.94 -1, A120 3 18.63

The results showed that the beryl sample was one of high qualit a its empirical formula was 3Be0, Al 0 61102

(AO Determination of the. Available Beryllium and A111 Contents in the 0onoentrated sulphuric Acid Extract, A 1,g. portion of the sintered reaction product of the beryl and sodium carbonate with sodimh fluoride as catalyst was weighed and spread out on a platinum dish, 10 ml. of la concentrated sulphuric acid. were added, and the mass was thoroughly mixed with a platinum rod. 100 ml. of water were cautiously added. Silica was filtered off, ignited, and d atermi.ned by the treatment with hydrofluoric acid. The filtrate was evaporated an a sand—bath until white fumes came off, and filtered again. The silica separated on dehydration was determined in the usual way. 23.

Aluminium and beryllium ions in combined filtrate were precipitated as hydrated oxideo with dilute ammonium hydroxide and ignited to Oxides.

Bery3.3.ium oxide was then separated from alismirrium de by fusing twice with 5-g. portion of sodima carbonate. Aluottnium was determined from the filtrate by double precipitation with ammonium hydroxide and ignition. The analytical results were as followsz g sample 1.0002 1.0002 g. SiO2 from first treatment 0.3789 0.3772 g. sic) 2 from dehydration 0.0079 0.0086 g. S10 2 0.3868 0.3858 g. mixed oxides 0.1954 0.1949 g. 380 0.0831 04832 g. Al 0 2 3 0.1119 0.1120 g. si0 2 in the sample (calculated) 0►3925 0.3925 g. Me0 in the sample (calculated) 0.0838 0.0838 g. d12 d3 in the sample (calculated) 0.1120 0.1120 SiO2 converted by lot treatment 96.5 96.1 SiO converted b dehydration 2.0 2.2 SiO converted 98.5 98.3 Be0 converted 99.2 99.3 converted Al 03 99-9 100.0

It thus shown that when one gram of the produot was treated with 10 ml. of 181 sulphuric acid and extra et e4 with 100 ml. of water, the beryllium and aluminium contents 22

were almost completely converted to ol ble sulphate and silicon content was nearly completely separated out as sili ca

(h) 2,yntheeiu 0f the Unknown Compound in the Reactio duet from the Constituent Oxides of .Beryl and Sodium Carbonate. The uncatalysed and catalysed reactions of beryl and sodium carbonate in the solid state gave the X—radiogram of a. water insoluble compound. No standard data were available from A.S.T.M. index or elsewhere for identifying this compound. It was attempted to synthese this unknown compound from the

constituent oxides of beryl and sodium carbonate. I GS Planned to start with the sintering of the following mixtures and the examiring of the X radiogram of each product: and NA CO (A) BeO, Al 03' 3i02 2 B007 Al 0 and /la CO (B) 2 3 2 3 BeO, SiO and Na CO 1 (0) 2 23 SiO2 and Na 00 (D) Al2 03 3' The cos osition of the es were so adjusted that the oxides w the BUM as in the natural beryl and that sodium carbonate was in exosss. The mol ratios of the constituents of these four mixtures were as faiewss 23

Be0 A120 33.0

3 1 6 7 3 3. 2 3 6 . 7 0 6 7

The aluminium oxide and sodiumcarbonate used for preparing these mixtures were of " nalar" grade; beryllia was of pure grade, and silica was a pure precipitated one. All of these were supplied by Hopkin and Williams Ltd. These Chemicals had previously been heated in electric furnace at 7600 for at least four hours. The mixtures were heated i.n electric furnaceat 760 for 72 hours. Mixtures A, B and C were still in powder form, while mixture D had slightly sintered. appreciable change in weight was shown from mixture B. In mixtures A, 0 and D the weights of sodium carbonate and that of carbon dioxide evolved were in the ratio of 7 mole t o 4.15, 3.21 and 3.05 m018 - respective X-Ray analysis of the reaction product of B showed the existence of the original components with no evidence for the occurrence of any reaction. The X-radiogram of the reaction product of A ah ved the existence of sodium sill et 24 sodium aluminium oxide and the unknown, compound which was produced by sintering beryl with sodium carbonate. The S--radiogram of the reaotion product of C ahowed the ence of the unkno compound and sodium carbonate. ay analysis of the product of D showed that sodium silicate, silica, alumina and sodium carbonote were the constituents; sodium s lumi.nium to NaAlSiO and sodium aluminate were probably also present. By examining the radiograms of the products of mixtures A, C and D, it was obviously seen that every line on the film of the product of A was found in either of the film of the product of C or that of the product of D. Based upon this fact and the existence of the unknown compound in the products of A and C, it could be concluded that no compound of sodium aiumwtua beryllium silicate was formed by tering the constituent oxides of beryl with excess sodium carbonate and the unknown compound was a sodium beryllium silicate. Another mixture B wo prepared by wing Be0, 8i02 and

Na CO x in the ratio of to 6 to 3 mole as modified tire C from the fact that three seventh of sodium carbonate was sed in the reaction. The mixture. was 25 heated to 7800 for 88 hers. It was heavi tared; and an evolution of a theoretic- 1 aulo t of carbon dioxide was showed by the change in weight X-Ray analysis gave the evidence of the existence of the unknown compound and an excess of silica. Owing to the presence of an excess of silica in the product of B, the preparation of a mixture containing smaller amount of silica was attempted. An equimolecular mixture F of be llia silica and sodium carbonate was o prepared and heated at 770 for one hundred hours; an evolution of 80,1 of the theoretical amount of carbon dioxide was recorded. The product vivo a heavily sintered M06. X-Ray analysis showed the predominance of the unknown compound and traces of sodium silicate. The mixture F was prepared and heated to 8800 for four hours. The product was a friable mass, and a theoretical amount of carbon dioxide was given off. The X-radiogram of this reaction product showed the existence of the unknown compound, and no additional lines indicating he presence of sodium carbonate, silica, or sodium silicate were found. It was difficult to say whether an excess of b ryllia was present or not, as the interplanar spacing 26

data of beryllia were almost completely interfered with by those of the unknown compound. Another mixture, G, was then prepared by mixing beryll, silica and sodium carbonate in the mol proportion of . 3 to 4 to 4. It was heated at 6600 for four hours. An evolution of the theoretical amount of carbon dioxide was recorded. X Ray analysis showed that the unknown compound and sodium silicate. were the components of the reaction product. From the results of these experiments it may be concluded that the nknown compound formed by sintering the beryl and sodium carbonate has the empirical formula Ha BeSiO 2 4 A 19-.cm. photograph of this compound was taken with Cu IL radiation for the purpose of determining the structure of this compound. The structure was so compl that the lines could not be indexed. The interplanar spacing data were as follows: 27

'"' .-... d I d I

, 1 , .. .. "' 4.033 0.6 1.418 0.8 3.489 0.4 1.358 O.J. 3.376 0.2. 1.336 0.1 3.195 0.2 1.307 0.1 3.044 0.2 J..227 0·4 2.789 0.3 1.215 0.1 2.462 1.0 l.1t1 0.1 2.)52 0.6 1.176 b·2 2.256 0.1 1.156 0.2 2.172 0.4 1.145 0.1 2.09'1 0.6 1.125 ChI 2.007 0.4 1.116 0.1 l.g63 0.1 J..097 0.5 1.890 0.1 1.04-7 0.1 1.841 C>-2 I.OO) 0.1 1.811 0.2 0·972 (').1 1.737 0.5 0.g63 0.1 1.687 0.1 0.946 0.1 1.659 0.1 0·928 0.3 1.638 0.1 0·913 0.1 1.600 0.3 0.903 0.-1 1.553 0.2 0.841 (hI 1.524 0.1 0.818 0 .. 2 1.47; 0.2 0.796 0.1, 1.456 0,,1 28

41) Summary and Disaupsion.

Both the uncatalysed end catalysed reactions of beryl and sodium carbonate in the solid state gavv an unknown product. It was insoluble in water, and could be quantita ively converted into soluble beryllium and aluminium sulphatee by concentrated sulphuric acid. The plan of identifying this unknown product was to synthesize from the oxide constituents of beryl and sodium carbonate. This appeared to be the only method for identifying a new compound obtained from the decomposition of an ore. The results fully justified the plan adopted. No evidence of the existence of any aluminium compound was found in the X.-radiogram of the reaction product of beryl and sodium earbonate. The aluminium compounds formed in this reaction might be amorphous substances or they were interfered by the beryllium compound. It had often been found that the resolution of lines of a particular constituent of a (Amass:mixture was difficul Sodium fluoride showed an exoellent result in facilitating the decomposition of beryl with sodium carbonate. Although no evidence of existence of intermediate compounds was found in the X—radiogram of the reaction product it was 29

difficult to determine whether or not any intermediate compoUni was formed in the reaction. It is well known that it is very often not possible to detect less than of a constituent. It is interesting to fir the role played by. the sodium fluoride in the decomposition of beryl with sodium carbonate. This investigation will be described later. The sodium fluoride used in this reaction seemed still

in excess. No attemp owever, had been made to determine the minimum amount of the catalyst. required. With sodium fluoride as catalyst beryl could be compl.€ tely decomposed by sintering with sodium carbonate at 760° in fourteen hours, and the beryllium and aluminium contents could be quantitatively converted into available sulphates. In view of these facts, this sintered reaction can perhaps be considered as a good process of decomposing the refractory beryl ore. REACTIONS BETWEEN BERYL & Ne2CO3 IN THE SOLID STATE

UNCATA LYSED

e0 zb 3b ab sb 6.40 TIME IN HOURS 30

(III) REACTIONS BBTW ODIUM CARBOBATB WITH WOL MIT4,

CH ITB COLtt ITB AND BAUXITE IN 'THB SOLID A B.

(a) The Reaction between oiframite and podium _Carbonate in the Solid State.

framite is isomorphous mixture of ferberite ferrous tungstate, and hibnerital sanganous tan Late. It is one of the chief minerals of tungsten. The element is generally obtained by fusing wolframite ore with sodium carbonate to convert to sodium 'Wimpbate. The sodium tungstate is then extracted with water. The solution is digested with hydrochloric acid to precipitate tungstic acid. It was attempted to investigate the reaction between wolframite and sodium carbonate in the solid state and the effects of sodium fluoride and air on this reaction.

A wolframite ore supplied by MUrex Ltd. was ground to 200 mesh and dried at 140° overnight; sodium carbonate of "Analar" grade was heated to 670° for four hours.

Pal Portions by weight of .the ore and sodium carbonate were thoroughly mixed and tranaferred into a magnesia boat. The boat was heated in electric furnace at 620-670° for four hours. It was then cooled and weighed. The heating was repeated until there was no appre eb e decrease in weight. The product WOS a reddish brown hard mass and heavily sintered. The lose of weight on heating was listed as follows:

g. wolframite 7.003

g. sodium. carbonate 7.008

Temperature Decrease in weight (hour (S.) 620.665 4 0.880 620-670 4 0.035 620-665 4 0.090 620.667 4 0.058 620-670 4 0.053 620-670 4 . 0.016

620-670 24 1.132 "..1•1111.

It was predicted that sodiam tungstate would be one of the components of the reaction product. As so far no interplanar spacing data of anhydrous sodium tungetate for reference were available, it was decided to prepare the anhydrous salt both by heating the hydrated salt and by fusing an equimolecular mixture Na 24w0.2a 2 0 at 140° of tungsten trioxide and sodium carbonate. 9 an. X—ray photographs were taken for the anhydrous salt prepared and the reaction product of wolfremite and sodium carbo te. 32

The interplanar spacing data were listed as follows:

Reaction product of wolframito Anhydrous sodium and sodium carbonate. tungstate prepared. d 1 7.523 0.2 6.341 0.1 5 487 0.6 5.209 0.5 4.505 0.1 4.532 0.2 3.864 0.4 3.884 0.4 3.278 0.2 3.309 0.3 3.199 0.9 3.193 0.8 2.923 0.1 2.731 1.0 2.735 1.0 2.516 0.1 2.509 0.1 2.432 0.1 2.241 0.1 , 2.247 0.3 2.075 0.1 2.079 0.1 2.4507 0.1 ',2.000 0.1 1.853 0.7 1.854 0.8 1.747 0.6 .14747 0.6 1.655 0.2 1.653 0.1 1.606 0.6 1.608 0.7 1.537 0.3 1.536 0.5 1.474 0.2 1.470 0.1 1.439 0.4 1.437 0.6 1.386 0.2 1.387 0.2 1.274 0.3 1.274 0.4 1.246 0.1 1.215 0.6 1.216 o.7 1.184 0.6 1.184 0.7 1.136 0.1 1.139 0.1 1.125 0.1 14111 0.1 1.083 0.1 1.072 0.3 1.073. 0.4 1.051 0.4 1.051 0.4 1.016 0.1 1.009 0.2 1.000 0.2 1.000 0.2 0.985 0.1 0.98.6 0.1 0.971 0.2 '0,971 0.1 0.954 0.1 0.955 0.2 0.937. Oil 0.929 0.3 0.9 0.2 0.9 0.1 33

T -radiogram showed the complete decomposition of ate and the formation of anhydrous sodium tungetate in the reaction of sinteringlframite with sodium

carbonate 'No existence of any iron and manganese compound was found in the X--radiogram. 2t was probably due to the poor crystallization of the iron and manganese compound and the interference of sOdlum tungetate, which had a high scattering power.

Ch) The Reaction between Wolframite and odium Carbonate in the solid state with Sodium. Fluoride as a Catalyst The previous experiment was repeated with a mixture containing equal portions by weight of wolframite and sodium carbonate and 3.4, by weight of sodium fluoride as a catalyst. The product was a reddish brown heavily sintered hard maes. The decreases in weight . on heating are shown in the following list:

g. wolframite 7.001 g. sodium, carbonate 7.001 g. sodium fluoride 0.490

Tempera Time hour Decreasesinweighrar ' 4 620..660 4 0.900 620-667 4 0.032 620-660 4 0.034 620-670 4 0.059 624-675 0.035 620 675 20 1.060 34

Ray an yeis of this reaction product howed the presence of the same product as in the pr ding experiment.

( ci The Reaction between Wolframite and. Sodium rhona 9 in the Solid state in a Currant of Air. The sintered reaction of wolframite and sodiwn carbonate was repeated, and air was bubbled through concentrated sulphuric acid and sodalime into the electric furnace during the heating. A reddish brown heavily sintered hard mass was obtained. The results of the reaction was tabulated as follows: g. wolframite 7.003 g. sodium carbonate 7.003

Temperature Time (hour) De crease in wt . g)

620.660 4 1.212 620.660 4 0.039 620-660 4 0.035 620.660 4 0.027 620-660 16 1.313

The X—ray analysis showed that the product was the anhydrous sodium tungst te and gave no evidence of the existence of an iron or manganese compound. 35

(d) Determination og Tungeten and Iron n the Wolframite Ore. One gram of the wolframite sample was digested with 100 ml. of 1.16 hydrochlerio acid and the solution evaporated to about 10 ml., 10 ml. of conc. nitric acid were added, and the volume reduced to about 5 ml. The residue was taken up with 50 ml. of boiling water and 5 ml. of 5 einchonine solution added. After standing overnight the insoluble substances were filtered and washed with cinchonine washing solution until, free from iron. The insoluble substances were treated with 5 ml. of strong ammonia and washed with ammonia wash solution. The filtrate was evaporated until most of the ammonia was expelled. 10 ml. of cone. hydrochloric acid and 5 ml. of cinchonine solution were added. After standing, the precipitate was filtered and washed thoroughly with cinchonine washing aolation. The filter was ignited .in muffle furnace at 800. The residue from the ammonia extraction was ignited and the silica content was determined by treating with hydrofluoric( acid. The fixed residue was then fused with 4 grans of sodium carbonate. and the melt was leached with water. The 36 trace of niobium and tantalum compounds in the extract was removed by treating the extract with 40 ml. of a freshly prepared slightly ammonical scaution of 1.6 g. of magnesium sulphate and 3.2 g. of ammonium chloride in 40 ml. of water. After the removal 0f niobium and tantalum, 20 g. of ammonium chloride and a freshly prepared solution of 0.6 g. of tannin in 12 ml. of het water were added to the extract at 50 . Dilute hydrochloric acid was dropped in until the solution became acid towards litmus, then 5 ml. were added in excess. 5 ml of ainchonine solution were added. The tungsten comPound recovered was filtered and ignited to tungatic oxide. The residue from the sodium carbonate fusion was dissolved in dilute hydrochloric acid and the solution was combined with the filtrate from the oinchonine precipits ion. The base metallic ions in this solution were removed by saturating the solution with hydrogen sulphide at the hydrogen ion concentraction of 1 M. The filtrate was freed from hydrogen sulphide by boiling, and treated with ammonia. The hydrated oxide precipitated was filtered, washed, and dissolved in hydrochloric acid. 37

The manganese ion in the solution was separated from iron by Brunckle basic acetate method, and the iron content

was determined as Pe2 03 The results of the determination were given as follows: g. sample 0.9985 0.9985 g. W03 0.6757 0.8751 g. 8102 0.0189 0.0183 g.. Fe2 0.1658 0.1662 W0 67.69 3 67.63 8102 1.89 1.83 16.60 Fe2 0 3 16.65

(el Determinatioa of Tungsten in the Water a of the Reaction Products. 1—g. portions of the reaction products were leached with 200.-m1. portions of water and filtered. The residues were leached again with 100m1. portions of water and filtered again . The combined filtrates were evaporated to about 50 ml., and 10 ml. of concentrated hydrochloric acid and 5 ml. of ciachonine solution were added. After standing overnight, the precipitates were filtered washed thoroughly with ainchonine washing solution, and ignited at 800°. The water insoluble residues were reddish brown in colour and highly magnetic. X—Ray analysis showed the 38

existence of magnetite. The results of the determination of the 'hinge en contant0 in the water extracts were tabulated as follows:

g asap e g. WO3 W * W in obtained ealcula ed the extract am101.111.101••••.1komm.

1:MA81m1/tied 0.9999 0.3309 0.3678 89.97 reaction 0.9996 0.3305 0.3677 89.87 • motion, with 1.0000 0.3029 0.3527 85.88 NAY 1.0005 0.3030 0.3529 85.86 Reaction with 1.0006 0.3438 0.3727 92.26 air 1.0012 0.3447 0.3730 92.42

(f), The Reaction between Chromite and Sodium Carbonate in the Solid State. Chromite is one of the maabers of the spinel group of mineral, consisting essentially of ferrous oxide and chromic oxide. It is the chief source of chromium and chromium compounds. To prepare ferroohrOme, it is directly reduced by carbon. To prepare chromium compounds, it is usually fused with sodium carbonate in the air, and then the sodium chromite is extracted with water. The reaction between dhromite and sodium carbonate in the solid state had not been reported. An investigation on this reaction and on the effects of sodium fluoride wa a therefore aade. 3,

A mixture was prepared by mixing equal portions by weight of a ground end dried ehromite ore and sodium carbonate which had previously been heated to 670° for Four hours. The mixture was placed in a magnesia boat and heated in an electric furnace at 620-680°. After every four-hour heating, the boat was cooled and weighed. The product was a pale brown powder. The results were shown as follows:

g. chromite 7.001

g. sodium carbonate 7.002

Temperature Time (hour) Decreasein wt.(g.)

62o 680 4 0.359 624-665 4 0.004

X-Ray analysis of the reaction product showed the existence of the original reactants. No evidence of the occurrence of any reaction was found.

(g The Reaction between Chromite and sodium Carbonate in the Solid State in a Current of Air. The previous experiment was repeated, and slow current of dry air was passed into the furnace during the heating. The product was a yellowish-brown powder. The decreases f weight ere shown in he following t

. chromite 7.005 sodium carbonate 7.003

TemPeratare Time (,b, Decrease g.) 624-675 4 0.463 620-680 4 0.076 620-680 4 0.064 620-690 4 0.027 620-690 16 0.630

X—Ra r analysis showed that unreacted, chromite and sodium carbonate were the constituents of the reaction product.

(h) The Reaction between Chromite and Sodium Carbonate

in the Solid state:.: uoride as a Catal at

and in a Current of Air.

The previous experiment was repeated.; 7f, by weight of sodium. fluoride based. upon the weight of chromite was used. as a catalyst, and a current of dry air was allowed to pass in. The product was a pale brown hard. mass, heavily sintered. The results were tabulated as follows: 41

g. chromite 7.010 g. sodium carbonate 7.002 g. sodium fluoride 0.491

Temperature Time (hour) Decrease in wt.(g.) 620-675 4 0.461 620.-680 4 0.054 60m.680 4 0.099 620..690 4 0.031 620-690 16 0.645

X—Ray analysis of this reaction product showed the predorirance of chromite and a trace of sodium carbonate.

O.) Determination of Chromium in the 0hromite Ore. 0.5 g. of the ore was Awed. with 5 g. of sodium peroxide in a heavy—walled porcelain crucible. After cooling the melt was extracted with water. The residue was filtered and washed until free from chromate. The filtrate viLls concentrated by evaporation and acidified with dilute sulphuric acid. The silica separated on acidificatiou was filtered and washed thoroughly. The filtrate was diluted up to 200 mi. in a volumetric flank. A 50—ml. portion of the filtrate was pipetted out. 50 ml. of 0.I.N. ferrous ammonium sulphate, 5 mi. of syrupy phosphoric aoid, and 8 drops of sodium diphenylamine salphonate indicator were added and the solution dilated

to 200 ml. and titrated with standard potass dichronat solution. The analytical results were as follows:

sample g. 0r20 Or

0.5010 0 «2299 45.87 0.5000 0.2305 46.10

CJ) Determination of Ohromi!ne in the Water J xtsracts of the. Reaction Productui 1-g. portions of the reaction products were extracted with two 100-ml. portions of water. The residue was ignited and weighed. The filtrates were acidified and diluted up to 250 ml. 50-ml. portions were remoyed with a pipette, ferrous ammonium sulphate solution, phosphoric acid and indicator were added. The solution was diluted and titrated with standard potassium diohromate solution. The results were tabulated as follows:

Or recovered Residue in the extract n the product Vrmalalysed p.6 50.99 rea cation 0.6 51.22 Reaction with 14.1 48.89 air 14.1 48.79 Reaction with 15,6 47.88 NO and air 15.6 47.80 43 tk) neatalyeedang. Catalysed Reactions between Columbite and Sodium Carbonate in the Solid State. Columbite is a niobate of iron containing usually some manganeee and tantalum. Its general formula is (replin)0. (141,Ta)205. This ore is usually decomPosed by fusing with eau tic soda which converts the niobium and tantalum partly into sodium niobnte and tantalite and partly into iron niobate and tantslate. The sodium salts are practically insoluble in water containing free alkali. The mixed iron and sodium salts are separated from the excess alkali by extracting the melt with water and filtering. The residua is then digested with hot hydrochloric acid which leaves a fairly white mixture of niobic and tantalic acids. These acids are then dissolved in hydrofluoric acid and the solution treated with requisite amount of potassium fluoride. With properly regulated concentration, practically all the niobium will remain in solution and the tantalum preeipitatea out as the double fluoride ligTaP7. The oxides of these elements are readily produced from the double fluoride by treating their solutions with ammonia. The earth acids precipitated may be ignited into oxides. 44

As the ileac ion between r o umbite and sodium carbonate in the solid state has not yet been reported, it was decided to investigate the reaction in the solid state and the effect of sodium fluoride on this reaction. A pulverized columbite ore supplied by Murex Ltd. was dried in oven at 1400 and an "Analar" sodium carbo to was heated at 660° for four hours. Two mixtures containing equal parts b weight of the ore and sodium carbonate were prepared. To one of these was added 71; of sodium fluoride (on the weight of the ore) as a oatalyst. These mixtures were placed in magnesia boats and heated side by side in an electric furnace at 640-690°. They were cooled and weighed atter every four.,hour heating. As the reaction proceeded rather slowly at 690°, the 0 temperature was raised to 790 . The product of the uncatalysed reaction was a reddish brown powder and that of the oatalyaed reaction was red in colour and heavily sintered at 794°• The results of heating were tabulated as follows: 45

g. columbite 7.001 7.000 g. sodium carbonate 7.003 7.000 g. sodium fluoride 0.490

T erature Time Decrease in weights (g.) (hour) Uncatalysed Catalysed 640-675 4 0.449 0.611 640-685 4 0.057 0.089 640-683 4 0.063 0.046 740-790 4 0.127 0.144 740-780 4 0.060 0.102 740-7&L 4 O.o53 _0051

24 0.809 1.051

X-Ray analysis of the reaction products showed the complete. decomposition of cOlumbite, and give the evidence Na 0.10) 0 of the existence of sodium niobium oxide 2 2 5' Besides the lines of sodium niobium oxide there were a few lines showing the presence of exoess of sodium carbonate. SOdium tantalum oxide hid the same interplanar spacing data as sodium niobium oxide, and tantalum was contained in the columbite ore. It might be, inferred that sodium tantalum oxide W48 also one of the components of the products. The interplanar spacing data were as follows: 46

0.1••••••••••••mln•mlg...... Product of a 0.Nb 0, Na 0.Ta 0 Unost. reaction 2 2 2 2 5

5.491 0.1 3.890 1.0 3.883 0.9 3.88 0.8 2.960 0.2 2.737 1.0 2.745 1.0 2.74 1.0 2.357 0.2 2.244 0.1 2.247 0.2 2.24 2.174 0.2 0.4 1.946 0.? 1.943 1.0 1.94 0.9 1.741 0.7 1.735 1.0 1.736 1.0 1.586 0.8 1.583 1.0 1.585 1.0 1.488 0.1 1.374 0.4 1.373 1.0 1.372 1.0 1.296 0.4 1.294 1.0 1.293 1.0 1.230 0.4 1.230 1.0 1.227 1.0 1.174 0.1 1.173 0.7 1.169 0.9 1.123 0.1 1.123 0.7 1.121 0.9 1.078 0.2 1.078 0.9 1.077 0.9 1.040 0.4 1.038 1.0 1.036 1.0 0.974 0.7 0.971 0.8 0.944 0.1 0.943 0.9 0.941 0.9 0.917 0.2 0.914 1.0 0.915 1.0 0.868 0.9 0.847 1.0 The composition of the oolumbite ore was given by Murex Ltd. as follows: Nb/Ta205 66.0 4P TS25 9.5 Nb205 56.5, 1,9 TiO2 4.0 11 1.9 1 116'2°3 26.4 • 8n02 0.16 47

(1) Unicata;Yeed and Catalysed Reactions between podium Carbonate and a Bauxite Ore in the solid State. Bauxite is a elay—Iike aluminium hydroxide. It varies widely in composition owing to intermixture with quartz-- sandy clay and iron hydroxide It shows no indication of crystalline structure, being always compact or earthy, and often having a concretionary structure. Occasionally microscopic crystals of diaspore, gibbsite and boehmite can be distinguished optically. It is thus largely a mixture of colloidal aluminium hYdroxides with various iron hydroxides, clays, and the crystalloids — diaspore and gibbsite. Bauxite is commonly used in the manufacture of aluminium. It is, converted into sodium aluminate by digesting with caustic soda solution under pressure. Sodium aluminate is then separated from iron oxide by lixiviation, and aluporlitun hydroxide is precipiUted by passing carbon dioxide into the sodium aluminate solution. Alumina obtained by igniting the hydroxide is then dissolved in the fused cryolite and electrolysed. An attempt of investigating the reaction between bauxite and sodium carbonate in the solid state was made. The effects of sodium fluoride on this reaction were also

investigated. A bauxite sample supplied by Gregory Bottley of Fulham was ground to 200-mesh and dried at 1400 overnight. Two mixtures were prepared by mixing equal parts by weight of the bauxite and sodium carbonate which had been previously heated a.t 700 0 for 4 hours. 7 Of sodium fluoride based upon the weight of the ore was added to ane of the mixtures and mixed thoroughly. These two mixtures were placed in magnesia boats and heated in an electric furnace at 720-7700. They wore then cooled and weighed after every 4-hOur heating. The product of the uncatalysed reaction was a brown sand-like substance, and that of the catalysed reaction was a pale yellowish brown heavily-sintered mass. The decreases in weight were tabulated in the following: it. bauxite 7.011 7.008 g. sodium carbonate 7.001 7.001 g. sodium fluoride 0.491

emperat a Time Decrease in weight (g.) (hour) Uneatalysed Catalysed 720-745 4 1,617 2.309 720-760 4 0.298 0.140 720-770 4. 0.202 0.060 720-760 4 osi, 0.078 720-770 16 2.198 2.587

X-Radiograms of both of the reaction products gave the evidence of the existence of 04-carnegieite (BaAlSiO4) and sodium silicate,and showed no signs of the existence of sodium aluminate. It had been expected that the sodium aluminate would be the &lief ,product of the reactione. The reaction products of th bauxite ore and sodium carbonate consisted mainly of NaAlSiO4 and Na2SiO3, inst ead. of NaA1O2. It was obvious that a high percentage of ilica was present in the ore. An X-ray photograph of the ore was taken. The X radiogram was identical with that of .4-quarts, and gave no evidence of the presence of bauxite, diaopo e gibbsite- and iron compounds.

Chemical Analysis of the Bauxite Ore. The sample of the bauxite ore was analysed b, chemical process. A half-gram portion of the ore was ignited over a blast burner for the determination of loss on ignition. One gram of the sample was digested with 60 ml of an acid mixture of sulphuric, hydrochloric and nitric acids, and evaporated until white fumes came off. The silica separated was filtered and determined in the usual way. The filtrate was diluted to 250 ml. in a volumetric A 100-el. portion of this solution was pipette& otat end hydrated oxides were precipitated with ammonium hydroxide and ignited to 11000 as mixed axides. The iron content in the solution was determined volumetrically by reducing with stannous chloride solution and titrating with standard potassium dichromate solution, using sodium N—diPhenylamine sulphonate as indicator. Ths titanium content in the solution was determined colorimetrically by comparing the intensity of the yellow colour of that produced by adding hydrogen peroxide to the solution with that developed from. a standard titanium sulphate solution.

The analytical results were as follows: g. sample for ignition 0.4928 0.4926 g. loss on ignition 0.0553 0.0547 g. sample for analysis 0.9895 0.9969 g. Si02 0.3957 0.3999 g. mixed oxides 0.1916 0.1911 0 g. Ps2 3 0.3482 0.3514 g. TiO2 0.0066 0.0066 14 loss on ignition 11.2 11.1 35.02 39.99 40.12 1, mixed °xi es 48.40 47.91 Pe2 03 35.20 35.25 TiO2 0.67 0.66

A1203 by f 12.53 12.00 51

The resulte of- cilemical analysis agreed with that

reached, by X—ray analysis. The silica was the chief constituent of the ore. Prom the fact that the percentage of alumina in the ore was extremely low, the plan of extracting the products with water and determining the aluminium content in those extracts was abandoned:

(n) Summary and Discussion. On heating with sodium carbonate in the solid state, the wolframite gave sodium tungetate and magnetite as their products. The reaction proceeded to such an extent that about 9( of the tungsten content was found in the water extract of the reaction product. The presence of sodium fluoride showed no effect on the reaction, and the tungsten content in the water extract was slightly lower than that of the uncatalysed reaction. Passing of the air into the farnnce showed, a marked effect on the reaction of the wolframite and sodium carbonate in the solid state, and it gave a slightly higher percentage of tungsten oxide in the water extract. It was probable that the passing of the air gave an oxidation of the manganese and iron

components of the woiframite rd hence facilitated the

decomposition of the ore. remit° was an extremely refractory mineral. It was very difficult to decompose by heating with sodium carbonate in the solid state. Although the passing of air showed a marked eftect an the reaction, the decomposition of the ore was still very low. Sodium fluoride gave no appreciable effect on this reaction. It was interesting that a bauxite ore containing a high percentage of silica on heating with sodium carbonate in the eolid state yielded NaAlSiO4 and sodium silicate as their products. It was different from a high grade bauxite ore, as that ore would give sodium aluminate on fusing with sodium carbonate.

By calculation from the analytical data and the changes of weight the reaction between the bauxite ore and sodium carbonate and that between the columbite ore and sodium carbonate were found to be practically complete. Sodium fluoride showed a marked effect only on the first heating of the mixture of columbite and sodium carbonate and that of bauxite and sodium carbonate, but ve no appreciable effect on subsequent heatings. In these reactions sodium fluoride acted probably as a surface catalyst. REACTIONS BETWEEN WOLFRAMITE & Na2CO3 IN THE SOLID STATE 10

WITH AIR

UIVCATA1-YS ED •

WITH HO

12 16 20 TIME IN HOURS

REACTIONS BETWEEN COLU M BITE

10 & Na2CO3 IN THE SOUD STATE at 640-685* at 740-790'

CATALYSED

1 UN CATALYSED

4 8 12 16 20 24 TIME IN HOURS REACTIONS BETWEEN CHROMITE & Na2CO3 IN THE SOLID STATE

8 12 TIME IN HOURS

CATALYSED

IS UNCATALYSE z

10 REACTIONS BETWEEN BAUXITE & NazCO3 IN THE SOLID STATE

12 16 TIME IN HOURS 53

(IV) REACTIONS BETfl3EN SODIUM CA N,TE AN DISTAL ()AID

IV THE SOLI➢ STATE. Oxides of metal ions with small positive charge are lly basic, whereas oxides of non—metals end even of metals in the higher oxidation states are uswilly The properties of the oxides are dependent upon the site of the atom of the element other than oxygen, and on its charge. Aluminium oxide, titanium dioxide, zirconium dioxide, stannic oxide, lead monoxide, vanadium pentoxide, antimony trioxide, and zinc oxide show amphoteric properties; molybdenum trioxide and tungsten trioxide show weak acid properties. These oxides on fusing with sodiam hydroxide or carbon,ite forte sodium oxysalts. Chromic oxide is a basic oxide, but Chromic hydroxide may Get as a week acid forming Chromites. Beryllium oxide is umattaoked even by fusing with aodium carbonate, though beryllium hydroxide is readily soluble in excess of alkali. Biumuth trioxide is a basic anhydride but acts as a weak M acid under certain circamstance . It diesolves in very concentrated potassiaa hydroxide solution on warming. Some of these oxides give different salts with sodium carbonate et different temperatures. It was decided to investigate the reactions between

these oxides and sodium carbonate in the solid atte and

investigate the effects of sodium fluoride on these re2ctions. Pure oxides supplied by Hopkins & Williams .ltd. had

previously been dried in oven at 140u overnight, and pure sodium mirbonate was heated to 760 0 for 4 hours to remove the water of crystallization. Mixtures of these oxides and sodium carbonate were prepared in proper proportions. Mixtures containing. the oxides and Sodium carbonate in the same proportions and a certain amount of sodium fluoride were also prepered. The quantity of sodium fluoride used in each case was based upon the relative weight of the oxide and the carbonate, ranging from 8 to 15% of the weight of the oxide. The mixtures were ground in an agate mortar for fifteen to twenty minutes to make sure that they were thoroughly mixed. Magneeia boat and a mullite tube were employed in these experiments for the purpose of the heating. They were found to be =attacked up to about 8000 by the minute amount of sodium fluoride. The effects of sodium fluoride were inves ted by 55

heating side by side two mixtures containing the same amount of oxide and sodium carbonate. To one of these sodium fluoride was added as catalyst.

The products of both the mixtures we.re in each case examined by X.ray analysis.

(a) The Reaction between. Aluminium Oxide and Sodium Carbonate in the Solid State. There are two principal crystalline varieties of alumina pc-Al2O3 and r-A1 2 03. The former is hexagonal. rhombohedral insoluble in acids; and the latter is cubic, hYgroscoPio soluble in acids. The Change from t-41203

to bk..Al 2O3 occurs at about 850. Strongly calcined alumina dissolves with difficulty in acid or alkalis. On fusion with alkali hydroxide or carbonate, it .c'n be converted into soluble sodium altuninate• An attempt was made to investigate the reaction between alumina and sodium carbonate at 760°. Both the alprOlop and the sodium carbonate were of "Aralar" grade. Two equimolecular mixtures of the oxide and sodium carbonate were prepared. To one of these 1,0 of sodium fluoride

(based on the weight of aluminium oxide) was added and the powder mixed thoroughly. The two mixtures were placed 56 in magnesia boatel and heated in an electric furnace at 680_7620. They were cooled andweig)asid after every 4-hour heating. The product of the entalysed reaction was a white sintered mass, and that of the unca talysed reaction was a white powder. The decreases in weight of the mixtures. were tabulated as follows:

g. aluminitua oxide 6.000 6.000 go aodtmm carbonate 6.002 6.002 g. sodium fluoride 0.601 mol oxide/mol carbonate 1/1 1/1

Temperature Time Decrease in wt. Mel CO evolved (hour) (6.) per a 1 oxide Uncut. Cat. tincat. Cat. 680.760 4 0.170 0.688 0.068 0.276 oa-760 4 0.111 0.224 0.045 0.090 680-758 4 0.076 0.129 0.030 0.052 680-762 4 0.062 0.111 0.025 0.045 680-760 4 0.061 0.101 0.025 0.040 680.762 20 0.480 1.253 0.193 0.503

X-Ray analysia showed the evidence of the exiatence of sodium almminate, aluminium oxide and sodium cE,rbOnate in the products of both of the uncatalysed and catalysed reactions. Sodium fluoride showed an excellent effect on this reaction, in particular during the first 4-houre0 heating. As seen from the loss in weight, the catalysed reaction proceeded in the first heating four times as fast as the 57

alys ed change.

(b) The Reaction betweext Titanium Dioxide and odtwn Carbonate in the Solid State. Titanium dioxide is amphoteric in that it feebly basic properties and is also oidie in forming titanates. It has been reported that sodium metatitanate and orthoti an— ate were formed on fusing titanium oxide with sodium carbonate. An investigationof the reaction between the oxide and sodium oarbonate in the solid state and the effect of sodium fluoride on the reaction was conducted on the line adopted for that' of aluminium oxide and sodium carbonate, described previouely. Two mOleoalar proporti.ona of wail= carbonate were mixed with one of the oxide. The mixtures were firstly heated at 500-548°. As the reaction was very slow at that temperature, they were then heated at 680-770° in the subsevenb heatings. The product of the unmatalysed reaction was a white powder, and that of the catalysed reaction was a white heavily— sintered hard mass. The decreases in weight were tabulated

as follows: 58

g. titanium dioxide 4.002 4.001 g. sodium carbonate 10.608 10.606 g. sodium fluoride - 0.599 Mol oxide/mol m,, rbonate 1/2 1/2

Temperature Time Decrease in wt. Mel CO evolved (hour) ) per m4.1 Oxide Utical. Cat. Tjnoat. Cat. 500-548 4 0.131 0.462 0.059 0.210 680.758 4 1.192 0.825 •0.541 0.374 6813.758 4 0.233 0.557 0.106 0,253 680.765 4 0.200 0.175 0.091 0.079 680.770 4 0.044 0.184 0.020 0.084 20 1.800 2.203 0.817 1.000

In the sintered reactions only one molecular proportion

of carbon dioxide was van off by one molecular proportion

of titanium dioxide, hence the product wa probably sodium metatitanate, Ka2TiO3' As no interplanar spacing data

of eodiwxi motatitanate ware available for reference, it

was decided to prepare the salt by fusing an equimolecular mixture of the oxide and sodium carbonate in a platinum

crucible et 900°. An evolution of 88.64 of the theoretical amount of carbon dioxide was recorded in the preparation

of sodiulawatatitanate. g. T JO g.Ka OD3 g.002 evolved .002 calculated 0.9999 1.3257 0.4880 0.5508 59

X—Ray photographs of the fusion product and the sintered— reaction products were taken. It was found that sodium mstatitanate and excess of sodium carbonate were the. components of the product of the uncatalyaed reaction; sodium mstatitanate sodium carbonate and sodium fluoride were the components of that of the catalysed- -reactiOn.

The interplanar spacing date of the sodium.metatitanate sample prepared and the reaction product are listed below:

Product of titanium Sodium metati anate dioxide and sodilim prepared. carbonate at 77

7.160 0.7 7.102 0.6 3.989 0.5 3.942 0.3 3.077 0.1 x 2.960 0.5 x 2.698 0.1 2.605 0.7 2.599 0.5 x 2.531 0.3 2.461 0.3 2.477 0.5 x 2.362 0.5 2.213 1.0 2.322 1.0 x 1.948 0.5 x 1.879 0.4 x 1.708 0.1 x 1.669 0.1 x 1.620 0.4 1.569 0.6 0.7 1.485 0.2 1.1.498581 0.2 1.448 0.2 1.440 0.2 1.411 0.1 1.403 0.1 X 1.383 0.2 1.348 0.2 1.351 0.5 0..306 0.2 1.298 0.4 1.269 0.1 1.274 0.2 1.250 1.256 0.1 1.194 0.1. 1.144 0.1 .119 0.3 1.108 0.1 1.104 0.1 1.087 0.1 1.086 0.1 1.069 0.1 1.055 0.2 1.055 0.1 1.039 0.1 1.035 0.2 1.025 0.1 1.025 0.1 1.008 0.1 1.007 0.3 0.996 0.3 0.980 0.1 0.981 0.1 0.947 0.1 0.917 0.3 0.903 0.1 0.865 0.2 An 6steri,sk indicates that the lines were due to soditua carboxlate.

The reaction between titanium dioxide and. sodium o carbonate at 770 may therefore be represented by the following equation:

Na 003 sommimsolloommowl.M.4. 0 + CO Ti02 3

( a) The Reaction between Zirconium Dioxide and. Sodium.

Carbonate in the Solid State. Zirconium dioxide is amphoterio in that it acts both as an acid. and as a bas e. The alkali zircoz:otes are forraed either by adding a solution of a zirconium salt to alkali— lye or by melting zirconium dioxide with alkali oxide, 6].

hydroxide or carbonate.

T. Hiortdahl (Ccinpt. Rend. 1865, 6I, 175) found that

when equimolar proportions of ziroonia and sodium a rbonate were kept at a dull red heat for 9 hours ell the available

carbon dioxide was evolved, nd a crystalline hygroscopic mass remained. This mass he used to be sodium metasirconate,a Zr0 If an excess of sodium carbonate 2 3 was used, he found that the molar proportions of carbon dioxide evolved per mol tulle of zirconia were

Dull Bright !sitar/ White redness redness heat heat

Hours 23 5.5 5.5 6 1.2 1.45 1.92 CO2 1.41

Hence he concluded that sodium orthozirconate was formed.

An investigation of the ;a/action between the oxide and sodium carbonate in the solid state and the effect of sodium fluoride on this reaction was conducted in the same way as in the investigation of that of aluminium oxide and sodium carbenate. Two melecular'proportions of sodium carbonate were mixed with one of sirconia. The mixtures were heated at 500-548° on the first heating; and at 60-750° on subsequent h tings, as the reaction

proceeded slowly at 500-548°. The product Of the uncutalysed reaction was a white powder, and. thi t of the catalysed reaction was a white heavily-sintered hard mass. The decreases in weight were as follow g, zirconium dioxide 5.002 •5.003 g. sodium carbonate 8.620 8.620 g. sodium fluoride 0.500 mol oxide/Mol cirbonate 1/2 1/2

Temperature Time Deorease in wt. Mel. •CO evolved (hour) (g.) per ma oxide Uncat. Cat. _lancet. eat. 500-548 4 0.118 0.176 0.066 0.098 680-733 4 0.3C4 0.271 0.170 0.151 680.750 4 0.357 0.391 0.200 0.219 680-720 4 0.130 0.191 0.073 0.107 680.730 4 0.140 0.289 0.078 0.162 680-718 4 0.026 0.14? 0.015 0.080

24 1.075 1.465 0.602 0.817 No interplanar-spacing data of sodium zirconate were available for references Sodiva metazirconate was therefore prepared by fasing an equimolecular mixture of zirconium oxide and sodium carbonate in a platinum crucible at 900°.

A theoretic1 amount of carbon dioxide was evolved.

..11111011•10.11•••..111.0,.•...101. g.ZrO g.Wa 0 3 g.002 evolved g.002 2 2 calculated 1.0022 0.8631 0.3534 0.3576

X-Ray photographs of sodium metazirconate and the

reaction products were taken. The x.rediograms bowed that sodium metaziroonate and zirconium dioxide. were the constituen a of the pro&acts of both the catalysed and uncatalysed reactions. The interplanar spacing data of sodium motaziroonate and the reaction product are listed below:

Product of zirconium Sodium metaz ir corm t e dioxide and sodium prepa red carbonate at 7500

5.491 o.6 5.895 0.5 4.751 0.2 3.673 0.1 3.141 0.3 2.951 0.3 2.988 0.1 2.813 0.2 2.755 0.1 2.750 0.4 2.646 0.6 2.636 0.5 2.413 0.1 2.313 1.0 2.311 1.0 x 2.249 0.1 x 2.176 0.3 2.128 0.2 x 2.015 0.2 1.944 0.2 1.933 0.2 1.882 0.3 1.881 0.1 1.798 0.4 1.789 0.5 1.65.3 0.7 1.650 0.7 1.619 0.7 1.616 0.7 1.552 0.4 1.550 0.4 1.506 0.1 1.416 0.3 1.411 0.3 1.391 0.4 1.391 0.5 1.362 0.2 1.363' 0.2 1.325 0.5 1.323 0.5 64

1.243 0.1 1.234 0.1 1.208 0.2. 1.204 0.2 1.157 0.4 1.156 0.4 1.112 0.1 1.116 0.1 1.092 0.1 1.080 0.1 1.080 0.1 1.068 0.1 1.063 0.1 1.052 0.2 1.043 0.3 1.043 0.1 1.027 0.5 1.026 0.1 1.010 0.2 1.009 0.1 0.993 0.1 0.984 0.1 0.963 0.2 049 63 0.1 0.943 0.3 0.941 0.1 0.936 0.2 0.93/ 0.1 0.923 0.1 0.921 0.1 0.905 0.1 0.897 0.1 An asterisk indict es that lines were due to zirconium dioxide. The reaction betyfeen zirconium dioxide and sodium carbonate at ?50 © may be represented by the following equation:

r02

(d) The Reaction between Stannic Oxide and Sodium OarbOnats in the Solid State. Stannic oxide forma soluble matastannates on fusing with alkalis. anti. rind Movawietz (h. anorg. Chem. 1938, 2 272) found that sodium orthostannate, Eten s formed on heating stannic oxide with Na20 41 '4 in o 4t 700() The reaction between stannic oxide and sodium carbonate in the solid state was inTestigated. Two equimoleoular mixtures of the oxide and sodium carbonate were prepared. To one of these ws added 10,4 Of sodium fluoride (on the weight of oxide) . TThese two mixtures were placed in magnesia boats and heated side by side in an electric furnade at 550-620° for four hours. No reaction was indicited between stannic oxide and sodium carbonate at 6200. The temperature was therefore raised to 680..765 on subsequent heatings. At this temperature the rear on proceeded very quickly The reaction almost complete within 4 hours with sodium fluoride as catalyst. The products of both the catalysed and uncat lysed re lotions were white sintered masses. The decreases in weight were as follows: est *stannic oxide 9,002 9.001 g. sodium cerbonate 6.300 6.301 g. sodium fluoride 0.900 DM. oxideAol. carbonate 1/1

Temperature Time Decrease in wt M01.000 evolved (hour) 010 per mtl.oxide lnaet . t. Uncat. Oat. 550 4 0.015 0.018 0405 0.007 680.735 4 1.745 2.375 0.667 0.908 680.765 4 0.465 0.046 0.178 0.018 680-765 4 . 0.210 0.02.5 0.080 0.010 680-758 4 0.117 0.045 20 2.5j52 ;464 0.9:75 0.907 ••••••••=10••••14.00. ►6

metasta te. was prepared by fusing an equimolece of stannic oxide and sodium carbonate. 96.5E the theoretical amount of oarbon dioxide was evolved.

0 g.Na200 02 evolved .002oalcalated

1. 046 1.0005 0.4008 0.4154

X..aadiograms of the sod ium metastanrte prepared were almost completely identical. with that of the reaction products. It showed that sodium metastannate was the only produot of both the uneatalysed and catalysed reactions. The interplanar spacing data were as follows:

rodizct of SnO and Sodium metastannate 1152 003 at 765°2 PrePared X 5.380 0.5 5.330 0.5 2.708 0.5 2.706 0.5 2.603 0.5 2.597 0.5 2.279 1.0 2.275 1.0 2.104 0.2 2.096 0.2 1.809 0.2 1.807 0.2 1.780 0.2 1.774 0.3 1.640 0.7 1.636 0.7 1.590 0.7 1.588 0.7 1.524 0.4 1.525 0.4 1.405 0.3 1.405 0.3 1.373 0.4 1.373 0.5 1.359 0.3 1.358 0.3 1.305 0.5 1.307 0.6 1.197 0.2 1.089 0.1 1.073 0.2 1.075 0.3 Of

67 1.054. 0.2 1.053 0.2 1.034. 0.6 1.034 0.9 1.010. 0.6 1.010 0.9 0.993 0.2. 0.993 0.3 0.970. 0.1 0.958 0.2. . 0.958. 04 0.952 0.2. 0.952 , 0.3 . 0.929 0.4. 0429 . 0.6 0.920 0.2 0.920. 0.3 0.907 O.) . 0.107. 0.4

tion between stannic oxide 'and sodium oarb at 7 may be represented b following equations n0 2 Na CO ) Na2 SnO 3 + CO

The React betwInt Lead lionoxid in the Solid State,

ad monoxide is amphoterl.c. It soluble in acids and alkalis forming plumbous salts and pituabil s respectively. Alkali .astaPlumbAtes may be formed by basing lead dioxide with alkalis. Zintl and Novawiets (Z. anorg. angels. Chem. 1938, al, 272) found that Tia4Pb04.14a20 was formed on healing lead dioxide with Zia 20 in vacao at 400°. An attempt was made to investigate the reaction between lead monoxide and sodium carbonate in the solid state. Two estaimolecular mixtures of lead monoxide and sodium carbonate were prep.red. To one of these 8', of sodium fluoride (based on the weight of the, oxide) eras added. 68

These mixtures aed in magctesia boats and. heated in an electric furnace at 550.62 o. The twerature was raised to 680 760 in the subsea ie t heatingm One of these mixtures showed'aninoreasi in weight on the second heating; this was probably dao to the partial oxidation of the lead compound to a higher valanoy state. The products of both the catalysed and unoatalysed reactions were yellowish orange. The change in, weight was as follows: g. lead monoxide 10.001 10.002 g. sodium carb©a te 4.753 4.751 g. sodium fluerid 0.800 Mol oxide/Mol carbonate 1/1 1/1

perature Time Change weight (hour) VI:catalysed Catalysed 550-625 4 —0.274 -0.277 680-738 4 1.0.156 0.525 680-760 -0.01 .4.015 12 0.137 •..o.877

X—Ray analysis showed the existence of =reacted lead monoxide and 'a tree of lead dioxide in the products of both of the unoatalyaed and catalysed reactions There were no additional lines indicating the presence *f compounds other than lead monoxide and dioxide. (f) Reactions bet rra ear Vaaadiu pentoxde Carbonate in the sold State. Vanadium pentoxide is amphoterisa. When it s as an acid, a series of salts vanadates — is formed. It has been reported that sodium erthovanadate was produced by fusing onemeecular proportion of vanadium pentoxide with three of sodium carbonate; sodium pyrovanadate was obtained by melting one molecular proportion of vanadium► pentoxide with two of sodium carbenate The reaction between vanadium pentoxide and sodium carbonate in the solid state has not yet been reported. An attempt was therefore made to investigate the products formed by heating vanadium pentoxide with en excess of sodium carbonate in the solid state over various ranges of temperature, and investigate the effects of eodtws fluoride on these reactions. Two mixtures were prepared by ►icing one molecularr r►portion of vanadium, pentoxide with three of sodium Carbonate. To one of these 10% of sodium fluoride (based en the weight of the oxide) was added as a catalyst. The Product of the uncatalyeed reaction %um a white powder , and that of the catalysed reactionn was a white heavily. 70

sintered hard mass. The changes in weight as on 02

g. vanadium pentoxide 5.001 5.001 g. sodium carbonate 8.761 8.751 g. sodium fluoride 0.500 Mel oxide/Pol Carbonate 1/3 1/3

• Temperatur Time Decrease tn wt. Mel 000 evolved (hour) (a.) per m31 oxide truce t cat. Dnoat. Oat 500-538 4 2.546 2.495 2.102 2.061 500-542 4 0.313 0.092 0.258 0.076 500-550 4 0.242 0.046 0.200 0.038 500-545 4 0.181 0.149 500448 4 0.119 0.098 500-550 4 0.095 0.018 500-550 24 3.498 2.633 2.885 2.175 Notarimaramispermorariromet In this reaction nearly three molecules of carbon dioxide

were evolved by one molecule of vanadium pentoxide. This ehoffed that sodium orthovanadate was the product of this

reaction,

As no interplanar spacing data of anhydrous sodium orthovanadate were available for reference, this salt

was prepared from vanadium pentoxide and sodium hydroxide.

Two grams of vanadium pentoxide were completely dissolved

in a solution of 2.6 g. of sodium hydroxide in 20 ml.

of water. The solution was evaporated to dryness, end o the residue was then annealed at 550 71

ThirtAhovanadate sample prepared and the rez,ction products or sintering vanadium pentoxide with sodium carbonate were highly hygroscopic. The samples for ray analysis

h.d been previously dried at 1400. Both ends of the Lindemann glass capillary tubes filled with samples we re sealed. The X.radiogrema gave evidence that sodium orthovanadate was the product of the uneatalysed and catalysed reactions. The interplanar spacing data are listed below:

Product of V 0 So um orthova Na CO 2 at 55 0 prepared.

5.174 0.1 5.131 0.3 4.802 1.0 4.809 1.0 4.447 0.1 4.423 0.3 4.145 1.0 4.124 1.0 3.672 0.1 3.629 0.3 3.352 0.2 3.349 0.2 3.144 0.4 3.151 0.3 2.876 0.4 2.878 0.3 2.678 0.5 2.676 0.5 2.520 0.2 2.513 0.2 2.381 0.1 2.375 0.2 2.267 0.2 2.267 0.2 2.086 0.1 2.034 0.3 2.031 0.2 1.946 0.1 1.870 0.1 1.790 0.1 1.783 0.1 1.612 0.1 1.616 0.3 1.352 0.1

Two. mixtures were prepared in the sans way as the previous experiment. They were heated firstly .at 350-398° • As the reaction proceeded very.slowly at that temperature* they were then heated t'420 4800 in subsequent heating® . Both the eatfilysed and uncatalysed reaotions gays a mixture of blaok and white powders as their products. The changes in. weight of these mixtures were as follows:. g. vanadium. p ent oxide 5.000, 5.000 g. sodium carbonate 8.751 8.750 g. sodium fluoride 0.501 Mol oxide/mol carbona 3 1/3

emperatura Time Decrease 2401 00 evolTed (hour .) 'per m81 oxide Uncat Uncat. Cat 350-398 4 0.204 0.248 0.168 0.205 420478 4 0.615 0.707 0.508 0.554 420'480 4 0,106 04210.088 0.100 420-475 4 4.068 0.082 0,056 0.068 16 0.993 158 0.520 0.957

In this reaction only 0moleculecarbon dioxide was evolved for one molecule pentoxide? The reaction might have been a coJltplete reaction with sodium motavanadate as its product* or 421 incomplete reaction with sodium pyrovanadate or sodium orthovanadate as its proftot.

X-Ray analysis d that sodi a etava date end

excess of sodium carbonate were the co,mponents Of the product of the uncatalysed reaotion; sodium mstamanadate, sodium carbonate amd sodium fluoride were the components of that of the catalysed reaction. The interplanar spacimg data of sodium metalsaadate were obtained by

taking an X.. ray photograph of this compound supplied by Ropkta & Williams Ltd., The data are listed below*

Product of V2 0'and Qd um tayamadate . Na2 CO3 at 480o

4.997 0.3 4.733 0.1 3.424 0 1 3.423 0.2 3.254 1.0 3.263 1.0 3.144 0.3 3.152 0.7 x 2.960 0.4 2.830 0.1 2.778 0.5 2.783 0.7 . 2.685 0.3_ 2.678 0.5 x 2.600 0.3 x 2.539 0.3 2.454 0.1 2.440 0.1 2.404 0.1 x 2.361 0.8 2.300 0.2 2.251 0.3 2.247 0.2 2.180 0.4 2.175 0.2 x 2.021 0.1 1.950 0.2 1.952 0.1 1.912 0.1 x 1.871 0.3 1.860 0.1 1.810 0.3 1.804 0.5 74

1.748 O*2 1.505 1.505 0.4 1.453. .0.1 1.456 0.2 1.422 . 0.1 1.417 1.372 0.1 1.328 . An asterisk indisates t the lines were due to sodiumearbonstp,. Vanadium pentoxide givesdifferentproducts with sodium cartmna4e at different tempera totes w At a temperature

not higher than 5000, the pr act is motavansdate In this case one molecule of sodium carbonate is required for each molecule of oxide, and the reaction is 3 Na2 00 3 2N8 V0 CO2. At a tempo ture of 500-554 the roduct is sodium orthe— vansdate. In this case three m01 miles of sodium carborte

are required for each molecule of oxide, and the reaction may be represented by the following equation.:

V 0 CP3 2Na TO 0 3Na2 3 Sodium: ortbO1ranadate absorbs moisture easily and probably gives hydrated s alts. LAD The Reaction between Antimo T aide a oainm Carbonate in the Solid S tate.

Antimony trioxide is amphoteric* It olves in

concentrated acids, but only basic salts can ordinarily 75 be crystallized from the solution. It dissolves in alkalis forming salts of antimenous acid. 8alts of meta ortho and pyro—acids are known. It has been reported that sodium metaantimonite is obtained by melting antimony trioxide with an excess of sodium carbonate, and isolated by washing away the excess of sodium carbonate. When antimony trioxide is used With alkali hydroxide in the air, the antimOnite is oxidized.

An attempt was made to in resti,gateeation between antimony trioxide and sodium carbonatein the solid stets. The investigation was conducted in the same way as in the previous experiments. Three moleoular proportions of podium carbonate were mixed with one of antimony trioxide. The products of both the uncatalysed and catalysed reactions were white and hard The changes in weight were as follows:

g. antimony trioxide 7.004 7.005 g. sodium carbonate 7.660 7.602 g. sodium. fluoride 0.701 MO1 oxide/Me carbonate 1/3 1/3 Temperature Time Decrees w Mal. 00 e lved (hour) (61) per al.oxide Tincat • Cat. Uncet. Cat . 500-580 4. 0.325 0.325 0.309 0.309 500-.560 4 0.003 0.000 0.003 0.000 550-620 4. 0-41 0.013 ooplo 0.013 12 0.338 0.338 0.322 0.322

Sodium metaantimoiiite wee prepared by fusing equimolecu ar

ProPortious antilaony trioxide and aodium carbonate in a porcelain cruoible. 9.4 of the theoretioal amount of rbon dioxide was evolved.

.8b a 00, 41.00 svol d .aced 2 013 4 2.000 0.7217 0.2824 0.2996 x-Bay analysis showed that aodium metaant mvnite and sodium carbonate were the products of both of the unzatalysed and catalysed reaction. The interplanar pacing data are listed below:

5.239 0.3 5.214 0.6 3.942 0.2 3.925 0.3 2.993 0.3 2.965 0.3 2.29 0.5 2.623 0.9 539 0.1 355 0.7 2.348 0.9 2.259 03 385 03 2.176 0.1 1.982 0.2 1.973 0.2 1.870 1.0 1.867 1 0 1.812 0.4 1.717 0.1 688 0.2 1 . 683 0.2 619 0.1 1.619 0.2 584 0.4 1.583 0.3 77

1.546 0 3 1.523 0.6 1.522 0.5 1.500 0.2 1.501 0.1 1.466 0.8 1.466 0.7 1.418 0.1 1.377 0.1 1.374 0.1 1.338 4.1 1.322 0.4 1.321 0.4 1.307 0.2 1.306 0.2 1.281 0.2 1.281 03 1.265 0.1 1.264 0.1 1.253 0.1 1.252 0.1 1.208 0.1 1.209 0«I 1.184 0.5 1.182 0.5 1.171 0.2 1.169 0.1. 1.155 0.2 1.155 0.2 1.149 0.1 1.058 0.2 1.060 0.3 1.048 0.3 1.033 0.1 1.032 0.2 1.016 0.1 1.015 0.2 1.000 0.4 0.999 0.5 0.988 0.2 0.982 0.3 0.984 0.4 0.961 , 0.1 0.959 ' 0.1 0.953 0.1 0.953 0.935 0.5 0.935 0.7 An a teriak indicates that the lines were due to aodiam carbonate. The reaction between antimony trioxide and sodium carbonate at 6200 may be rePrasented by the following equation: 81320 32a CO 3 Sb02 C°2` This reaction pro ded to an extent f about 3Qa at 6200; though it w s almoat completed by fusion. 78

) The Reaction between:o Oxide and Sodium. Carbonate U. the Solid Stet A.

Chromic oxide is a basic anhydride; and, on being dissolved in a ads, yields chromic compounds. After being strongly ignited it becomes insoluble in acids.

On fusing with an oxidising flux such as sodium *arta:late and pote.ssium nitrate or sodium peroxide, sodium .ohromate is _formed. The reaotion. between chromium oxide and sodium

corbonate in the solid state was investigated. The

experiment was conducted. in the same way as in the previous

caaes. Two .molecular proportions of sodi= carbonate were mixed with one of the oxide, and the amount of sodium fluoride used was one tenth of the weight of the oxide.

The product of the uncatalysed reaotion was yellowish green in colour, slightly sintered, and t1 t of the

catalysed reaction was a, yellowish green bard mass. The

changes in weight were as follows: 79

g. chromium oxide 6.001 g. sodium carbonate 8.405 g. sodium fluoride 0.601 Mol oxideimol carbonate 1/2 1/2

Decrease

500.-5 4 0.424 0.730 500-552 4 0.229 '0.149 500-558 4 0.203 0.165 500-555 4 0.121 0.100 500-553 4 0.089 0.067 oftemlawroonomm 500-560 20 1.066 211

ray analysis it was found that the of

both the unaatalyaed aril catalyaad re on consisted of sodium ch.romate chromic oxide, and sodium carbonate.

It was obvious that the trivalent shramium was et! to h.exavalant by oxygen in the air, and the ove

reaction may be represented

Or 0 + 4Na 00 + 30 4Na 4. 400 3 As indicated by the change in weight, the tncatalysed

and catalyzed otions Proaeeded to an extent of 67 and

77: 1 reape cti

(11 The Reaction between U.01Ybdiamam Trioxide as d Sodtmm Carbonate in the Solid State.

molybdenum trioxide forms normal molybda tee 0ri fcsing

with basic oxides or rbonates. These normal salts are in general unstable, soluble ter, and tend to form polymolybdates.

An investigation vas made of the reaction between this

de and toodium carbonate in the solid state. Two equimoleoular mixtures of molybdemtm trioxide and sodium carbonate were prepared To one of these was added 10% of sodium fluoride (based on the weight of the oxide).

TheY were heated at 500-560° and cooled, and weighed after every four hours. Both the products (of the catalysed and uncatalysed reactions) were white powders.

The changes in weits were ae follows:

g. molybdenum. trioxide 8.100 8.102 g. sodium carbonate 6.002 6.000 g. sodium fluoride 0.811 1101 oxide/m.01 carbonate 1/l 14

emperature Time Decrease in w Mof 000 evolved per m11.1 oxide 1 e • Unmet. Sat. 500.545 4 2-208 2.363 0.892 0.955 500-554 4 0.082 0.070 0.033 0,028 500-552 4 0.059 0.026 0.024 0.011 500-554 2.459 0.949 0.994

o X.-ray data of anhydrous sodium molybdate were

ble for refs renoe • it was prepared by dissolving twa grams of molybdenum.:tr, oxide in a sonoentrated solution of 1.1 g. of sodium hydroxide in 10 ml. of water. The oxide dissolved completely on. warming The solution was evaporated to dryness and the residue was annealed. L-Ray analysis showed that anhydrous sodium molybdate was the product of the unoatalysed and catalysed reactions between molybdenum trioxide and sodium oarbonate at 500-554°. The interplanar spacing data were listed as follower

Product of M00 sodiummolybdate 1a2003 at 554° prepared.

5.197 0.5 5.197 0.3 3.879 0.1 3.189 1.0 3.187 0.8 2.724 1.0 2.727 1.0 2.240 0.1 2.241 0.1 2.077 0.1 2.078 0.1 1.847 0.7 1.849 0.7 1.742 0.6 1.743 0.6 1.600 0.8 1.602 0.9 1.531 0.4 1.531 0.4 1.432 0.5 1.434 0.5 1.383 0.4 1.384 0.4 1.269 0.3 1.271 0.3 1.213. 0 6 1.213 0.7 1.181 0.8 1.182 0.8 1.135 0.3 1.134 0.3 1.070 0.5 1.070 0.6 1.049 0.5 1.049 0.6 0.997 0.2 0.997 0.3 0.984 0.1 0.984 0.2 82

0.969 0.3 0.969 0.3 0.953 0.3 0.953 0.3 0.927 0.5 0.928 0.5 0.914 0.2

The reaction between molybde trioxide and. sodium carbonate proceeded very quickly at 500-554°. It was almost completed in the firat 4—hour heating at that te.mperature even in the absence of sodium fluoride. An

Investigation of the rection at a lower temperature was thus made. Two mixtures were prepared in the same proportion as in the previou.s experim.ent. They were heated at 350-4000 The products of both the uncatalysed and catalysed remotions were white powders. The decreases in weight were as follows:

g.. maybdertuni trioxide 8.102. 8.105 g. s odium oarb ono t e 6.002 6,002 g. sodium fluoride - 0.810 Mol (mid efinol carbonate 1/1 1/i

era tare Time Decrease in wt. viol CO evolved (hour) (p•) per m 1 oxide meat. _ cat. Uneat. Cat. 350-398 4 0.613 0.910 0.248 0.368 350-400 4 0.170 0.190 0.069 0.077 350-392 4 0.078 0.089 0.032 0.036 350-400, 4 0.027 0.065 04023 0.026 350-400 16 0.918 1.255 0.372 0.507 o f the reao proda tt s at 3 0-400

a • ce of sodium oirbdat and =reacted 83

molybdenum trioxide. There were a few additional lines indicating the presence of one or more unidentified oompemni9 Two grams of molybdenum trioxide were treated with a solution of 0.55 g. of sodium hydroxide in 10 ml. of water. The oxide dissolved completely on warming, and a white solid substance was formed. An X—ray photogxsph was taken for this product. The X.-radiogram showed no evidence of the presenee of sodium hydroxide, molybdenum trioxide or sodium molybdate. This product was sodium dimolybdate Na2Mo207. It was found that the n.nidentifi6d lines on t X—radiogram of the product of the reiction between molybdenum trioxide end sodium carbonate 01 350-400° were due to this compound. The interplaner daU are listed below; roduct of X003 and 'o207Linea due to Lines due 41 Na 3 prepared No0 tQ Mo0 Ne CO at 350-400° 2 4

5.369 0.4 5.529 04 4.665 0.5 4.662 0.6 3.773 0.7 3.769 0.3 3.430 0.3 it 3.225 1.0 It 3.118 0.3 3.122 1.0 2.732 0.8 2.574 0.3 2.570 0.2 2 296 0.3 2.297 0.2

2.246 0.1 2.145 0.2 2.061 0.1 1.975 .0.8 1.973 0.4 .909 0.2 1.849 0.7 1.795 0.6 1.789 0.4 :1.746 0.i 1.672 0. 1.669 0.5 1.618 0.1 1.602 0.3 1.560 0.3 1.535 0.3 1.546 0.2 1.499 0.2 1.497 0.1 1.472 0.2 1.437 0.3 1.443 0.2 1.382 0.1 11 1.362 0.2 1.360 0.3 1.323 0.3 1.271 '0.1 11 1.239 0.2 It 1.227 0.2 1.223 Q.2 1.195 0.4 1.192 0.3 1.181 0.4 11 1.168 p.7 1446 0.3 1.138 0.7 1.138 0.3 11 1.121 0.2 1.081 0.1 14080 0.1 1.070 0.2 1.058 0.3 1.057 0.1 1.049 0.3 1.023 0.2 1.022 0.1 1.011 0.5 . 1.010.. 0.2 0.985 0.2 0.984 0.1 0069

00.554° 1 ►trioxide a ®Odium molybdete on sintering rbonate he reaction may be

represented by the ing °vatic)

1100 + lie, 00 is 002 At 350.4000 so ate and sodium dimo Mate are

f armed 0 im.tans dimolybdate being formed by the reaction: 00 aoo3 2

etweon Tangflten Trioxide and Softwa

sodium tungstate on wing with ax equimoleoular proportion of alkali

de or carbonate. Anhydrous• sodium tungetate is

alto, produced by allowing the hydrated salt to stand for

time over oonoentrated sulphuric acid or by heating the hydrate at a temperature above 14O°. The anh,ydrona

salt had already been prepared both by Awing tun ten trioxide with sodium carbonate and by heating the hydrated

sit at 140 ,as described in the earli part of this thesis « An invest on was made of the reaction between the oxide and sodium carbonate in the solid state. The effect of sodium fluoride on this reaction was aleo investi ated. Two equimolemlar mixtures of the oxide and sodium carbon te were prepared. To one of these ltd of sodium fluoride Chemed on the weight of the oxide) was added ae a cattily' The were heated at 500-560 and cooled and weighed eve: heating After heating for 16 hours, ptoilito the uncatalysed reaction was still bright in colour and in powder form, whereat' the product of the catalysed reaction was a white powder. The deareasea in weight were as follows: g. tungsten trioxide 10.002 10.002 g. sodialli carbonate 4.570 4.571 is. sodium fluoride . 1.001 MO1 oxide/ma carbolic 0 1/1

Time crease in wt. Idol CO evalyee. (hoar) (g.) per mil oxide neat. Uneat. Cat.

500-555 4 0.702 1450 0.370 0°.659 500-552 4 '0405 0.237 0403 0 500-550 4 0422 0.114 0464 o,o. 500-553 4 9400 0464 9442 0-434 500-555 16 1.098 1.665 0.579 0.8713

X-Ray aria ys e showed evidence of the existence of anhydrous sodium tungstate in the products t f the =catalysed and catalysed reaction. The reaction between tungsten trioxide a sodium carbonate at 56C° may be represented by the 'lowing equation: WO 4. Na 00 3 2 87

diem fluoride s towed a Met particularly in the first our heating. It was decided to investigate the role played by sodium fluoride in this reaction. The investigation will be described later.

re is a very weak base weaker than ferrous oxide. It can also apt as a weakly acidic oxide forming ferrites such as NaFe02 Beryllium hydroxide is amphoteric. It dissolvea in aside to form solutions of beryllium salts and in alkalis to form beryllatee. Beryllium oxide cannot be rendered soluble even by fusion with sodium carbonate. Zinc oxide dissolves readily in acids and also in alkalis, with which it forms zineatea. Solid alkali zinoates are formed by fusing zino oxide with alkalis. 24asnth trioxide is not soluble in bases but dissolves im oids. On fusing it with potassium hydroxide in air, a brown mass of potassium bismuthate, possibly XBJ.0 is formed

atiga reactio between these four 88

oxides.and sodium carbonate in the ee a th effect of (sodium fluoride on hess e Gondieted on the line adopted in the p rev o p ente

On heAting an eemimolecular mixtare era° oxide nd eodium carbonate at 0_7600 for 4 hours an evolution

f 0.038 molecule of ea pan per molecmle of oxide wee reoorded. The presence sod.. fluoride showed no appreciable effect in accelera ing the reaction. The product of the uncatalysed reaction wee a red powder, and that of the catalyeed reaetion wee a reddish brown hard mass. X Ray analyaie showed the existenee of the original componente, with no evidence of the occurrence of any reaction . On heating an act moleoula 'dere of b 0 oxide and sodium carbonate at 680.760 for 4 de's 4.008 f carbon dioxide was evolv for molecale t the oxide. The presence of sodium fluoride showed no marked effect in a ccelerati a.g the. reaction. The product of the =catalysed reactiona a white Powder, and that of the teed reeetion, wee hard mase. • di evidence for the of beryllium oxide and e rbonate in the product*. a9

0.017 molecule of carbon dioxide was evolved for one molecule of zinc oxide when an equimolecular mixture of zinc oxide and sodium carbonate was heated at 550-620° The presence of sodium fluoride had no appreciable effect on this reaction. The product of the uncatalysed reaction was a white powder and that of the catalysed reaction was a white hard mass. Two mixtures of bismuth trioxide and sodium °arboreta in the proportion of one to three molecules were prepared.

To one of these was added 10, of sodium fluoride, based on the weight f bismuth trioxide. These mixtures were heated side by side in an electric furnace at 550-620° for 4 hours. 0.081 molecule of carbon dioxide was evolved in the uncatalysed reaction for one molecule of the oxide, and 0.093 molecule w,313 evolved in the catalysed reaction. On raising the temperature to 680-765° the unoatalysed mixture melted slightly, and the mixture containing sodium fluoride melted extensively. The products of both two mixtures were yellow in colour. Ferric oxide gave no reaction with sodium carbonate at 760° although it has been reported that sodium ferrite is formed at a high temperature. Beryllium oxide was not

of ed by sodium bo on fu. ion. Therefore no rea of .on occurred on si terixag the oxide and sodbms oarbonate. Sodium fluoride had no effect Zinc oxide did not react with sodium carbonate at 620° although it dis■o19ea readily in sodium hydroXide so.uton. Bismuth trioxide is much .more basic than antimony trio de ►

It is insoluble in sodium hydroxide No a 0 et en occurred between the oxide and sod

620 t _Sum= ard Disaus According to their bebe.our toward sodium+rbo te and sodium luoride the metal oxides might be class ed as follows: (1) Those which a owed anexcellent eat with sodium fluoride in their reactioc with sodiumcarbonate were aluminium oxide and tungeten trioxide. (2) Those which showed a marked effeot with sodium oride, but a noticeably smaller effect than those user (1) above, in their reactions with sodium carbonata• particularly in the fillet heating, were titanium dioxide, zirconium dioxide chromic oxide, molybdenum trioxide, and stannic oxide. ( 3) Those which reaeted. with carbonate but

d no ef est toward sodium fluoride were vanadium

petto,de, ioxide and lead monoxid

(4) Those e no appreciable reaction with

sodium carbonate n tderthe experimental andition were

beryllium oxide, zinc ids, ferric oxide, and biemuth

trioxide.

Some metal oxides e different products with sodium

carbonate at different temperatures. midi= pentoxide

gave sodium erthcnranadate at 5500, and sodium metavanadate

below 5000. Itolybdenum trioxide gave sodium molybdate

t 500..554 # and both sodium molybdate and sodium

dimolybdate at 300-40e

Stennis oxide showed no appreciable reaction with ° sodium carbonate at 620 , but reacted fiery qua. . r at

680.4650.

The same products were obtained in 'both the sncatalysed and catalysed ,reactions of the Oxides and sodium carbonate.

Sodium fluoride may act as a surface catalyst in certain reactions and give intermediate compounds in others. As

the amount of the catalyst was only. abaci 51.4 of the w hole mixture, the presence of any int mediete ootuide could 92

be detected only with difficulty by the X—ray powder

.method. REACTIONS BETWEEN VANADIUM PENTOXIPE AND SODIUM CARBONATE IN THE SOLID STATE

UNCATALYSED O AT SCO-SILO. $1 25- 0

CATALYSED AT 500-550°

S -1 1.5 0

ko- . Aizo - 4e0 CATALYSED d UNCATALYSED X OS

16 24 TIME IN HOURS

yr) CATALYSED

0 X

UNCATALYSED > 2

REACTION BETWEEN TUNGSTEN TRIOXIDE AND SODIUM CARBONATE IN THE SOLID STATE d O2

4 > 124 16 TIME IN HOURS 93

) EPPECTS OF VARIOUS -CATALYST ON THE REACTION BETWEEN ALUMINIUM OXIDE Am SODIUM CARBONATE IN THE. SOLID STATE.

Sodium fluoride showed an excellent effect on the reaction between aluminium oxide and sodium carbonate in the solid otbte. The reaction was however incomplete even in the presence of sodium fluoride. It was attempted to investigate the effect of a smaller amount of sodium fluoride on this reaction, and the effects of ouch other catalysts as calcium fluoride ;magnesium fluoride, sodium fluoride, sodium pyrophosphate and sodium borate.

(a) The Effect of Sodium fluoride on the Reaction of

Bids, and Sodi1m Carbonate in the Solid State. A mixture was prepared by mixing equimolecular quantities of slpmilnium oxide and sodium, carbonate, and 2f, of sodium fluoride (based on the weight of alwilivium oxide). The mixture was placed in a vrgneaia boat and was heated in an electric furnace at 680-767°• The product was a white powder. The decreases in weight were as follows: 1 Aluminium 6 000 it optima, oarb 6.001 g. Odium fluorip 0.1210 Mol oxide/m01 earboi 14

680.762 4 0.399 0.160 680-762 4 0.161 0.065 640-767 4. 0.130 0.052 680-765 4 0.118 0.047 680-767 16 808 0.324

It wee found that the ga vonce of of sodium flu() • eti11 shorted a mawed ewffect ou this reaction. This iment was thus repeated bi using 3 of sodium fluoride as a catalyst. The product was a White powder. The decreases in weight were as fellows; j. aluminium oxide 6.000 g. sodium carbonate 6.01 44, sodium fluoride 0.0604 MO1 oside/Mol carbonate 14

Te attire Tinto "ease in wt. o1, evolved hoar) r ma oxide 680.762 4 00342 0..137 680.765 4 0458 0463 680467 4 0.129 0.052 680.765 4 0.'106 Q*043 680-767 16 0.735 0.295

t t. was anti alight difference between the ef ium fluoride and that of 95

34 of sodium fluoride Cu this reaction. It was decided to repeat this experiment with o.2$ of sodium fluoride as a catalyst. A mixture was prepared of equimolecular proportions of aluminium oxide and sodium carbonate and o.1 of sodium fluoride (based on the weight of the oxide In order to examine the effect of each a smell amount of talyst, this mixture was heated side by side with another equimolecuIar mixture of aluminium oxide and sodium carbonate. The products from both mixtures were white powders. The decreases in weight were as follows: g. aluminium oxide 6.000 6.002 g. sodium carbonate 6.002 6,002 g. sodium fluoride 0.0063 Mel oxide/mot carbon 1/1 1/1

Temperature Time Decrease in w t. tool CO evolved (hour) (g.) per MA oxide. Ducat. Oat. Unost. Cat. 680-754 4 0.05o 0.082 0.020 0.033 680-758 4 0.041 0.045 0.017 0.018 68o-758 8 0.091 0.127 0.037 0.051

It was thus shown tk at the presence of 0.1,A of sodium fluoride still gave an appreciable effect daring the first 4-hours, heating. (b) T a,a _Si sot ,of Calcium )3n on he Reaction lu iniom Qxide and So d. State

An equintolecular of aluminium oxide aM sodium

carbonate W prepared f calcium. fluoride (based on the weight of aluminlam oxide) was then added and the powders mixed thoroughly. The mixture was placed in a magnesia boat and heated in electric furnace at 680-755 The product was white in colour, ightly sintered The decreasee 4n weight were as

go aliusixitant oxide 6.001 g. sodinm carbonate 6.Q02 g. calcium fluoride 4.0648 .1401 oxide/ma carbonate 1/1

Time • in wt 0 evolred (hear) g.) oxide

680-745 4 0.489 0.196 680-745 4 0.070 0.028 680-755 4 0.058 4.023 680-755 0. 617 0.247

It f that the catalytie effeot of calcium

11uorls1 reaction. was higher than that of the same amount of sodium fluoride.

Two equimolar mixtures of al oxide and, sodium carbonate were prepared; to one of these 0.* of calcium 97

fluoride (based on h eight of the o de) wawas added• The effect of Q.11 of ealcium fluoride was examined by heating these two mixtures side by side in an electric

furnace. The decreases in weight were as follows*

uminium oxide 6.003 6 000 dium carbonate 6400 g. calcium fluoride 0.0062 Vol oxide/r ol carbonate

0-760 4 0461 0.103 0.025 0.041. Q. 760 4 0.035 0441 0.014 0.017 680...760 0.096 0.144 0.039 0.058

The presenceof 9.2S of 10 um fluoride in the

111 gays an appreciable t on the first heating, and the effect was plight than that of the same amount of sodium fluoride.

(.0) The Effept ofliasnesium ride On the Reaction

bILIroan Aluminium Oxide and flodiur -- rb*nate 4.31 the Solid State.

The offset of 2$ of rague um fluoride on the reaction of aluvi1i0um oxide and sodium carbonate was examined in the same way as that of calcium fluoride. The Pr (Meet was a white, slightly sintered mass. The decreases in It was shown that of 1% of magne imm fluoride gave nearly eat as the same amount of calcium fluoride.. The gation of the effe0t of 0.1$ Of •magneeluza fluoride on this re tion was then conducted on the line 'adopted Or the same amount of

Oalcatul fluoride The product was a white alertly cantered, mass• The dectreases in weight were as allows; 6.002 6.000 6.002 6.003. 0.0063 1 Tempera 14101 000 eyolvea per m.et Oxide Mca* Gat 680-762 4 0,055 •104 0.022 0.042 680-.762 4 0.037 06066 0'433 0.027 680-762 8 0,092 170 0.037 0.069

It w la thus shown that in, the r f a

oxide and sodium carbonate at 760 tb a effect"f 0.11% of main fluoride was nearly the same a, that of the same amount of calcium fluoride.

d) The Effect ..of Sodium Chloride oa the, Rea ion or

and Sodium Ca boast, in the Solid ate. Two e tmoleoxlar mixtures of alumi ium oxide and medium carbonate 'were PrePorod, To one of theme wac added 10 of sodium chloride (based on the weight of he oxide). These mixtures were heated aide by side at 00.762° The products were slightly wintered. The decrsas ee in weight were shown as follows; oxide. 6.000 6.002 bonate 6.003 64400 sod *ride 0.6013 o de 'carbonate 1/3.

wtCO elrolrod (h der ml oxide Cat. Cat 753 4 0.049. 0.753 0.020 0.302 760 4 0.025 0.127 0.010 0.051 0-762 4 ' 0.019 0.044 0.008 0.018 762 12 0.093 0.924 0.038 0.371

Sodium chloride Showed a marked effect in accelerating reaction of aluminium oxide and sodium carbonate in the solid state. 10

tecnthe odium carbonate was the same way. The pyrophosphate was. prepared by heating disodium hydrogen phosphate hydra 0. The products were slightly sintered. The decreases in welsh* were as follows it. aluminium oxide 6.000 6.002<} g. sodium carbonate 6.004 6.000 g. aad11 pyrophosphate 0.6010 Mel nide/aol carbonate 1/1

Tiae Decreases Mol C0 evolved

(hear) • (60, per an oxide. Unest Cat. Thicat Cat G-758 0.055 0.321 0.022 0.129 60.76o 0.029 04049 4.012 0.020 68o-760 0.084 00370 0.034 0.149

It was ound tlutt in etion between alunarlux oxide and odi►t rbonate, :Lodi= pyrephosphate

Was not so effective as sodium fluoride, calcium fluoride,

sium fl ide, and sodi chi though it showed

effect the ing 101

1_, a of 8 Q e on the I action. Aluminium Oxid Carb onste in the Solid Stet

Two egu.imoleettlar mixtures of aluminium oxide and podium carbonate were prepared. To one of these was added lc* of anhydrous sodium beret based on the weight of the oxide. The anhydrous salt wqs prepared by fusing sodium borate hydrate These two mixturee were heated aide by aide at 68o-765°. The produet of the catalysed reaction w a a white sintered mass. The decreases in weight are shown belows g. salmi-mum, oxide 6.001 • 6,002 g. sodium carbonate 6.003 6.00 g. sod gwa borate 0.6014 Mol mids/mol carbona 3.4

moolooliegewiftlatiopirepoimermootra Temperature Timm Du cease in wt. Mol CO a © Ted (hour) (14) per mtl oxide. t. Cat. tent. Cat.

. 660-760 4 0.03 0.520 0.016 0.205 680-762 4 04007 0.427 0.003 0.3.71 600-758 4 0.007 04292 4'.003 0417 680-755 4 0.004 0.24 0.002 0.097 650465 4 o*oil 0.202, 0404 0.081 0-765 4 0.013 0.180 0.005 0.072 680765 24 •081 1.854. 0.033 0-743

acceleratinghe reaction betwee altunirium oxide and sodium carbonate in the solid stilte sodium borate showed an excellent effect. It was still effective even 3.02.

at the eith four—houref eating. As so a at 7400 , silent effeet on the rea a due to the of a d phase in was decided to at this experiment at a teapot lower than the melti point of aodiuua borate. The decreases in w eight were as follovrat

g• aluminium oxide 6.000 6.003. g. sodium carbonate 6.003 6.001 Vii. sodium borate 0.600 6 X01 oxide/moo carbonst e 3.4 1/1

Te Time Decreases in wt. MO1 00 evolved (hour (g.) per mb oxide. neat. Cat. Mutat. Cat.

0 4 0.09 0.165 0.028 0..066 4 0.012 0.114 0.005 0.046 4 0.004 0.115 0.002 0.046 6 4 0.002 0.093 0.003. 0.037 'immoloorso. 6404.695 16 0.0811 0.487 0.036 0.195

tioditun borate gave a oh poorer result on the reaction

690 than that at 765 It was obvious that at 765° toted a liquid phase whioh accelerated the reaction.

(g)‘ _ Summary end Diem @A. The increase in weight of a catalyst gave an increared effeot in acoeleratin the sinter macs ion between alurcinitua oxide and sodium carbonate. The effect was

103

eimply dir otly ortionaI, ever, o the arne the catelys

he same amounts O eaieiii oride ABS gne Just fluoride and sodium chloride gay 3y the same effect

a sodium flttoride. Calcium „nuoride, ma6neeium fluorid.er and sodium chloride tteually showed a higher affect then sodium fluoride in the.first 4—hours' heating, but lower effects in the subsequent heatinge

dl pyrophosphate was obviou y a poor catalystlyst fo r the reaction. Its effect was far below that of the halides.

In 'these expo s lOS of sodium, borate showed the best effect on the reaction between aIuminitua oxide and sodium carbonate at 765° When the temperature was lowered to695°, the effeot'was greatly reduced. As sodium borate melted eb 740° was i hown that the great acceleration of the reaction at 765° was due to the presence of a liquid phase in the reaction mixture. EFFECTS OF VARIOUS CATALYSTS ON THE REACTION BETWEEN ALUMINIUM OXIDE AND SODIUM CARBONATE IN THE SOLID STATE

at 680 - 770° ------at 640 -700°

0.7 % Na2/407

10% NaF

re OA 0 1/1 10% NaCI

0 2 % NaF 0.3 I % NaF O

0 1 % 0 F2 1 % MgIF2

Q2- 10% isuaE1.07

-Jr 0.1 .... 0.1 96 Mel if ..• 0.1% .0 0.1% ..., * VN CATALYSED

8 12 16 20 24 TIME IN HOURS 104

In the earlier part of .this thesis it has been shown that sodium fluoride shows excellent catalytic effects on the reactions between sodium carbonate and beryl, aluminium oxide, and tungsten trioxide in the solid state. It also has marked effects on the reactions of sodium carbonate with stannic oxide, zirconium dioxide, chromic oxide, titanium dioxide and molybdenum trioxide. In these heterogeneous mixtures, sodium fluoride may act as a surface catalyst. On th surface of the catalyst the oxide molecules react more easily with sodium carbonate to form sodium oxyualt. On the other hand, sodium fluoride may give intermediate compounds with certain metal oxides, and the intermediate compounds may turn react with sodium carbonate to form oxysalts and liberate sodium fluoride. It is of vrtioular interest to investi to the role played by sodium fluoride in the reactions of sodium carbonate with beryl and the oxides mentioned above. It was decided to heat each oxide with an excess of sodium fluoride at the temperature at which the

105

ion of the reaction between the ozcide and carbonate was made. The products Of the reaotions were examined by powder method.

(a) The Reaction be fan Aluminiem Oxide and Sodium .Fluoride. A mixture of aluminium oxide and sodium fluoride was prepared in the proportion of one to twelve molecules. The mixture was placed in a magnesia boat and heated at 7100 for twenty-.four hours The product was a white heavily sintered MO®, There was no appreciable change in. weights I.Ray analysis showed the predominance of sodium fluoride and the existence of aluminium oxide. Bo Indication of the occurrence of any reaction was observed. The mix re wap then heated in a platinum boat at

1045° for six The product was a white fused hard mass. X Ray analysis, gave the evidence of the existence of ,sodium. fluoride and alumina Except these two compound°, there were three additional weak lines indicating the existence of ory lite, Ia3A1,6.

The on betwee ,cucde and Sodium

t p6010

A of titanium dioxide and sodium f uoride was

106 prepared in the proport on of to six eau es. It was placed in a magnesia boat and heated in an electric furnace at 560° for twenty.four hours. The product wee white in colour and slightly sintered. No appreciable change in weight was recorded. X Ray analysis showed the existence of the original. comPonents of the mixture with no indication ofthe occurrence of any reaction.

Lei.i.stiteaction TI between Zirconium Dioxide and SodiUX fluoride at 5700 . Zirconium dioxide raa used with sodium fluoride in the proportion of one to six molecules• The mixture wee planed in a magnesia boat and heated in an electric furnace at 570° for twenty-four hours The product was a white powder. There was no appreciable change in weight. Z..Bay analysis allowed the existence of zirconium dioxide ard sodium fluoride with no indication of the occurrence of any reaction.

,(d) The Reim-kJ between Siazu o Oxide and 5tidiula 0 at 660 .

A mixture containing stann4 o oxide and fluoride in the proportion of one to =locales was prepared.

It was placed in a ma.gnesis boat and heated in an. electric 107 furze* at 660° for tw hours. The product was a white pcwder. There was o appreciable change in weight. 1-Ray an,aiysia existence of stannic oxide and a odium fluori ign of QC011=023.420 of any reaction was ob aimed

(01 The 4eac :between ride 70°. A mixture of ehrom.i.c oxide a prepared• in the proportion of one to two; clear les The mixture was placed in a magnesia boat and heated in an electric fume°. at 570° for twenty-four hoarse The product was a green powder. X-Ray analysis showed the predominance of sodium fluoride and a trace of ehromio oxide. There were no additional lines showing the Presence of podium dhromate or any other compound.

(11The Boas tlen bet eni Trioxide and, kodium at. 560°•

A mixture (A) of go and fluoride

was prepared in ths n of one to six molecules. The mixture was plao magnesia boat and heated in electric furnace a tour hours The Product wee white in .Radio a showed the prodon4 SOU= fluoride

There were a few additional lilies indicating the .existence of one or more utlkilown compounds.

Another mixture (B) was prepalted in. the proportion of

One molecule of the oxide to three fluoride.

It was placed in a small platinum dish and, Leated in an electrio Ihrnace at 560 for twenty-four hours. The product was a white ellitatly fused mass. X-Ray analysis showed the existence of one or more uYik-rosvn. compounds and an excess of Ooditua fluoride. The tuiknown compound, was predicted to be sodium oxyfluomolybdate, 213100274

Sodium dioxytetrafluomolybdate e was prepared by 1+1. Aelafontaine (Jour=. prakt Chem. 1865, 21, 136) from a solution. of normal mo4bdate in a swill excess of hydrofluoric acid. It was found, that the crystals lost their water when heated in a closed vessel, and were decomposed when heated in air forming the normal molybdate.

As no interplanar spa c data of sodium dioxytetra flaemolybdate were Eris S for reference, it was prepared from sodium mo3,ybdate and. hydrofluoric acid, and dried in an oven at 140t) 109

Ah i'may photograph of sodium divas 110210 bdate was taken. The interpls rap data of this salt are listed below*

6.584 0.3 1.787 0.2 5.095 O*5 1.737 0.1 4.609 1.0 1.MS 0.3. 4.501 1.656 0,3 44,155 1.633 0.1 4.033 1.0 1.613 0.1 3.906 0*9 1.583 0.2 3.418. 0.1. 1.550 0.1 2446 0.7 1.528 0.1 2.514 0.1 1.496 0.1 2.447 0.3 1.430 0.1 2.398 0.3 1.295. Oil 2.335 0.2 1.261 0.1 2.259 1.232 0.1 2.209 0.1. 1.208 0.1 2.123 0.1 1.178 0.1 2.036 0.3 1.115 0.2 1.969 0.6 2080. 0.2 1.904 0.7 1.065 0.1 1.831 0.2 1.047 0.1 The salt was heatedt 80° overnight, and an

X ray photograph The X-radiogram showed that the eel.* was (maple ely daeomposed into normal sodium molybdate. This agreed with the results obtained by Delatontaine. From the fast tw t di uomo • decomposed on heating in air at 580 th Mound would not be the 110 product of the reaction between.molybdenam trioxide and sodium fluoride at that temperature. It was verified by

-radiograns that the unknown compound formed by heating

olybdenam trioxide with sodium fluoride was not identical with sodium dioxgtetrafluomolybdate prepared.

A mixture (C) of molybdenum trioxide and sodium, fluoride was prepared in the proportion of one to two molecules.

It was placed in a platinum dish and. heated at 580° f' eighteen hours. The product was a white fused mass.

X-Ray analysis showed the existence of the unknown compound and an excess of sodium fluoride.

An equimolecular mixture (D) was prepared and heated at 550° for twenty-four hours. The product was a white fused mass. XdRay analysis shamed the existence of the unknOwn compound and a trace of sodium fluoride in excess.

When the mixture was heated for forty hours longer the

X-radiograms showed the existence of the unknown compound and the absence of sodium fluoride. The interplanar spacing data of this unknown compound were as follows: 111

5.613 0.4 1.503 0.1 4.614 ..0.18 1.469 0.1 3.814*- t 4,463 0.1 3442 140": 14323 0.1 All#154 1.220 041 4.056 0.2 1.193 0.1 1.971 0.4 1.166 0.2 1.902 0.1 1.135 0.1 1.858 0.]. 1.118 0.1 1.789 0.3 1.010 -0.1 1.747 0.1 0.846 10.1 1.672 0.4 0.840 q.1 1418 0.1 0.829 .0..1 1.555 0.1

Prom these experiments it warn tcund 1St alarm trioxide reacted with sodium 540 terming a oxyfluomolybdate. The e t'mows of this salt was probably NaMo0 P.

) The Reaction between Sodium trioxymonefluomolybdate

and ecaltun carbonate at 54Q° . Equal molecular portion. a Of medium trioxymonofluomolybdate and anhydrous sodium carbonate were mixed. The mixture was placed in a emll platinum dish and heated at 5404 fcr twenty—four hours. The product was a white powder. 6 of the theoretical amount of carbon dioxide was eyolved.

g.Ja.B oO,F giNa 0 OTO1Valit 00 calculated 1.000 0.572 0.150 0.237 version of ea ium trioxymonofluom. lybdainto sodium aolybdate was established by X-4133r amlysis of the reaction product.

(b) The Reactionbetween get en Trioxide aid Sodium oxide at, 5 60° . A mixture (A) of tungsten t ide and sodium fl uori.de in the proportion of one to six moleoules was prepar It was placed in a magnesia boat and heated in an. electric

00 at 5600 for twenty-four hours. The product was a white sintered mass. X. Ray analysis showed the existence of one or more unknown compounds and an excess of .sodium fluoride. Another mixture s prepared in the proportion of one to three mo3.eoules. It was plaoed in a small platizatm dish,. and heated at 5500 for twenty-four hours. The product was a heavIly-sintered'mass. X Ray analysis showed that in the product the unknown product was predominant and an excess of sodium flu,oride still existed.

A mixture (0) 'consisting of twigaten trioxide and. medium fluoride in. the molecular proportion of one to two was propared. The mixture was heated at 560 for twenty. four 'hours. The product was a white gartered mass • Xp-Ray

product.. An equicuoleeu.1ar mixttir oxide and

sodium. fluoride for twenty- hour hours. der. X Ray analysis of the product gave the evi of the existence of the unknown compound and tungsten trioxide. From the results of these experiments it was ehcern that an unknown compound was formed by sintering tungsten

trioxide with sodium fluoride at 560°. The unknown compound was probably sodium trio ngetatep 1ta2ff03P2 The

iztterplanar compound were as follows 2

5.873 0.2 001 165 0.5 0.5 3.621 0.7 .503 0.3 3.120 0.1 1.452 0.2 2.973 1.0 1.394 0.2 85 0.3 1.304 0.1 09 0.2 1.266 0.1 130 0.3 1.196 0.2 2.005 0.1 1.005 002 1.834 0.7 0.944 0.1 1.729 0.2 Sodium diexytetrafluotungs pared by C. G. a solution

114

nor. 1. o acid tit in hydro o a It was found thatwhen. the ea end in closed uel at a dal red heal; thoro' Gee in maee; but it melted with a. 1 , and the molten mails became yellow probably, eparation of tungsten triodists This salt was prepared by tree ous sodium tumgetate with an =ease of hydro uorio acid, and dried in an oven at 1400

An Z.-ray photograph of this salt aken. The interplanar apasing data were ae followss

4.76004' 2 0.3 4.564 0.6 0.1 3.800 0.4 571 0:1 3.573 0.3 . 10544 0.4 3.114 1.0 1400 0.2 2.916 0.2 1.453 0.1 2.686 0.2 1.421 0.2 2+621 0.2 1.390 0.1 2.337 04 1.362 0.1 2.205 0.5 1.294 0.1 2.114 0.2 1.200 0.2 1.929 0.1 1.232 0.1 1,662 0.2 . 1.2*5 0.1 1 638 00. 1.192 0.1

1.814 0.3 2.1,46 0.2 1.766 011 salt Was then heated at 560 owernight, sad an —ray photograph. was taken. It was faand that the X—radiogram was identical with that of sodtan trioxydi

1354a e.

Tungsten trioxide gave a new co °and, Na heating with sodium fluoride at 560• It was dad to investigate the reaction between this oomPound as sodium carbonate. An equiRolecular mixture of this ,compound

and sodtam Garb to was pxepared. It was P in a small platinum dish and heated, at 540 for teen four hcan The product was a white powder. 9a% of the theoretical amount of carbon dioxide was avolved.

Q336 0.129 0.140

ed the , complete d ►co on of demi of the existence of

sodium to tat Besides the lines dme

sodizut 1ru sta et There *rat additional lines 115 in the X.-radiogram indicating the presence of one or more unidentified compounds, No evidence of the presence of sodium fluoride was found.

0 (1) The Reaction between Bevirl and Sodium Pluorid.e at 760

One part by weight of beryl wr5a mixed 'with two parts by weight of sod um fluoride. The mixture was heated in an electric furnace at 760° for twenty—four hours. The product was a white fused hard mega. There was no appreciable change in weight. X—Ray analysis of the product established the complete decomposition of beryl. It showed the existence of an excess of sodium fluoride and one or more unknown compounde. No indication was obtained of the presence of sodium fluoalemtnate t sodium fluosiliestet or sodium fluoberyllate.

Another mixture was prepared in the proportion of two parts by weight of beryl to one part of sodium fluoride.

It was placed in a small platinum dish and heated at 755° for eighteen h The product was a white fused hard mass. X—Ray analysis showed that only the unknown comp ound existed in the product.

(k) The Synthesis of the Unknown Oompounde Produced in the Reaction between Beryl and Sodium 'fluoride at 7600

In the reaction between beryl and sodium fluoride at 60° one or more new come a mere pro t ed. The und might be ioate oberyllosilicate sodium beryllium fluoalumina

or an OV1131 more complicated compound. It was vary int era ing try establish the empirical formula of the unknown

co and examine the faaction between the unknown sodium carbonate. Therefore it was decided basics the u nary compound from the xides of beryl, a sodium fluoride. Dies were prepared.:The composition of these mixtmres Were so - adjusted that the oxides were in the same ratio as in natural boril, and that the sum of the eights of the oxides was nearly twice the weight of sodium fluoride. The molecular proportions of the constituents of these mires were as. follows:

••••••••••••11011.11011.111.00 Nes i1011 1 0 1 leryl 3 3 0 Silica 6 0 6 6 NaP 6 6 6 6

The Chemicals red or preparing these mixtures were pug grade an revionely been heated at 760° f least four hours. 117

heated in a

The prOducts ed fa= in app The produot of mixture A wee a *lite hard fused mass of mixture 2 wee a white powders that of mixture a colourless that of mixture D wa a white sintered was • The product of C gave a diffuee X...,radiogram. ae it was as glassy substance. Ray analys 13 showed the existence of the original components, with no Indication of the occurrence of any reaction. Z-Bay analysis of the product of A showed the existence of the unknown compound I which was formed in the reaction

f ha Ling beryl. with sodium fluoride. Apart from the ting the existence of the unknown compound some additional Urea were found in the 1-radiogram.The Z-ray analysis of the Product of D ehowed the existence of sodium fluoride and silica. There were also some additional lines indicating the presence of an unknown compound. It was found that these lines were identical with those unidentified lines in the X radiogram. of the product of A these reao,1 a, it was shown that thi unknown compoundprodueed is the reaction between. beryl-and sodium fluoride might probably be a complicated compound composed of sodium, alr ir4un4 beryllium, silicon, oxygen and fluorihe On heating a mixture of alumina beryllia, silica and sodium fluoride the unknown compound I wan formed. Besideo the unknown compound I, another unknown cOmpOund Ix, .was found It was probablyformed by a aide reaction between an excess of alnmAAA, silica, and sOdium fluoride in the mixture A mixture (E) of alumina, b ca and xodium fluoride was prepared in the moleeal r proportion of 11313'6. A mixture (7) of alumina silica and sodium fluoride was also prepared in the molecular proportion of 1,3,3. The mixtures were placed in small platinum diehes and heated at 75O for sixty two hours. The prodtet of E was a white Awed mass, and that of P was a white sintered mass. -.Bay analysis of the product of B showed the existence of the unknown compound I and an excess of sodium fluoride and her, llia. No evidence of the presence of the unknown compound II and silica was found in the x..radiogram, X,Bsy analyaie of the product t showed the existence of the WOknorin sodium fluoride. As the unknown compound of fluoride and beryllia existed in B, two mixtures, G and H, of alumina beryl lie silica and sodium fluoride were Prepared in the molecule Proportions 101314 and lt30 Peotiyely. They were placed in small platinum dishes and heated at 7600 for sixty-two hours. The products of both mixtures were white fused massee. -Ray analysis showed the existence of the unknown compound I and a trace of beryllia in the prodact of mixture G; and the existence of unknown compound I, unknown compound II, and an excese of beryllia in that of mixture)"

Owing to t presence es f bergin t& in the product of pillar. G, two mixtures, nd IT of alumina, berylliat silica and °odium fluoride were prepared in the molecular ratios 1:20t4 and 1:113t4, resPeCtively. The mixtures ware heated at 7600 for aixty.two hours. The product of I W98 a white famed mass, and that of J was a white friable mass. X-Ray analysis showed that the unknown compound I e only compound found in the product of mixture I. e X-ray anal:mist of the product l20 of showed the existence of .the unknown camp d.o .I and

nd an excess of sodium fluoride.

a an excess of sodium fluoride in addition to the unknown• compound.II was found in the produot of 1r, two mixtures, S and.I, of alarn1vot silica and sodium fluoride were prepared in the molecular ratios 1:3i2 and Wilt respectively. These raiturea were plaoed in small Platinum dishes and heated at 750° for sixty—two hover s. The produ.ots of both mixtures were white and slightly sintered. An X radiogram. of the product of IL showed the presence of the IT,*Ti 0 vm. compound II and sodium fluoride.

In the product of I the unknown oompouth II wee the only compound found on X—ray analysis.

As the interplanar spa sing data of alumina were interfered with by those of the unknown compound II, it was suspected that the unknown compound II might not contain alondy,ium It was decided to check this by heating a mixture-of silica and sodium fluoride without alumina A mixture M was thus prepared by mixing silica and sodium. fluoride in the proportion of three molecules to one. It was heated at 7600 fors ty—two hours. The product nag a colourlees fused mass. X—Ray analysis show e ex t VO the existence of o II, sodium fluoride,

or sodium fluosili n the Za , that no sodium fluoride was found in the product, And the aneed into a transparent fused substance actor th heatin e was probably a reaction between ilioa d sodium oride.

Unforttuiately the products the inn could not be found by ray a xalysis. p roduc were probably in the amorphous form.

The results of the ayntheaie e unknowncomprauhda may be tabulated as follows:

Molecular ratio Compounds nd A1203 Bea 3i0 aJ in. the pr

6 6 nkaown compounds and 11. 1 3 0 6 Ufa', berylliat abamina. 3 6 6 1 0 6 UnknoWn compound II, Nal? silica 1 Unknown compound It Nalt, 00. Unknown comPound II, Nap 1 4 Unknown 0011Woumd I, 3o0. 1 Unknown compounds I and I Be0. I 4 Unimown oqmPound I. I 4 Unknom compounds I and II NaP. 1 0 Unknown compotutd II, Na?. 1 0 3 Unknown compound II 0 0 3 i1ioa

is seen that there were saTaral r et betvireen the constituent oxides of be ium. fluoride. The

on be beryllis, s it and sodium fluoride gave ey product. The re Cation between alum tiP, and aftliumfluerid aye the unknown compound U. The

on between alumina, beryIliasilica and sodium

de gave the unknown oompound I, Both the unknown compounds I and II were formed. alma neously when silica and sodium fluoride were in excess« The empirical formula of the unknown compound. II was probably A103 3$i02, Naf or NaA128i309P, and that of the unknown compound I was probably A1203, 23410, 381021 4NaF or Na4A123.23i3024. Many oases have been reported. of elt t ion of fluoride from, metal fluorides en heating in air, and these empirical formulae must be regfitrded as tentative until they can be confirmed by further study

The in.te.rplanar spacing data of the product of heating beryl and sodium fluoride, the compound A1203, 23•0, 3$i0, 4 IMP and the compound Al 3$i02, Nal were as followsi 123

Pilodattt ► '13,171 a, , ISP A 1- 1 '$ k1 3410 Viar' 0'y3S fp 4 9*082 0. 4 0.6 6.424 0.6 6.461 ;0.3 4.050 0.6 3.738 0.6 34,692 1.0 3-695 1.0 3.479 0.1 3.192 0.3 3.197 1.0 2.949 0.2 2.853 0.4 2.86 0.4 2.823 0.1 2.656 0.1 2.599 0.5 2. X3.0 0.7 2.529 0.5 2.370 0.2 2.248 0.1 2.259 0.1 2486 0.1 2.123 0.3 2.131 0.3 2.13.6 0.1 2.074 0.2 2.080 0.5 1.997 0.1 1.920 0.2 1.827 0.2 1.763 0.3 1.771 0.3 1.775 0.2 1.735 0.1 1.734 0.3 1.648 0.1 1.590 0.1 1%597 0.3 1.597 0.5 1.541 0.3. 1.549 0.2 1.500 0.1 1.505 0.2 1.479 0.1 1.460 0.1 1.463 0.2 1.400 0.1 1.401 0.3 1.357 0.2 1.363 0.3 1.372 0.5 1.327 0.3. 1.333. 0.1 1.343 0.3. 1.302 0.1 1.302 0.2 1.315 0.1 1.272 0.1 1.276 0.1 1.284 0.2. 1.256 0.3. 1.227 0.2. 3..229 0.3 1.235 0.2 1.208 0.1 1.23.0 0.2 1.187 0.1 1.185 0.1 1.164 0.1 - 1.146 04 1.145 0.3. 14,124 0.1 1.111 0.1 1.095 0.1 1.097- 0.1 1.075 0.1 1.075 0.1 1.048 0.1 1.037 0.1 1.040 0.1 10024 1.010 0.1 0.996 • 0.1 0.994 0.2 o.91.6 0.1 0.830 1

(1) • The Reactionbetween the 0o ponied.. 1 0 2Be0, 02 , 4NaY and Sodium tCarbonate at 770°. t ways: shown in the earlier part of this thesis that sodium fluoride showed an excellent effect on accelerating the reaction between beryl and *odium carbonate in the solid state. Here it was found that beryl. gay* a EAW complicated compound, A1203, 2360 3Si02, 4Nar on heati a with sodium fluoride. It was decided to heat this compound with sodium carbonate at 760 0to see whether this compound would be converted into sodium bevy .l.imm silicate product the between Ne2 BOJO4' which was the of reaction beryl and sodium oarbonate at 7600. The compound Al2 03, 2B00, 33102, 4NaV was s ed with anhydrous sodium carbonate in the proportion of one to cur mole. The mixture was placed in a email platinum dish, and heated in an eleetric fUrnace at 770° for thirty.. 125 eight hour The produn white friable of carbon dioxide c t in sodiam carbonate were Yed.

he compound a 002

1.000 0.851 0.241

-may analysis of the product wed the couplet d000Eposition of the co icated poand and gave the evidence of existence of NaBe-SiO4 and sodium fluoride. Bo aluminium compound was found in the product. It was probably formed in the amorphous state or it was interfe with by the beryllium compomnd and sodium fluoride.

(m) =Man' and Die ouseion. awilinium oxide fluoride gays no re n with l stannio oxide titanium dioxide, zirconium dioxide and chromic oxide in the solid at ate Under the experimental conditions. Bat it showed good effects on accelerating the reactions between these oxides and sodium carbonate.

In these reactions sodium fluoride acted probably simply as a surface catalyst as no intermediate product was ound between the catalyst and these Oxides. Molybdenum trioxide- gave a new compound with sodium fluoride The empirical formula of this compound was uoride. This Oompound reacted with sodium tie to form sodium molybdate. It was thus inferred, sal sodium fluoride was used as a catalyst in the reaction between molybdenam trioxide and so um carbonate , UMW might be formed as an intermediate product, which was in turn oonverted into sodium melybdate The catalytic effect of the acceleration of the reaction was primarily due to the formation of this intermediate compound. Like molybdenum trioxide, tungsten trioxide, gave a new compound with sodium fluoride. The empirical formula of the compound was determined as Na2W039i by synthesis • This compoted reacted with sodium carbonate giving sodium tangstate. It was inferred that in the reaction between tungsten triOxide and sodium mrbonate with sodium fluoride as catalyst, this compound might be formed as an inter. mediate compoand and then converted into *odium estate. The catalytic effect of sodium fluoride on.• accelerating the reaction was due to the formation of this intermediate

004Potad Sodium flao ide gave a new complicated compound with at 760o beryl 37 sYnialaiming this MAP °and from the 127

oOnstituent oxides of beryl and Audi t fluoride, it was

found that the empirical formula o oomPound was probably A.1203, 2e0 38i02,4Nar. Bee use of the possibUitr partial reaction with air and aide reactions

between the constituent oxides and sodium fluoride, the formula of this compound could not be a etabli.shed definitely. The conversion of this neh complicated coupound into

Na BeS1.0 and sodium de on heating with sodium 2 4 carbonate was established. b X ray analysis. It was thus

inferred that this new complicated oompoun4 might be

formed as an intermediate compound in the decomposition

of beryl with sodium carbonate using sodium fluoride as

catalyst. The formation of this intermediate compound would be responsible for the accelerated decomposition of beryl with sodium *arbors

Sodium. dioxytetralluomol,ybdate and a odi dioxytetralluotangatate were prepared from the normal salts and an excess of hydrofluoric acid. It was found that these two compounds were converted into Naiio04 and Ne2w03P2respectively when they were heated in air at 560 C G um tams=

The following investigations head been atte tads (a)the decomposition of beryl, woiframite, chromite, oolumbite and bauxite with sodium. carbonate in the solid state and the effects of sodium fluoride on these reactions; (b)the reactions between metal oxides and sodium carbonate in the solid state any the effects of eodium fluoride on these reactions; (o) the effects of various catalysts on the reaction between alum', "1 um oxide and sodium oarbonate in the solid state; and (d) the mechanism of sodium fluoride on the reactions between metal.oxide systems and sodium, carbonate in the solid state. A clear picture has been worked out for the react between beryl and sodium oarbenate in the solid state with salvia fluoride as catalyst. On decomposing beryl with sodium carbonate at 760°, a new compound was produced. The empirical formula of this compound Na2BeS1.04, was established by synthesizing it from beryllia silica and sodium carbonate. This reaction was greatly accelerated by the addition of sodium fluoride as catalyst. The same produot was obtained in the catalysed reaction. The beryllium and aluminium contents of the ore could 129 be Want tatively converted into berylliam and aluminium sal hates by treating the reaction product with concentrated sulphuric acid. The mechania of sodium fluoride an this rear an was studied by heating berg ith sodium fluoride. Qd compound was found in this reaction; i formula was probably Al„4,, 2BeO, 313i0 4NaP. On heating with sodium carbonate, this complicated compound wa converted into Na2BeSiO4 and sodium fluoride. It is inferred that this cempound is an intermediate formed in the catalysed reaction between beryl and sodium oarbonate, and the acceleration of this reaction is primarily due to the formation of his intermediate compound. Furthermore, at 760 this intermediate compound appears to be in a fused state. . The existence of a liquid phase in the reaction mixture will also play a role on facilitating the reaction. The investigations of the reactions between sodium carbonate with beryllia and with alumina had also teen made. Beryllia showed no reaction with sodium carbonate. Alamtaa reacted with sodium carbonate in the solid state and sodium aluminate as the product, but the reaction was far from complete under the experimental conditions. 1

gaye the compound Na2Be8iO4

Sodium fluoride was found to be an ;active cat the decomposition of beryl with sodium mrbonate and it

a i also an active catalyst in the reactions of sodium carbonate with tungsten trioxide, molybdenum trioxide,

litainium oxide stannic oxide, zirconium dioxide, titanium dioxide, and. chromic oxide. On heating tungsten trioxide with sodium fluoride a sodium oxyfluotsungstate Na2WO

um trioxide with sodium fluorid a sodium oxiyfluom lybdate, NaKoO rmed,

These o salts were converted by sodium carbonate into sodium st to and sodium molybdate, respectively formation of these intermediate compounds may account the acceleration of the r4raoti,ore between these two me oxides and. sodium carbonate.

Sodium fluoride e na reaction with aluminium ida,

dioxide, z onittra dioxide ,

oxide in the solid et conditions good effects on the reactions

bete and these oxides. The acceleration of these reactions b addition of sodium fluoride was not due to the formation of intermediate compound. is the oxides and sodium carbcamte were

powder form Or slightly sintered , presence of sodium el.uoride, the products were usu heavily sintered or even hard =sees. 1t is obvious that

the presenae of the lyst will give closer cO me eat between the reactants on heating. tI V. Jander (Angel.

Ohms. 1934, Li, 235) :stated tm t in the solid reactions a molecular layer of the reaction product is formed by the two component coutpounde at the contact eurface, and the reaction is propagated by the diffusion of one or

(Bull sOc. chin. 1941: 209) has made an investigation of the diffUsiOn in the solid y68(41°210 The addition of sodium fluoride to the reaction mixtures of sodium

acbonate and the metal oxides mentioned abeve usually caused heavy 51.ntering cat ion in volume of the reaction mixture makes Ration of the molecular layer and the fusion the rea ds this layer much easier, and hence it accelerates

tone. It was found in most oases of sintering sodium earbonate with de epitome that the presence of sodium 132 fluoride usually showed a ked effect he first heating and gave no signifi effect subsequent heati.

It seems that on e as ta3.yet the .molecules of the reactants roe en these which ar e not on the surface. The products formed surface of the oa in in the same position pr event the access 0 molecules to the surface. The

ow mobility of end reactants also prevents the access

Awl Ball face. Therefore

alyst shows no more on the subsequent la atingle.. The formation of a liquid phase gives a great, effect on the acceleration of solid reactions It gay be shown by the catalytic effect of sodium borate on the reaction of aluminium oxide and sodium carbonate. The catalysts melts at 7400. At 760° it ehows an excellent effect on the reaction. At 693° the is greatly reduced. The presence of a liquid ph b forms a solu.tion of the reactants in the catalyst, and thus facilitates the reaction The presence of a ligUid phase any also probably increase the diffusion of the reactants and hence accelerate the reaction. in the catalysed reactions b n e . tith beryl 6=1 with molybdenum trioxide

e °Mounds formed are in a fused sta te under the experimental conditions. The preemie. of a liquid phase will, however, play a role of a coolers ing the. reactione•

The intermediate compounds catalysed reactions of sodium carbonate with beryl, tungeten trioxide, and molybdenum triezide were new complicated oos3P,Otulde They haite been synthesized by heating orreoot proportions of the constituent oxides ••nd sodium fluoride.

Their empirical formulae hay* been established tentatiTely by X-say powder methods, though definite formals(' could not be easily, assigned on account of possible side reactions.

I- Bay analysis showed that in every case the same coi ponds were produced i both the aata]ysed and uneatalyied lea etioame in stint ering the metal-oxide systems and sodium carbona The amounts of lx.Ltermediate compounds formed in the reaction mixture were so 'email that it was very diffit+ul.t to detect them by the I ray'. powder method • An indirec ethod was therefore employed to detect whether intermediate compounds were produced in the catalysed reaction and also to examine their suture In this

PrOcwes the reaction betteen the metal.ox system and

sodiumlfuo de was examined first; if MAO near" the product was then heated with sodium carbonate. The intermediate compounds were identified by oomparizw their

interplanar spacing data with those of known compounds

or newly synthesized. compounds• This appeared to be the best way of studying the mechanism of catalysis. The

results Italy justified the plan adopted Par the purpose of investigating 1 reactions and eynthesising'a complicated compound from two or more

constituents aM of determining the empirical formula

of a new compound. the X-ray powder method appears to be an excellent one, th.olgh the formation of amorphous compounds

and the side reactions of the constituents usually cause

some inconvenience. A an OWZEDGEMENTS

The writer wishes to thank the Imperial College of

Science and. .Technology azttt Professor H. V. A. Briscoe for the research accommodation provided.

It is n2,y ple&sant duty to extend my sincere thanks to my supervisor, Dr. A. 3. 3. Welch, for his excellent supervision, personal interest, unfailing co—operation, and untiring efforts on my behalf.

Fixtensive use of the X—ray equipment, provided by a grant from. the Royal oelety to Professor Briscoe end

Dr. Welch, has bean made and is gratefully acknowledged.

The writer is oleo greatly indebted to the British

Council for the award of a British Council u cholarship for the period 190-50.

k. C. C1 44-, erial College of Science and Technology.

December 1950.