Vol 57 Issue 2 April 2013

Published by Johnson Matthey Plc

A quarterly journal of research on the science and technology of the platinum group metals and developments in their application in industry

Vol 57 Issue 2 April 2013 www.platinummetalsreview.com

Platinum Metals Review is published by Johnson Matthey Plc, reﬁ ner and fabricator of the precious metals and sole marketing agent for the six platinum group metals produced by Anglo American Platinum Ltd, South Africa.

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No warranties, representations or undertakings of any kind are made in relation to any of the content of this publication including the accuracy, quality or ﬁ tness for any purpose by any person or organisation. E-ISSN 1471-0676 • Platinum Metals Rev., 2013, 57, (2), 85• Platinum Metals Review A quarterly journal of research on the platinum group metals and developments in their application in industry http://www.platinummetalsreview.com/

APRIL 2013 VOL. 57 NO. 2 Contents

Johnson Matthey and Alfa Aesar Support Academic Research 86 An editorial by Sara Coles

Platinum-Based and Platinum-Doped Layered Superconducting Materials: 87 Synthesis, Properties and Simulation By Alexander L. Ivanovskii

CAT4BIO Conference: Advances in Catalysis for Biomass Valorization 101 A conference review by Eleni Heracleous and Angeliki Lemonidou

Johnson, Matthey and the Chemical Society 110 By William P. Grifﬁ th

SAE 2012 World Congress 117 A conference review by Timothy V. Johnson

“Complex-shaped Metal Nanoparticles: 123 Bottom-Up Syntheses and Applications” A book review by Laura Ashﬁ eld

Crystallographic Properties of Ruthenium 127 By John W. Arblaster

“Polymer Electrolyte Membrane and 137 Direct Methanol Fuel Cell Technology” A book review by Bruno G. Pollet

Kunming–PM2012 143 A conference review by Mikhail Piskulov and Carol Chiu

Publications in Brief 148

Abstracts 151

Patents 154

Final Analysis: NOx Emissions Control for Euro 6 157 By Jonathan Cooper and Paul Phillips

Editorial Team: Jonathan Butler (Publications Manager); Sara Coles (Assistant Editor); Ming Chung (Editorial Assistant); Keith White (Principal Information Scientist) Platinum Metals Review, Johnson Matthey Plc, Orchard Road, Royston, Hertfordshire SG8 5HE, UK Email: [email protected]

Editorial Johnson Matthey and Alfa Aesar Support Academic Research

As many of our readers are no doubt aware, Alfa We are delighted to formally announce our Aesar is Johnson Matthey’s catalogue chemicals partnership with Alfa Aesar who from April 2013 business. As well as supplying research chemicals will be supplying the chemicals from their stocks. to the fi ne chemicals and pharmaceuticals We look forward to working with our colleagues at industries, Alfa Aesar also supplies universities Alfa Aesar. and can deliver at any scale from bench to SARA COLES, Assistant Editor pilot plant and through to commercial scale Platinum Metals Review production (1). Platinum Metals Review has now teamed up with Alfa Aesar to administer the “Johnson Matthey References 1 Alfa Aesar, A Johnson Matthey Company: Alfa Aesar Research Chemicals Scheme”, formerly http://www.alfa.com/ known as the “Loans Scheme”. Since the early years 2 D. T. Thompson, Platinum Metals Rev., 1987, of the 20th century, Johnson Matthey has used this 31, (4), 171 scheme to support fundamental research centred on the platinum group metals (pgms) (2). Academics and university groups can apply to receive small Contact Information amounts of pgm salts for use in their research, with a Johnson Matthey Precious Metals Marketing focus on novel applications which may have future Orchard Road commercial potential. Royston The scheme is currently well-subscribed. In the Hertfordshire past year we have supported projects in diverse areas SG8 5HE including anticancer drugs, asymmetric catalysis, UK biomass conversion, nanoparticles, pharmaceuticals, photovoltaics and renewable energy. Email: [email protected]

“PGMs in the Lab” Look out for the new section and see if it inspires you From the next issue of Platinum Metals Review, in to try some new collaborations of your own. July 2013, we will feature a new section called “PGMs Finally don’t forget that we are always interested in the Lab” in which we will profi le one of the many to hear from you about your research into new researchers whose work has benefi ted from the areas of application for the pgms. So if you have support of Johnson Matthey and Alfa Aesar. This work some new pgm research to report, a book that you has expanded the boundaries of pgms research and would like reviewed, or a conference that you have we hope that many new applications for the pgms organised or attended, please contact us at the will arise from this exciting collaborative approach. above address.

Platinum-Based and Platinum-Doped Layered Superconducting Materials: Synthesis, Properties and Simulation

Experimental and theoretical results for newest group of high-temperature superconductors

http://dx.doi.org/10.1595/147106713X663780 http://www.platinummetalsreview.com/

By Alexander L. Ivanovskii In 2011, the newest group of layered high-temperature superconductors were discovered: platinum-based Institute of Solid State Chemistry, Ural Branch of the Russian quaternary 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and 10-3-8 Academy of Sciences, 620990 Ekaterinburg, Russia ((CaFe1–xPtxAs)10Pt3As8) phases with superconducting Email: [email protected] transition temperatures (TC) up to 35–38 K. Intensive studies have been carried out to investigate their preparation and properties. This fi nding stimulated much activity in search of related materials and has attracted increased attention to platinum as a component of layered superconductors. This review presents experimental and theoretical results devoted to two main groups of superconducting materials with platinum: Pt-based materials (where Pt forms individual sub-lattices inside building blocks of corresponding phases such as SrPtAs, SrPt2As2 and LaPt2B2C) and Pt-containing materials, where Pt acts as a dopant. Synthesis, basic properties and simulation of these materials are covered.

1. Introduction Platinum and a rich series of Pt-based alloys and compounds (as bulk, fi lms or nanostructured species) are well known as critical materials for many applications (besides jewellery and investment) – for example they are excellent catalysts for chemical processing, and have many uses in the automotive industry (for example, in catalytic converters, spark plugs and sensors), in electronics (for high-temperature and non-corrosive wires and contacts), in petroleum refi ning, and also in medicine, electrochemistry and fuel cells. However, the participation of Pt in the formation of superconducting materials is much less well known (1–3). Superconductors fi nd use in applications such as magnetic levitation (‘maglev’) trains, magnetic resonance imaging (MRI) scanners and particle accelerators and have further potential for more effi cient electricity generation and distribution as well as fast computing applications.

The face-centred cubic (fcc)-Pt metal remains non- symmetry. Related Pt-based noncentrosymmetric superconducting (1) even at the lowest accessible superconductors are also known: BaPtSi3 (16), Li2Pt3B temperatures of solid matter, T ~1.5 μK (4, 5). It is (17) and LaPt3Si (18). believed that one of the obstacles to a possible Another exciting material is platinum hydride superconducting transition is the purity of the (PtH) (19–21), for which the superconducting metal, especially with regard to the concentration transition was predicted at TC ~12 K (19) – the of magnetic impurities (6). Strong electron-phonon highest superconducting transition temperature coupling, favourable for the formation of Cooper pairs among known metal hydrides – at pressure P ~90 GPa. in fcc-Pt, may also be a factor. Enhanced electronic Recent theoretical estimates confi rm that the critical susceptibility and the Sommerfeld coeffi cient (owing temperature of the two high-pressure phases of PtH to low-dispersive near-Fermi bands and high carrier correlates with electron-phonon coupling (19). concentration) bring Pt close to magnetic instability Another group of low-TC (< 8.5 K) superconductors (Stoner factor ~4 (7)), when spin fl uctuations may include germanium-platinum compounds with the completely suppress superconductivity in this skutterudite-like crystal structure MPt4Ge12 (where metal (4). A very low-temperature superconducting M are alkaline earth metals (strontium or barium), transition (at TC ~1.9 mK) was observed for compacted rare earth metals, thorium or uranium) (23–26).The high-purity Pt powder with average grain sizes of ~2 majority of the listed Pt-based materials (a) belong μm (6, 7); for Pt powders with nanosized grains (~100– to three-dimensional (3D)-like crystals; and (b) adopt

300 nm) T C increases to ~20 mK (8, 9). It is supposed that low-temperature superconductivity. the granular structure and the lattice strains related to One of the most remarkable achievements in local inhomogeneity (which is incommensurate with physics and materials sciences was the discovery of the Fermi surface nesting vectors (10)) are the key high-temperature superconductors with TC values factors for the occurrence of inter- and intragranular equal to or above the historical limit of TC ~23 K superconductivity in granular Pt (8–10). In any case, for niobium-germanium (Nb3Ge). Starting with the ‘pure’ Pt as a superconductor seems unlikely. discovery of the superconducting transition at TC = However, a new set of Pt-based alloys and 35 K in Ba-doped La2CuO4 in 1986 (27), several exciting compounds represent very attractive groups of modern families of high-TC materials were subsequently found. superconducting materials, and these have become Among these are the discoveries of superconductivity the subjects of much research interest, particularly in layered materials: MgB2 (TC ~39 K) in 2000 (28) owing to clear evidence of unconventional pairing and fl uorine-doped LaFeAsO (TC ~26 K) in 2008 (29). mechanisms for these systems. These discoveries have inspired worldwide research Traditional John Bardeen, Leon Cooper and Robert efforts and have been the subject of many reviews Schrieffer (BCS)-like theories of superconductivity (30–51). Most recently, phases with considerably hold that pairs of electrons within nonmagnetic increased values of TC ~56 K were synthesised materials are coupled to phonons. In the case (Gd1–xThxFeAsO (52), Sr1–xSmxFeAsF (53) and of unconventional superconductors, various Ca1–xNd1–xFeAsF (54)), and these form a new class of so- mechanisms without phonons are suggested. called iron-based high-temperature superconductors.

For example, the unusual properties of UPt3 (11) The unconventional superconductivity of these including a heavy fermion state below T = 20 K, materials, including various types of pairing and the dynamic antiferromagnetism (AFM) with onset at coexistence of superconductivity with magnetism, has magnetic transition temperature, TN = 6 K, and an been widely discussed. anisotropic superconducting state with three distinct Several groups in this class of Fe-based superconducting phases, provide strong evidence for superconductors are now known. The majority of them unconventional spin-triplet superconductivity. In turn, are iron-pnictide (Pn) (or chalcogenide (Ch)) phases

CePt3Si is the fi rst heavy-fermion superconductor (Fe-Pn or Fe-Ch, respectively). These materials can be without inversion symmetry, and its discovery (12) categorised into the following major groups. From has initiated widespread research activity in the fi eld the chemical point of view, the simplest of them are of so-called noncentrosymmetric superconductors binaries: 11-like phases (such as FeSex (45, 55)); ternary (13–15). Recently such superconductors lacking 111-like (such as AFeAs, where A are alkali metals a lattice inversion centre have been investigated (56)) and 122-like (such as BFe2Pn2, where B are alkali for the possibility of spin-triplet dominated pairing earth metals (57), or AxFe2–yCh2 (58)) materials; and a

wide group of quaternary 1111-like superconductors arsenide blocks (78–80). Thus, the role of Pt in the including pnictide oxides or pnictide fl uorides such as formation of superconducting materials becomes RFeAsO (R are rare earth metals) and BFeAsF. very intriguing. Recently, more complex materials such as Pt as a component of layered superconducting

B3Sc2Fe2As2O5 (32225 phases) (59) and B4M2Fe2Pn2O6 materials has been investigated for a long time, (M are d block metals) (42226 (or 21113) phases) and Pt has been found to play a triple role: (a) as a were proposed (60, 61) as parent phases for new high- dopant, (b) as a component of non-superconducting

TC superconductors (46). For some of these, relatively blocks (spacer layers), and (c) as a component of high transition temperatures were established, for superconducting blocks. Thus, all superconductors example TC ~17 K for Sr4Sc2Fe2P2O6 (60) and TC with Pt can be divided onto two groups: Pt-based ~37 K for Sr4V2Fe2P2O6 (61). This family was further materials (where Pt forms individual sub-lattices expanded when new pnictide oxides such as Can+2(Al, inside blocks) and Pt-containing materials, where Pt Ti)nFe2As2Oy (n = 2, 3, 4) (62), Ca4Al2Fe2(P,As)2O6–y (63), acts as a dopant. Sr4(Sc,Ti)3Fe2As2O8, B a 4Sc3Fe2As2O7.5, B a 3Sc2Fe2As2O5 The following sections will focus on the above (64), Ca4(Mg,Ti)3Fe2As2Oy (65), Sr4MgTiFe2Pn2O6 mentioned materials to cover the basic issues of their (66, 67), and Ba4Sc2Fe2As2O6 (68) were successfully synthesis, main properties and simulation. prepared and studied (69–77). For all the listed iron-based superconducting 2. Pt-Based Superconducting Materials materials: Besides the 10-3-8 and 10-4-8 phases, some other Pt- (a) The crystal structure includes two-dimensional based superconductors are known, such as SrPtAs

(2D)-like (Fe-Pn) (or Fe-Ch) blocks, which are (86), SrPt2As2 (87) and RPt2B2C (where R are rare earth separated by A or B atomic sheets (for 111- and metals or Th) (88–94), see Table I.

122-like phases, respectively) or by (RO), (B3M2O5) or (B2MO3) blocks for more complex 1111, 32225 2.1 1221 Phases (Borocarbides) or 21113 phases; the simplest 11-like binaries Historically, the systematic study of layered Pt-based consist of stacked (Fe-Ch) blocks; superconducting materials began with borocarbides

(b) The electronic bands in the window around the RPt2B2C (1221 phases) in the mid-1990s and was Fermi level are formed mainly by the states of continued in the new millennium (87–99). These

(Fe-Pn) (or Fe-Ch) blocks, which are responsible phases crystallise in the tetragonal LuNi2B2C-type for superconductivity, whereas the A and B atomic structure, which is an interstitial modifi cation of the

sheets or oxide blocks, which are often termed ThCr2Si2-type, and attract attention mainly because of also as spacer layers, serve as insulating ‘charge the coexistence of various types of magnetic ordering reservoirs’; and and superconductivity. Since data about the properties (c) These materials have high chemical fl exibility to of these materials are discussed in detail in a set of a large variety of constituent elements together available reviews (100–104), here only the structural with high structural fl exibility, and atomic and superconducting parameters for known Pt- substitution inside the blocks (electron or hole based superconductors are listed (Table I). All these

doping) is one of the main strategies for designing materials belong to the class of low T C superconductors. new superconducting systems with desirable properties (30–51). 2.2 SrPtAs The next promising step in expanding of this In 2011, the hexagonal phase SrPtAs was discovered family of high-temperature superconductors was (86) as a new low-temperature superconductor with made in 2011, when a unique group of Pt-based TC ~4.2 K. Polycrystalline samples of SrPtAs were materials: 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and 10-3-8 prepared (86) by a solid-state reaction with PtAs2 as a ((CaFe1–xPtxAs)10Pt3As8) phases was discovered precursor mixed with Sr and Pt powders using several (78–80) and intensive studies of their properties were steps of heating. SrPtAs adopts a hexagonal structure initiated (81–85). For these materials superconductivity (space group P63/mmc, #194) derived from the well- has been detected up to TC ~35–38 K, which is probably known AlB2-type structure and can be schematically induced either by Pt doping of the blocks (FeAs) in described as a sequence of two honeycomb planar the 10-3-8 phase or by indirect electron doping in the sheets, where one plane is formed by Sr atoms, and the 2+ 10-4-8 phase owing to additional Pt in the platinum other (PtAs) by hexagonal Pt3As3, see Figure 1. The

Table I

Pt-Based Layered Superconducting Materials: Structural Properties and Critical Temperatures, TC

Type Material Space Lattice constants, Å TC, K Refs. group abc

1221 YPt2B2C I4/mmm – – – 10–11 (88, 89)

LaPt2B2C I4/mmm 3.875 3.875 10.705 10.5–11 (88)

PrPt2B2C I4/mmm 3.837 3.837 10.761 6–6.5 (88, 89)

NdPt2B2C I4/mmm 3.826 3.826 10.732 2.5 (90, 91)

ThPt2B2C I4/mmm 3.83 3.83 10.853 6.7–7 (92–94)

111 SrPtAs P63/mmc 4.244 4.244 8.989 4.2 (86)

122 SrPt2As2 P4/nmm 4.46 4.51 9.81 5.2 (87)

10-4-8 (CaFe1–xPtxAs)10Pt4–yAs8; P4/n 8.716 8.716 10.462 ~11–31 (80) -phase

(CaFe1–xPtxAs)10Pt4–yAs8; P1 8.7282 8.7287 11.049 ~30 (80) -phase, x ~0.13

(CaFe1–xPtxAs)10Pt4–yAs8; P1 8.719 8.727 11.161 32.7–38 (88) x ~0.36

10-3-8 (CaFe1–xPtxAs)10Pt3As8; P1 8.776 8.781 10.689 ~11–35 (80) x ~0.05

(CaFe1–xPtxAs)10Pt3As8; P1 8.795 8.789 21.008 13.7 (83) x ~0.16

atomic coordinates are Sr: 2a (0;0;0), Pt: 2c (⅓ ;⅔ ;¼), (a) (b) A1 Sr and As: 2d (⅔ ;⅓ ;¼), the lattice constants are a = 4.244 Å and c = 8.989 Å (86, 105). B As Some theoretical efforts have been undertaken to predict the electronic and some other properties of SrPtAs (106–108). It is thought that this material should be characterised as a quasi-2D ionic metal Pt (106), which consists of metallic-like (PtAs) sheets alternating with Sr atomic sheets coupled by ionic interactions. The near-Fermi valence bands are derived from the Pt 5d states with an admixture of the As 4p states. The Fermi surface of SrPtAs is formed Fig. 1. Crystal structures of: (a) AlB2 and (b) SrPtAs. The structure of SrPtAs can be described as an by two quasi-2D (cylindrical-like) sheets parallel to ordered variant of the AlB2-type structure, where the kz direction (along the Г-A direction) and by two the Al sites are occupied by Sr and the boron sites sheets at the zone corners (around K-H). All the Fermi are occupied either by Pt or As atoms so that they surfaces are hole-like. A very small closed electronic- alternate in the honeycomb layer as well as along the c-axis (86) like pocket was found around K, see Figure 2.

(a) (b) 4

2 A 0 L EF

H –2 Energy, eV Energy, M K –4

–6  A L M K H A

Fig. 2. (a) Fermi surface; and (b) Electronic bands of SrPtAs (106)

Taking into account the relativistic effects, this 2.3 SrPt2As2 small electronic-like pocket disappears (102), and For the chemically similar phase SrPt2As2 (110), low- the Fermi surface of SrPtAs becomes fully hole-like. TC superconductivity (~5.2 K) has also been found This feature distinguishes SrPtAs from other layered (87), and this phase seems very attractive as the fi rst pnictogen-containing superconductors. It was also superconductor from the wide family of related Pt- pointed out that SrPtAs provides a prime example containing 122-like materials: for example, ThPt2Si2, of a superconductor with locally broken inversion YbPt2Si2, UPt2Si2, RPt2Si2 (R = La, Nd, Er, Dy, Ce), symmetry (107). The calculated anisotropy in Fermi ThPt2Ge2, YbPt2Si2, UPt2Ge2 and RPt2Ge2 (112). velocity, conductivity and plasma frequency related Polycrystalline samples of SrPt2As2 were to the layered structure were found to be enhanced synthesised using stoichiometric amounts of Sr, owing to spin-orbit coupling; further, it was predicted PtAs2 and Pt powders by a solid-state reaction (87). that electron doping would be favourable for an SrPt2As2 adopts a tetragonal CaBe2Ge2-type structure increase in TC (108). Finally, SrPtAs was found (106) (space group P4/nmm, #129) (87, 110, 111). The atomic as a mechanically stable and soft material with high positions are Sr: 2c (¼, ¼, zSr); 2a (¾, ¼, 0); Pt2: 2c compressibility lying on the border of brittle/ductile (¼, ¼, zPt); As1: 2b (¾, ¼, ½); and As2: 2c (¼, ¼, zAs), behaviour, and the parameter limiting its mechanical where zSr,Pt,As are the internal coordinates. The lattice stability is the shear modulus G, Table II. parameters are listed in Table I. This structure can be

Table II Calculated Bulk Modulus (B, in GPa), Compressibility (, in GPa–1), Shear Modulus (G, in GPa), and

Pugh’s Indicator (G/B) for SrPtAs (106) and SrPt2As2 (113)

b c Phase/parameter SrPtAs SrPt2As2 SrPt2As2 a BV,R,VRH 79/10/44.5 101/99/100 71/71/71  0.023 0.010 0.014 a GV,R,RVH 30/15/22.5 27/25/26 29/5/17 G/B 0.51 0.26 0.24 a B(G)V,R,RVH as calculated within Voigt (V)/Reuss (R)/Voigt-Reuss-Hill (VRH) approximations, see for example (109) b For SrPt2As2 polymorphs of CaBe2Ge2-type c For SrPt2As2 polymorphs of ThCr2Si2-type

schematically described as a sequence of Sr sheets (b) Formation of a 3D system of strong covalent Pt-As and [Pt2As2] and [As2Pt2] blocks consisting of {PtAs4} bonds (inside and between [Pt2As2]/[As2Pt2] and {AsPt4} tetrahedrons: …[Pt2As2]/Sr/[As2Pt2]/Sr/ blocks, see Figure 3), which is responsible [Pt2As2]/Sr/[As2Pt2]… as shown in Figure 3. for enhanced stability of this polymorph – in For SrPt2As2, superconductivity coexists with the comparison with the competing ThCr2Si2-like charge density wave (CDW) state (87) and this material phase; and exhibits a CDW transition at about 470 K (110). (c) Essential charge anisotropy between adjacent

Theoretical probes (113, 114) predict that SrPt2As2 [Pt2As2] and [As2Pt2] blocks. is essentially a multiple-band system, with the Fermi It has also been predicted that CaBe2Ge2-like level (EF) crossed by Pt 5d states with a rather strong SrPt2As2 will be a mechanically stable and relatively admixture of As 4p states, Figure 4. It was found (113) soft material with high compressibility, which will that CaBe2Ge2-type SrPt2As2 is a unique system with an behave in a ductile manner, Table II. However, the ‘intermediate’-type Fermi surface (Figure 3), which ThCr2Si2-type SrPt2As2 polymorph, which contains consists of electronic pockets having a cylinder-like only [Pt2As2] blocks, is less stable and will be a ductile (2D) topology (typical of 122 FeAs phases) together material with high elastic anisotropy. with 3D-like electronic and hole pockets. The latest A family of higher-order polytypes has been are characteristic of ThCr2Si2-like iron-free low-TC proposed (113), which can be formed as a result of superconductors. The non-monotonic behaviour of various stacking arrangements of the two main types the density of states (DOS, see Figure 4) near the EF of building blocks ([Pt2As2] and [As2Pt2]) in different suggests the possibility of signifi cant changes of TC combinations along the z axis. This may provide due to various (electron or hole) doping. an interesting platform for further theoretical and Analysis (113) revealed that other features of experimental work in the search for new Pt-based

CaBe2Ge2-like SrPt2As2 are as follows: superconducting materials. (a) Essential differences in contributions to the In 2012, a new family of related ternary platinum

near-Fermi region from the [Pt2As2] and [As2Pt2] phosphides APt3P (A = calcium (Ca), strontium (Sr) blocks when conduction is anisotropic and or lanthanum (La)) was discovered (115). These

occurs mainly in [Pt2As2] blocks; phases crystallise in a tetragonal structure, where

(a) (b) (c) (d) Sr Sr

Sr Sr As Pt Pt As

As As Pt Pt Pt Pt

As As

Z Pt Z A As R N As Pt M  P X A X

Fig. 3. Left: Crystal structures of: (a) SrPt2As2 with CaBe2Ge2-type; and (b) ThCr2Si2-type structures (87) and the corresponding Fermi surfaces (113). Right: Charge density maps of SrPt2As2 polymorphs illustrating the formation of directional “inter-block” covalent bonds: (c) As-Pt bonds for CaBe2Ge2-type; and (d) As-As bonds for ThCr2Si2-type structures (113)

Fig. 4. Total and partial densities Total of states (DOSs) of SrPt2As2 (a) EF polymorphs with structures of:

–1 Pt1 5d 10 (a) CaBe Ge -type; and (b) Pt2 5d 2 2 ThCr Si -type (113) As1 4p 2 2 5 As2 4p formula unit –1 0 (b) 10 Total Pt 5d As 4p 5

Densities of states, eV 0 –8 –6 –4 –2 0 2 4 Energy, eV

the anti-perovskite units Pt6P are placed between Sr has also been suggested that similar phases with sheets. All three materials showed low-temperature additional metallic-like blocks might provide an superconductivity. The highest TC ~8.4 K was found for interesting platform for the discovery of novel high-TC SrPt3P. Local-density approximation (LDA) calculations superconducting materials. (116) reveal the 3D-like multiple band structure of Single crystals of Ca10(PtnAs8)(Fe2–xPtxAs2)5 were APt3P phases. The increase of TC for SrPt3P with hole grown (78) by heating a mixture of Ca, FeAs, Pt and doping (for example, by partial replacement of Sr with As powders. The mixture was placed in an alumina potassium (K), rubidium (Rb) or caesium (Cs)) was crucible, sealed in an evacuated quartz tube, and predicted. heated in one of two ways. Heating at 700ºC for 3 h and then at 1000ºC for 72 h followed by slow cooling

2.4 Quaternary 10-4-8 and 10-3-8 to room temperature yielded an -phase with TC ~38 K, Superconducting Phases whereas heating at 1100ºC and slow cooling to 1050ºC

In 2011, superconductivity with TC ~25 K was reported for 40 h yielded a -phase with TC ~13 K (78). for the tetragonal phase Ca10(Pt4As8)(Fe2As2)5 formed The atomic structures of the -phase Ca10(Pt4As8)- in the quaternary Ca-Pt-Fe-As system (76). Very (Fe2–xPtxAs2)5 (termed also as 10-4-8 phase) and the soon, additional reports (78, 80) became available, -phase Ca10(Pt3As8)(Fe2–xPtxAs2)5 (10-3-8 phase) are where the related Ca-Pt-Fe-As systems are examined depicted in Figure 5; the lattice parameters are listed and enhanced superconductivity with transition in Table I. temperatures up to TC ~38 K, achieved by substitution These structures can be schematically described as of Pt for Fe in the (Fe2As2) blocks, is reported. a sequence of 2D-like [Pt4As8]([Pt3As8]) and [Fe2As2]5 One of the most intriguing features of these new Pt- blocks separated by Ca sheets; in turn, platinum- based materials (78–85) is the presence of (Fe2As2) arsenide blocks [Pt4As8]([Pt3As8]) are formed by blocks, which are typical of the family of Fe-Pn corner-shared {PtAs4} squares, whereas iron-arsenide superconductors, together with oxygen-free blocks blocks consist of {FeAs4} tetrahedrons. In both cases [PtnAsm]. [Pt4As8]([Pt3As8]) and [Fe2As2]5 blocks contain a set Based on Zintl’s chemical concept of ion electron of non-equivalent types of Fe, Pt and As atoms (78–85). counting, it was proposed (79, 80) that [Pt4As8] and Further studies of superconducting gap anisotropy [Fe2As2] blocks in the Ca10(Pt4As8)(Fe2As2)5 phase are (82), low energy electronic structure, and Fermi metallic-like (i.e. both blocks will give appreciable surface topology (using angle resolved photoemission contributions to the density of states at EF) leading spectroscopy, see Figure 5) (117), the critical magnetic to enhanced inter-block coupling and thus to an fi elds (118), and some transport properties (84, 119) enhanced transition temperature of this system. It together with theoretical calculations of the electronic

(a) (b) (c)

X0 Fe2As2

Ca Z0/ M Pt4As8 Fe As 0 2 2 kZ// /Z0 Ca Ca kc//kc0 Fe As ky//kb0 2 2 Pt3As8

Ca kx//ka0

Fe2As2

Fig. 5. Crystal structures of: (a) 10-4-8 phase (-phase Ca10(Pt4As8)(Fe2–xPtxAs2)5); (b) 10-3-8 phase (-phase Ca10(Pt3As8)(Fe2–xPtxAs2)5) (83); and (c) Experimentally-derived Fermi surface for the -phase (117) band structure and parameters of interatomic bonds The fi rst studies of electronic properties and (80, 81) reveal some interesting features of these interatomic bonding (80, 81) reveal that for materials. In particular, Pt doping into FeAs blocks Ca10(Pt4As8)(Fe2As2)5: was found to play a critical role for the occurrence of (a) The electronic bands in the window around the superconductivity. This doping-dependent evolution Fermi level are formed mainly by the Fe 3d states of the superconducting state is illustrated in Figure 6, of [Fe2As2]5 blocks; where the electronic phase diagram for Ca10(Pt3As8)- (b) The [Pt4As8] blocks will behave as semi-metals (Fe2–xPtxAs2)5 is depicted. About 2 wt% Pt doping with very low densities of states at the Fermi level; produces superconductivity, and the superconducting (c) The near-Fermi bands adopt a ‘mixed’ character: transition temperature reaches its maximum TC ~13.6 K simultaneously with quasi-fl at bands, a series of in the doping range 0.050 < x < 0.065. With further Pt high-dispersive bands which intersect the Fermi doping, TC slowly decreases. level was found; and (d) The chemical bonding in Ca10(Pt4As8)(Fe2As2)5 is complicated and includes an anisotropic mixture of covalent, metallic and ionic interatomic and inter-block interactions, see Figure 7.

Inside [Fe2As2]5 blocks covalent Fe-As and metallic- 100 Metallic like Fe-Fe bonds take place, whereas inside [Pt4As8] blocks a system of covalent Pt-As and As-As bonds Semiconducting emerges. Further, inside these blocks interatomic ionic interactions occur owing to charge transfer Fe  As and Pt  As. The inter-block charge transfer 10 occurs from the electropositive Ca ions to [Pt4As8] Temperature, K Temperature, and [Fe2As2]5 blocks. It is important that the charge Superconducting transfer Ca10  [Pt4As8] is much greater than the transfer Ca10  [Fe2As2]5, i.e. in contrast to the 0 0.02 0.04 0.06 0.08 0.10 majority of known superconducting Fe-containing Platinum doping level, x materials (38–43, 51), the new phase Ca10(Pt4As8)- (Fe2As2)5 includes two negatively charged blocks, Fig. 6. Electronic phase diagram for Ca10(Pt3As8)- where the charge of the conducting [Fe2As2]5 blocks (Fe2–xPtxAs2)5 (84) which illustrates the doping- dependent formation of semiconducting, metallic- is much smaller than for the Pt-As blocks. The like, and superconducting states for this material chemical modifi cation of PtnAs8 blocks may lead

(a) (b) (c) 6 6 As 4 Fe 3d 4 As Pt 5d Pt Pt 2 2 Pt-As As 0 0 As As –2 –2 Energy, eV Energy, Energy, eV Energy, 0.5 As –4 Pt 5d –4 0 Pt Pt –0.5 –6 –6 As 0 1 Bonding As Densities of states, Crystal orbital Hamilton arbitrary units population, arbitrary units

Fig. 7. (a) Partial density of states; and (b) Crystal orbital Hamilton population (COHP) of the Pt-As bonds (80); and (c) Charge density map for Ca10(Pt4As8)(Fe2As2)5 phase, which illustrates the formation of directional covalent As-As bonds inside (Pt4As8) blocks (81)

to the discovery of similar materials with increased For non-magnetic superconductors such as YNi2B2C TC (83). and LuNi2B2C, the introduction of Pt atoms at the nickel sites leads to modifi cations of their superconducting

3. Platinum-Doped Layered properties. For series of single crystals of YNi2–xPtxB2C Superconducting Materials (x = 0.02, 0.06, 0.1, 0.14 and 0.2), which were grown by The fi rst attempts to investigate Pt as a dopant the travelling solvent fl oating zone method (125), with which can optimise the properties of layered an increase in the Pt content the critical temperature superconductors were undertaken as early as the decreases from TC ~15.9 K to TC ~13 K for x = 0.14, 1990s when the high-temperature superconductor Figure 8. The results were explained (125) assuming cuprates were examined (120, 121). Next, the effects the increase in inter-band scattering in the multi-band induced by Pt doping of 1221 phases (borocarbides), superconductor YNi2B2C. which exhibit a rich variety of phenomena associated Pseudo-quaternary samples Y(Pd1–xPtx)2B2C were with superconductivity, magnetism, and their interplay, prepared by mechanical alloying followed by a were studied (122–131). thermal treatment (126). It was found that Pt stabilises

(a) (b) 0

‘ 10  –0.2 x = 0.0 6 TC , K N

–0.4 x = 0.1 T 8 –0.6 x = 0.14 x = 0.02

x = 0 and C

x = 0.2 T 6 –0.8 TN AC susceptibility, AC susceptibility, –1.0 4 12 13 14 15 16 0 0.05 0.10 0.15 0.20 Temperature, K Platinum concentration, x

Fig. 8. (a) Normalised real part of alternating current (AC) susceptibility as a function of temperature in YNi2–xPtxB2C (125); and (b) Superconducting transition temperature (TC) and magnetic transition temperature (TN) in Er(Ni1–xPtx)2B2C as functions of the Pt concentration, x (131)

the formation of the tetragonal superconducting phase YPd2B2C (which adopts the highest TC ~23 K 150 among the borocarbides), when an almost single- phase material with TC near 15 K for Y(Pd0.8Pt0.2)2B2C was formed after annealing at 1273 K. 100 For magnetic superconductors such as ErNi2B2C, the introduction of Pt atoms infl uences both TC and T (129–131). For example the measurements for Antiferro- N 50 Er(Ni1–xPtx)2B2C (polycrystalline samples with magnetic Pt content x = 0.0, 0.05, 0.10, 0.15 and 0.20 were K Temperature, synthesised by standard arc melting under protective Superconducting argon atmosphere (131)) reveal that the variation of TC 0 0.05 0.10 0.15 0.20 0.25 as a function of x contains two intervals, see Figure 8. Platinum concentration, x At the fi rst step, a strong decrease in TC in the range 0 ≤ x < 0.10 occurs, whereas a much weaker drop of TC was Fig. 9. Phase diagram of BaFe2–xPtxAs2 for the doping observed with a further increase of x (131). The value level x = 0–0.25 (133). At x < 0.02 a magnetic state with AF spin ﬂ uctuations exists. Superconductivity of TN, by contrast, decreases almost monotonically. appears at x = ~0.02, and TC reaches its maximum Thus, the Pt impurities in superconducting 1221 value (25 K) at x = 0.1 borocarbides usually lead to reduction of TC. The explanation of the observed effects requires further studies. electrons between the doped transition metal (Pt) and A different effect accompanies the introduction iron, i.e. the chemical scaling of the electronic phase of Pt inside layered 122-like Fe-based pnictides diagram (137, 138). such as BFe2Pn2 (132–136). It is known that ‘pure’ However, some exceptions can exist here: for BFe2Pn2 phases (parent materials for Fe-based the related system CaFe2–xPtxAs2 it was established superconductors) are located on the border (134) that the substitution of Pt is ineffective in the of magnetic instability and commonly exhibit reduction of AFM ordering as well as for inducing of temperature-dependent structural and magnetic superconductivity up to a solubility limit at x ~0.08. transitions with the formation of collinear AFM spin This challenge calls for further studies. ordering, whereas superconductivity emerges either as a result of hole or electron doping into these 4. Conclusions parent compounds (38–43, 47). Accordingly, this effect This overview has covered the relatively little-known was observed for some Pt-doped 122-like phases. role of platinum in design and modifi cation of modern

Polycrystalline samples of SrFe2–xPtxAs2 (0 ≤ x ≤ 0.4) superconducting materials. The main goal was to were prepared by a solid-state reaction method using highlight recent experimental and theoretical results SrAs, FeAs and metallic powders of Fe and Pt as that may give an insight into the current status and reagents. The mixture was pressed into a Ta capsule, possible development of layered superconducting sealed in an evacuated quartz tube, and heated at materials with Pt. 1000ºC for 48 h. The measurements demonstrated To date, two types of such materials have been that as a result of Pt doping, the magnetic order of the discovered: Pt-based materials (where Pt forms parent phase SrFe2As2 is suppressed, superconductivity individual sub-lattices inside building blocks of for SrFe2–xPtxAs2 emerges at approximately x = 0.15, corresponding phases such as SrPtAs, SrPt2As2, LaPt2B2C and TC reaches a maximum of 16 K at x = 0.2 (132). and (CaFe1–xPtxAs)10Pt3As8) and Pt-containing materials A similar effect was detected for the related system (such as Y(Pd1–xPtx)2B2C or SrFe2–xPtxAs2), where Pt acts BaFe2–xPtxAs2 (133), where at the doping level of x ~0.1 as a dopant. The role of Pt can be radically different. For the maximum transition temperature TC ~25 K was example, the Pt impurity in superconducting borocarbides achieved. This situation is well illustrated in Figure 9, usually leads to a reduction of TC; whereas the where the electronic phase diagram of BaFe2–xPtxAs2 introduction of Pt inside layered Fe-based pnictides such for the doping range x = 0–0.25 is depicted. In a as BFe2Pn2 leads to the occurrence of superconductivity simplifi ed way, these effects can be interpreted in (with high transition temperatures to TC ~25 K) in these terms of the difference in the number of valence non-superconducting parent materials. A very promising

step in expanding the family of superconducting 16 E. Bauer, R. T. Khan, H. Michor, E. Royanian, A. Grytsiv, materials with Pt was made in 2011, when the unique N. Melnychenko-Koblyuk, P. Rogl, D. Reith, R. Podloucky, E.-W. Scheidt, W. Wolf and M. Marsman, Phys. Rev. B, quaternary phases: 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and 2009, 80, (6), 064504 10-3-8 ((CaFe1–xPtxAs)10Pt3As8) with highest TC ~35–38 K were discovered. 17 K. V. Samokhin and V. P. Mineev, Phys. Rev. B, 2008, 77, (10), 104520 The author hopes that this overview will be useful as 18 Y. Aoki, A. Sumiyama, M. Shiotsuki, G. Motoyama, a compendium to guide further research into layered – A. Yamaguchi, Y. Oda, T. Yasuda, R. Settai and Y. Onuki, superconducting materials with Pt, which seem J. Phys. Soc. Jpn., 2010, 79, (12), 124707 interesting and challenging systems for providing new 19 T. Scheler, O. Degtyareva, M. Marqués, C. L. Guillaume, and promising superconductors. J. E. Proctor, S. Evans and E. Gregoryanz, Phys. Rev. B, 2011, 83, (21), 214106 Acknowledgements 20 X.-F. Zhou, A. R. Oganov, X. Dong, L. Zhang, Y. Tian and Financial support from the Russian Foundation for H.-T. Wang, Phys. Rev. B, 2011, 84, (5), 054543 Basic Research (RFBR) (Grant 12-03-00038-a) is 21 G. Gao, H. Wang, L. Zhu and Y. Ma, J. Phys. Chem. C, gratefully acknowledged. 2012, 116, (2), 1995 22 C. Zhang, X.-J. Chen and H.-Q. Lin, J. Phys.: Condens. Matter, 2012, 24, (3), 035701 References 23 R. Gumeniuk, W. Schnelle, H. Rosner, M. Nicklas, 1 R. N. Shelton, J. Less-Common Met., 1978, 62, 191 A. Leithe-Jasper and Yu. Grin, Phys. Rev. Lett., 2008, 2 S. Moehlecke, D. E. Cox and A. R. Sweedler, J. Less- 100, (1), 017002 Common Met., 1978, 62, 111 24 E. Bauer, X.-Q. Chen, P. Rogl, G. Hilscher, H. Michor, 3 Ch. J. Raub, Platinum Metals Rev., 1984, 28, (2), 63 E. Royanian, R. Podloucky, G. Giester, O. Sologub and A. P. Gonçalves, Phys. Rev. B, 2008, 78, (6), 064516 4 W. Wendler, T. Herrmannsdörfer, S. Rehmann and F. Pobell, Europhys. Lett., 1997, 38, (8), 619 25 R. Gumeniuk, H. Rosner, W. Schnelle, M. Nicklas, A. Leithe-Jasper and Yu. Grin, Phys. Rev. B, 2008, 78, 5 A. C. Clark, K. K. Schwarzwälder, T. Bandi, D. Maradan (5), 052504 and D. Zumbühl, Rev. Sci. Instrum., 2010, 81, (10), 103904 26 D. Kaczorowski and V. H. Tran, Phys. Rev. B, 2008, 77, (18), 180504(R) 6 R. König, A. Schindler and T. Herrmannsdörfer, Phys. Rev. Lett., 1999, 82, (22), 4528 27 J. G. Bednorz and K. A. Müller, Z. Phys. B Condens. Matter, 1986, 64, (2), 189 7 A. Schindler, R. König, T. Herrmannsdörfer and H. F. Braun, Phys. Rev. B, 2000, 62, (21), 14350 28 J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani and J. Akimitsu, Nature, 2001, 410, (6824), 63 8 A. Schindler, R. König, T. Herrmannsdörfer, H. F. Braun, G. Eska, D. Günther, M. Meissner, M. Mertig, R. Wahl 29 Y. Kamihara, T. Watanabe, M. Hirano and H. Hosono, J. and W. Pompe, Europhys. Lett., 2002, 58, (6), 885 Am. Chem. Soc., 2008, 130, (11), 3296 9 A. Schindler, R. König, T. Herrmannsdörfer, H. F. Braun, 30 A. L. Ivanovskii, Uspekhi Khimii, 2001, 70, (9), 811 G. Eska, D. Günther, M. Meissner, M. Mertig, R. Wahl 31 P. C. Canﬁ eld, S. L. Bud’ko and D. K. Finnemore, Phys. C: and W. Pompe, Phys. B: Condens. Matter, 2003, 329– Supercond., 2003, 385, (1–2), 1 333, Part 2, 1427 32 A. L. Ivanovskii, Phys. Solid State, 2003, 45, (10), 1829 10 I. Martin, D. Podolsky and S. A. Kivelson, Phys. Rev. B, 33 J. Akimitsu and T. Muranaka, Phys. C: Supercond., 2003, 2005, 72, (6), 060502(R) 388–389, 98 11 R. Joynt and L. Taillefer, Rev. Mod. Phys., 2002, 74, 34 J. Akimitsu, S. Akutagawa, K. Kawashima and T. (1), 235 Muranaka, Progr. Theor. Phys. Suppl., 2005, 159, Suppl. 12 E. Bauer, G. Hilscher, H. Michor, Ch. Paul, E. W. Scheidt, 1, 326 A. Gribanov, Yu. Seropegin, H. Noël, M. Sigrist and P. 35 K. Vinod, R. G. Abhilash Kumar and U. Syamaprasad, Rogl, Phys. Rev. Lett., 2004, 92, (2), 027003 Supercond. Sci. Technol., 2007, 20, (1), R1 13 S. Fujimoto, J. Phys. Soc. Jpn., 2007, 76, (5), 051008 36 A. L. Ivanovskii, I. R. Shein and N. I. Medvedeva, Uspekhi and references therein Khimii, 2008, 77, (5), 491 14 D. C. Peets, G. Eguchi, M. Kriener, S. Harada, Sk. Md. 37 T. C. Ozawa and S. M. Kauzlarich, Sci. Technol. Adv. Shamsuzzamen, Y. Inada, G.-Q. Zheng and Y. Maeno, Mater., 2008, 9, (3), 033003 Phys. Rev. B, 2011, 84, (5), 054521 and references therein 38 A. L. Ivanovskii, Physics–Uspekhi, 2008, 51, (12), 1229 15 J. Chen, M. B. Salamon, S. Akutagawa, J. Akimitsu, 39 R. Pöttgen and D. Johrendt, Z. Naturforsch. B, 2008, 63, J. Singleton, J. L. Zhang, L. Jiao and H. Q. Yuan, (10), 1135 Phys. Rev. B, 2011, 83, (14), 144529 and references 40 F. Ronning, E. D. Bauer, T. Park, N. Kurita, T. Klimczuk, R. therein Movshovich, A. S. Sefat, D. Mandrus and J. D. Thompson,

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131 C. Mazumdara, L. C. Gupta, K. Nenkov, G. Behr and G. The Author Fuchs, J. Alloys Compd., 2009, 480, (2), 190 Alexander L. Ivanovskii completed his 132 S. R. Saha, T. Drye, K. Kirshenbaum, N. P. Butch, P. Y. PhD in 1979 at the Institute of Solid Zavalij and J. Paglione, J. Phys.: Condens. Matter, 2010, State Chemistry in Ekaterinburg, Russia, and accomplished his habilitation in 22, (7), 072204 Chemistry at the same institute in 1988. 133 X. Zhu, F. Han, G. Mu, P. Cheng, J. Tang, J. Ju, He was promoted to Professor in 1992 K. Tanigaki and H.-H. Wen, Phys. Rev. B, 2010, 81, (10), and since 1994 he has been head of the Laboratory of Quantum Chemistry 104525 and Spectroscopy at the Institute of 134 K. Kudo, M. Kobayashi, S. Kakiya, M. Danura and Solid State Chemistry at the Ural Branch M. Nohara, J. Phys. Soc. Jpn., 2012, 81, (3), 035002 of the Russian Academy of Sciences. Professor Ivanovskii is the author or 135 K. Kirshenbaum, S. R. Saha, T. Drye and J. Paglione, coauthor of more than 470 research Phys. Rev. B, 2010, 82, (14), 144518 articles and 12 monographs. His main research interests are focused on the 136 S. B. Zhang, Y. F. Guo, J. J. Li, X. X. Wang, K. Yamaura theory of electronic structure, chemical and E. Takayama-Muromachi, Phys. C: Supercond., bonds, and computational materials 2011, 471, (21–22), 600 science of superconductors, superhard materials and inorganic nanostructures. 137 S. R. Saha, N. P. Butch, K. Kirshenbaum and J. Paglione, Phys. Rev. B, 2009, 79, (22), 224519 138 N. Ni, A. Thaler, A. Kracher, J. Q. Yan, S. L. Bud’ko and P. C. Canﬁ eld, Phys. Rev. B, 2009, 80, (2), 024511

CAT4BIO Conference: Advances in Catalysis for Biomass Valorization

Highlights of platinum group metal catalysts development for conversion of biomass to energy, fuels and other useful materials

http://dx.doi.org/10.1595/147106713X663889 http://www.platinummetalsreview.com/

Reviewed by Eleni Heracleous Introduction Laboratory of Environmental Fuels and Hydrocarbons, The transformation of biomass into fuels and Chemical Process Engineering Research Institute, Centre for chemicals is becoming increasingly popular as a Research and Technology Hellas, 6th klm Charilaou – Thermi way to mitigate global warming and diversify energy Road, PO Box 361, 57001 Thermi, Thessaloniki, Greece sources. Catalysis will serve as key technological driver to achieve effi cient and practical biomass conversion routes to useful products. As part of the satellite Angeliki Lemonidou* conferences complementing the 15th International Laboratory of Petrochemical Technology, Department of Congress on Catalysis 2012 (held 1st–6th July 2012, Chemical Engineering, Aristotle Univerisity of Thessaloniki, in Munich, Germany), the Greek Catalysis Society 54124 Thessaloniki, Greece organised CAT4BIO, an international conference *Email: [email protected] on “Advances in Catalysis for Biomass Valorization”, that was successfully held in Thessaloniki, Greece, on 8th–11th July 2012 (1). The conference was held under the auspices of the Aristotle University of Thessaloniki (AUTH) and the Centre for Research and Technology Hellas (CERTH), with fi nancial support from the Faculty of Engineering and the Department of Chemical Engineering at AUTH and the School of Engineering of the University of Patras. Industrial sponsors included the companies Arkema (France), BIOeCON (The Netherlands) and Hellenic Petroleum (Greece). The conference’s scientifi c programme covered the most recent progress in fundamental and applied catalysis research for the conversion of biomass. It consisted of eight keynote lectures from internationally renowned experts in the fi eld, 36 high quality oral presentations and 95 posters from research groups worldwide. The programme was organised in nine sessions, structured around the following main topics: (a) Conversion of cellulose/hemicellulose into platform molecules; (b) Conversion of oils extracted from seeds and algae; (c) Conversion of biomass into fuels and chemicals via thermochemical processes; (d) Catalytic routes for lignin valorisation; and (e) Upgrading of biomass-derived products to high added value fuels and chemicals.

Overall, there was excellent attendance with around the past decade. Noble metal catalysts can be used to 135 participants from both industry and academia from achieve the one-pot synthesis of sorbitol from cellulose, 28 countries worldwide. The conference succeeded in however commercial application is hindered by the serving as a platform for the presentation of the most cost of the catalyst. The high stability of cellulose recent progress in fundamental and applied catalysis presents another problem, as the reaction requires research for the conversion of biomass. Presenters harsh process conditions which degrade the fi nal shared their most up to date results on catalyst design, products and reduce selectivity. In a paper presented synthesis and characterisation, surface and catalytic by Jorge Beltramini and coworkers (University of reaction mechanisms and catalytic reaction processes Queensland and Monash University, Australia), it in the area of biomass valorisation. The conference was shown that small amounts of Pt promote nickel also provided ground for fruitful discussions among catalysts and signifi cantly improve their catalytic catalysis experts from industry and academia. Selected activity. This synergistic effect was attributed to Pt and oral and poster contributions will be published as Ni particles in close vicinity. Figure 1 shows sorbitol full papers in a special issue of Applied Catalysis B: and mannitol yields, as well as cellulose conversion, Environmental (2). from the aqueous phase hydrolysis and hydrogenation This review focuses on the progress presented at the of cellulose using supported alumina and alumina conference on platinum group metal (pgm) catalysts nanofi bre (‘Alnf’) catalysts. for the conversion of biomass to fuels and chemicals. Hirokazu Kobayashi and colleagues (Hokkaido The main bulk of the pgm work reported at CAT4BIO University, Japan) showed that cellulose can also involved platinum catalysts, followed by papers on be hydrolysed effectively to glucose by carbon- ruthenium, palladium and rhodium. The highlights of supported Ru catalysts. 2 wt% Ru supported on the pgm work presented in this review are categorised ordered mesoporous CMK-3 carbon gave a yield of based on the type of reaction employed for the 24% glucose and 16% cello-oligosaccharides at 503 K. conversion of biomass and biomass-derived products The conversion of cellulose was 56%, and thereby to high added value fuels and chemicals. the selectivity for glucose was 43%. The conversion of cellulose was slightly improved by increasing Hydrolysis of Cellulose/Hemicellulose to the content of Ru. This showed that the Ru species Platform Chemicals hydrolyse both cellulose and oligosaccharides, and The catalytic conversion of cellulose to platform show especially high activity for the latter substrate. chemicals has gained increasing research attention in Results from X-ray absorption fi ne structure (XAFS)

Keynote Lectures Professor Enrique Iglesia (University of California at Berkeley, USA), François Gault Lecture: ‘Monofunctional and Bifunctional C–C and C–O Bond Formation Pathways from Oxygenates’ Professor Johannes Lercher (Technical University of Munich, Germany), ‘From Biomass to Kerosene – Tailored Fuels via Selective Catalysis’ Professor Daniel Resasco (University of Oklahoma, USA), ‘Deoxygenation of Phenolics, Acids and Furfurals Derived from Biomass’ Professor Atsushi Fukuoka (Hokkaido University, Japan), ‘Conversion of Cellulose into Sugar Compounds by Carbon-Based Catalysts’ Professor George Huber (University of Massachusetts, USA), ‘Aqueous Phase Hydrodeoxygenation of Carbohydrates’ Jean Luc Dubois (ARKEMA, France), ‘Added Value of Homogeneous, Heterogeneous and Enzymatic Catalysts in Biorefi neries’ Paul O’Connor (BIOeCON, The Netherlands), ‘Catalytic Pathways towards Sustainable Biofuels’ Claire Courson (University of Strasbourg, France), ‘Strategy to Improve Catalytic Effi ciency for Both

Thermal Conversion of Biomass, Tar Reduction and H2S Absorption in a Fluidized Bed’

Fig. 1. Sorbitol and 35 55 mannitol yield and Mannitol cellulose conversion 30 Sorbitol 50 from the aqueous phase hydrolysis Cellulose 45 and hydrogenation 25 of cellulose using supported platinum 40 Conversion, % and nickel on alumina 20 and alumina nanoﬁ bre 35 (Alnf) catalysts 15 (Courtesy of Jorge Yield, % Beltramini, University 30 of Queensland, 10 Australia) 25

5 20

0 15 3 O 3 O 3 O 2 2 2 Ni/Alnf Ni/Al Pt/Alnf Pt/Al Ni-Pt/Alnf Ni-Pt/Al Catalysts

analysis for the Ru catalyst were also presented. the catalyst leads to blocking of catalytic Pt sites and Characterisation showed that the Ru species on CMK-3 hence deactivation of the catalyst, as observed with is not metal but RuO2·2H2O regardless of the hydrogen transmission electron microscopy (TEM) (Figure 2). reduction in its preparation. Accordingly, one possible Taking their work one step further, the authors origin for the catalytic activity is that the Ru species reported the development of stable Pt catalysts for works as Brønsted acid by the heterolysis of water ethylene glycol supercritical aqueous phase reforming molecules on Ru. supported on carbon nanotubes (CNTs). CNTs were found to be stable in hot compressed water. Moreover, Hydrogen Production via Reforming of the Pt/CNT catalysts exhibited stable activity for the Biomass-Derived Products reforming of both ethylene glycol and acetic acid,

A good number of contributions dealt with the use confi rming that deactivation of Pt/Al2O3 is caused by of pgms, mainly Pt, for the reforming of alcohols the support and demonstrating the great importance and other oxygenates from biomass to hydrogen. of the type of support for reactions under supercritical Leon Lefferts (University of Twente, The Netherlands) conditions. The aqueous phase reforming of ethylene presented interesting results on the aqueous phase glycol and other polyols (glycerol and sorbitol) over reforming of ethylene glycol in supercritical water over Pt supported on hollow-type ordered mesoporous Pt-based catalysts. Ethylene glycol was investigated as carbon (OMC) with three-dimensional (3D) pore a representative model compound for the aqueous structure was also reported in a poster contribution phase of bio-oil, derived from biomass pyrolysis. Pt/Al2O3 by Chul-Ung Kim and colleagues (Korean Research and Pt-Ni/Al2O3 catalysts, although active in the Institute of Chemical Technology, Korea). Better reaction, were shown to deactivate rapidly with time catalytic performance, including carbon conversion, on stream. Acetic acid, an intermediate of the reaction, hydrogen selectivity, yield and production rate was was shown to be responsible for the deactivation of observed over these materials, implying that 3D Pt and Pt-Ni catalysts. The presenter explained that interconnected mesopore systems allow faster pore acetic acid behaves as a strong acid in sub- and diffusion of reactive molecules. supercritical water resulting in hydroxylation of the The steam reforming of bioethanol over Pt catalysts

Al2O3 surface. Redeposition of the dissolved Al2O3 on was discussed in two oral presentations at the

Fig. 2. TEM image of a deactivated platinum catalyst for the aqueous phase reforming of ethylene glycol in supercritical water (Reproduced 0.71 nm from (3), Copyright 2012, with permission from Elsevier) 2.5× Al2O3 support

Pt particle covered by migrated Al2O3 0.71 nm 2 nm 2.5×

conference. An especially interesting contribution, Similar conclusions were also reported in the reporting mechanistic aspects of the reaction over presentation of Filomena Castaldo et al. (University of Pt, came from the group of Professor Xenophon Salerno, Italy) who investigated the ethanol reforming

Verykios (University of Patras, Greece). Paraskevi reaction over a 3 wt% Pt/10 wt% Ni/CeO2 catalyst. Panagiotopoulou (University of Patras, Greece) Investigation of the reaction pathway by kinetic fi rst presented a very systematic work on ethanol experiments showed that ethanol steam reforming reforming over catalysts with different pgms (Pt, Pd, Rh is probably not the reaction that actually occurs at and Ru) and different supports (zirconia, Al2O3 and 370ºC. Instead, the involved reactions are most likely ceria). Catalytic performance was found to depend to be the following: ethanol dehydrogenation; ethanol strongly on the nature of the dispersed metallic and acetaldehyde decomposition and reforming; phase employed, with Pt and Pd exhibiting good water gas shift reaction; and methanation. The same activity and selectivity towards hydrogen. However, seems to apply for feedstocks other than ethanol, the presenter showed that specifi c activity is defi ned based on the work that was presented by Ricardo primarily by metal crystallites and secondarily by Reis Soares (Universidade Federal de Uberlândia, metal/support interface. The normalised reaction rates Brazil). This contribution reported results on glycerol were found to increase with decreasing perimeter of reforming over Pt/C catalysts and also showed that the metal/support interface and with increasing Pt dehydrogenation is the key limiting step of the reaction. crystallite size, implying that active sites are terrace Moreover, the reaction is sensitive to the structure of sites and that ethanol adsorbs fl at on the Pt surface. the Pt/C catalysts, with the activity decreasing and the In situ diffuse refl ectance infrared Fourier transform selectivity shifting towards acetol and glycolaldehyde spectroscopy (DRIFTS) experiments also showed as particles decrease in size. In other words, C–O that the oxidation state of Pt seems to affect catalytic cleavage seems to occur preferentially on smaller activity, which decreases with increasing population particles. of adsorbed carbon monoxide (CO) species on In a poster contribution by Weijie Cai and Pilar partially oxidised (Pt+) sites. Moreover, the combined Ramírez de la Piscina (University of Barcelona, results of temperature programmed surface reaction Spain) and Narcís Homs (University of Barcelona (TPSR) and in situ DRIFTS experiments provided and Catalonia Institute for Energy Research, Spain), evidence that the key step for ethanol reforming at low the importance of pgms for the effective oxidative temperatures is the ethanol dehydrogenation reaction, reforming of bio-butanol was reported. Doping producing surface ethoxy species and subsequently of cobalt/zinc oxide catalysts with Rh, Ru and Pd acetaldehyde, which is further decomposed toward signifi cantly improved the catalytic performance and methane, hydrogen and carbon oxides. stability of the materials, with CoRh/ZnO exhibiting the

best catalytic performance in bio-butanol oxidative the surface chemistry of the catalyst components in reforming. water allow suitable stable catalysts to be designed for the aqueous phase hydrodeoxygenation of biomass Hydrodeoxygenation of Biomass and and biomass-derived components to alkanes. Results Biomass-Derived Products to Fuels and relevant to pgms were shown on the kinetics of the Chemicals catalytic conversion of palmitic acid and intermediate Currently, there is considerable interest in investigating products, 1-hexadecanol and palmityl palmitate. the hydrodeoxygenation process, due to the high The impacts of the catalytically active metal (Pt, Pd oxygen content of the feedstocks used for the or Ni) and the support (C, ZrO2, A l 2O3, silica, or the production of renewable fuels. One of the main zeolites HBEA or HZSM-5), as well as the role of H2, advantages of the hydrodeoxygenation route relative were explored in order to elucidate the reaction to other methods for making biomass-derived fuels pathway. The speaker shared results on the conversion is that the corresponding renewable fuel product is of palmitic acid at 260ºC in the presence of H2 for a high quality, oxygen free, hydrocarbon fuel which three monofunctional metal catalysts: Pt/C, Pd/C and can be readily blended with conventional petroleum- Raney Ni (Table I). High selectivity to n-pentadecane based refi nery fuel blendstocks and components. was obtained on all three metals (70% on Ni; 98% Johannes Lercher (Technical University of on Pt and Pd), but relatively low conversions were Munich, Germany) reported exciting aspects of the attained on Pt and Pd at 31% and 20%, respectively. deoxygenation of components from both proteinaceous A high selectivity to lighter hydrocarbons (16%) biomass (grown in an aqueous environment) and through C–C bond hydrogenolysis together with a low lignocellulose (grown terrestrially) during his keynote selectivity to palmityl palmitate (4.6%) was observed lecture. Professor Lercher showed how detailed over the Raney Ni catalyst. In a H2 atmosphere, the knowledge of the elementary reaction steps and of direct decarboxylation or decarbonylation routes

Table I Comparison of Palmitic Acid Conversion on Carbon- or Zirconia-Supported Metal Catalystsa

Catalyst Conversion, % Selectivity, %b Initial rate, mmol g–1 h–1

C15 C16 ABC

Raney Nic 100 71 3.7 16 4.6 4.6 2.0

5% Pt/C 31 98 1.6 0.2 – – 0.4

5% Pd/C 20 98 1.9 0.3 – – 0.3

5% Ni/ZrO2 100 90 0.8 9.0 – – 1.3

5% Pt/ZrO2 99 61 6.5 0.5 22 7.3 1.0

5% Pd/ZrO2 98 98 0.7 1.0 – 0.1 1.2 a Reaction conditions: 1 g palmitic acid, 100 ml dodecane, 0.5 g catalyst, 260ºC, 12 bar H2 with a ﬂ ow rate of 20 ml min–1, 6 h b A: Lighter alkanes, B: 1-Hexadecanol, C: Palmityl palmitate c 0.25 g catalyst (Reproduced from (4), Copyright 2013, with permission from Wiley-VCH Verlag GmbH & Co KGaA)

proceeded in parallel to the hydrogenation pathway. and optimisation of reaction conditions. In terms of Direct decarboxylation and/or decarbonylation of fatty catalyst design, Professor Huber showed that the Pt acids were the major pathways on carbon supported metal sites and the acid sites can be atomically mixed

Pt or Pd, much faster than the hydrogenation of (as in the case of a Pt-ReOx/C catalyst) or atomically the fatty acid. However, the hydrogenation route separate (as in the case of a platinum/zirconium took precedence over decarbonylation on the phosphate catalyst). These differences in the catalyst pure metallic Ni, as the decarbonylation on Ni was properties result in the formation of different products. much slower than on Pt or Pd. When the support The product selectivity can be further adjusted by was changed from carbon to ZrO2, the conversion tuning the metal to acid site ratio. The type of acid sites increased from 20–30% to 100% for supported 5 wt% Pt is also important in this reaction to avoid undesired and Pd catalysts under identical conditions, indicating coking reactions. that the hydrogenation of fatty acids was promoted Another excellent keynote lecture was delivered by by ZrO2. High selectivity for n-pentadecane (98%) was Daniel Resasco (University of Oklahoma, USA) who observed on Pd/ZrO2, while Pt/ZrO2 led to a relatively focused on the deoxygenation of phenolics, acids and low selectivity towards C15 alkanes (61%) due to the furfurals derived from biomass to monofunctional high concentrations of 1-hexadecanol (22%). Ni/ZrO2 compounds or hydrocarbons. Of interest to the progress also led to 90% selectivity towards n-pentadecane at of pgms in the area of biomass valorisation were the 100% conversion. These results imply that by using developed ruthenium/titania/carbon catalyst for the

ZrO2 as support, the three metals (Pt, Pd and Ni) liquid phase conversion of acetic acid to acetone and varied the primary route from direct decarboxylation/ the palladium-iron catalysts for the hydrogenation of decarbonylation to hydrogenation-decarbonylation, furfural. The novel Ru/TiO2/C catalyst proved to be very as large concentrations of alcohol intermediates were effective at temperatures much lower than typically observed during the reactions. Thus, support aided needed for the reaction using existing catalysts. After hydrogenation became the primary route for reaction detailed characterisation of the material, Professor on these ZrO2-based catalysts in H2. The three metals, Resasco proposed that the origins of this high activity however, also led to different hydrogenolysis activities; are the oxygen vacancies and the Ti3+ sites which for example, Pt/ZrO2 or Pd/ZrO2 produced less than 1% are promoted by the presence of Ru. Moreover, the lighter alkanes, while Ni/ZrO2 led to 9%, in line with the hydrophobicity of the carbon support is believed to marked hydrogenolysis activity of Ni. decelerate the inhibiting effect that water typically George Huber (University of Massachusetts, has on catalysts with hydrophilic surfaces. Concerning USA) gave a comprehensive keynote lecture on the furfural conversion, the presenter showed that whereas aqueous phase hydrodeoxygenation of carbohydrates Pd is active for the decarbonylation of furfural to produce a wide range of products including C1– to furan and methylfuran, by alloying Fe with Pd C6 alkanes, C1–C6 primary and secondary alcohols, a dramatic change in selectivity occurs. It seems cyclic ether and polyols. The lecture focused on the that hydrogenolysis of the C–O bond is favoured on hydrodeoxygenation of sorbitol, xylose and glucose, Pd-Fe alloys, whereas on Pd the preferred reaction as well as pyrolysis oils, and discussed several is C–C bond breakage. Selectivity to methylfuran aspects of the hydrodeoxygenation process, such was found to be a strong function of the degree as catalytic challenges, chemistry, kinetic modelling of Pd-Fe alloying. The extent of Pd-Fe interaction and reaction engineering. The reaction takes place also strongly depended on the type of support over Pt bifunctional catalysts that involve both metal (SiO2 > -Al2O3 > -Al2O3). and acid sites. The presenter showed that three The pgm catalysts were also reported to be active classes of reactions occur during the aqueous phase for the hydrodeoxygenation of fatty acids to renewable hydrodeoxygenation of carbohydrates: (a) C–C bond diesel fuel. In an oral contribution from Bartosz cleavage on metal sites; (b) C–O cleavage reaction Rozmysłowicz (Åbo Akademi University, Finland), on acid sites; and (c) hydrogenation on metal Pd/C was shown to be an effective catalyst for the sites. Figure 3 shows the rich reaction chemistry deoxygenation of algae oil, tall oil fatty acids and involved in aqueous phase hydrodeoxygenation of macauba oil, which were chosen as representative biomass derived oxygenates that according to the renewable oils of different origins (algae, wood and speaker can be further tuned by adjusting the relative fruits). The presented work also included a set of kinetic reaction pathways through further catalyst design experiments which revealed the reaction pathway over

106 © 2013 Johnson Matthey http://dx.doi.org/10.1595/147106713X663889 •Platinum Metals Rev., 2013, 57, (2)• C6 + Pt H Dehydration Hydrogenation Dehydration and hydrogenation Retro-aldol condensation Dehydrogenation and decarbonylation r, OH Key Classes of Reactions Key Aqueous phase hydrodeoxygenation of sorbitol + HO H Pt Pt + Pt H C4–C5 + OH Pt H Pt Pt OH + HO H Pt OH + O OH Pt H OH OH C1–C3 Pt Pt OH 6 + H H 2 + C Pt H Pt O OH Pt OH + OH + Pt H HO H Pt Pt + Pt H OH OH O OH + OH O Pt + HO O O Pt H + Pt OH H Pt Pt OH HO OH Pt + + Pt + H H OH H OH OH Pt H Pt O 4 O OH O CH HO + HO OH + Pt H Pt HO Pt HO + Pt OH H + + H H OH OH OH 3 OH Pt CH Pt HO OH OH OH OH Fig. 3. Reaction pathways for the hydrodeoxygenation of sorbitol over a platinum bifunctional catalyst (Courtesy George Hube University of Massachusetts, USA)

Pd/C. The results showed that the catalyst deactivates Efterpi Vasiliadou and Angeliki Lemonidou (Aristotle in a low hydrogen atmosphere due to unsaturation University of Thessaloniki, Greece) presented a novel of the feedstock. Moreover, deactivation is related to one-pot catalytic route for effi cient 1,2-PDO production feedstock purity and its production technology. using a crude glycerol stream as a feedstock under Worth mentioning is an interesting poster inert conditions in the presence of Pt-based catalysts contribution by the group of Regina Palkovits (RWTH (Pt/SiO2 and Pt/Al2O3). A European patent application Aachen University, Germany) which demonstrated has been fi led (5). The H2 needed for glycerol the feasibility of using a heterogeneous Ru catalyst to conversion was formed via a methanol reforming- convert levulinic acid (LA), a versatile intermediate glycerol hydrogenolysis cycle taking advantage of that can be obtained directly from cellulose, to the unreacted methanol after biodiesel production

-valerolactone (-VL), a compound that can be through transesterifi cation. The use of a Pt/SiO2 utilised directly as a fuel additive. The contribution catalyst results in satisfactory 1,2-PDO yields (~22%) at investigated the effect of different supports (carbon, 250ºC, 3.5 MPa nitrogen and 4 h reaction time.

TiO2, SiO2 and Al2O3) on 5 wt% Ru. Catalyst screening demonstrated that variation of the catalyst support can Concluding Remarks have a profound infl uence on the reaction outcome. The conversion of biomass and biomass-derived The Ru/C catalyst exhibited the highest -VL yield compounds to platform molecules and high added (89.1%) when reacted with LA at 130ºC in an ethanol/ value fuels and chemicals is a dynamic area of water solvent mixture. research, which holds the attention of numerous research groups worldwide. It is clear that catalysis Hydrogenolysis of Glycerol to Chemicals plays a key role in achieving effi cient and practical Glycerol, a byproduct of biodiesel production, can be biomass conversion routes to useful products. The converted by hydrogenolysis to different high value CAT4BIO conference on “Advances in Catalysis added chemicals, such as 1,2-propanediol (1,2-PDO) for Biomass Valorization” was a successful event, and 1,3-propanediol (1,3-PDO), which are promising where groups from all over the world presented the targets because of the high production cost using most recent progress in fundamental and applied conventional processes and the reasonably large catalysis research for the conversion of biomass. production scale. The production of propanediols As demonstrated in the conference, pgm constitute from glycerol, however, normally requires the use essential components of catalysis research for of organic solvents and high hydrogen pressures. biomass conversion reactions. Either as main active Two contributions presented novel results on the components or as promoters, pgms fi nd use in a wide hydrogenolysis of glycerol to 1,2-PDO and 1,3-PDO range of chemical reactions. Their impact will render over Pd- and Pt-containing catalysts without the need them an essential component of future catalytic for externally added hydrogen. Gustavo Fuentes processes for biomass valorisation. (Universidad A. Metropolitana Iztapalapa, Mexico) showed that it is possible to obtain 1,3-PDO and 1-hydroxyacetone with signifi cant selectivity (30% and 46%, respectively at 220ºC) without the addition References of external hydrogen and without the production of 1 CAT4BIO: International conference on “Advances in appreciable amounts of ethylene glycol, the main Catalysis for Biomass Valorization”, Thessaloniki, Greece, degradation product in basic medium, over a copper- 8th–11th July, 2012: http://www.cat4bio2012.gr/ (Accessed on 31st January 2013) palladium/titania-5% sodium catalyst. It is important to note that the highest selectivity reported so far 2 Appl. Catal. B: Environ., Special Issue: CAT4BIO, to be published for 1,3-PDO using hydrogen pressure is 34%, a value 3 D. J. M. de Vlieger, B. L. Mojet, L. Lefferts and K. Seshan, comparable to the authors’ results. J. Catal., 2012, 292, 239 Another approach to alleviate the need for an 4 B. Peng, C. Zhao, S. Kasakov, S. Fortaita, J. A. Lercher, external hydrogen supply is the in situ formation and Chem. Eur. J., 2013, 19, (15), 4732 consecutive consumption of H , either by using a part 2 5 E. Vasiliadou and A. Lemonidou, Aristotle University of the glycerol via a reforming reaction or by adding of Thessaloniki, Greece, European Appl. 11179515.9; a hydrogen donor molecule via dehydrogenation. August 2011

The Reviewers Eleni Heracleous is currently a Research Angeliki Lemonidou is Professor of Scientist at the Chemical Processes & Chemical Engineering at Aristotle Energy Resources Institute (CPERI) in University of Thessaloniki, Greece, and the Centre for Research and Technology Head of the Petrochemical Technology Hellas (CERTH) in Thessaloniki, Greece. Laboratory. She holds a Bachelor’s She obtained her PhD in Chemical degree in Chemistry and a PhD in Engineering from Aristotle University Chemical Engineering from Aristotle of Thessaloniki in 2005, under the University. Her research interests are in supervision of Professor Lemonidou. the area of catalysis and catalytic reaction After her PhD she worked as a post-doc engineering focusing on processes related for two years in Shell Global Solutions to the valorisation of hydrocarbons and in Hamburg, Germany. Since 2008, she oxygenated compounds. Her expertise works in CPERI and is involved in the involves kinetic and mechanistic development of tailor-made catalysts for measurements of well-designed catalytic the valorisation of hydrocarbons (mainly materials and their structural and selective oxidation reactions) and the morphological characterisation. She has conversion of biomass to high added extensively studied the performance of value ‘green’ chemicals and fuels, with rhodium- and platinum-based catalysts in a special focus on syngas conversion reforming and hydrogenolysis of biomass processes. intermediates.

Johnson, Matthey and the Chemical Society

Two hundred years of precious metals expertise

http://dx.doi.org/10.1595/147106713X664635 http://www.platinummetalsreview.com/

By William P. Grifﬁ th The founders of Johnson Matthey – Percival Johnson and George Matthey – played important roles in the foundation Department of Chemistry, Imperial College, London SW7 and running of the Chemical Society, which was founded in 2AZ, UK 1841. This tradition continues today with the Royal Society Email: w.grifﬁ [email protected] of Chemistry and Johnson Matthey Plc.

The nineteenth century brought a ferment of discovery and research to all branches of chemistry; for example some twenty-six elements were discovered between 1800 and 1850, ten of them by British chemists, including rhodium, palladium, osmium and iridium. In 1841 the Chemical Society – the oldest national chemical society in the world still in existence – was established. Both Percival Johnson (Figure 1(a)) and George Matthey (Figure 1(b)) were prominent members, Johnson being one of its founders.

The Origins of the Chemical Society Although there had been an earlier London Chemical Society in 1824 it lasted for only a year (1). The Chemical Society of London (‘of London’ was dropped in 1848) was founded at a meeting held on 30th March 1841 at the Society of Arts in John Street (now John Adam Street), London, UK; Robert Warington (1807–1867), an analytical chemist later to become resident Director of the Society of Apothecaries (2), was instrumental in setting it up and his son, also Robert Warington, later wrote an account of its history for its 1891 Jubilee (3). There were 77 founder members, of whom Percival Johnson was one: others included William Cock (Figure 2) (later to join Johnson in his new fi rm – see below), Thomas Graham (Professor of Chemistry at University College and the Society’s fi rst President), Lyon Playfair, John Daniell and Warren de la Rue (4). Michael Faraday joined in the following year (5). The aim of the new Society was “The promotion of Chemistry and those branches of Science immediately connected with it…” The annual subscription was to be £2 or £1 for those living twenty or more miles outside London. It gained a Charter of Incorporation in 1848

(a) (b)

Fig. 1. (a) Portrait of Percival Johnson (1792–1866); (b) Portrait of George Matthey (1825–1913) and occupied a series of premises before its Jubilee Hanover Square (3) it moved in 1849 to No. 142 Strand. in 1891. The original accommodation at the Society In 1851 it moved to share premises with the Polytechnic of Arts in John Street became too cramped for the Institution at 5 Cavendish Square and then in 1857 successful enterprise; having failed to rent rooms at relocated to Old Burlington House (3, 6). The latter had the newly instituted Royal College of Chemistry at been built in 1664–1667 for the Earl of Burlington, a brother of Robert Boyle; Henry Cavendish lived there in his early years (7). The accommodation was shared, rather uneasily, with the Royal and Linnaean Societies and comprised two back rooms on the east side of the ground fl oor. In 1873 the Society moved to better premises in ‘New’ Burlington House, an extension built (1868–1873) in the Eastern part of the courtyard by Richard Banks and Charles Barry (7). Here it has remained, albeit with various room changes (7–9).

The Foundation of Johnson Matthey The involvement of the Johnson family in the platinum metals industry dates back to John Johnson (1765–1831), whose father (also John Johnson) had been an assayer of ores and metals at No. 7 Maiden Lane, London, in 1777 (10–12). On his father’s death in 1786 his son John became the only commercial assayer in London and was involved in the rapidly developing platinum trade (11, 12). He supplied William Hyde Wollaston (1766–1826) with large quantities of platinum ore from which Wollaston was to establish an efficient process for isolation of pure platinum metal (11); Wollaston also discovered and isolated rhodium Fig. 2. Portrait of William Cock (1813–1892) and palladium (13).

In 1807 John Johnson’s son Percival Norton medal for Queen Victoria’s coronation (Figure 3) Johnson (1792–1866) (11, 12, 14) was apprenticed to and 100 ounces of the metal for the new Imperial the fi rm – he already had good scientifi c credentials, pound weight standards in 1844. Cock resigned in having published a paper on ‘Experiments which 1845 through ill-health, though he continued to help prove Platina, when combined with Gold and Silver, Johnson until much later. to be soluble in Nitric Acid’ (15) (reproduced in George Matthey (1825–1913) (11, 24, 25) was taken (16)). This showed that small quantities of platinum on as an apprentice by Johnson and Cock in 1838 at mixed with gold and silver in nitric acid facilitated the age of thirteen and quickly became interested in a separation of pure gold from the solution. He platinum refi ning, William Cock becoming his mentor. became a partner in 1817, the year often regarded Matthey was an excellent chemist, having spent some as that in which the fi rm, later to become Johnson time at the Royal College of Chemistry in the late 1840s Matthey, was established (11, 17). with August Wilhelm von Hofmann (26). His younger By happy chance, 1817 was also the year in which Sir brother Edward later studied chemistry and metallurgy Humphry Davy showed that a platinum wire catalysed at the sister institution the Royal School of Mines and the combination of hydrogen with oxygen in the air later became a partner in the company (11). George and became white-hot in the process (18) and he had a shrewd business mind and he persuaded observed a similar effect when a coil of platinum (or a rather reluctant Johnson to show samples of palladium) was placed within his wire gauze safety platinum, palladium, rhodium and iridium at the Great lamp (19). These were really the fi rst observations of Exhibition of 1851: these exhibits were awarded a prize heterogeneous oxidation catalysis (20, 21). In 1822 (24). Johnson made him a partner in 1851 and thus the the business moved to 79 Hatton Garden and in 1826 fi rm of Johnson and Matthey was fi nally established Percival Johnson employed an assayer, George Stokes, in that year (17, 27). It was very largely Matthey who taking him into partnership in 1832. The fi rm was now transformed the fi rm from a largely laboratory-based called Johnson and Stokes. On the death of Stokes in enterprise into a fully commercial business. 1835 another assayer, William John Cock (1813–1892) Johnson and Matthey were elected Fellows of the (11, 22), the son of Johnson’s brother-in-law Thomas Royal Society in 1846 and 1879 respectively; Johnson’s Cock (also an expert in platinum metallurgy), election was supported by Michael Faraday amongst joined Johnson in 1837 and the fi rm was now called others. Faraday had many connections with Johnson Johnson and Cock (22). Like Johnson, William Cock and, in particular, Matthey (28). Faraday mentions was a founding member of the Chemical Society in having ingots of platinum, which he describes as 1841 and had devised a process for making platinum “this beautiful, magnifi cent and valuable metal” in his more malleable. He wrote a paper in the fi rst volume celebrated lecture-demonstration ‘On Platinum’ at the of the Memoirs of the Chemical Society of London, Friday Discourse at the Royal Institution in Albemarle the Society’s fi rst journal, titled ‘On Palladium – Its Street on 22nd February 1861. He acknowledged Extraction, Alloys, &c.’ (23), a remarkable summary of “Messrs. Johnson and Matthey, to whose great kindness the preparation and major properties of palladium. I am indebted for these ingots…” (29). Matthey The fi rm of Johnson and Cock, amongst much other published a number of papers, mainly in mining business, provided platinum for a commemorative journals, but a key one concerns ‘The Preparation

Fig. 3. A commemorative medal for Queen Victoria’s coronation in 1838. A number of these medals were struck by the Royal Mint in platinum

in a State of Purity of the Group of Metals Known as the Faraday medals for the next ten years of the value the Platinum Series and Notes upon the Manufacture of £200. The offer was accepted and a vote of thanks to of Iridio-Platinum’. This presented a new method of Messrs. Johnson and Matthey carried by acclamation” refi ning the platinum group metals (pgms) in which (3). The fi rst six recipients of this palladium medal lead was used to remove rhodium and iridium (30). (later medals were cast in bronze after the palladium The “New Oxford Dictionary of National Biography” had run out) were all still-famous chemists: Jean- has articles on Johnson (14) and Matthey (25). Baptiste Dumas, Stanislao Cannizzarro, August Wilhelm Obituaries of Johnson (31, 32), William Cock (33) and von Hofmann, Charles-Adolphe Wurtz, Hermann von George Matthey (34) were published; McDonald (12) Helmholtz and Dmitri Mendeleev (3). has established that both the Johnson obituaries (31, George Matthey was prominent in the Society: 32) were written by George Matthey, albeit in edited he joined in 1873 and served on its Council from forms. The full original version has been given (12). 1877–1878 (3). He was present at the Jubilee dinner Sir William Crookes was probably the author (22) of of the Society on 25th February 1891 (at which eleven Cock’s obituary (33). courses, fi ve wines, brandy and port were served) and gave a speech after the dinner in his capacity as Prime Early Collaborations of Johnson, Matthey Warden of the Goldsmiths’ Company. In the afternoon and the Chemical Society preceding the dinner there was an exhibition at which Percival Johnson (listed as of 38 Mecklenburgh Matthey showed samples of all six pgms and other Square) appears in the list of the original members related objects, including a platinum snuff-box made of the Chemical Society of London in 1841, together by Percival Johnson in 1816 and used by Johnson until with other famous names (4). He was one of the his death (3). early members of the Council of the Society, serving from 1842–1844 (Michael Faraday joined him on the The Royal Society of Chemistry in the Council in 1843) (3, 5). William Cock also appears on Twentieth Century the list of founder members of 1841 (4) and was one In 1972 the process of unifi cation began of the Chemical of the few who gathered informally, prior to the offi cial Society, the Royal Institute of Chemistry (established formation of the Society, to consider setting up such an 1877), the Faraday Society (established 1903) and the institution. He served on the Council of the Society in Society of Analytical Chemistry (established 1874). 1845 (3), giving in that year a specimen of palladium to The Queen signed a Royal Charter for the new Royal the Society’s Museum. In 1868 the Society established Society of Chemistry (RSC) on 15th May 1980 (9). That a Faraday medal and this was, for its fi rst six issues, cast and subsequent periods saw continued collaboration in palladium, donated by Johnson Matthey. An item in with Johnson Matthey, as the following examples show. the Society’s minutes says that “a letter was read from The Badge of Offi ce of the President of the RSC Messrs. Johnson and Matthey containing an offer to (Figure 4) was originally presented in 1979 to the present to the Society an amount of palladium to form President of the Royal Institute of Chemistry (35) and

Fig. 4. (a) The badge worn (a) (b) by the President of the Royal Society of Chemistry. It was inherited from the Royal Institute of Chemistry and modiﬁ ed to carry the name of the RSC; (b) The badge is in the form of a spoked wheel, with the standing ﬁ gure of Joseph Priestley depicted in enamel. The rim of the wheel is gold and the twelve spokes are of non-tarnishable metals with catalytic importance: palladium, nickel, titanium, iridium, niobium, tungsten, platinum, molybdenum, tantalum, rhodium, zirconium and cobalt

the materials for it made and donated by Johnson Centre in Sonning Common, UK, on 21st March Matthey. The fi rm’s Chief Chemist at that time, A. R. 2001, for “Pioneering Work in Platinum research……. Powell FRS (1894–1975) (37), gave a detailed account which led to the development of car exhaust catalysts of the fabrication of this unique and remarkable and the design of platinum-based, anti-cancer drugs” object (38). In the centre is an enamelled medallion (39). The manufacture of the fi rst autocatalysts is of Joseph Priestley, set within a hexagon to symbolise also commemorated by a plaque at the company’s benzene. In the circular rim of gold surrounding manufacturing premises in Royston, UK (Figure 6). the medallion are set, like spokes in a wheel, twelve The company has sponsored or co-sponsored a metals of catalytic importance. Four pgms mark the number of RSC events. Among these, the triennial cardinal points (north is palladium, south platinum, International Conferences on Platinum Group Metals east iridium and west is rhodium); in a clockwise meetings from 1981 to 2002 were a major feature. They direction after palladium lie nickel and titanium; after were sponsored jointly by the Dalton Division of the iridium there are niobium and tungsten; after platinum RSC and Johnson Matthey and brought together many we have molybdenum and tantalum; and fi nally after experts on pgm chemistry, dealing in particular with rhodium lie zirconium and cobalt. The synthetic aspects of organometallic, catalytic and coordination fi bre ribbon of nylon, viscose and cellulose acetate is chemistry. These were held in July at the following dyed with mauveine, discovered by Sir William Perkin universities and from 1981 were reviewed in Platinum (1838–1907) in 1856 (35, 36, 38). Metals Review (references given in parentheses):  Bristol, 1981 (40) Collaborations in the Twentieth and  Edinburgh, 1984 (41) Twenty-First Centuries  Sheffi eld, 1987 (42) In 2001 Johnson Matthey received the fi rst RSC  Cambridge, 1990 (43) National Historic Chemical Landmark award (Figure  St. Andrews, 1993 (44) 5); it was unveiled at the Johnson Matthey Technology  York, 1996 (45)  Nottingham, 1999 (46)  Southampton, 2002 (47) A more recent meeting was held at York University on 30th November 2011 to mark the 250th anniversary of the birth of Smithson Tennant (1761–1815), discoverer of osmium and iridium (48), sponsored by the RSC and Johnson Matthey Catalysts.

Fig. 5. The ﬁ rst Royal Society of Chemistry National Historic Chemical Landmark award at Johnson Fig. 6. A plaque commemorating the manufacture of Matthey Technology Centre, Sonning Common, UK autocatalysts by Johnson Matthey in Royston, UK

In 2008 Johnson Matthey sponsored the new pivotal and innovative role in creating new catalysts biennial RSC Lord Lewis Prize, awarded “for distinctive and catalytic processes for use in the automotive and distinguished chemical or scientifi c achievements, industry” (53) and in 2012 Dr Thomas J. Colacot, of together with signifi cant contributions to the Johnson Matthey Catalysis and Chiral Technologies, development of science policy” (49). The fi rst awardee USA, won the same award “for exceptional was Lord Robert May of Oxford, FRS, OM (born in contributions to the development and availability of 1938), President of the Royal Society from 2000 to ligands and catalysts crucial for the advancement of 2005, former Government Chief Scientifi c Advisor, metal-catalysed synthetic organic chemistry” (54, 55). Professor of Zoology at the University of Oxford and Thus Johnson Matthey and the RSC have Fellow of Merton College. In 2010 the Prize went to Sir collaborated over many years, continuing into John Cadogan CBE, FRS (born in 1930), formerly Chief the twenty-first century, making use of the firm’s Scientist at the BP Research Centre and President of expertise in chemistry and catalysis, with particular the RSC from 1982–1984. The most recent winner, in emphasis on their unrivalled experience with the 2012, was Sir David King FRS (born in 1939), from precious metals. 2000–2007 the Government’s Chief Scientifi c Advisor and the founding Director (2008–2012) of the Smith Conclusions School of Enterprise and Environment at the University This article has sought to show that Percival Johnson of Oxford. and George Matthey, in effect the founders of Johnson Other joint RSC–Johnson Matthey projects have Matthey Plc, were closely associated with the Chemical included a book and workshop on teaching of pgm Society (of which Johnson was a founder and Matthey separations created in 1998 (50). Teachers spent two a prominent member) since its inception in 1841 and to three days at the Johnson Matthey Technology that this tradition has been continued to the present Centre in Sonning Common, UK, with the late Phil with Johnson Matthey Plc and the Royal Society of Smith of the RSC at the invitation of David Boyd, Chemistry. Technology Manager at the Centre. Boyd gave a series of presentations and workshops on the chemistry, Acknowledgements extraction, refi ning and uses of platinum. These were It is a pleasure to thank David Allen and Pauline turned into teaching aids, with a variety of exercises, Meakins from the RSC for their help; as well as David games, questions and experiments. Prest, David Boyd, Sally Jones, Haydn Boehm and Johnson Matthey also partnered with the RSC on its Richard Seymour from Johnson Matthey; and Martyn ‘Faces of Chemistry’ initiative, a series of short videos Twigg, formerly of Johnson Matthey, for their help in aimed at bringing to life careers in industry for young providing some of the source material for this article. people (51). Johnson Matthey scientists explain the chemistry of pgm-based emission control catalysis References in three short fi lms, which were made available via 1 W. H. Brock, Ambix, 1967, 14, (2), 133 website and social media links from 2011. 2 C. Hamlin, ‘Warington, Robert (1807–1867), Chemist’, The company also contributed materially to the in “New Oxford Dictionary of National Biography”, RSC Roadmap objectives (‘Chemistry for Tomorrow’s Oxford University Press, Oxford, UK, 2004, Volume 57, pp. 423–424 World’) prepared in 2009 (52). Dr David Prest, 3 R. Warington, “The Jubilee of The Chemical Society of Managing Director for the European Region in the London. Record of the Proceedings Together with an fi rm’s Emission Control Technologies division and a Account of the History and Development of the Society member of the RSC Council, chaired the steering group 1841–1891”, Harrisons and Sons, London, UK, 1896, p. – a cross section from industry and academia – which 1, 115 prepared the Roadmap. The aim of their report was to 4 Anon., Proc. Chem. Soc., Lond., 1842, 1, A001 identify the role of the chemical sciences in helping 5 Anon., Mem. Chem. Soc., Lond., 1841, 1, B001–B008 to solve major global challenges. The Roadmap was 6 T. S. Moore and J. C. Philip, “The Chemical Society 1841– developed via expert workshops and extensive online 1941: A Historical Review”, Chemical Society, London, UK, 1947 consultations; many challenges were identifi ed, with specifi c objectives with timescales of up to 15 years. 7 D. A. Arnold, “The History of Burlington House”, Royal Society of Chemistry, London, UK, 1992: http://www. In 2010 Dr Martyn Twigg, then Chief Scientist of the rsc.org/AboutUs/History/bhhist.asp. (Accessed on 14th fi rm, won the RSC Applied Catalysis award “for his February 2013)

8 P. Schmitt and O. Hopkins, “Burlington House: a 38 A. R. Powell, J. Proc. R. Inst. Chem., 1949, 73, Brief History”, Royal Academy of Arts, London, UK, Part VI, 476 2010: http://static.royalacademy.org.uk/secure/fi les/ 39 ‘First National Historic Chemical Landmark Recognises architecture-guide-fi nal-785.pdf (Accessed on 14th Impact of Pioneering Work in Platinum Research’, RSC February 2013) News Release, 16th March, 2001: http://www.rsc.org/ 9 D. H. Whiffen and D. H. Hey, “The Royal Society images/Platinumlandmarkpressrelease_tcm18-18976. of Chemistry: the First 150 Years”, Royal Society of pdf (Accessed on 14th February 2013) Chemistry, London, UK, 1991 40 L. B. Hunt and B. A. Murrer, Platinum Metals Rev., 1981, 10 D. McDonald, “The Johnsons of Maiden Lane”, Martins 25, (4), 156 Publishers, London, UK, 1964 41 B. A. Murrer, Platinum Metals Rev., 1984, 28, (4), 168 11 D. McDonald and L. B. Hunt, “A History of Platinum and 42 B. A. Murrer, G. G. Ferrier and R. J. Potter, Platinum its Allied Metals”, Johnson Matthey, London, UK, 1982 Metals Rev., 1987, 31, (4), 186 12 D. McDonald, “Percival Norton Johnson: The Biography 43 C. F. J. Barnard, Platinum Metals Rev., 1990, 34, (4), 207 of a Pioneer Metallurgist”, Johnson Matthey, London, 44 O. J. Vaughan, Platinum Metals Rev., 1993, 37, (4), 212 UK, 1951 45 A. Fulford, Platinum Metals Rev., 1996, 40, (4), 161 13 W. P. Griffi th, Platinum Metals Rev., 2003, 47, (4), 175 46 C. F. J. Barnard and W. Weston, Platinum Metals Rev., 14 I. E. Cottington, ‘Johnson, Percival Norton (1792–1866), 1999, 43, (4), 158 Metallurgist’, in “New Oxford Dictionary of National Biography”, Oxford University Press, Oxford, UK, 2004, 47 J. Evans, Platinum Metals Rev., 2002, 46, (4), 165 Volume 30, p. 293 48 R. N. Perutz, Platinum Metals Rev., 2012, 56, (3), 190 15 P. Johnson, Phil Mag., 1812, 40, (171), 3 49 Lord Lewis Prize, RSC: http://www.rsc.org/ 16 D. McDonald, Platinum Metals Rev., 1962, 6, (3), 112 ScienceAndTechnology/Awards/LordLewisPrize/Index.asp (Accessed on 14th February 2013) 17 D. McDonald, Platinum Metals Rev., 1967, 11, (1), 18 50 “Learning About Materials: Three Workshop Exercises”, 18 H. Davy, Phil. Trans. R. Soc. Lond., 1817, 107, 45 eds. E. Lister and C. Osborne, The Royal Society of 19 H. Davy, Phil. Trans. R. Soc. Lond., 1817, 107, 77 Chemistry, London, UK, 1998 20 L. B. Hunt, Platinum Metals Rev., 1979, 23, (1), 29 51 Faces of Chemistry Videos – Catalysts – Learn Chemistry, 21 A. J. B. Robertson, Platinum Metals Rev., 1975, 19, RSC: http://www.rsc.org/learn-chemistry/resource/ (2), 64 res00000378/faces-of-chemistry-video-catalysts 22 L. B. Hunt, Platinum Metals Rev., 1983, 27, (3), 129 (Accessed on 14th February 2013) 23 W. J. Cock, Mem. Chem. Soc., Lond., 1841, 1, 161 52 Chemistry for Tomorrow’s World, RSC Roadmap, RSC: http://www.rsc.org/ScienceAndTechnology/roadmap/ 24 L. B. Hunt, Platinum Metals Rev., 1979, 23, (2), 68 index.asp (Accessed on 14th February 2013) 25 I. E. Cottington, ‘Matthey, George (1825–1913), Refi ner 53 Applied Catalysis Award 2010 Winner, RSC: and Metallurgist’, in “New Oxford Dictionary of National http://www.rsc.org/ScienceAndTechnology/Awards/App Biography”, Oxford University Press, Oxford, UK, 2004, liedCatalysisAward/2010winner.asp (Accessed on 14th Volume 32, p. 372 February 2013) 26 H. Gay, Notes Rec. R. Soc., 2008, 62, (1), 51 54 Applied Catalysis Award 2012 Winner, RSC: 27 History, Johnson Matthey: http://www.matthey.com/ http://www.rsc.org/ScienceAndTechnology/Awards/ about/history.htm (Accessed on 14th February 2013) AppliedCatalysisAward/2012-Winner.asp (Accessed on 28 I. E. Cottington, Platinum Metals Rev., 1991, 35, (4), 222 14th February 2013) 29 M. Faraday, Chem. News, 1861, 3, 136 55 S. Coles, Platinum Metals Rev., 2012, 56, (4), 219 30 G. Matthey, Proc. R. Soc. Lond., 1878, 28, (190–195), 463 31 Anon., J. Chem. Soc., 1867, 20, 392 The Author 32 Anon., Proc. R. Soc. Lond., 1867, 16, xxiii Bill Griffi th is an Emeritus Professor 33 Chem. News, 1899, 80, 287 of Chemistry at Imperial College (IC), London, UK. He has much experience 34 T. K. Rose, J. Chem. Soc., Trans., 1914, 105, 1222; W. with the platinum group metals, Crookes, Chem. News, 1913, 107, 96 particularly ruthenium and osmium. He has published over 270 research 35 RSC – The President’s Badge of Offi ce: http://www. papers, many describing complexes of rsc.org/AboutUs/History/badge.asp (Accessed on 14th these metals as catalysts for specifi c February 2013) organic oxidations. He has written eight books on the platinum metals, and is 36 The 13-Metal Medal – Periodic Table of Videos, YouTube: currently writing, with Hannah Gay, a http://www.youtube.com/watch?v=D5_zdap8ycE history of the 170-year old chemistry (Accessed on 14th February 2013) department at IC. He is responsible for Membership at the Historical Group of 37 G. Raynor, Biogr. Mems Fell. R. Soc., 1976, 22, 306 the Royal Society of Chemistry.

SAE 2012 World Congress

Vehicular emissions control highlights of the annual Society of Automotive Engineers (SAE) international congress

http://dx.doi.org/10.1595/147106713X663933 http://www.platinummetalsreview.com/

Reviewed by Timothy V. Johnson The annual SAE Congress is the vehicle industry’s Corning Environmental Technologies, Corning Incorporated, largest conference and covers all aspects of HP-CB-2-4, Corning, NY 14831, USA automotive engineering. The 2012 congress took Email: [email protected] place in Detroit, USA, from 24th–26th April 2012. There were upwards of a dozen sessions focused on vehicle emissions technology, with most of these on diesel emissions. More than 70 papers were presented on this topic. In addition, there were two sessions on gasoline engine emissions control with eight papers presented. Attendance was up relative to the previous year, with most sessions having perhaps 100 attendees, but some had more than 200. This review focuses on key developments from the conference related to platinum group metals (pgms) for both diesel and gasoline engine emissions control. Papers can be purchased and downloaded from the SAE website (1). As in previous years, the diesel sessions were opened with a review paper of key developments in both diesel and gasoline emissions control from 2011 (2).

Lean NOx Traps The lean NOx trap (LNT) is currently the leading deNOx concept for smaller lean-burn (diesel and direct injection gasoline) passenger cars and is of interest in applications with limited space or in which urea usage is diffi cult. The deNOx effi ciency is nominally 70–80%, much lower than that of the next generation selective catalytic reduction (SCR) system at >95% and the pgm usage is high (~8–12 g for a 2 l engine). As a result, efforts are focused on improving effi ciency while reducing pgm loadings. Only two papers on LNTs were reported this year, much reduced from previous years. Katsuo Suga et al. (Nissan Motor Co Ltd, Japan) used a selective pgm deposition process to enhance platinum dispersion (3). The concept is to use a surfactant to preferentially apply the Pt to the ceria rather than to the alumina in the washcoat. Upon ageing, the grain growth of Pt is greatly constrained

by the small size of the CeO2 grains, Figure 1. Usage of pgm is cut by 50% without compromise in NOx emissions. The researchers have also identifi ed that

which have shown enhanced reactivity for biodiesel Conventional catalyst: Pt soot in thermal regeneration. The Arrhenius plot did Ageing not take into account the possibility of lowered DOC activity, which can occur with biodiesel usage due to more severe ash poisoning and thermal degradation. CeO2 Al2O3 Interestingly, the investigators quantifi ed the internal

New concept catalyst: generation of NO2 in the catalysed fi lter, wherein Pt NO2 fi rst passes through and reacts with the soot; the resulting nitric oxide (NO) is oxidised back to

Ageing NO2 in the underlying catalyst and recycled back for another round of soot oxidation. Recycling rates were quite low at temperatures less than 300ºC, but Al2O3 were very high (each NO molecule recycled three to CeO 2 four times) at 450ºC. Fig. 1. Platinum is preferentially deposited on small Carl Justin Kamp et al. (Massachusetts Institute of ceria grains to minimise grain growth upon ageing of Technology, USA) (6) looked at the recycling of the a new concept NOx trap catalyst (3) NO molecule, among other phenomena, in catalysed fi lters in an entirely different way – they used a novel ‘focused beam ion milling’ technique to vaporise the NOx desorption rate is considerably slower away layers of material, ending up with a clean than either adsorption or catalyst reactions at low cross-section of the substrate, washcoat, catalyst, temperatures. The NOx desorption rate appears to be ash and soot. Figure 2 shows one such image. There increased by enhancing contact with CeO2 and baria, are voids between the soot and the catalyst that are the NOx trapping material. Work is continuing to verify likely formed by the back diffusion of NO2 generated the effect. by the catalyst. Other images show metal oxide ash (from wear and burning lubricant oil) coating the Diesel Particulate Filters catalyst, but mostly not interfering with this recycling Although diesel particulate fi lters (DPFs) have been phenomenon. Curiously, images were shown of ash in commercial production for original equipment agglomerates measuring 20 μm in diameter that manufacturer (OEM) application for more than 10 mostly consisted of relatively large voids. years, there is still much optimisation activity in the fi eld. Papers were offered on DPF regeneration and several papers were presented on next generation DPF substrates. Contrary to light-duty diesel applications, wherein system architecture and operating conditions necessitate burning of the collected soot using mostly Soot thermal means at temperatures of about 600ºC, in heavy-duty applications most (or all) of the soot is burned passively using nitrogen dioxide (NO2) generated in a pgm-based diesel oxidation catalyst (DOC) and in the catalysed fi lter. Kenneth Lee Shiel Catalyst et al. (Michigan Technological University, USA) quantifi ed this effect for ultra-low sulfur diesel (ULSD) Substrate fuel and biodiesel blends (5). They loaded the fi lters to about 2 g l–1 soot in a controlled fashion and then introduced exhaust gas with the desired composition 1 m and temperature to measure oxidation of the soot with the NO . They found that soot generated by 2 Fig. 2. Cross-section of the soot-catalyst layer in a burning biodiesel oxidised slightly more slowly than platinum-catalysed diesel particulate ﬁ lter made that from ULSD fuel, contradicting other studies possible by a new ion milling technique (6)

Particulate oxidation catalysts (POCs) are a can improve performance. Conversely, if the NO2 level cross between a DPF and a DOC wherein the soot is at or below the optimum 50% (of total NOx) level, is trapped by turbulence mechanisms, forcing the soot can impair the SCR performance. particles to make contact with the Pt-catalysed fi lter. POCs are a leading approach to particulate Diesel Oxidation Catalysts emissions control in developing countries because DOCs are generally catalysed with platinum and/ they do not require active regeneration. However, or palladium. They play two primary roles in these countries might not have low-sulfur fuel. Piotr commercial emissions control systems: (a) to Bielaczyc (BOSMAL Automotive R&D Institute Ltd, oxidise hydrocarbons (HCs) and carbon monoxide, Poland) et al. (7) looked at the effects of fuel sulfur either to reduce emissions coming from the engine on the performance of these devices. Although the or to create exothermic heat used to regenerate a dry soot coming from the engine was the same in DPF; and (b) to oxidise NO to NO2, which is required all tests, the total particulate matter (PM) coming to continuously oxidise soot on a DPF and/or to from the engine increased with increasing levels enhance the SCR deNOx reactions, particularly at of sulfate. Between 20 h and 40 h of operation the low temperatures. fi ltration effi ciency using a high sulfur fuel (365 ppm) Ageing of DOCs is a critical phenomenon to dropped by about 10% across the particle size range, understand. It can impact HC emissions, DPF while that of a clean (sulfur-free) fuel changed very regeneration and SCR performance. Junhui Li et al. little. The loss of effi ciency seen in the high-sulfur (Cummins Inc, USA) (9) retrieved several fi eld-aged fuel is likely due to the reduced availability of NO2 DOCs from in-use vehicles, sectioned them and studied for cleaning and maintaining the fi lter effi ciency, the ageing characteristics of the segments. As shown since NO2 generation in the DOC is hampered by the in Figure 3, irreversible ageing caused different types presence of sulfur. of deterioration. Catalyst samples cut from the rear of An important emerging trend is to coat DPFs with the DOC had a higher NO light-off temperature than an SCR catalyst as a way of consolidating parts and those taken from the front. The opposite was true for getting the SCR closer to the turbocharger for faster HC (propene) oxidation, wherein the rear parts had heating. Friedemann Schrade et al. (IAV GmbH, a lower light-off temperature. The front catalysts were Germany) (8) showed that when soot is on the Cu-zeolite aged primarily by ash contamination, while the back coated fi lter, the change in NO2 levels across the catalysts were generally thermally aged. The overall soot layer caused by soot oxidation can impact SCR light-off characteristics of the catalyst deteriorated due performance. If the NO2 level going into the fi lter is to both effects as the mileage increased. The authors higher than ideal for the ‘fast’ SCR reaction, the soot also reported reversible deterioration caused by HC

Fig. 3. NO and hydrocarbon 310 (propene) light-off Rear properties for samples taken 290 Reference from the front and rear of ﬁ eld-aged platinum-based Front diesel oxidation catalysts. 270 The reference catalyst was , ºC laboratory aged (9) 25 T 250

230

NO lightoff, NO lightoff, 210

190

170 100 120 140 160 180 200

Propene lightoff, T50, ºC

and sulfur poisoning, which could be removed with a Vehicle – 30 mg mile–1 non-methane HC+NOx (LEV thermal treatment. III SULEV30) standard. The close-coupled catalyst is A new type of DOC was reported by Federico Millo layered with higher activity Pd and a lower activity and Davide Fezza (Politecnico de Torino, Italy). They oxygen storage capacity (OSC) on the top, to better added a low-temperature NOx adsorber material withstand phosphorous poisoning and to achieve (probably an alkaline earth oxide) to the DOC (10). better HC conversion. The catalyst demonstrates that The material stores NOx (presumably as a nitrate) at Pd-only catalysts can have application for the lowest low temperatures and then releases the NOx at higher emissions applications. The underbody catalyst utilises temperatures when the downstream SCR catalyst is a zirconia-based OSC, allowing 50% less Rh to be used operative. The adsorber aged substantially, but could versus the current version of the catalyst. still provide signifi cantly better NOx removal than an System design and calibration are signifi cant SCR-only confi guration. This ‘passive NOx adsorber’ contributors to lowering emissions from gasoline (PNA) concept is being developed by Cary Henry et al. vehicles. Douglas Ball and David Moser (Umicore (Cummins Inc, USA) and Howard Hess et al. (Johnson Autocat Inc, USA) (14) benchmarked fi ve of the cleanest Matthey Inc, USA) with quite impressive results (11). gasoline engine vehicles on the market with a variety of hardware calibration strategies, including port-fueled Gasoline Emissions Control and direct injection, with and without secondary air, Catalytic gasoline emissions control has been and with different injection timings, engine speeds commercialised for more than 35 years and the three- and air:fuel ratios. The light-off strategies used various way catalyst (TWC) for more than 30 years. Yet, it is still combinations of high idle speed, aggressive ignition evolving and showing signifi cant improvements. Since retard, secondary air and split injections. All designs the mid-1990s, when the TWC was perhaps in its third achieved catalyst light-off during idle before the fi rst generation, emissions have dropped by more than 95% hill in the test cycle. Secondary air was not necessarily and pgm loading is down by upwards of 70% of what it needed, but helped the catalyst heat to 950ºC in the fi rst was then. The progress is still continuing. idle. Only 500ºC was reached in the same time without For example, Yoshiaki Matsuzono et al. (Honda secondary air. Turbocharged direct injection engines R&D Co, Japan) and Takashi Yamada et al. (Johnson use split injection, secondary air and late injection to Matthey Japan Inc) described a new layered catalyst aid cold start. The investigators ran emissions tests to for improving the performance of both close-coupled help estimate what volume of catalyst will be needed and underbody catalysts (13). The improvements cut to meet the new California regulations. Figure 4 pgm usage by 75% while meeting the new California shows the case for a highly calibrated, port-fuel injected, Low Emission Vehicle III, Super Ultralow Emission naturally aspirated 2.0 l engine without secondary air.

Fig. 4. Estimated required 100 amount of pgm catalyst to

) achieve various emissions –1 levels on a 2.0 l port- 1.33 injection fuelled engine mile without secondary air (14)

LEV70 Target Relative pgm loading 49 1.25 NOx (mg 35 LEV50 Target 1.17

1.08 SULEV30 Target 21 1.00

14 SULEV20 Target

10 Non-methane hydrocarbons + 0 0.5 1 1.5 2 2.5 3 Catalyst volume, l

Approximately 2 l of catalyst will be needed to achieve of Pt in fi eld-aged DOCs was impaired by ash in the the SULEV 30 target, compared with about 2.5 l of front portions, adversely impacting HC oxidation, and catalyst to achieve the same result on a 2.4 l engine by thermal ageing in the back, affecting NO oxidation. with secondary air. The pgm loading of TWCs could be cut by 75% by In an entirely different approach to evaluating pgm layering the catalyst, placing higher activity Pd and a loadings and emissions, Michael Zammit (Chrysler lower activity oxygen storage catalyst in the top layer. Group LLC, USA) et al. (15) changed the distance from Also, more is being learned on whole system design, the engine of a close-coupled TWC and measured such as the effects of catalyst placement, turbocharging, the emissions. They made estimates of the increased secondary air and fuel injection strategies, and the pgm loadings to offset the increased distance while impacts that these factors have on catalyst loadings. keeping the emissions the same: an additional 37–50 mg Finally, this Congress featured catalysed GPFs for the Pd per cm of distance from the engine. fi rst time, showing better system performance if some To meet the new gasoline particle number pgm was moved from the close-coupled catalyst to regulations of the light-duty Euro 6 regulation in 2017, the GPF. there is much interest in gasoline particulate fi lters (GPFs). Early testing was done with uncatalysed fi lters, but current evaluations use a TWC coating on the References 1 SAE International: http://www.sae.org/ (Accessed on fi lter. Joerg Michael Richter et al. (Umicore Autocat 29th January 2013) Luxembourg) (16) evaluated two different coated 2 T. V. Johnson, ‘Vehicular Emissions in Review’, SAE Int. J. confi gurations with identical total pgm loadings. In Engines, 2012, 5, (2), 216 one confi guration the pgm was distributed evenly 3 K. Suga, T. Naito, Y. Hanaki, M. Nakamura, K. Shiratori, between the close-coupled TWC and the GPF; in Y. Hiramoto and Y. Tanaka, ‘High-Efﬁ ciency NOx Trap another confi guration, the close-coupled catalyst was Catalyst with Highly Dispersed Precious Metal for Low optimised by zone-coating the Pd so that 80% of it is Precious Metal Loading’, SAE Paper 2012-01-1246 on the front half. The investigators found that the NOx 4 Y. Tsukamoto, H. Nishioka, D. Imai, Y. Sobue, N. Takagi, emissions dropped by 20% in the fi rst coated GPF T. Tanaka and T. Hamaguchi, ‘Development of New Concept Catalyst for Low CO Emission Diesel Engine confi guration compared to the baseline confi guration 2 Using NOx Adsorption at Low Temperatures’, SAE Paper without a GPF. With an optimised zone coating on 2012-01-0370 the close-coupled catalyst, 6% less pgm was used 5 K. L. Shiel, J. Naber, J. Johnson and C. Hutton, ‘Catalyzed compared to the baseline, NOx emissions remained Particulate Filter Passive Oxidation Study with ULSD and at the low level, but CO emissions were reduced by Biodiesel Blended Fuel’, SAE Paper 2012-01-0837 30% compared to the other GPF confi guration. The 6 C. J. Kamp, A. Sappok and V. Wong, ‘Soot and Ash researchers reported that the TWC on the GPF aided Deposition Characteristics at the Catalyst-Substrate fi lter regeneration. No fuel penalty was observed when Interface and Intra-Layer Interactions in Aged Diesel Particulate Filters Illustrated Using Focused Ion Beam the GPF was applied. (FIB) Milling’, SAE Paper 2012-01-0836 7 P. Bielaczyc, J. Keskinen, J. Dzida, R. Sala, T. Ronkko, Conclusion T. Kinnunen, P. Matilainen, P. Karjalainen and M. J. Work is continuing on utilising Pt and other precious Happonen, ‘Performance of Particle Oxidation Catalyst metals more effectively to meet tightening tailpipe and Particle Formation Studies with Sulphur Containing emission regulations and reduce costs. Examples Fuels’, SAE Paper 2012-01-0366 highlighted in this Congress review include the more 8 F. Schrade, M. Brammer, J. Schaeffner, K. Langeheinecke effi cient use of Pt in LNTs by distributing it preferentially and L. Kraemer, ‘Physico-Chemical Modeling of an Integrated SCR on DPF (SCR/DPF) System’, SAE Paper on the CeO portion of the washcoat. In other work, Pt 2 2012-01-1083 was applied to a DPF resulting in the enhancement of 9 J. Li, T. Szailer, A. Watts, N. Currier and A. Yezerets, soot burn by NO2 by three or four times at 450ºC due ‘Investigation of the Impact of Real-World Aging on to the recycling of the NOx molecule in the vicinity Diesel Oxidation Catalysts’, SAE Paper 2012-01-1094 of the soot layer. Soot oxidation by NO2 was found to 10 F. Millo and D. Vezza, ‘Characterization of a New Advanced be adversely impacted by sulfur in fuel and this could Diesel Oxidation Catalyst with Low Temperature NOx impair the performance of POCs. The functionality Storage Capability for LD Diesel’, SAE Paper 2012-01-0373

11 C. Henry, A. Gupta, N Currier, M. Ruth, H. Hess, M. 15 M. Zammit, J. Wuttke, P. Ravindran and S. Aaltonen, Naseri, L. Cumaranatunge and H.-Y. Chen, ‘Advanced ‘The Effects of Catalytic Converter Location and Technology Light Duty Diesel Aftertreatment System’, Palladium Loading on Tailpipe Emissions’, SAE Paper US Department of Energy 2012 Directions in Engine- 2012-01-1247 Efﬁ ciency and Emissions Research (DEER) Conference, 16 J. M. Richter, R. Klingmann, S. Spiess and K.-F. Wong, Dearborn, Michigan, USA, 16th–19th October, 2012 ‘Application of Catalyzed Gasoline Particulate Filters to 12 K. Ishizaki, N. Mitsuda, N. Ohya, H. Ohno, T. Naka, GDI Vehicles’, SAE Paper 2012-01-1244 A. Abe, H. Takagi and A. Sugimoto, ‘A Study of PGM- Free Oxidation Catalyst YMnO3 for Diesel Exhaust The Reviewer Aftertreatment’, SAE Paper 2012-01-0365 Timothy V. Johnson is Director – Emerging 13 Y. Matsuzono, K. Kuroki, T. Nishi, N. Suzuki, T. Yamada, Regulations and Technologies for Corning T. Hirota and G. Zhang, ‘Development of Advanced Environmental Technologies, Corning and Low PGM TWC System for LEV2 PZ EV and LEV3 Incorporated, USA. Dr Johnson is responsible SULEV30’, SAE Paper 2012-01-1242 for tracking emerging mobile emissions regulations and technologies and helps 14 D. Ball and D. Moser, ‘Cold Start Calibration of Current develop strategic positioning via new PZEV Vehicles and the Impact of LEV-III Emission products. Regulations’, SAE Paper 2012-01-1245

“Complex-shaped Metal Nanoparticles: Bottom-Up Syntheses and Applications”

Edited by Tapan K. Sau (International Institute of Information Technology, Hyderabad, India) and Andrey L. Rogach (City University of Hong Kong, Hong Kong), Wiley-VCH Verlag & Co KGaA, Weinheim, Germany, 2012, 582 pages, ISBN: 978-3-527-33077-5, £125.00, €178.80, US$200.00

http://dx.doi.org/10.1595/147106713X664617 http://www.platinummetalsreview.com/

Reviewed by Laura Ashﬁ eld Introduction Johnson Matthey Technology Centre, Blounts Court, “Complex-shaped Metal Nanoparticles: Bottom-Up Sonning Common, Reading RG4 9NH, UK Syntheses and Applications” offers a comprehensive Email: ashﬁ [email protected] review of shaped metal nanoparticles through synthetic strategies, theoretical modelling of growth, discussion of properties and present and future applications. The book is brought together by editors Tapan K. Sau (International Institute of Information Technology, Hyderabad, India) and Andrey L. Rogach (Department of Physics and Materials Science at the City University of Hong Kong). Between them, they draw on their considerable expertise in the synthesis of metal and semiconductor nanoparticles, spectroscopy, photonics and applications of nanomaterials, to combine 16 chapters from a large number of specialist authors. This review will cover the majority of the book, which refers in the main to noble metal particles, with the exception of a few chapters which are specifi cally related to non-platinum group metal (pgm) materials and are therefore beyond the scope of this review. The fi eld of nanoparticle preparation has enjoyed an explosion in interest in the last decade as new applications exploiting the novel physical, electronic and optical properties of the particles have been discovered. The properties of nanoparticles are highly dependent on their morphology and thus, a vast number of academic articles have been published tackling the subject of the synthesis of specifi c shapes of nanomaterials. “Complex-shaped Metal Nanoparticles: Bottom-Up Syntheses and Applications” aims to bring together this research in one volume giving a sound understanding of the general principles, with copious references to more detailed research papers if required and looking towards potential future applications.

Practical Aspects The book opens with the most substantial chapter, written by the editors, which gives a more general

introduction to complex-shaped noble metal literature, for example, the growth of branched nanoparticles and is an essential read for those less platinum nanoparticles from twinned seed crystals or familiar with the subject. The brief discussion on the role of the common growth directing surfactant, the classifi cation of different shaped nanoparticles cetyltrimethylammonium bromide (CTAB), in the and accompanying fi gure of transmission electron formation of gold nanorods. The editors are pleasingly microscopy (TEM) images (Figure 1) serves to frank about the limitations of the synthetic methods emphasise the breadth of this topic. The synthesis and emphasise the need for post-synthesis separation methodologies are introduced by the means of due to the prevalence of polydisperse particles in reduction, with a heavy emphasis on chemical many of the preparations. The chapter concludes reduction but also including electrochemical, with an outlook on where research is lacking and photochemical and biochemical routes. It does knowledge needs to be improved in order to progress omit other methods such as sonochemical and the applications for shaped nanoparticles. hydrothermal reduction, but gives references to A more in depth look at templating techniques is alternative sources that cover these. described in the following chapter by Chun-Hua The chapter provides a useful introduction to Cui and Shu-Hong Yu (University of Science and topics such as the use of hard templates, for example Technology of China). Templating covers a variety aluminium oxide porous membranes, and soft of techniques including galvanic displacement, templates, for example micelles, to control the growth such as the formation of platinum nanotubes from of the particles. It also covers galvanic replacement the treatment of silver nanowires with platinum and seed-mediated synthesis. Many of these topics are acetate, the use of the porous membrane template discussed in greater detail in subsequent chapters. In anodic aluminium oxide for the electrodeposition addition to synthesis, the chapter also briefl y reviews of palladium nanowires, hard templates, such as the many analytical methods that are commonly lithographically produced patterns or soft templates, used to characterise nanoparticles and discusses such as CTAB micelles. the pros and cons of each method. It goes on to Na Tian et al. (Xiamen University, China) provide a address the mechanisms of morphology evolution well set out chapter on high surface energy nanoparticles with comprehensive references to the academic and their use in electrocatalysis. Nanoparticles with a

(a) (b) (c) (d) 1 μm (e) 1D

100 nm 20 nm 100 nm 200 nm

(f) (g) (h) (i) 2D

100 nm 100 nm 500 nm 1 μm

(j) (k) (l) (m) [111] (o) (n) 3D

500 nm 100 nm 500 nm 500 nm 100 nm 50 nm

Fig. 1. TEM and SEM images of one-, two- and three-dimensional noble metal nanoparticles: (a) nanorods; (b) nanoshuttles; (c) nanobipyramids; (d) nanowires; (e) a nanotubule; (f) triangular nanoplates; (g) nanodiscs; (h) nanoribbons; (i) nanobelts; (j) nanocubes; (k) nanotetrapods; (l) and (m) star-shaped nanoparticles; (n) a nanohexapod; and (o) a nanocage (Reproduced with permission from Wiley-VCH)

high surface energy have an increased proportion of pyramidal or triangular superlattices made up of active surface atoms, with obvious advantages in fuel truncated platinum nanocubes (Figure 2). cells, electrooxidation of ethanol and other catalytic This leads nicely into a chapter on ordered and applications. The pgm nanoparticles have a face- non-ordered porous superstructures written by Anne- centred cubic structure and under thermodynamic Kristin Herrmann (Technische Universität Dresden, equilibrium conditions are enclosed by low energy Germany) et al. These have applications in a variety of facets {111} giving an octahedral or tetrahedral areas including gold substrates for surface-enhanced shape. The authors describe electrochemical and wet Raman spectroscopy and ordered hollow palladium chemistry routes to alternative high energy shapes -- spheres for use as catalysts in the Suzuki reaction. The concave hexaoctahedrons, 5-fold twinned nanorods, authors cover techniques including the use of artifi cial rhombic dodecahedrons and many more. They opals or polystyrene spheres as templates, which can provide a very useful table including pictures of the be removed by acid etching leaving metal nanoparticle shapes, the indices of their facets and references to the shells. Biotemplates and non-ordered templates, such literature. as aerogels and hydrogels, are also discussed. Chapter 9, written by Christophe Petit and Caroline Salzemann (Université Pierre et Marie Curie, Paris, Theory France) and Arnaud Demortiere (Argonne National Chapters 6--8 cover the theoretical aspects of complex- Laboratory, USA), is specifi c to platinum and palladium shaped nanoparticles. Tulio C. R. Rocha (Fritz-Haber- nanoparticles, bringing together some of the more Institut der Max-Planck-Gesellschaft, Germany) et al. general principles covered earlier in the book. It discuss Monte Carlo simulations of growth kinetics with illustrates the complexity of controlling the numerous an emphasis on defects, such as stacking faults and twin variables involved in defi ning particle morphology. planes, using the synthesis of shaped silver particles as The authors compare the use of alkylamine capping an illustration. Vladimir Privman (Clarkson University, agents in the Brust and reverse micelle synthesis USA) looks at the modelling of nucleation and growth methods, resulting in faceted platinum nanocrystals and its application to shape selection and control of and polycrystalline worms, respectively. They go on to the morphology of growth on surfaces. Amanda S. discuss the effect of reaction conditions, for example Barnard (Commonwealth Scientifi c and Industrial the timing of capping agent addition or the presence Research Organisation (CSIRO), Materials Science and of dissolved gasses, on the resultant particle shape. Engineering, Australia) takes a thermodynamic rather Platinum rods, cubes or tripods can be generated than a kinetic approach with the emerging technique by using a nitrogen atmosphere; in the presence of thermodynamic cartography. This involves mapping of hydrogen, platinum nanocubes are formed. The the thermodynamically preferred structure within chapter is completed by a short discussion on self- specifi ed parameters such as temperature, pressure or assembled supercrystals, for example square-based chemical environment.

(a) (c) Fig. 2. SEM images of supercrystals of truncated platinum nanocubes: (a) superlattice of pyramidal shape; (b) ensemble of pyramidal supercrystals on a substrate; (c) superlattice of triangular shape; and (d) ensemble of triangular supercrystals on a substrate (Reproduced 5 μm 3 μm with permission from (b) 50 μm Wiley-VCH)

20 μm (d)

No text on nanoparticles would be complete of metal nanoparticles in biomedical applications in without a section on surface plasmons and optical Chapter 15, covering subjects from diagnostics and responses. This is provided by Cecilia Noguez and imaging to therapy. Some of these topics are discussed Ana L. González (Universidad Nacional Autónoma de in more detail in the preceding chapters, but this México, Mexico) in Chapter 11. It is quite a theoretical chapter gives a well-written overview of all aspects chapter, illustrated by numerous equations, which at of biomedical applications. The only criticism is the fi rst appear a little daunting to the synthetic chemist. lack of real-world examples, as the references are all However, the chapter provides a useful discussion based on academic literature. The fi nal chapter deals on how surface plasmon resonances are sensitive to with thermoelectric materials, which are generally particle shape. semiconductor materials.

Applications Summary Chapters 12 to 16 take a more detailed look at the In conclusion “Complex-shaped Metal Nanoparticles: applications for complex-shaped nanoparticles. The Bottom-Up Syntheses and Applications” is an order of these chapters does appear to be a little extremely useful reference, whether the reader is haphazard with chapters on biomedical applications interested in synthesis, application or theory of interspersed with other topics but as the book is complex-shaped nanoparticles. Although there is designed as a reference to be dipped into it does some repetition between chapters written by different not detract too much from the overall experience. authors this serves to give the reader a choice of the In Chapter 12 Thomas A. Klar (Johannes-Kepler- depth to which they wish to explore the subject and Universität Linz, Austria and Center for NanoScience I would recommend it as an informative resource to (CeNS), Germany) and Jochen Feldmann (Ludwig- anyone from students to experienced researchers. Maximilians-Universität München, Germany) introduce The book clearly shows the potential for use of noble fl uorophore-metal interactions and their application metals in a broad spectrum of applications, including in biosensing. It begins by going through the catalysis, fuel cells, sensors, diagnostics and targeted theories behind the subject, before moving on to the drug delivery. It becomes obvious that more research applications, such as ion sensing or immunoassays, into the reliable production of shaped nanoparticles but is written in an understandable way for those new would be highly benefi cial. to the topic. The chapter would benefi t from some concluding remarks on future trends in this area. “Complex- Chapter 13 deals with surface-enhanced Raman shaped Metal spectroscopy (SERS) and is written by Frank Nanoparticles: Jäckel and Jochen Feldmann (Ludwig-Maximilians- Bottom-Up Syntheses and Universität München). It gives a good overview of the Applications” subject without going into too much detail, and gives references to further reading. The authors clearly emphasise the effect of particle morphology in SERS and compare different particle shapes, in keeping with the aims of this publication. The following chapter, written by Alexander O. Govorov et al. (Ohio University, USA) moves back to bioapplications and the photothermal effect of plasmonic nanoparticles. It is mainly concerned with the theory of the The Reviewer plasmonic photothermal effect with a small section Laura Ashﬁ eld received her DPhil on applications and although it is of interest in the in Inorganic Chemistry from the more general context of nanoparticle applications, it University of Oxford, UK, in 2005 and subsequently joined Johnson is not in keeping with the main theme of this book -- Matthey Technology Centre, Sonning complex-shaped nanoparticles. Common, UK, where she is a Principal Scientist. Her work centres Jun Hui Soh (Institute of Bioengineering and around the synthesis of nanomaterials Nanotechnology, Singapore) and Zhiqiang Gao with controlled morphology for a (National University of Singapore) discuss the role range of applications.

Crystallographic Properties of Ruthenium

Assessment of properties from absolute zero to 2606 K

http://dx.doi.org/10.1595/147106713X665030 http://www.platinummetalsreview.com/

John W. Arblaster The crystallographic properties of ruthenium at temperatures from absolute zero to the melting point at Wombourne, West Midlands, UK 2606 K are assessed following a review of the literature Email: [email protected] published between 1935 and to date. Selected values of the thermal expansion coeffi cients and measurements of length changes due to thermal expansion have been used to calculate the variation with temperature of the lattice parameters, interatomic distances, atomic and molar volumes and densities. The data is presented in the form of Figures, Equations and Tables.

This is the sixth in a series of papers in this Journal on the crystallographic properties of the platinum group metals (pgms), following two papers on platinum (1, 2) and one each on rhodium (3), iridium (4) and palladium (5). Ruthenium exists in a hexagonal close- packed (hcp) structure (Pearson symbol hP2) up to the melting point which is a secondary fi xed point on ITS-90 at 2606 ± 10 K (6). The thermal expansion is represented by fi ve sets of lattice parameter measurements, those of Owen and Roberts (7, 8) (from 323 K to 873 K), Hall and Crangle (9) (from 799 K to 1557 K), Ross and Hume- Rothery (10) (from 1793 K to 2453 K), Schröder et al. (11) (from 84 K to 1982 K) and Finkel’ et al. (12) (from 80 K to 300 K) and one set of dilatometric measurements, those of Shirasu and Minato (13) (from 323 K to 1300 K). The measurements of Hall and Crangle, Ross and Hume-Rothery and Finkel’ et al. were only shown graphically with actual data points as length change values being given by Touloukian et al. (14). Because there is a certain degree of incompatibility between the high- temperature measurements, and those obtained at low-temperature by Finkel’ et al., the high- and low- temperature data were initially treated separately. Available thermal expansion data covers the range from 293.15 K to 2453 K with estimated values below the lower limit whilst in the high-temperature region the derived equations are extrapolated to the melting point.

Thermal Expansion Crangle (9) deviate continuously from selected values High-Temperature Region and both axes are 0.14 low at the experimental limit Length change values derived from the measurements 1557 K. Above room temperature the a-axis values of of Owen and Roberts (7, 8) and Ross and Hume- Schröder et al. (11) initially trend to be 0.080 low at Rothery (10) agree satisfactorily and were combined 1300 K before increasing to 0.089 high at 1982 K. The to give Equations (i) and (ii) to represent the thermal c-axis values behave similarly, initially trending to 0.072 expansion from 293.15 K to the melting point. On the low at 1100 K before increasing sharply to 0.35 high at basis ± 100L/L293.15 K Equation (i) for the a-axis has 1982 K. The dilatometric measurements of Shirasu and an accuracy of ± 0.009 and Equation (ii) for the c-axis Minato (13) trend to 0.10 low. The deviations of these an accuracy of ± 0.025. Crystallographic properties three sets of values are shown in Figure 1. derived from Equations (i) and (ii) are given in Tables I and II. Low-Temperature Region On the basis of the expression: The lattice parameter measurements of Finkel’ et al. (12), given as length change values by Touloukian 100 × (L/L – L/L ) 293.15 K (experimental) 293.15 K (calculated) et al. (14), were fi tted to cubic Equations (v) and where L/L293.15 K (experimental) is the experimental length (vi) for the a- and c-axes respectively. Derived change relative to 293.15 K and L/L293.15 K (calculated) is thermal expansion coeffi cients at 293.15 K of 6.5 the selected length change value, then length change × 10–6 K–1 for the a- axis and 11.5 × 10–6 K–1 for the values derived from the measurements of Hall and c-axis are notably higher than those derived from

Table I High-Temperature Crystallographic Properties of Ruthenium

Temperature, Thermal Thermal Thermal Length Length Length K expansion expansion expansion change, change, change,

coeffi cient, coeffi cient, coeffi cient, a/a293.15 K c/c293.15 K avr/ –6 –1 –6 –1 –6 –1 a, 10 K c, 10 K avr, 10 K × 100, % × 100, % avr293.15 K × 100a, % 293.15 5.77 8.80 6.78 0 0 0 300 5.79 8.83 6.80 0.004 0.006 0.005 400 6.09 9.29 7.16 0.063 0.097 0.074 500 6.40 9.77 7.52 0.126 0.192 0.148 600 6.72 10.25 7.90 0.191 0.292 0.225 700 7.05 10.76 8.28 0.260 0.398 0.306 800 7.39 11.27 8.68 0.333 0.509 0.391 900 7.73 11.80 9.09 0.409 0.625 0.481 1000 8.09 12.34 9.51 0.488 0.746 0.574 1100 8.46 12.90 9.94 0.571 0.873 0.672 1200 8.83 13.47 10.38 0.658 1.006 0.774 1300 9.22 14.05 10.83 0.749 1.145 0.881 1400 9.61 14.65 11.29 0.844 1.291 0.993 1500 10.02 15.26 11.76 0.943 1.442 1.110 1600 10.43 15.88 12.24 1.046 1.600 1.231 1700 10.85 16.51 12.74 1.154 1.765 1.358 1800 11.28 17.16 13.24 1.266 1.936 1.489 (Continued)

Table I (Continued)

Temperature, Thermal Thermal Thermal Length Length Length K expansion expansion expansion change, change, change,

coeffi cient, coeffi cient, coeffi cient, a/a293.15 K c/c293.15 K avr/ –6 –1 –6 –1 –6 –1 a, 10 K c, 10 K avr, 10 K × 100, % × 100, % avr293.15 K × 100a, % 1900 11.71 17.82 13.75 1.382 2.115 1.627 2000 12.16 18.49 14.27 1.503 2.300 1.769 2100 12.61 19.17 14.80 1.629 2.493 1.917 2200 13.08 19.86 15.34 1.760 2.693 2.071 2300 13.55 20.56 15.89 1.895 2.901 2.231 2400 14.03 21.28 16.44 2.036 3.117 2.396 2500 14.51 22.00 17.01 2.182 3.340 2.568 2600 15.01 22.74 17.58 2.333 3.571 2.746 2606 15.04 22.78 17.62 2.342 3.586 2.756 a avr = average

Table II Further High-Temperature Crystallographic Properties of Ruthenium

Temperature, Lattice Lattice c/a Interatomic Atomic Molar Density, K parameter, parameter, ratio distance, volume, volume, kg m–3 a, nma c, nm d1, nm 10–3 nm3 10–6 m3 mol–1 293.15 0.27058 0.42816 1.5824 0.26502 13.574 8.174 12364 300 0.27059 0.42819 1.5824 0.26503 13.576 8.175 12363 400 0.27075 0.42857 1.5829 0.26524 13.604 8.193 12337 500 0.27092 0.42898 1.5834 0.26547 13.634 8.211 12310 600 0.27110 0.42941 1.5840 0.26570 13.666 8.230 12281 700 0.27128 0.42986 1.5845 0.26595 13.699 8.250 12251 800 0.27148 0.43034 1.5851 0.26620 13.734 8.271 12220 900 0.27169 0.43083 1.5858 0.26647 13.770 8.293 12188 1000 0.27190 0.43135 1.5864 0.26676 13.809 8.316 12154 1100 0.27213 0.43190 1.5871 0.26706 13.849 8.340 12118 1200 0.27236 0.43247 1.5878 0.26737 13.891 8.366 12082 1300 0.27261 0.43306 1.5886 0.26769 13.936 8.392 12043 1400 0.27286 0.43369 1.5894 0.26803 13.982 8.420 12003 1500 0.27313 0.43434 1.5902 0.26838 14.030 8.449 11962 1600 0.27341 0.43501 1.5911 0.26875 14.081 8.480 11919 1700 0.27370 0.43572 1.5919 0.26913 14.134 8.512 11874 1800 0.27401 0.43645 1.5929 0.26953 14.189 8.545 11828 (Continued)

Table II (Continued)

Temperature, Lattice Lattice c/a Interatomic Atomic Molar Density, K parameter, parameter, ratio distance, volume, volume, kg m–3 a, nma c, nm d1, nm 10–3 nm3 10–6 m3 mol–1 1900 0.27432 0.43722 1.5938 0.26995 14.247 8.580 11780 2000 0.27465 0.43801 1.5948 0.27038 14.307 8.616 11731 2100 0.27499 0.43883 1.5958 0.27083 14.369 8.653 11680 2200 0.27534 0.43969 1.5969 0.27130 14.434 8.692 11627 2300 0.27571 0.44058 1.5980 0.27178 14.502 8.733 11573 2400 0.27609 0.44150 1.5911 0.27229 14.572 8.776 11517 2500 0.27648 0.44246 1.6003 0.27281 14.646 8.820 11459 2600 0.27689 0.44345 1.6015 0.27335 14.722 8.866 11400 2606 0.27692 0.44351 1.6016 0.27338 14.727 8.869 11396 a a = d2

Fig. 1. The 0.36 difference between length change values derived from 0.31 the measurements

] of Hall and Crangle 0.26 (9), Schröder et al. (11) and Shirasu and Minato (13) 0.21 293.15 (calculated) L / L

 0.16 Ref. (9), a-axis – Ref. (9), c-axis 0.11 Ref. (11), a-axis Ref. (11), c-axis 0.06 Ref. (13) 293.15K (experimental)

L 0.01 / L

 300 800 1300 1800 –0.04 Temperature, K 100[

–0.09

–0.14

Equations (i) and (ii) as given in Tables II and III and were rejected. Therefore in order to extrapolate indicate the degree of incompatibility between the below room temperature Equations (i) and (ii) were high- and low-temperature data. Various manipulations differentiated and derived values of the thermal of subsets of the low-temperature measurements expansion coeffi cient relative to 293.15 K, *, were to try and reconcile the differences proved to be converted to thermodynamic thermal expansion, , unsatisfactory and the measurements of Finkel’ et al. using  = */(1 + L/L293.15 K). The  values obtained

Table III Low-Temperature Crystallographic Properties of Ruthenium

Temperature, Lattice Lattice c/a Interatomic Atomic Molar Density, K parameter, parameter, ratio distance, volume, volume, kg m–3 a, nma c, nm d1, nm 10–3 nm3 10–6 m3 mol–1 0b 0.27028 0.42742 1.5814 0.26462 13.520 8.142 12414 10 0.27028 0.42742 1.5814 0.26462 13.520 8.142 12414 20 0.27028 0.42743 1.5814 0.26462 13.520 8.142 12414 30 0.27028 0.42743 1.5814 0.26462 13.520 8.142 12414 40 0.27028 0.42743 1.5814 0.26462 13.520 8.142 12413 50 0.27028 0.42744 1.5815 0.26462 13.521 8.142 12413 60 0.27028 0.42745 1.5815 0.26463 13.521 8.143 12412 70 0.27029 0.42746 1.5815 0.26464 13.522 8.143 12411 80 0.27030 0.42748 1.5815 0.26465 13.524 8.144 12410 90 0.27031 0.42750 1.5815 0.26466 13.525 8.145 12409 100 0.27031 0.42752 1.5816 0.26467 13.527 8.146 12407 110 0.27033 0.42755 1.5816 0.26468 13.529 8.147 12406 120 0.27034 0.42757 1.5816 0.26470 13.531 8.148 12404 130 0.27035 0.42760 1.5817 0.26471 13.533 8.150 12402 140 0.27036 0.42763 1.5817 0.26473 13.535 8.151 12400 150 0.27037 0.42766 1.5817 0.26475 13.537 8.152 12398 160 0.27039 0.42769 1.5818 0.26476 13.539 8.154 12396 170 0.27040 0.42772 1.5818 0.26478 13.542 8.155 12394 180 0.27041 0.42776 1.5819 0.26480 13.544 8.156 12391 190 0.27043 0.42779 1.5819 0.26482 13.547 8.158 12389 200 0.27044 0.42782 1.5820 0.26484 13.549 8.159 12387 210 0.27045 0.42786 1.5820 0.26485 13.552 8.161 12385 220 0.27046 0.42789 1.5820 0.26487 13.554 8.162 12382 230 0.27048 0.42793 1.5821 0.26489 13.557 8.164 12380 240 0.27050 0.42796 1.5821 0.26491 13.559 8.166 12377 250 0.27051 0.42800 1.5822 0.26493 13.562 8.167 12375 260 0.27053 0.42804 1.5822 0.26495 13.565 8.169 12373 270 0.27054 0.42807 1.5823 0.26497 13.567 8.170 12370 280 0.27056 0.42811 1.5823 0.26499 13.570 8.172 12368 290 0.27058 0.42815 1.5824 0.26501 13.573 8.174 12365 293.15 0.27058 0.42816 1.5824 0.26502 13.574 8.174 12364 a a = d2 b Since all values below 293.15 K are estimated they are given in italics

at 293.15 K and over the range 300 K to 800 K at 50 K maximum deviation of only 0.006 low at 80 K for the intervals were then fi tted to Equations (iii) and (iv) a-axis and then converge towards the selected values. where the values of the specifi c heat used, Cp, are For the c-axis, there is initially agreement with the given by Equation (vii). Equations (iii) and (iv) were selected values and a maximum deviation of only then extrapolated below the room temperature region 0.010 low at 220 K. These small differences would using specifi c heat values given in the Appendix in actually suggest agreement between the high- and order to represent the thermal expansion to absolute low-temperature data; however, the fi tting procedure zero, although a-axis thermal expansion coeffi cients is so sensitive that these differences represent above 240 K were slightly adjusted in order to give a incompatibility. The low-temperature measurements smooth continuity with the high-temperature selected of Schröder et al. (11) are initially 0.027 low at 84 K values. Crystallographic properties derived from for the a-axis and then converge towards the selected Equations (iii) and (iv) are given in Tables III and IV. values, whilst for the c-axis the value is initially 0.026 There is the possibility of signifi cant uncertainty low but there is agreement to better than 0.001 above in this procedure but it is noted that in comparison, 210 K. using the same procedure as for the high-temperature Normally, as an alternative method of calculation, data, the measurements of Finkel’ et al. (12) show a Equations (iii) and (iv) would be fi tted to a series of

Table IV Further Low-Temperature Crystallographic Properties of Ruthenium

Temperature, Thermal Thermal Thermal Length Length Length K expansion expansion expansion change, change, change, avr/

coeffi cient, coeffi cient, coeffi cient, a/a293.15 K c/c293.15 K avr293.15 K –6 –1 –6 –1 –6 –1 a, 10 K c, 10 K avr, 10 K × 100, % × 100, % × 100, % 0a 0 0 0 –0.113 –0.172 –0.132 10 0.04 0.06 0.05 –0.113 –0.172 –0.132 20 0.09 0.16 0.12 –0.113 –0.172 –0.132 30 0.32 0.48 0.37 –0.112 –0.171 –0.132 40 0.70 1.07 0.83 –0.112 –0.171 –0.131 50 1.25 1.91 1.47 –0.111 –0.169 –0.130 60 1.85 2.82 2.17 –0.109 –0.167 –0.129 70 2.39 3.66 2.56 –0.107 –0.163 –0.126 80 2.88 4.40 3.39 –0.105 –0.159 –0.123 90 3.30 5.04 3.88 –0.102 –0.155 –0.119 100 3.66 5.58 4.30 –0.098 –0.149 –0.115 110 3.95 6.03 4.65 –0.094 –0.144 –0.111 120 4.20 6.42 4.94 –0.090 –0.137 –0.106 130 4.42 6.74 5.19 –0.086 –0.131 –0.101 140 4.60 7.02 5.40 –0.081 –0.124 –0.096 150 4.75 7.25 5.58 –0.077 –0.117 –0.090 160 4.88 7.44 5.73 –0.072 –0.109 –0.084 170 4.98 7.61 5.86 –0.067 –0.102 –0.079 180 5.08 7.76 5.97 –0.062 –0.094 –0.073 190 5.17 7.89 6.07 –0.057 –0.086 –0.067 200 5.25 8.01 6.17 –0.052 –0.079 –0.061 (Continued)

Table IV (Continued)

Temperature, Thermal Thermal Thermal Length Length Length K expansion expansion expansion change, change, change, avr/

coeffi cient, coeffi cient, coeffi cient, a/a293.15 K c/c293.15 K avr293.15 K –6 –1 –6 –1 –6 –1 a, 10 K c, 10 K avr, 10 K × 100, % × 100, % × 100, % 210 5.32 8.12 6.25 –0.046 –0.070 –0.054 220 5.38 8.22 6.33 –0.041 –0.062 –0.048 230 5.45 8.31 6.40 –0.036 –0.054 –0.042 240 5.50 8.40 6.47 –0.030 –0.046 –0.035 250 5.58 8.48 6.55 –0.024 –0.037 –0.029 260 5.63 8.56 6.61 –0.019 –0.029 –0.022 270 5.68 8.63 6.66 –0.013 –0.020 –0.016 280 5.71 8.70 6.71 –0.008 –0.011 –0.009 290 5.75 8.77 6.76 –0.002 –0.003 –0.002 293.15 5.77 8.80 6.78 0 0 0 a Since all values below 293.15 K are estimated they are given in italics

spline fi tted equations; however as there are two axes International Council for Science: Committee on Data this could involve a signifi cant number of equations for Science and Technology (CODATA) Fundamental and therefore the much simpler procedure has Constants (16, 17) conversion factor for CuK1, which been adopted of substituting values of Cp from the is 0.100207697 ± 0.000000028 whilst values given in Appendix into the equations. angstroms (Å) were converted using the default ratio 0.100207697/1.00202 where the latter value represents The Lattice Parameter at 293.15 K the old conversion factor from kX units to Å. Lattice The values of the lattice parameters, a and c, parameter values were corrected to 293.15 K using the given in Table V represent a combination of those values of the thermal expansion coeffi cient selected values selected by Donohue (15) and more recent in the present review. Density values given in Tables measurements. Values originally given in kX units II and III were calculated using the currently accepted were converted to nanometres using the 2010 atomic weight of 101.07 ± 0.02 (18) and an Avogadro

Table V Lattice Parameter Values at 293.15 Ka

Authors (Year) Reference Original Original Lattice Lattice Notes temperature, units parameter, a, parameter, c, K corrected to corrected to 293.15 K, nm 293.15 K, nm

Owen et al. (18) 291 kX 0.27044 0.42818 (a) (1935)

Owen and Roberts (7) 291 kX 0.27042 0.42819 (a) (1936)

Owen and Roberts (8) 293 kX 0.27040 0.42819 (a) (1937) (Continued)

Table V (Continued)

Authors (Year) Reference Original Original Lattice Lattice Notes temperature, units parameter, a, parameter, c, K corrected to corrected to 293.15 K, nm 293.15 K, nm Ross and Hume- (10) 303 Å 0.27042 0.42799 (a), (b) Rothery Finkel’ et al. (12) 293 Å 0.27062 0.42815 (a), (b) (1971) Hellawell and (19) 298 kX 0.27058 0.42817 Hume-Rothery (1954) Swanson et al. (20) 300 Å 0.27059 0.42819 (1955) Hall and Crangle (9) rtb Å 0.27058 0.42805 (1957) Anderson and (21) 293 kX 0.27058 0.42814 Hume-Rothery (1960) Černohorský (22) 295 Å 0.27059 0.42812 (1960) Savitskii et al. (23) rt kX 0.27059 0.42819 (1962) Schröder et al. (11) 284 Å 0.27056 0.42826 (1972) aSelected values for the present paper are: a = 0.27058 ± 0.00002 and 0.42816 ± 0.00007 brt = room temperature Notes to Table V (a) For information only – not included in the average (b) Lattice parameter values given by Touloukian et al. (14)

23 –1 constant (NA) of (6.02214129 ± 0.00000027) × 10 mol change is avr/avr293.15 K = (2 a/a293.15 K + c/c293.15 K)/3 (16, 17). From the lattice parameter values at 293.15 K (avr = average). selected in Table V as: a = 0.27058 ± 0.00002 nm and c = 0.42816 ± 0.00007 nm, the derived selected Summary density is 12364 ± 3 kg m–3 and the molar volume is Because there is disagreement between the high- (8.1743 ± 0.0018) × 10–6 m3 mol–1. In Tables II and III and low-temperature measurements for ruthenium, the interatomic distance d1 = (a2/3 + c2/4)½ and satisfactory thermal expansion data is only available d2 = a. The atomic volume is (√3 a2 c)/4 and the above 293.15 K with a novel approach being used to 2 molar volume is calculated as NA (√3 a c)/4 which extrapolate below this temperature to derive values is equivalent to atomic weight divided by density. which must be considered to be tentative. Clearly

Thermal expansion is avr = (2 a + c)/3 and length further measurements are required for this element.

High-Temperature Thermal Expansion Equations for Ruthenium (293.15 K to 2606 K)

–3 –6 –9 2 –13 3 a/a293.15 = –1.56642 × 10 + 4.93471 × 10 T + 1.34455 × 10 T + 1.69158 × 10 T (i)

–3 –6 –9 2 –13 3 c/c293.15 = –2.39045 × 10 + 7.52727 × 10 T + 2.06251 × 10 T + 2.61425 × 10 T (ii)

Low-Temperature Thermal Expansion Equations for Ruthenium (0 K to 293.15 K)

–1 –7 –11 –6 a (K ) = Cp (1.92207 × 10 + 8.09046 × 10 T + 7.16082 × 10 / T) (iii)

–1 –7 –10 –5 c (K ) = Cp (2.93088 × 10 + 1.24609 × 10 T + 1.09421 × 10 / T) (iv)

Thermal Expansion Equations Representing the Measurements of Finkel’ et al. (12)

–3 –6 –9 2 –12 3 a/a293.15 = –1.40337 × 10 + 3.25082 × 10 T + 4.63332 × 10 T + 2.07266 × 10 T (v)

–3 –6 –9 2 –11 3 c/c293.15 = –1.87652 × 10 + 3.44170 × 10 T + 2.91501 × 10 T + 2.44946 × 10 T (vi)

High-Temperature Speciﬁ c Heat Equation (298.15 K to 2606 K)

–1 –1 –3 –6 2 –9 3 2 Cp (J mol K ) = 23.1728 + 7.28378 × 10 T – 2.703021 × 10 T + 1.50844 × 10 T – 97572.6/T (vii)

Appendix: Speciﬁ c Heat Values for Ruthenium

Because of the large number of spline fi tted equations that would be required to conform to Equations (iii) and (iv), a simpler approach is used for the non-cubic metals in that specifi c heat values are directly applied to these equations. However this would require that the Table of low-temperature specifi c heat values originally given by the present author (24) has to be more comprehensive and the revised Table is given as Table VI. The high-temperature specifi c heat values corresponding to the above reference is given as Equation (vii) and is derived by differentiating the selected enthalpy equation.

Table VI Low-Temperature Speciﬁ c Heat Values for Ruthenium

Temperature, Specifi c Temperature, Specifi c Temperature, Specifi c K heat, J K heat, J K heat, J mol–1 K mol–1 K mol–1 K 10 0.0438 50 3.682 130 17.130 15 0.0955 60 5.838 140 18.050 20 0.186 70 7.991 150 18.837 25 0.359 80 10.000 160 19.509 30 0.731 90 11.839 170 20.093 35 1.233 100 13.455 180 20.607 40 1.877 110 14.854 190 21.066 45 2.707 120 16.071 200 21.480 (Continued)

Table VI (Continued) Temperature, Specifi c Temperature, Specifi c Temperature, Specifi c K heat, J K heat, J K heat, J mol–1 K mol–1 K mol–1 K 210 21.857 250 23.047 290 23.889 220 22.200 260 23.277 293.15 23.950 230 22.514 270 23.490 298.15 24.046 240 22.796 280 23.693 300 24.071

References 16 P. J. Mohr, B. N. Taylor and D. B. Newell, Rev. Mod. Phys., 1 J. W. Arblaster, Platinum Metals Rev., 1997, 41, (1), 12 2012, 84, (4), 1527 2 J. W. Arblaster, Platinum Metals Rev., 2006, 50, (3), 118 17 P. J. Mohr, B. N. Taylor and D. B. Newell, J. Phys. Chem. 3 J. W. Arblaster, Platinum Metals Rev., 1997, 41, (4), 184 Ref. Data, 2012, 41, (4), 043109 4 J. W. Arblaster, Platinum Metals Rev., 2010, 54, (2), 93 18 E. A. Owen, L. Pickup and I. O. Roberts, Z. Kristallogr., 1935, A91, 70 5 J. W. Arblaster, Platinum Metals Rev., 2012, 56, (3), 181 19 A. Hellawell and W. Hume-Rothery, Philos. Mag. Ser. 7, 6 R. E. Bedford, G. Bonnier, H. Maas and F. Pavese, 1954, 45, (367), 797 Metrologia, 1996, 33, (2), 133 20 H. E. Swanson, R. K. Fuyat and G. M. Ugrinic, “Standard 7 E. A. Owen and E. W. Roberts, Philos. Mag., 1936, 22, X-Ray Diffraction Powder Patterns”, NBS Circular Natl. (146), 290 Bur. Stand. Circ. (US) 539, 1955, IV, 5 8 E. A. Owen and E. W. Roberts, Z. Kristallogr., 1937, 21 E. Anderson and W. Hume-Rothery. J. Less Common A96, 497 Met., 1960, 2, (6), 443 9 E. O. Hall and J. Crangle, Acta Cryst., 1957, 10, Part 3, 22 M. Černohorský, Acta Cryst., 1960, 13, (10), 823 240 23 E. M. Savitskii, M. A. Tylkina and V. P. Polyakova, Zh. 10 R. G. Ross and W. Hume-Rothery, J. Less Common Met., Neorgan. Khim., 1962, 7, (2), 439; translated into 1963, 5, (3), 258 English in Russ. J. Inorg. Chem., 1962, 7, (2), 224 11 R. H. Schröder, N. Schmitz-Pranghe and R. Kohlhaas, Z. 24 J. W. Arblaster, CALPHAD, 1995, 19, (3), 339 Metallkd., 1972, 63, (1), 12 12 V. A. Finkel’, M. Palatnik and G. P. Kovtun, Fiz. Met. Metalloved., 1971, 32, (1), 212; translated into English in Phys. Met. Metallogr., 1972, 32, (1), 231 The Author 13 Y. Shirasu and K. Minato, J. Alloys Compd., 2002, 335, (1–2), 224 John W. Arblaster is interested in the history of science and the evaluation of 14 Y. S. Touloukian, R. K. Kirby, R. E. Taylor and P. D. Desai, the thermodynamic and crystallographic “Thermal Expansion: Metallic Elements and Alloys”, properties of the elements. Now retired, he Thermophysical Properties of Matter, The TPRC Data previously worked as a metallurgical chemist in a number of commercial laboratories and Series, Vol. 12, eds. Y. S. Touloukian and C. Y. Ho, IFI/ was involved in the analysis of a wide range Plenum Press, New York, USA, 1975 of ferrous and non-ferrous alloys. 15 J. Donohue, “The Structure of the Elements”, John Wiley and Sons, New York, USA, 1974

“Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology”

Edited by Christoph Hartnig (Chemetall GmbH, Germany) and Christina Roth (Institute for Applied Materials – Energy Storage Systems, Karlsruhe Institute of Technology, Germany), Woodhead Publishing Series in Energy, Woodhead Publishing Ltd, Cambridge, UK, 2012; Volume 1: Fundamentals and Performance of Low Temperature Fuel Cells, 436 pages, ISBN: 978-1-84569-773-0, £150.00, €180.00, US$255.00; Volume 2: In Situ Characterization Techniques for Low Temperature Fuel Cells, 524 pages, ISBN: 978-1- 84569-774-7, £165.00, €200.00, US$280.00

http://dx.doi.org/10.1595/147106713X664824 http://www.platinummetalsreview.com/

Reviewed by Bruno G. Pollet Introduction HySA Systems Competence Centre, SAIAMC, University of This book set covers polymer electrolyte membrane the Western Cape, Modderdam Road, Private Bag X17, fuel cells (PEMFCs) and direct methanol fuel cells Bellville 7535, Cape Town, South Africa (DMFCs). It is aimed at novice readers as well as Email: [email protected] experienced fuel cell scientists and engineers in this area. There are 34 contributors in Volume 1 and 30 in Volume 2, predominantly from Germany, with some contributions from the UK, France, Denmark, Italy, Switzerland, the USA and Canada. The editors are well known for their research, work and contributions in the fi elds of low-temperature fuel cell technology and materials components characterisation. Dr Christoph Hartnig is based at Chemetall GmbH and was formerly Head of Research at both BASF Fuel Cell GmbH and the Centre for Solar Energy and Hydrogen Research (Zentrum für Sonnenenergie- und Wasserstoff- Forschung Baden-Württemberg (ZSW)), Germany. Professor Dr Christina Roth is Professor for Renewable Energies at the Technische Universität Darmstadt and Head of a Research Group at the Institute for Applied Materials – Energy Storage Systems, Karlsruhe Institute of Technology (KIT) in Germany.

Volume 1: “Fundamentals and Performance of Low Temperature Fuel Cells” Volume 1 consists of two parts. Part I is entitled ‘Fundamentals of Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology’, and Part II is entitled ‘Performance Issues in Polymer Electrolyte Membrane and Direct Methanol Fuel Cells’.

Fuels and Materials Part I consists of fi ve chapters. Chapter 1: ‘Fuels and Fuel Processing for Low Temperature Fuel Cells’ deals with the effects of fuel type and quality on low-temperature fuel cell performance and degradation. The chapter

gives short overviews of fuel processing, fuel storage Electrocatalysts methods and alternative sources of hydrogen. An Chapter 3: ‘Catalyst and Membrane for Low Temperature excellent diagram overview of fuel processing for Fuel Cells’ focuses on fuel cell electrocatalysis and fuel cell systems (Figure 1) by Iain Staffell (Imperial the importance of the type and loading of the College, London, UK) (1) is given. Chapter 2: ‘Membrane cathode catalyst. The current anode and cathode Materials and Technology for Low Temperature Fuel catalyst loadings for low-temperature PEMFCs are ca. –2 –2 Cells’ gives a very good overview of the most recent 0.2 mgPt cm and 0.4 mgPt cm , respectively, with a investigations in PEM materials for low-temperature target for automotive applications of a total catalyst –2 PEMFCs with a section on PEM materials for high- loading of 0.2 mgPt cm (with anode catalyst loading of –2 temperature applications. It reviews perfl uorosulfonic 0.05 mgPt cm and cathode catalyst loading of –2 acid PEMs and non-perfl uorinated PEMs including 0.15 mgPt cm ) for a cell voltage of 0.85 V, assuming a sulfonic acid, phosphonic, heterocycle functionalised CO-free hydrogen supply. Figure 2 shows the evolution of and acid doped membrane materials. A short section Pt loading and estimated fuel cell balance of plant from is specifi cally dedicated to the morphology and 2006 (2). Both carbonaceous and non-carbonaceous microstructure of ionomer membranes. electrocatalyst support materials are mentioned

Natural gas Function Methods Output gas composition Remove the sulfur based Hydro- odorants added to natural gas desulfurisation, 95% CH for safety reasons: Desulfuriser C selective 2 H 6 , 1% 4CO, 4% Al adsorption ZnO + H2S ZnS + H2O 25ºC 2 Catalytically process methane Steam reforming, 10% CO, into hydrogen with steam and 10% CO , 0.5–1% CH an absence of oxygen: partial oxidation, Reformer 2 4 SOFC Ni-Al/Pt-Pd autothermal CH4 + H2O CO + 3H2 reforming 650–850ºC Improve the hydrogen yield and reduce concentration of the High-temperature 0.5–1% CO, 15% CO2 waste carbon monoxide: (HT) and low- Shift reactor PAFC Cu-Zn/Fe-Cr temperature (LT) CO + H2O CO2 + H2 350–450ºC (HT) shift 175–300ºC (LT) Reduce CO concentration to Preferential ppm levels: oxidation, pressure 10 ppm CO, 15% CO2 Pt-Ru/Rh-Al swing adsorption, CO removal PEMFC CO + ½O2 CO2 150–200ºC methanisation

10 ppm CO, Reduce CO2 concentration to Soda lime ppm levels: 100 ppm CO2 adsorption, CO scrubber AFC regenerative 2 CO2 + Ca(OH)2 CaCO3+ 25ºC H O amines, electrical 2 swing adsorption

Fig. 1. An overview of fuel processing for fuel cell systems (1) (Courtesy of Iain Staffell, University of Birmingham, UK, and Woodhead Publishing)

Fig. 2. Evolution US$30 kW–1 (US DOE target) Key 2015 –2 of platinum 1 W cm Power density (W cm–2) loadings and estimated –1 Estimated balance of plant US$51 kW fuel cell 2010 –2 (US$ kW–1) (including assembly 833 mW cm balance and testing) –1 of plant US$61 kW Platinum loading (mg cm–2) used 2009 –2 Pt (Reproduced 833 mW cm in automotive PEMFC stacks at a from (2) by cell voltage of 0.676 V permission of Year US$73 kW–1 2008 Platinum loading (g kW–1) used in Elsevier) 715 mW cm–2 Pt automotive PEMFC stacks –1 2007 US$94 kW 583 mW cm–2

–1 2006 US$108 kW 700 mW cm–2 0 0.2 0.4 0.6 0.8 1.0 1.2 –1 –2 Platinum loadings, gPt kW or mgPt cm

(including, for example, metal oxides (3)) for both highlight other ex situ characterisation methods for PEMFCs and direct methanol fuel cells (DMFCs). bulk or contact resistance, surface morphology or fi bre The chapter also highlights some of the most structure and mechanical strength measurements (7). recent developments in anode and cathode catalysts There is also little information on the possible thermal (including ultra-low Pt) used in low-temperature fuel conductivity effect of the microporous layer on cell cells. These include core-shell and binary and ternary performance. alloy electrocatalysts – platinum alloyed with cobalt, The chapter then broadly discusses the role of fl ow copper, iron, molybdenum, nickel and/or ruthenium. fi eld design for both low-temperature PEMFC and DMFC The chapter also discusses new approaches in fuel with some brief discussions around the importance cell electrocatalysis research and development, for of fl ow fi eld plate material, especially its interaction example the reduction of the Pt content and the with the gas diffusion layer material under various investigation of Pt-free compounds (for example operating conditions and applications (7, 8). Perhaps Co and Fe incorporated in nitrogen macrocycle for completeness the authors could have added a short structures) based upon either non-precious metals section on ex situ characterisation and accelerated or alloyed transition metals. However, the chapter ageing/accelerated stress tests for fl ow fi eld plate does not touch on advanced cathode catalysts such materials. This chapter also discusses the importance as the famous 3M platinum nano-structured thin fi lm of the system layouts of the two low-temperature fuel (NSTF) (4), which is a bit of a disappointment. For cells, i.e. balance of plant, including reactant supplies those who are interested in learning further about fuel and thermal management. For Chapter 4, perhaps cell electrocatalysis, there are a number of additional the section on system aspects of low-temperature books which I would strongly recommend (4–6). fuel cells could have been a separate chapter in the book emphasising the correlation between the fl ow Gas Diffusion Media fi eld plate design and material, the gas diffusion layer Chapter 4: ‘Gas Diffusion Media, Flow Fields and material and the overall system design and layout. System Aspects in Low Temperature Fuel Cells’ covers the role and importance of gas diffusion media Environmental Aspects (tefl onated/untefl onated woven and non-woven), fl ow Chapter 5: ‘Recycling and Life Cycle Assessment of fi eld plate designs on performance and degradation Fuel Cell Materials’ focuses on the environmental and system design criteria for low-temperature aspects of fuel, fuel cell components and fuel cell applications. The chapter briefl y states characterisation stacks as well as recycling. The chapter highlights the methods for gas diffusion layers, although it does not fact that pgms such as Pt, Pd and Rh are successfully

recycled from today’s vehicles (principally from all operating conditions and briefl y describes how catalytic converters – modern vehicles may contain that degradation can be minimised, in turn increasing around 1 g of Pt for petrol and around 8 g of Pt for performance and durability, by improving the overall diesel (2)) and the technologies can be adopted to stack design at component material and operational recycle Pt from fuel cell systems. This chapter is very levels. interesting and well-written as recycling of fuel cell Chapter 7: ‘Catalyst Ageing and Degradation in components and systems and their impact on the Polymer Electrolyte Membrane Fuel Cells’ focuses on environment is often neglected, and a ‘zero-to-landfi ll’ performance degradation of electrocatalysts affected approach is required in order to lead to long-term by the relatively harsh operating conditions within cost savings. It also highlights that recycling in the fuel low-temperature fuel cells and discusses catalyst cell manufacturing industry will become paramount ageing mechanisms. For example, it explains the for mass-produced systems in which environmental three principal mechanisms attributed to the loss considerations will have to be taken into account of electrochemical surface area for pure Pt and Pt (for example, collection/separation systems, recycling alloys supported on carbon, i.e. dissolution (leading processes, component reuse, remanufacturability and to Pt redeposition or Pt precipitation), migration energy recovery). Life cycle assessment models of with concomitant coalescence and detachment of fuels and fuel cell components are discussed in detail Pt nanoparticles from the carbonaceous support as and the standardised life cycle assessment protocol well as complete or incomplete carbon corrosion (International Organization for Standardisation – ISO of the support material. The discussion then focuses 14040 series) is briefl y mentioned. on the main effects causing such mechanisms: temperature, pH, anion types, water partial pressure, Operation and Ageing Pt particle size and electrode potential variations Part II in Volume 1 consists of seven chapters: and for Pt alloy electrocatalysts, dealloying of the Chapter 6: ‘Operation and Durability of Low non-precious metal (mainly transition metals as they Temperature Fuel Cells’ gives an excellent overview are not stable in acidic environments – for example of the effects of low-temperature PEMFC operating Pt-Co catalysts are known to exhibit poor performance conditions (thermal, water and reactant management, under intense cycling conditions). The chapter also contamination types and levels and duty cycling) on briefl y reviews ex situ and in situ catalyst degradation performance and durability (which is also correlated characterisation methods with an emphasis on a very to component material properties, their designs and useful, powerful and newly developed technique – cycling abilities). The chapter highlights the major identical location transmission electron microscopy degradation processes occurring in the pgm-based (IL-TEM) – that was originally developed by the cathode catalyst layer and PEM regions present for chapter’s authors (Figure 3). The technique provides

(a) (b) (c) 100 nm

50 nm

Fig. 3. Series of IL-TEM micrographs of platinum particles on a carbon support, showing: (a) Particle detachment; (b) Particle movement and agglomeration; and (c) Displacement of the carbon support under various harsh potential cycling conditions (Reproduced by permission of Woodhead Publishing)

insights into electrocatalyst stability on the nanoscale to elucidate ageing mechanisms and their possible level under various regimes and thus allows a direct predictions. The author also discusses the newly (visual) observation of the effect of electrochemical developed transient, multi-scale and multi-physics treatments on carbon-supported high surface area single cell model MEMEPhys® (13) and emphasises electrocatalysts (9). the need to generate representative accelerated testing methods in the fi eld. Durability Tests Finally, Volume 1 ends with Chapter 12 entitled Chapter 8: ‘Degradation and Durability Testing of ‘Experimental Monitoring Techniques for Polymer Low Temperature Fuel Cell Components’ is well- Electrolyte Membrane Fuel Cells’. This chapter written and well-structured. It discusses accelerated describes the various techniques and methods durability test protocols (ex situ and in situ) mainly employed for on-line and off-line logging, monitoring for the critical low-temperature PEMFC components and diagnosis of important fuel cell parameters (for which are the PEM, the electrocatalyst and the example, temperature, humidity, current distribution, electrocatalyst carbonaceous support materials. local pressure distribution and pressure drop) during The chapter also briefl y covers the effect of fuel operation. contaminants on durability. Chapter 8 nicely highlights the main publications dealing with Volume 2: “In Situ Characterization degradation and durability studies and protocols for Techniques for Low Temperature Fuel Cells” the membrane electrode assembly (MEA) and its Volume 2 consists of three parts: Part I entitled subcomponents. ‘Advanced Characterization Techniques for Polymer Chapter 9 is a very good and systematic discussion Electrolyte Membrane and Direct Methanol Fuel of the stochastic microstructure techniques for the Cells’, Part II entitled ‘Characterization of Water determination of transport property parameters as well and Fuel Management in Polymer Electrolyte as the study of the effect of porous structure materials Membrane and Direct Methanol Fuel Cells’ and Part upon transport behaviours within the critical PEMFC III entitled ‘Locally Resolved Methods for Polymer catalyst layer, gas diffusion layer and microporous Electrolyte Membrane and Direct Methanol Fuel layer regions. Cell Characterization’. I thoroughly enjoyed reading Volume 2 as it covers comprehensively the important Modelling and main (in situ) techniques and methods currently Chapter 10: ‘Multi-scale Modelling of Two-Phase employed in characterising in detail MEA and MEA Transport in Polymer Electrolyte Membrane Fuel subcomponents (fuel cell electrocatalyst, catalyst Cells’ discusses in detail the pore network model and layer, membrane and gas diffusion medium) as the lattice Boltzmann model for the modelling of well as water and fuel management. It would have two-phase fl ow in porous PEMFC materials such as been very useful to have included a summary table gas diffusion layers and catalyst layers. The chapter showing the in situ and ex situ characterisation describes how pore-scale information (for example, techniques which help to elucidate the degradation microstructure, transport and performance) can be mechanisms for all MEA components and water useful for more predictive macroscopic scale-up. and fuel management (including extended X-ray Chapter 11, entitled ‘Modelling and Analysis of absorption fi ne structure (EXAFS), IL-TEM, three- Degradation Phenomena in Polymer Electrolyte dimensional (3D)-TEM, in situ X-ray tomography Membrane Fuel Cells’, is an excellent review of (XRT), small angle X-ray scattering (SAXS), X-ray the various available models describing PEMFC adsorption near edge structure (Δμ XANES), degradation phenomena and mechanisms. The neutron radiography, neutron tomography, magnetic chapter highlights the most important work on resonance imaging, synchrotron radiography, the subject in the last 20 years and also briefl y Raman spectroscopy, scanning electron microscopy introduces pioneering work by, for example, Springer (SEM) and laser optical methods). et al. (Los Alamos National Laboratory, New Mexico, USA) (10), Bernardi and Verbrugge (General Motors Conclusions Research and Environmental Staff, USA) (11) and This two-volume set presents a fairly comprehensive Antoine (Université de Genève, Switzerland) et al. and detailed review of low-temperature PEMFCs and (12). This chapter also describes systematically and DMFCs and their in situ characterisation methods comprehensively the various modelling approaches by reviewing in detail their fundamentals and

performance as well as advanced in situ spectroscopic 10 T. E. Springer, T. A. Zawodzinski and S. Gottesfeld, techniques for their characterisation. I was impressed J. Electrochem. Soc., 1991, 138, (8), 2334 by the content and breadth of this detailed work. There 11 D. M. Bernardi and M. W. Verbrugge, J. Electrochem. are of course already books available covering similar Soc., 1992, 139, (9), 2477 areas and there is some duplication between chapters 12 O. Antoine, Y. Bultel and R. Durand, J. Electroanal. (for example, fuel cell descriptions), but this does not Chem., 2001, 499, (1), 85 detract from the overall experience. The book set also 13 A. A. Franco, ‘A Physical Multiscale Model of the highlights the key challenges for the commercialisation Electrochemical Dynamics in a Polymer Electrolyte Fuel Cell – An Inﬁ nite Dimensional Bond Graph Approach’, of PEMFC-based systems, mainly related to life cycle PhD Thesis, Université Claude Bernard Lyon-1, analysis of the overall systems and global research France, 2005 and development efforts on materials development for durability and long term operation. This is a very informative work, especially with regard to current progress on in situ characterisation techniques (Volume 2). Although I was a little disappointed at the lack of high-temperature PEMFC information, I would defi nitely recommend this book set for readers who are either experienced or new in this exciting fi eld.

References 1 I. Staffell, ‘Fuel Cells for Domestic Heat and Power: Are They Worth It?’, PhD Thesis, School of Chemical Engineering, University of Birmingham, UK, September 2009 2 B. G. Pollet, I. Staffell and J. L. Shang, Electrochim. Acta, 2012, 84, 235 and references therein 3 S. Sharma and B. G. Pollet, J. Power Sources, 2012, 208, 96 4 M. K. Debe, Nature, 2012, 486, (7401), 43 5 “Catalysis in Electrochemistry: From Fundamentals to Strategies for Fuel Cell Development”, eds. E. Santos and W. Schmickler, John Wiley & Sons, Inc, Hoboken, New Jersey, USA, 2011 “Polymer Electrolyte Membrane and Direct Methanol 6 “PEM Fuel Cell Electrocatalysts and Catalyst Layers: Fuel Cell Technology”, Volumes 1 & 2 Fundamentals and Applications”, ed. J. Zhang, Springer- Verlag London Ltd, Guildford, Surrey, UK, 2008 The Reviewer 7 A. El-kharouf and B. G. Pollet, ‘Gas Diffusion Media Bruno G. Pollet FRSC recently joined and Their Degradation’, in “Polymer Electrolyte Fuel Cell Hydrogen South Africa (HySA) Systems Degradation”, eds. M. M. Mench, E. C. Kumbur and T. Competence Centre at the University N. Veziroglu, Elsevier Inc, Waltham, Massachusetts, USA, of the Western Cape as Director and 2012, pp. 215-247 Professor of Hydrogen and Fuel Cell Technologies. Pollet has extensive 8 P. J. Hamilton and B. G. Pollet, Fuel Cells, 2010, 10, expertise in the research ﬁ elds of (4), 489 PEMFC, fuel cell electrocatalysis and electrochemical engineering. Website: 9 K. J. J. Mayrhofer, S. J. Ashton, J. C. Meier, G. K. H. http://www.hysasystems.org/ Wiberg, M. Hanzlik and M. Arenz, J. Power Sources, 2008, 185, (2), 734

Kunming–PM’2012

5th International Conference “Platinum Metals in the Modern Industry, Hydrogen Energy and Life Maintenance of the Future” http://dx.doi.org/10.1595/147106713X666291 http://www.platinummetalsreview.com/

Reviewed by Mikhail Piskulov* The 5th international biennial conference in the series Johnson Matthey Moscow Ofﬁ ce, Ilyinka 3/8, Building 5, “Platinum Metals in the Modern Industry, Hydrogen Ofﬁ ce 301, 109012 Moscow, Russia Energy and Life Maintenance of the Future” was held *Email: [email protected] from 15th to 19th October 2012, in Kunming, China. The conference was organised by the Kunming Institute of Precious Metals under the patronage of Carol Chiu** the International Organisation “Professor Ye. I. Rytvin Johnson Matthey Technology Centre, Blounts Court, Foundation” and with the support of the Non-Ferrous Sonning Common, Reading RG4 9NH, UK Metals Society of China and OJSC Supermetal, Russia. **Email: [email protected] The conference was attended by 125 participants from seven countries. The conference covered both production and a wide range of applications of the platinum group metals (pgms), including uses in the automotive, electronics, glass, dental, jewellery, hydrogen and solar energy sectors. The programme included 18 Plenary Session reports and over 40 reports were published in the conference proceedings. The following main topics were covered during the Plenary Sessions.

Structure Control of Noble Metal Nano- and Microparticles Professor Nanfeng Zheng (Xiamen University, China) gave a presentation on ‘Multilevel Control of Noble Metal Nanostructures for Catalysis and Bio- applications’. The presentation was focused on how surface structure can optimise activity and stability for surface-dependent catalysis (e.g. ammonia synthesis and carbon monoxide (CO) oxidation) and surface-dependent electrocatalysis (e.g. fuel cells). There is a large difference in the surface energies of platinum and palladium with different surface crystal structures, and the dominant surface structure affects catalytic activity. Small adsorbents (e.g. halides, formaldehyde, carbon monoxide or amines) were used to control the metal nanostructures to prepare unique Pd and Pt nanocrystals. One of the examples discussed was Pd hexagonal nanosheets. The edge length of the hexagons increased with reaction time while the thickness remained fi xed at 1.8 nm. It was proposed that the dominant surface was {111}, which gives improved electrocatalytic properties compared

with commercial Pd black as well as unique optical spheres. The aggregation of primary particles is affected and photothermal effects. One of the proposed by changes in the ionic strength or pH. The presenter applications is in near infrared photothermal cancer concluded that research on structure control of noble therapy. Many other types of pgm nanostructures have metal microparticles is at least as important as that on also been synthesised by the CO adsorption method, the corresponding nanoparticles. such as tetrapod nanocrystals, nanocubes and Tatjana Buslaeva (Lomonosov Moscow University octapods. In the oxidation of ethanol, the activity of Pt of Fine Chemical Technology, Russia) presented octapods was measured to be four times higher than joint work with the University of Eastern Finland Pt black or Pt on carbon. on ‘The Synthesis of Catalytic Systems Based Professor Xudong Sun (Northeastern University, on Nanocomposites Containing Palladium and Shenyang, China) presented a paper on ‘Controllable Hydroxycarbonates of Rare-Earth Elements’. For this Synthesis of Dispersed Precious Metal Powders’ which work yttrium and cerium hydroxycarbonates were reviewed achievements and problems related to used as the support and Pd nanoparticles were preparation of dispersed precious metals powders directly reduced from solution. Nanocomposites by chemical reduction, more specifi cally synthesis Pd/Y(OH)CO3 and Pd/Ce(OH)CO3 were synthesised of various morphologies, such as monodispersed using two methods: (a) simultaneous production spheres, single crystalline particles and nanowires. of a nanoscale substrate and immobilisation of Pd In addition to nanoparticles, microparticles of silver, nanoparticles on its surface; or (b) prior synthesis gold, silver-palladium alloy, ruthenium and tungsten of polyvinylpyrrolidone stabilised Pd nanoparticles also have a wide range of commercial applications, followed by their immobilisation on the nanosized such as electrode pastes and catalysts. Microparticles substrate surface. The new systems synthesised have two representative categories, dispersed demonstrated high conversion effi ciency and can be crystalline particles and monodispersed spherical used for homogeneous catalyst production. particles. Formation of dispersed crystalline particles is explained by the LaMer model (Figure 1) which Applications of the Platinum Group Metals assumes that nucleation and growth are separate. By Professor Zhuangqi Hu (Institute of Metal Research adjusting the nucleation rate, the resulting particle sizes of the Chinese Academy of Sciences, Shenyang, can be controlled. The nucleation rate is controlled China) explained the role of Ru in nickel-based single by the pH while agglomeration is avoided by a high crystal superalloys. Over the last few years there has stabiliser concentration. Monodispersed spherical been increasing research on superalloy materials particles are formed by nucleation and growth to due to their high mechanical strength and oxidation subunits from a supersaturated solution, followed resistance at elevated temperatures. Ni-based by aggregation of the subunits into monodispersed superalloys are widely used in turbine blades found in jet engines, ships and power plants. The blades operate in the hottest part of the engine at temperatures around 1100ºC. The most recently discovered microstructure Critical limiting supersaturation of superalloys is the third generation single crystal. By C max adding a refractory element, such as rhenium, strength Rapid self-nucleation is enhanced. However, over addition or segregation Cmin of Re causes topologically close packed (tcp) phase Growth precipitation which damages the continuity of the Solubility microstructure, promotes crack initiation and leads Concentration Cs I II III to a decrease in strength of the superalloy. To prevent this, tests were made with Ru-free alloy and with Time alloys containing 1.5% and 3% Ru additions. Cast Fig. 1. LaMer model of dispersed crystalline particle microstructure, structural evolution, tensility and formation (Cmax = maximum concentration for rupture properties and oxidation behaviour were nucleation, Cmin = minimum concentration for studied. It was noted that the addition of Ru suppressed nucleation, Cs = concentration for solubility, tcp phase formation and hence improved the creep I = prenucleation period, II = nucleation period, III = growth period) (Image courtesy of Professor properties, so that Ru-containing superalloys could be Xudong Sun, Northeastern University, China) used even under higher temperature conditions. There

was a strengthening effect on tensility, but no obvious catalyst performance, and the impact of future global effect on stress rupture life, and a weakening effect on emissions regulations on pgm usage in automotive heat/corrosion resistance. A higher oxidation rate was emissions control catalysts. also observed when the Ru-containing superalloys Junjun He (Sino-Platinum Metals Co Ltd, China) were heated to 1000ºC or 1100ºC. The conclusion was presented a review of the metal–support interaction that in future Ru might play an important commercial in automotive catalysts. The support can improve the role in such superalloys. dispersion of Pt, Pd and Rh and suppress the sintering Professor Yizhou Zhou (Institute of Metals Research of the pgms at high temperatures. The pgms can also of the Chinese Academy of Sciences, Xi’an, China) enhance the redox performance and oxygen storage presented a paper entitled ‘Effects of Platinum on capacity of the support. The presentation reviewed the the Micro-Segregation Behaviour and Phase Stability reaction phenomena and mechanism of pgms and in Nickel-Base Single Crystal Superalloys’. In addition supports such as Al2O3 and CeO2-based composite oxides. to the work on Ru discussed above, Pt has also Vitaly Parunov (Moscow State University of been examined as a potential alloying addition to a Medicine and Dentistry, Russia) made a report on the third generation single crystal superalloy. However, biocompatibility of different denture materials based experimental work on such materials has shown on research carried out amongst 109 patients. The noble that the incipient melting point, solidus and liquidus metal-based alloys Plagodent and Palladent (fabricated temperatures are decreased. Pt segregates to the by Supermetal, Russia) showed the best results when interdendritic region and intensifi es the segregation compared to other types of metal-based materials. of refractory elements such as Re and tungsten. Formation of a tcp phase is also promoted under PGM Reﬁ ning Technologies extended thermal exposure at 1100ºC. Although Pt Joseph L. Thomas (Metals Recovery Technology Inc additions enhance tensile strength at high temperature, (MRTI), USA) explained MRTI’s commercial precious it is unable to enhance rupture life. It was concluded metal recovery technologies. Recently, four different that Pt additions to single crystal superalloys do not types of pgm-containing waste feedstock have been have a benefi cial effect on phase stability. treated: Professor Guang Ma (Northwest Institute for Non- (a) Pd was recovered from various supported Pd Ferrous Metal Research, China) spoke on the topic of catalysts (100–5000 ppm Pd) by chlorine leaching. Pd alloy membranes in hydrogen energy. Hydrogen After addition of chlorine and polyamine resin, a is an alternative energy source which could reduce Pd-loaded polyamine composite resin (2) was our dependence on fossil fuels in the future. For produced, while other metals (e.g. Ni, copper many commercial applications hydrogen must be and iron) remained in solution. The capacity purifi ed and the use of Pd-based alloy membranes was 20 Mt per batch with a fi ve day cycle and a for purifi cation is very attractive. Pd-rare earth alloys recovery rate of 99% Pd. have improved hydrogen permeability compared to (b) Pt, Pd or gold were recovered from Cu alloys other alloys used for this purpose (1). This is because containing these metals. After adding Cu metal the rare earth elements not only expand the Pd lattice to Pt, Pd or Au ores or spent catalysts, the mixture but also readily adsorb hydrogen onto the membrane was melted by induction to give the Cu alloy. surface. Hydrogen separation rates increase with Then sodium chloride and chlorine gas were hydrogen permeability of the membrane. Improved added. The dissolved precious metals were then mechanical strength, heat resistance and hydrogen reduced to insoluble solids and separated from diffusion rates, as well as the development of low cost the solution. manufacturing routes, are seen as important research (c) Pd, Pt, rhodium and Au were recovered from and development targets for Pd-based hydrogen spent autocatalysts. The reaction again involved separation membranes. the addition of chlorine together with resin to Wei Li (General Motors, USA) reported on such the autocatalysts. Only Pd, Pt, Rh and Au were issues as catalyst deactivation due to pgm sintering absorbed onto the resin while other metals, and poisoning, recent trends in the use of pgms in including Group I and Group II chalcogens diesel catalysts (in particular the diesel oxidation and other transition metals, were not. The catalyst (DOC), lean NOx trap (LNT) and diesel metal resins were then burned to yield metal of particulate fi lter (DPF)), different factors affecting 98–99% purity.

(d) The pgms were recovered from a complex areas which can benefit from the unique properties mixture of pgms and other transition metals. The of pgms. pgms were refi ned using a substituted quaternary Alexander Andreev (Ekaterinburg Non-Ferrous ammonium salt (2) giving more than 99.9% pgm Metals Processing Plant, Russia) outlined in his paper recovery with a typical purity of 99.97% to 99.99% the role of Russia in the global pgm markets and the in six days. The procedure relied on precipitation, problems faced by Russian exporters due to internal fi ltration and washing and did not involve ion regulations. Andreev estimates that in 2011, the exchange or solvent extraction. This is based Russian share of global pgm supply amounted to 13% on the fact that only pgms will precipitate with (26 tonnes) Pt, 47% (108 tonnes) Pd and 8.9% (2.12 tetramethylammonium chloride. The reagent may tonnes) Rh. However, the Russian share of world pgm be recycled after use. trade was much lower. The discrepancy was explained Professor Jinhui Peng (Kunming University of by a lack of metal trading activities in Russia, compared Science and Technology, China) reviewed the recovery to the European and Asian markets, largely due to of pgms from secondary resources using microwave concentration of demand (end users for sectors like technology. This is believed to be more effi cient, electronics and automotive) in these regions, but also energy-saving and environmentally friendly than due to issues related to the limitations and shortcomings conventional metallurgical process. Three different of Russian customs and currency regulations. approaches were discussed: Mariya Goltsova (Donetsk National Technical (a) Microwave-assisted leaching improved the yield University, Ukraine) presented the ‘Hydrogen and process time for the recovery of pgms from Civilization (HyCi) Doctrine’, which describes a vision spent catalysts. After microwave heating at 600ºC of sustainable development, starting with a gradual for 60 minutes, the leaching effi ciencies of Pd and change to the use of hydrogen energy, followed by Rh were 99.8% and 97.4%, respectively (3). a more integrated hydrogen economy and fi nally (b) Microwave pyrolysis was used to recycle pgms what the HyCi doctrine calls a ‘hydrogen civilisation’. from waste printed circuit boards. The waste The authors anticipate that this will lead to global circuit boards were initially crushed into small transformation in all aspects of life, society, the pieces and microwave heated to decompose environment and industrial development. organic compounds. Subsequent heating to Jurgen Leyrer (Umicore AG & Co, Belgium) outlined 1100ºC allowed the pgms to be separated and Umicore’s ‘Process Exellence Model’ for the special recovered. glass and chemical industries. Umicore defi nes (c) Microwave augmented ashing was used to reduce process excellence as any achievement related to Pt the length of time required for the activation components before, during or after use in a customer’s process for recovery of Pt and Rh from scrap production process. They claim to offer cost savings, fi rebricks from the glass industry. for example by reductions in pgm inventory and pgm Although microwave assisted pgm recovery was losses in operation and during refi ning, reduction still at the laboratory stage, it has potential to be a of Rh requirements, energy and raw materials and next generation pgm refi ning technology due to its increase in the service time of pgm components. environmental benefi ts. Liudmila Morozova (Supermetal) made a presentation on this Russian fabricator’s pgm product Market Trends and the PGM Industry manufacturing activities. The company has been Mikhail Piskulov (Johnson Matthey Moscow, active for 50 years, and for the last 25 years it has Russia) reported on recent trends in industrial pgm been fabricating equipment for the production of applications. It was noted that industrial applications high-quality glass and monocrystals as well as other play an important role in the pgm markets, pgm products for technical and medical applications. accounting for 25–30% of the gross total demand for They use pyrometallurgical processing of scrap with Pt and Pd and close to 100% for such minor pgms high pgm content, which allows scrap alloys to be as Ru and Ir. In the last 10 years industrial demand refi ned without dealloying, substantially accelerating has been on the increase over the entire pgm range. processing time and reducing costs. They also use However, there is a constant need for new research electrophysical fabrication technologies to produce and development to fully explore and develop new dispersion strengthened materials (DSMs) based

on Pt and its alloys with Rh. DSMs allow the use of References manufacturing techniques such as rolling, stamping, 1 G. Ma, J. Li, Y. Li, X. Sun, Q. Cao and Z. Jia, Precious Met. drawing and welding, while the heat resistance of (Chin.), 2012, 33, (S1), 208 DSMs (as measured by the creep rate and long-term 2 J. L. Thomas and G. F. Brem, Metals Recovery Technology strength under operational temperatures and stresses) Inc, ‘Process for Recovery of Precious Metals’, US Patent is tens of times higher than that of traditional Pt-Rh 7,935,173; 2011 alloys. Laminar composite materials (LCM) combine 3 S. Wang, J. Peng, A. Chen and Z. Zhang, Precious Met. the properties of regular Pt-Rh alloys with the improved (Chin.), 2012, 33, (S1), 33 heat resistance and thermal stability of DSMs. In 4 J. Butler, “Platinum 2012 Interim Review”, Johnson combination with a new technology for producing Matthey, Royston, UK, 2012 solid stamped bushing base plates, bushings can be 5 Precious Met. (Chin.), 2012, 33, (S1), 1–304 made 20–30% lighter with increased service life. The company also manufactures thermocouple wire and The Reviewers catalyst systems and catchment packs for the nitric Dr Mikhail Piskulov is General Manager of Johnson Matthey Moscow, Russia, where acid industry. he is involved in market analysis, sales and Pavel Khorikov (Krasnoyarsk Non-Ferrous Metals new business development. Dr Piskulov graduated from Moscow State University Plant, Russia) reported on the company’s fabrication of International Relations with a degree of bushings and other glass making manufacturing in International Business. Before joining Johnson Matthey in 1993, he worked for units. The current bushing production range is the USSR Ministry of Foreign Trade. He 200–4000 tips. Materials include dispersion stabilised holds a PhD in Economics, obtained in 2002, on the competitive advantages of Pt10Rh DS. They also make combination bushings, foreign direct investment for the receiving where a bushing body manufactured from Pt20Rh country. alloy is welded to a base plate of Pt10Rh DS. In the fi rst fi ve months of 2012 the total weight of fabricated pgm Carol Chiu works in Technology Forecasting and Information at Johnson Matthey products for the glass industry made by the company Technology Centre. She specialises in the was in excess of 160 kg. provision of technical and commercial information to Johnson Matthey businesses Conclusions in Asia. Since she joined Johnson Matthey in 2011, she has worked on many different projects involving usage of pgms in the A number of pgm topics were covered during region. this conference including pgm nanostructures, superalloys, pgm refi ning, dental materials, emissions control and fabricated products, as well as market based information. In 2012 China was “Precious Metals Blue Book” the world’s leading platinum consuming country 《贵金属蓝皮书》 (4), and Kunming PM’2012 was a good platform for rest of the world to understand the most recent pgm developments in China and elsewhere. The conference was followed by a visit to Kunming Institute of Precious Metals and Sino-Platinum Metals Co, Ltd. The Kunming Institute of Precious Metals has published the “Precious Metals Blue Book” and distributed hard copies during the conference. A total of 63 papers were published in English and the conference proceedings are available (5). The next conference in this series will be held in 2014, venue to be decided upon.

Publications in Brief BOOKS “Inventing Reactions” Edited by L. J. Gooßen (TU Kaiserslautern, “Applied Cross-Coupling Reactions” FB Chemie - Organische Chemie, Germany), Edited by Y. Nishihara (Department of Series: Topics in Organometallic Chemistry, Chemistry, Okayama University, Japan), Vol. 44, Springer-Verlag, Berlin, Heidelberg, Series: Lecture Notes in Chemistry, Vol. Germany, 2013, 354 pages, ISBN: 978-3-642- 80, Springer-Verlag, Berlin, Heidelberg, 34285-1, £206.50, €245.03, US$309.00 Germany, 2013, 245 pages, ISBN: 978- This book analyses the creative 3-642-32367-6, £90.00, €106.95, US$129.00 process associated with some recent inventions of chemical reactions. Since the discovery of transition Leading academics describe their metal-catalysed cross-coupling creative solutions to longstanding problems in organic reactions in 1972, various synthetic chemistry. Each chapter provides short overviews of uses and industrial applications have been developed. the context and subsequent developments of their Cross-coupling reactions catalysed by pgms such respective transformations. The book includes a chapter as palladium can produce natural products, by Professor Keith Fagnou (posthumously) and David pharmaceuticals, liquid crystals and conjugate Stuart (University of Ottawa, Canada) on the discovery polymers for use in electronic devices. The Nobel Prize in Chemistry 2010 was awarded jointly to and development of a Pd(II)-catalysed oxidative cross- Richard F. Heck, Ei-ichi Negishi and Akira Suzuki “for coupling of two unactivated arenes. palladium-catalyzed cross couplings in organic “Modern Tools for the Synthesis of Complex synthesis”. In this book, recent trends in synthesis Bioactive Molecules” and catalytic activities of transition metal catalysts, Edited by J. Cossy and S. Arseniyadis mainly palladium, for cross-coupling reactions (Laboratoire de Chimie Organique, ESPCI are presented. ParisTech, Paris, France), John Wiley & Sons, Inc, Hoboken, New Jersey, USA, “How to Invent and Protect Your Invention: 2012, 596 pages, ISBN: 978-0-470- A Guide to Patents for Scientists and Engineers” 61618-5, £100.00, €120.00, US$149.95 J. P. Kennedy (The University of Focusing on organic, organometallic Akron, USA), W. H. Watkins with E. and bio-oriented processes, this book N. Ball (University of Akron Research covers the use of the latest synthetic Foundation, USA), John Wiley & Sons, Inc, Hoboken, New Jersey, USA, tools for the synthesis of complex 2012, 248 pages, ISBN: 978-1-1183- biologically active compounds. Innovative methods 6937-1 (Paperback), £40.50, €48.60, are described that make it possible to control the US$59.95 exact connectivity of atoms within a molecule in This book is based on lecture notes order to set precise three-dimensional arrangements. developed over twenty-fi ve years at Many of the transformations rely on palladium, The University of Akron, USA. It provides a clear, jargon- rhodium, ruthenium or other pgm catalysts. Chapters free and comprehensive overview of the patenting of interest include: ‘C--H Functionalization: A New process tailored specifi cally to the needs of scientists Strategy for the Synthesis of Biologically Active Natural and engineers, including: Products’, ‘Metal-Catalyzed C--Heteroatom Cross- (a) Requirements for a patentable invention; Coupling Reactions’ and ‘Metathesis-Based Synthesis (b) How to invent; of Complex Bioactives’. (c) New laws created by President Obama’s 2011 “Sustainable Preparation of Metal America Invents Act; Nanoparticles: Methods and Applications” (d) The process of applying for and obtaining a patent Edited by R. Luque (Departamento de Química Orgánica, in the USA and in other countries; Universidad de Córdoba, Spain) and R. S. Varma (National (e) Commercialising inventions and the importance Risk Management Research Laboratory, US Environmental of innovation. Protection Agency, USA), RSC Green Chemistry No. 19, The

Royal Society of Chemistry, Cambridge, broader materials community by welcoming papers UK, 2013, 230 pages, ISBN: 978-1- that cover the gamut of materials research”. It will 84973-428-8, £109.99 include content specifi cally aimed at educating and This book provides the state-of-the- engaging younger researchers. Due to launch late in art as well as current challenges 2013, access will be free until December 2015. and advances in the sustainable preparation of metal nanoparticles Special Issue: Asymmetric Gold Synthesis for a variety of applications. For Chin. J. Chem., 2012, 30, (11), 2601– 2725 example, wet chemistry methods are frequently used for biomedical applications, Asymmetric synthesis, particularly while gas phase deposition on solid supports is utilising catalysts, is very commonly employed in the preparation of catalysts important for providing chiral and electrocatalysts. Platinum, palladium, iridium compounds in an enantiopure and ruthenium are featured. Researchers interested form. Contributions dealing with in the green and environmentally safe production of recent progress in homogeneous nanoparticles will fi nd this book useful. asymmetric catalysis are collected here. This special issue contains 19 selected papers including: ‘Enantioselective and -Regioselective JOURNALS Allylic Amination of Morita-Baylis-Hillman Acetates Journal of Environmental Chemical Engineering with Simple Aromatic Amines Catalyzed by Planarly Editors: D. Fatta-Kassinos (University Chiral Ligand/Palladium Catalyst’, ‘Iridium-Catalyzed of Cyprus, Nicosia, Cyprus), Y. Allylic Alkylations of Sodium Phenyl Selenide’ Lee (Gwangju Institute of Science and ‘Stereoselective Synthesis of Optically Active & Technology (GIST), Gwangju, Hydrobenzoins via Asymmetric Hydrogenation of Republic of Korea), T.-T. Lim (Nanyang Benzils with Ru(OTf)(TsDPEN)(6-cymene) as the Technological University, Singapore) and E. C. Lima (Federal University of Pre-catalyst’. Rio Grande do Sul, Porto Alegre, RS, Special Issue: Electrocatalysis Brazil); Elsevier; e-ISSN: 2213-3437 Catal. Today, 2013, 202, 1–210 The new online-only journal Journal of Environmental Chemical Engineering A number of European universities (JECE) from Elsevier focuses on environmental (Alicante, Birmingham, Gothenburg, sustainability in engineering and chemistry. Published Leiden, Liverpool and Ulm), one four times per year, JECE will provide a forum for the research institute (Heyrovsky publication of original research on the development Institute, Prague) and two of alternative sustainable technologies for water and companies (Johnson Matthey, UK, wastewater treatment and reuse; treatment, reuse and and Permascand, Sweden) were disposal of waste; pollution prevention; sustainability involved in the EU-funded ‘ELCAT’ and environmental safety; green chemistry; and network. The aim was to train young researchers remediation of environmental accidents. in theoretical and experimental research methods and to provide theoretical and synthetic tools to Materials Horizons design new electrocatalysts. The collection of papers Editor: L. Dunn; Royal Society of in this special issue, many from groups outside the Chemistry; ISSN: 2051-6347; e-ISSN: ELCAT network, refl ects these aims and strategies. 2051-6355 ELCAT: http://www.elcat.org.gu.se/ Materials Horizons from the Royal Society of Chemistry is a new Special Issue: Fuel Cells 2012 Science & peer-reviewed journal publishing Technology – A Grove Fuel Cell Event primary research on materials Energy Procedia, 2012, 28, 1–198 science. Seth Marder (Georgia The Fuel Cells 2012 Science and Technology Institute of Technology, USA), conference took pace in Berlin, Germany, from 11th– chair of the Editorial Board, said “while published by 12th April 2012. It included the award of the 2012 a chemical society, the journal will seek to serve the Grove Medal to Professor Dr Hubert Gasteiger, Chair

of Technical Electrochemistry analyses both granted patents and patent applications at the Technical University published in 2011, by comparison with publications of Munich, Germany. Both as in 2010. The number of granted fuel cell patents industrial and university scientist, increased by 51% between 2010 and 2011. Fuel cell Professor Gasteiger has made patent applications also continue to grow, with a 58% remarkable contributions increase in 2011 versus 2010. The emergence of Asia as to the understanding of fuel a dominant patenting force has also been identifi ed, cell related electrochemistry with the World Intellectual Property Organization and to the vitally important observing double-digit growth in applications from task of translating application requirements Japan and China. Fuel Cell Today has tracked the into fundamental parameters. His interests emergence of China as a named country in the fuel include electrocatalysts for low-temperature cell patent literature and this is discussed in the 2012 fuel cells and electrolysers as well as materials Patent Review. degradation mechanisms. Twenty articles from Find this at: http://www.fuelcelltoday.com/analysis/ this conference are included in this special patents/2012/2012-fuel-cell-patent-review issue. Fuel Cells 2012 Science & Technology: Global Emissions Management http://www.fuelcelladvances.com/

Special Issue: The World of Catalysis – A Perspective from The Netherlands ChemCatChem, 2013, 5, (2), 357– 618 This ChemCatChem special issue Latest issue: Volume 3, Issue 05 (January 2013) is an anthology of the topics addressed over the last fi ve years The latest update of Global Emissions Management of The Netherlands Catalysis and (GEM) from Johnson Matthey Emission Control Chemistry Conference (NCCC). It Technologies includes: refl ects the development of new (a) Advanced Emission Control Concepts for Gasoline or renewed catalysis research Engines; from heterogeneous catalysis, homogeneous catalysis (b) Renault Awards for Johnson Matthey; (c) Johnson Matthey Acquires the Axeon Group. and biocatalysis. Items of interest include: ‘Pt/Al2O3 Catalyzed 1,3-Propanediol Formation from Glycerol Find this at: http://www.jm-gem.com/ Using Tungsten Additives’, ‘Stable and Effi cient Pt–Re/ Platinum Today TiO2 Catalysts for Water-Gas-Shift: On the Effect of Rhenium’, ‘NanoSelect Pd Catalysts: What Causes the High Selectivity of These Supported Colloidal Catalysts in Alkyne Semi-Hydrogenation?’ and ‘Effects of Support, Particle Size, and Process Parameters on Co3O4 Catalyzed H2O Oxidation Mediated by the Platinum Today has been redesigned. Its new 2+ [Ru(bpy)3] Persulfate System’. simplifi ed homepage presents easy access to all of its most frequently visited areas such as prices, news ON THE WEB and publications. An upgraded price charting system allows comparison pricing between all the platinum 2012 Fuel Cell Patent Review group metals. The navigation structure has been improved but still contains all the same elements as the old site, including the extensive news and publications archives. Find this at: http://www.platinum.matthey.com/

The “2012 Fuel Cell Patent Review” is the second Fuel Cell Today report on annual fuel cell patent activity. It

Abstracts CATALYSIS – APPLIED AND PHYSICAL and Ru/C) with high activity and high selectivity are ASPECTS widely used in the pharmaceutical as well as the fi ne chemicals industry. The application of these catalysts On the Key Role of Hydroxyl Groups in in drug synthetic reactions including coupling, Platinum-Catalysed Alcohol Oxidation in hydroformylation, hydrogenolysis, hydrosilylation, Aqueous Medium isomerisation and transfer hydrogenation is described. S. Chibani, C. Michel, F. Delbecq, C. Pinel and M. Besson, (Contains 25 references.) Catal. Sci. Technol., 2013, 3, (2), 339–350 In the aerobic selective oxidation of alcohols in Q. Meng et al., Precious Met. (Chin.), aqueous medium in a batch reactor, the addition of 2012, 33, (3), 78–82

H2O to dioxane solvent (10–50 vol%) substantially NO 2 NH2 increased the activity of a Pt/C catalyst. Periodic Pd/C DFT calculations were performed to compare the + [H] reactivity of alcohols on the bare Pt(111) surface and N N N N in the presence of adsorbed H2O or OH groups. The calculations were found to indicate that the presence CATALYSIS – REACTIONS of adsorbed OH groups promotes catalytic activity by participating directly in the catalytic pathways and Aqueous Phase Transfer Hydrogenation of Aryl reducing the activation barrier. Decarbonylation of Ketones Catalysed by Achiral Ruthenium(II) acetaldehyde at 373 K is thought to be the cause of and Rhodium(III) Complexes and Their Papain deactivation of the catalyst. Conjugates N. Madern, B. Talbi and M. Salmain, Appl. Organomet. Recyclable Pd-Incorporated Perovskite-Titanate Chem., 2013, 27, (1), 6–12 Catalysts Synthesized in Molten Salts for Ru and Rh complexes having 2,2-dipyridylamine the Liquid-Phase Oxidation of Alcohols with ligands substituted at the central N atom by an Molecular Oxygen alkyl chain terminated by a maleimide functional I. B. Adilina, T. Hara, N. Ichikuni, N. Kumada and S. Shimazu, group were evaluated along with a Rh(III) complex Bull. Chem. Soc. Jpn., 2013, 86, (1), 146–152 of unsubstituted 2,2-dipyridylamine as catalysts Pd-incorporated titanate catalysts (Pd/KSTO) were in the transfer hydrogenation of aryl ketones in prepared by the intercalation of Pd(NO ) into layered 3 2 H2O with formate as hydrogen donor. All of the potassium titanate (KTO), which proceeded via a complexes except one led to secondary alcohol cation-exchange reaction in molten salts. Perovskite products. Site-specifi c anchoring of the N-maleimide phases of Pd/KSTO were obtained at 600ºC and above, complexes to the single free cysteine residue of whereas a lepidocrocite-type layered titanate structure, the cysteine endoproteinase papain endowed this similar to that of KTO, was retained at 400ºC. The protein with transfer hydrogenase properties towards Pd/KSTO catalysts were then investigated for the 2,2,2-trifl uoroacetophenone. liquid-phase oxidation of alcohols using molecular O2. The perovskite-type Pd/KSTO catalyst, exhibited EMISSIONS CONTROL superior activity, giving a high TON of 800 in the aerobic oxidation of 1-phenylethanol with no loss of Effect of Barium Sulfate on Sulfur Resistance of catalytic activity after three runs. Pt/Ce0.4Zr0.6O2 Catalyst Y. Zheng, Y. Zheng, Y. Xiao, G. Cai and K.-M. Wei, Catal. CATALYSIS – INDUSTRIAL PROCESS Commun., 2012, 27, 189–192 BaSO4-doped ceria zirconia (CZ) solid solution Application of Precious Metal Catalysts in Drug was prepared using a coprecipitation method. The Synthesis synthesised samples were used as supports for

Q. Meng, Q. Ye, W. Liu and Y. Wang, Precious Met. (Chin.), preparing Pt catalysts. BaSO4 was evenly distributed 2012, 33, (3), 78–82 in the irregular mesoporous structure of the CZ.

Supported pgm catalysts (e.g. Pd/Al2O3, Pd/C, Pd-Co/C Furthermore, the addition of BaSO4 to the CZ improved

the desorption of sulfur species under a reducing surface area of 305 m2 g–1 and an electrical atmosphere, which could decrease the accumulation conductivity of 24 S cm–1. SRO-1 demonstrated of sulfur species in the catalyst. The sulfur poisoning 10-fold higher electrochemical stability than Vulcan resistance of the catalyst was thereby improved. XC-72R C when subjected to an aggressive accelerated stability test. The mass activity of Pt-doped SRO-1 was –1 FUEL CELLS 54 mA mgPt , whereas its specific activity was –2 115 μA cmPt . The fuel cell performance obtained Platinum Catalysts Supported on Naﬁ on with this catalyst was lower, but compared Functionalized Carbon Black for Fuel Cell favourably against commercial Pt/C. Application F. Luo, S. Liao and D. Chen, J. Energy Chem., 2013, 22, (1), 87–92 APPARATUS AND TECHNIQUE

A Pt/Nafi on functionalised C black catalyst was Preparation of Pd–Pt Co-Loaded TiO2 Thin Films characterised by IR spectroscopy, TEM and XRD. TEM by Sol-Gel Method for Hydrogen Gas Sensing showed that the active Pt component was in the form S. Yanagida, M. Makino, T. Ogaki and A. Yasumori, J. of NPs and highly dispersed on the carbon black. The Electrochem. Soc., 2012, 159, (12), B845–B849 catalyst showed improved activity towards methanol Pd-, Pt- and Pd–Pt-loaded TiO2 thin films were anodic oxidation and the ORR, resulting from the high prepared and their respective capabilities as H2 dispersion of the active Pt component. The catalyst gas combustion sensors were investigated. H2 gas produced an increase in the electrochemically sensing was assessed at 300ºC by measuring the accessible surface area and ion channels, as well sample resistance under H gas (3%–100%) and as easier charge-transfer at the polymer/electrolyte 2 air flow conditions. The Pd–Pt step-by-step loaded interface. sample showed higher sensitivity than either the Pd

Three-Dimensional Tracking and Visualization or Pt single-loaded sample for H2 concentrations of Hundreds of Pt−Co Fuel Cell Nanocatalysts of less than 30 vol%. STEM revealed its structure: during Electrochemical Aging Pt fine particles deposited selectively on the Pd

Y. Yu, H. L. Xin, R. Hovden, D. Wang, E. D. Rus, J. A. Mundy, particles predeposited on the TiO2 surface. D. A. Muller and H. D. Abruña, Nano Lett., 2012, 12, (9), 4417–4423 A 3D tomographic method for tracking the trajectories ELECTROCHEMISTRY and morphological changes of individual Pt-Co A Kinetic Description of Pd Electrodeposition nanocatalyst particles on a fuel cell C support, before under Mixed Control of Charge Transfer and and after electrochemical ageing via potential sweeps, Diffusion was developed. The growth in the Pt shell thickness M. Rezaei, S. H. Tabaian and D. F. Haghshenas, J. Electroanal. and observation of coalescence in 3D are proposed Chem., 2012, 687, 95–101 to explain the decrease in electrochemically The electrodeposition of Pd from an aqueous active surface area and the loss of activity of solution containing PdCl2 (0.001 M) and H2SO4 Pt-Co nanocatalysts in PEMFC cathodes. Along with (0.5 M) was studied by CV and potentiostatic current- atomic-scale EELS imaging, the experiment enables time transients (CTTs). From the polarisation curves, the correlation of catalyst performance degradation regions corresponding to charge transfer control, with changes in particle/interparticle morphologies, mixed control and diffusion control were identifi ed. particle–support interactions and the near-surface In the mixed control region, the CTTs results suggested chemical composition. processes involving adsorption, the ion transfer

SiO2–RuO2: A Stable Electrocatalyst Support reaction and 3D progressive nucleation with mixed C.-P. Lo and V. Ramani, ACS Appl. Mater. Interfaces, 2012, charge transfer-diffusion controlled growth. The 4, (11), 6109–6116 analysis of CTTs at short times was performed with

High surface area SiO2–RuO2 (SRO) supports the model proposed by Milchev and Zapryanova. were obtained using a wet chemical method. Pt The reduction reaction of Pd(II)  Pd(I), as an ion NPs were deposited on their surface. The optimal transfer reaction, occurs before the formation of the

1:1 mol ratio of SiO2–RuO2 (SRO-1) had a BET Pd nucleus.

PHOTOCONVERSION for the acidic leach liquor of PCBs from spent mobile phones. Porous, Platinum Nanoparticle-Adsorbed Carbon Nanotube Yarns for Efﬁ cient Fiber Solar In Situ Platinum Recovery and Color Removal Cells from Organosilicon Streams S. Zhang, C. Ji, Z. Bian, P. Yu, L. Zhang, D. Liu, E. Shi, Y. H. Bai, Ind. Eng. Chem. Res., 2012, 51, (50), 16457–16466 Shang, H. Peng, Q. Cheng, D. Wang, C. Huang and A. Cao, The recovery of Pt from organosilicon hydrosilylation ACS Nano, 2012, 6, (8), 7191–7198 streams is a potential source of cost savings. Here in situ A Pt NP-adsorbed C nanotube yarn was obtained by fi xed-bed adsorption technology was demonstrated solution adsorption and yarn spinning processes, with to be effective for Pt recovery and product colour uniformly dispersed Pt NPs throughout the porous removal. With the in situ Pt recovery process and nanotube network. TiO2-based dye-sensitised fi bre using a functionalised silica gel scavenging material, solar cells with a Pt--nanotube hybrid yarn as counter a Pt recovery >90% was achieved both from silane electrode were fabricated. A power conversion distillation heavy wastes (with initial Pt concentration effi ciency of 4.85% under standard illumination of ~50 ppm) and from organosilicon products (with (AM1.5, 100 mW cm–2) was achieved, comparable to initial Pt concentration of ~5 ppm). the same type of fi bre cells with a Pt wire electrode (4.23%).

Photochemistry between a Ruthenium(II) Pyridylimidazole Complex and Benzoquinone: Simple Electron Transfer versus Proton-Coupled Electron Transfer R. Hönes, M. Kuss-Petermann and O. S. Wenger, Photochem. Photobiol. Sci., 2013, 12, (2), 254–261 A Ru(II) complex with two 4,4-bis(trifl uoromethyl)- 2,2-bipyridine chelates and a 2-(2-pyridyl)imidazole ligand was synthesised. The proton-coupled electron transfer (PCET) between the Ru(II) complex and 1,4-benzoquinone as an electron/proton acceptor was investigated by spectroscopic means. Excited- state deactivation was found to occur predominantly via simple oxidative quenching, but a minor fraction of the photoexcited complex was thought to have reacted via PCET.

REFINING AND RECOVERY Selective Recovery of Precious Metals from Acidic Leach Liquor of Circuit Boards of Spent Mobile Phones Using Chemically Modiﬁ ed Persimmon Tannin Gel M. Gurung, B. B. Adhikari, H. Kawakita, K. Ohto, K. Inoue and S. Alam, Ind. Eng. Chem. Res., 2012, 51, (37), 11901– 11913 A tannin-based adsorbent was prepared by immobilising bisthiourea on persimmon tannin extract. The gel exhibited selectivity for precious metal ions such as Au(III), Pd(II) and Pt(IV) over base metal ions such as Cu(II), Fe(III), Ni(II) and Zn(II) in 1–5 mol dm–3 HCl. The real time applicability of the gel for the recovery of precious metals was demonstrated

Patents CATALYSIS – APPLIED AND PHYSICAL A method for the alkylation of an aromatic ASPECTS compound involves the aromatic compound making contact with an alkane of 1–12 C atoms at 200–500ºC, Palladium-Gold Catalyst preferably 320–400ºC, in the presence of a catalyst Lyondell Chemical Technology, US Appl. 2012/0,302,784 composition consisting of a catalytically active metal A Pd-Au catalyst is prepared by the following method: selected from Pt, Pd, Rh, Os, Ir, Ru or a combination

(a) mixing TiO2, a carboxyalkyl cellulose and a and a promoter metal, e.g. Zn, on a zeolite support. The hydroxyalkyl cellulose to form a dough; (b) extruding molar ratio of the promoter metal to the catalytically the dough to produce an extrudate; (c) calcining active metal is between 0.01 and 5, preferably the extrudate to produce a calcined extrudate; (d) between 0.1 and 0.5. impregnating the calcined extrudate with Pd and Au Catalyst for Naphtha Reforming compounds to produce an impregnated extrudate; OOO Nauchno-Proizvodstvennaya Firma, Russian Patent and (e) calcining the impregnated extrudate to 2,471,854; 2013 produce the Pd-Au catalyst. This catalyst is used in A catalyst for reforming gasoline fractions comprises producing vinyl acetate by oxidising ethylene with (in wt%): 0.1–1.0 Pt; 0.1–1.0 Cl; 0.5–3.9 zeolite; 1–2 oxygen in the presence of acetic acid. amorphous Al2SiO5; -Al2O3; and optionally 0.1–0.5 Re. Al(OH)3 powder is mixed with zeolite, this mixture CATALYSIS – REACTIONS is peptised with 0.5–20% organic acid, e.g. citric acid, Reusable Hydroformylation Catalyst it is then granulated, heat treated at 630–700ºC and this is followed by the addition of Pt in the form of Umicore AG & Co KG, World Appl. 2012/163,831 an aqueous solution of chloroplatinic acid and A novel process for producing 4-hydroxybutyraldehyde chlorine in the form of HCl. The catalyst is then is claimed, where an allyl alcohol is reacted in polar dried and annealed. solvents with CO and H2 in the presence of a catalyst which is formed from a Rh complex and a cyclobutane ligand e.g. trans-1,2-(1,3-dialkylphenylphosphinomethyl)- EMISSIONS CONTROL 1 cyclobutanes, 1, where R is alkyl, preferably methyl, Platinum Group Metal Catalyst ethyl or propyl; R2 is H or an alkoxy group; R3 and R4, Johnson Matthey Plc, World Appl. 2012/170,421 1 independently of one another, are H, CH2OR , C H 2O- 1 1 2 A catalyst for treating exhaust gas consists of an aralkyl, CH2OH, CH2-[P(3,5-R ,R -4-R -phenyl)2], or aluminosilicate molecular sieve comprising crystals CH2O-(CH2-CH2-O)m-H; where m is 1–1000. The with a porous network and at least one pgm with the hydroformylation takes place in a membrane reactor majority of the selected pgm embedded in the porous and the catalyst used is separated off from the reaction network relative to the pgm disposed on the surface mixture, optionally after adding water, by extraction in a ratio of ~4:1 to ~99:1. The catalyst comprises with hydrophobic solvents and is reused. ~0.01–10 wt% pgm relative to the weight of the molecular sieve and the crystals have a mean World Appl. 2012/163,831 crystalline size of ~0.01–10 μm. A method for treating 3 1 1 2 R CH2-[P(3,5-R ,R -4-R -phenyl)2] emissions comprises of: (a) contacting a lean burn

exhaust stream containing NOx and NH3 with the catalyst at ~150ºC–650ºC; and (b) reducing a portion

of NOx to N2 and H2O at ~150ºC–250ºC and oxidising a 4 1 1 2 R CH2-[P(3,5-R ,R -4-R -phenyl)2] portion of NH3 at ~300ºC–650ºC. 1 Cold Start Catalyst Johnson Matthey Plc, US Appl. 2012/0,308,439 Catalyst for Alkylation of Aromatic Compounds A cold start catalyst consists of: (a) a zeolite catalyst Stamicarbon BV, European Appl. 2,540,691; 2013 comprising a base metal, a noble metal and a zeolite;

and (b) a supported pgm catalyst comprising one or Platinum-Rhodium Catalyst more pgms and one or more inorganic oxide carriers. Tokuyama Corp, Japanese Appl. 2013-037,891 The noble metal is selected from Pt, Pd, Rh or a A Pt-Rh catalyst for DMFCs consists of a ratio of mixture. The zeolite catalyst and the supported pgm 0.10–2.00 mol Rh to 1 mol Pt. The catalysts show a high catalyst are coated onto a fl ow-through substrate in an MeOH oxidation current at a low voltage in an alkaline exhaust system. environment. Electrodes containing the title catalysts Three-Way Catalyst Microwave Drying can be bonded to anion-exchange membranes and used in MEAs. X. Weng et al., Chinese Appl. 102,614,942; 2012 A TWC drying technique consists of taking porous cordierite as the support and coating the surface METALLURGY AND MATERIALS of its internal pores with a catalyst slurry which Black Fire Retardant Silicone Rubber contains H2O, composite Al2O3, CeO2-ZrO2 oxygen Shanghai University of Engineering Science, Chinese Appl. storage material and Pd or Rh. The catalyst slurry 102,643,552; 2012 coated support is then introduced through A black fi re retardant silicone rubber is prepared microwave devices and dried at 1400–2500 MHz with (in wt%): 50–60 vinyl- or allyl-capped silicone microwave to have a water content <7%. The rubber; 5–10 hydrogen-containing polysiloxane; 0.1– advantages of the microwave drying technique 0.3 soluble Pt catalyst; and 29.7–44.9 fi re retardant include rapid heating speed, high production which is a mixture of carbonised residue of waste tyre efficiency, good working environment, reduced pyrolysis and (NH4)2HPO4. The method of preparing energy consumption and an increase of catalytic the black fi re retardant silicone rubber involves adding performance of the catalyst. the carbonisation residue of waste tyre pyrolysis and

(NH4)2HPO4 into the vinyl- or allyl-capped silicone FUEL CELLS rubber, stirring, adding the hydrogen-containing polysiloxane and the Pt catalyst, stirring, ball milling, Nanostructured Platinum Catalyst vacuum air exhausting and fi nally curing at 20–40ºC. Atomic Energy and Alternative Energies Commission, World Appl. 2013/017,772 MEDICAL AND DENTAL The process for producing a catalyst PtxMy for PEMFC, where M is a transition metal selected from Ni, Fe, Co Palladium Braze and Cr, involves: (a) deposition of PtxMy nanostructures Boston Scientiﬁ c Neuromodulation Corp, US Patent on a support by sputtering; (b) annealing the 8,329,314; 2012 nanostructures at 600–1200ºC preferably for 1 h; and An implantable microstimulator comprising a component

(c) depositing a layer of PtxMy onto the surface of the assembly housing which consists of a ceramic part, a nanostructures; and (d) then leaching the metal M. metal part selected from Ti and Ti alloys and a Pd interface

The catalyst is made with Pt3Ni. The support is the layer is claimed. The interface layer comprises Pd which GDL and the thickness is preferably 200 μm. is combined with a portion of one or both of the metal part or the ceramic part, forming a bond between the Microbial Fuel Cell two parts and further comprising an electrode contact. A Gwangju Institute of Science and Technology, US Appl. second Pd interface layer bonds the electrode contact to 2012/0,315,506 the ceramic part of the component assembly housing. A microbial fuel cell system consists of a unit cell where the anode is formed on the bottom surface and the cathode is formed on the top surface of a reactor REFINING AND RECOVERY which accommodates electrochemically active Separation of Pure Osmium microorganisms and an ion exchange membrane is The Curators of the University of Missouri, World Appl. interposed between the two electrodes. The cathode 2013/020,030 consists of a carbon electrode treated with Pt, Pd, Os A process for separating Os including from an or Ru. The unit cells are arranged vertically and are irradiated Os-191 mixture, involves: (a) the mixture is electrically connected to each other in series through put into contact with an aqueous solution of NaClO at a conductive fi lm to form a module. a concentration of ~12% available Cl2 to form a volatile

OsO4 vapour; (b) the OsO4 vapour is bubbled through a trapping solution which consists of an aqueous solution of KOH at a concentration of ~25% w/v to form dissolved K2[OsO4(OH)2]; (c) the dissolved K2[OsO4(OH)2] is put in contact with an aqueous solution of NaHS at a concentration of ~10% w/v to form an OsS2 precipitate; (d) the OsS2 precipitate is washed by agitating with H2O; (e) the OsS2 precipitate is separated from the KOH trapping solution by centrifuging; (f) the OsS2 precipitate is rinsed with acetone; and (g) the OsS2 precipitate is then dried. The advantages of this process are the use of simple reactions and equipment, and a shorter process time; therefore, limiting the exposure to potentially hazardous conditions.

SURFACE COATINGS Electroless Plating of Iridium Japan Kanigen Co, Ltd, Japanese Appl. 2012-241,258 A plating solution comprises either or both of Ir3+ and Ir4+ plus Ti3+. A preferable plating solution consists of 0.2–60 mmol l–1 Ir ions, 0.01–2 mol l–1 Ti3+ and has pH 1–6. The solution may also contain 0.001–1 mol l–1 mono- or dicarboxylic acids or their salts as stabilisers and 0.001–1 mol l–1 N- and P-free oxidation inhibiting agents of redox potential –0.1–0.8 V vs. SHE, e.g. ascorbic acid, erythorbic acid, catechol, catechol disulfonic acid and their salts. High quality Ir coatings are directly formed on Cu alloys.

FINAL ANALYSIS

NOx Emissions Control for Euro 6

The control of oxides of nitrogen (NOx) emissions to simultaneous reduction of NOx and oxidation of meet more stringent motor vehicle emission legislation CO and HCs can take place. Emissions standards has been enabled by the development of various for European gasoline vehicles which have been in exhaust gas aftertreatment technologies, notably those force since 2009 (2) specify NOx emissions must not that employ platinum group metals (pgms). exceed 0.06 g km–1 (Table I), a limit that is met by TWC technology. Technology Developments For diesel engines, which operate under lean For gasoline engines the most common aftertreatment conditions, NOx is harder to deal with. Previous for the control of NOx, as well as the other major diesel vehicles used advanced engine technologies regulated pollutants, carbon monoxide (CO) and to signifi cantly lower NOx emissions. For example, unburnt hydrocarbons (HCs), is the three-way exhaust gas recirculation (EGR) is used to recirculate catalyst (TWC). This technology was developed a proportion of the exhaust gas back into the engine in the late 1970s (1). It allows the oxidation of CO cylinders to reduce the cylinder temperature during and HC over platinum-palladium or just palladium combustion and thereby reduce formation of NOx. during lean (excess oxygen) conditions to form A disadvantage of this method is that it increases carbon dioxide and water, while rhodium performs emissions of particulate matter (PM). Tighter the reduction of NOx to N2 under rich (oxygen PM limits have now been enforced across many depleted) conditions. This technology relies on jurisdictions and are met by using a pgm-coated the engine operating around the stoichiometric diesel particulate fi lter (also known as a catalysed point (air:fuel ratio of 14.7:1) where maximum soot fi lter (CSF)).

Table I European Passenger Car NOx and Particulate Emissions Limits for Euro 5 and Euro 6

Stage Date NOx, g km–1 Particulate mass, Number of g km–1 particles, km–1 Compression Ignition (Diesel) Euro 5a 2009.09a 0.18 0.005d – Euro 5b 2011.09b 0.18 0.005d 6.0 × 1011 Euro 6 2014.09 0.08 0.005d 6.0 × 1011 Positive Ignition (Gasoline) Euro 5 2009.09a 0.06 0.005c, d – Euro 6 2014.09 0.06 0.005c, d 6.0 × 1011 c, e a 2011.01 for all models b 2013.01 for all models c Applicable only to vehicles using direct injection engines d 0.0045 g km–1 using the particulate measurement procedure e 6.0×1012 km–1 within ﬁ rst three years from Euro 6 effective dates

New Legislation Challenges diesel, and hence unfeasibly large urea tanks would New legislation in force for European heavy-duty be required. diesel vehicles from 2013, light-duty diesels from 2014 and some non-road diesel engines from 2014 The Future requires a further reduction of NOx emissions. NOx and other pollutant levels emitted from vehicles As shown in Table I, NOx emissions for light-duty are assessed by use of a standardised driving cycle diesel passenger cars reduce from the current Euro for Europe. The current driving cycle which is used 5 limit of 0.18 g km–1 to the Euro 6 limit of 0.08 g km–1 to measure emissions from light-duty vehicles may be from 2014. PM emissions are already regulated changed in the future to include an even wider range to the extremely low level of 0.005 g km–1 by the of driving conditions, for example further extended current Euro 5 legislation. The development of fuel low speed driving conditions such as common in effi cient lean-burn gasoline engines also presents congested city driving or much higher speed driving new challenges – NOx levels typically generated in conditions than used in the current drive cycle. the engine cylinder, whilst lower than conventional For diesel LNTs the future challenge is to maximise gasoline engines, are nevertheless still well above NOx conversion at low speed driving conditions as the Euro 6 limits and therefore some form of catalytic well as providing high NOx conversion during high aftertreatment is required. speed driving. For diesel SCR systems, the future The two leading catalyst technologies used to challenge is also to boost NOx conversion when remove NOx in a lean-burn engine to meet the above the engine is operating at very low speeds. This low legislation are lean NOx trap (LNT) or selective speed challenge may be helped by moving the SCR catalytic reduction (SCR). LNT catalysts remove NOx closer to the engine where it can benefi t from higher from a lean exhaust stream by oxidation of NO to NO2 temperatures, but there are space and system layout over a platinum catalyst, followed by adsorption of considerations. There is currently a good deal of

NO2 onto the catalyst surface and further oxidation research ongoing into diesel powertrain optimisation and reaction with metal species incorporated in the for a wide range of driving scenarios. catalyst, for example barium, to form a solid nitrate The proposed enforcement of a particulate number phase. Once the catalyst is fi lled with the solid limit (3) for gasoline engines in Europe also presents nitrate phase, the engine is then run rich for a short challenges by requiring control of PM to extremely period to release the NOx from its adsorbed state. low levels in addition to keeping emissions of other The released NOx is then converted during the rich pollutants at minimal levels. One possibility is to use a period to N2 over a rhodium catalyst. SCR systems use fi lter coated with similar material to a TWC as part of a platinum-based diesel oxidation catalyst (DOC) the overall aftertreatment system. or a combination of a DOC and a platinum-based For gasoline engines, new on-board diagnostic limits

CSF to oxidise a proportion of the NOx into NO2 and that come into force at Euro 6 part 2 in 2017 (3) reduce remove HC/CO. A NOx reductant, usually in the form by 70% the threshold amount of NOx emitted before of aqueous urea, is then injected into the exhaust gas the driver is notifi ed of a problem with the catalyst. after the oxidation catalyst and the NO/NO2 mixture Some manufacturers are therefore looking at ways of is then selectively reduced over the downstream SCR further improving the durability of catalysts, including catalyst. by increasing the relative loadings of rhodium. Due to The decision whether to use LNT or SCR on a the excellent NOx reduction capability of rhodium, it vehicle involves many factors. SCR requires space may be possible to substitute palladium with small on the vehicle to fi t the urea tank and dosing system, quantities of rhodium to give a cost- and performance- which is less of a constraint on heavy-duty and larger optimised system. light-duty vehicles. Furthermore, the need to run the engine rich for LNT systems is more technically Conclusions demanding for larger engines so LNT systems are There remains a good deal that can be done on more suited to smaller light-duty vehicles. SCR controlling NOx emissions from vehicles using pgms. systems are impractical for use on gasoline vehicles As regulations tighten, cover more vehicle types and are as their NOx output is signifi cantly higher than from adopted by more jurisdictions around the world, greater

use of pgm-containing emissions control systems can be European Parliament and the Council of the European anticipated. Good progress has been made on the control Union, Ofﬁ cial Journal of the European Union, L 171/1, of NOx from gasoline engines and developments are 29th June, 2007 being made on lowering NOx emissions from diesels to 3 ‘Commission Regulation (EU) No 459/2012 of 29 May 2012 amending Regulation (EC) No 715/2007 of the meet upcoming emissions limits. European Parliament and of the Council and Commission JONATHAN COOPER* and PAUL PHILLIPS** Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) (Text Johnson Matthey Emission Control Technologies, with EEA relevance)’, The European Commission, Ofﬁ cial Orchard Road, Royston, Hertfordshire SG8 5HE, UK Journal of the European Union, L 142/16, 1st June, 2012 Email: *[email protected]; **[email protected] The Authors Jonathan Cooper is Gasoline Development Manager at Johnson References Matthey Emission Control Technologies and has over 13 years’ 1 B. Harrison, B. J. Cooper and A. J. J. Wilkins, Platinum experience in global gasoline aftertreatment systems research at Johnson Matthey. He holds a degree and DPhil in Chemistry from Metals Rev., 1981, 25, (1), 14 the University of Oxford, UK. 2 ‘Regulation (EC) No 715/2007 of the European Parliament and of the Council of 20 June 2007 on type approval of motor vehicles with respect to emissions Paul Phillips is European Diesel Development Director at Johnson Matthey Emission Control Technologies. He has 17 years’ from light passenger and commercial vehicles (Euro experience at Johnson Matthey aiding the development of 5 and Euro 6) and on access to vehicle repair and emission control systems. Paul has a BSc in Chemistry and a PhD maintenance information (Text with EEA relevance)’, The in Organometallic Chemistry from the University of Warwick, UK.

Jonathan Butler Publications Manager Sara Coles Assistant Editor Ming Chung Editorial Assistant Keith White Principal Information Scientist

Email: [email protected] Platinum Metals Review is Johnson Matthey’s quarterly journal of research on the science and technology of the platinum group metals and developments in their application in industry http://www.platinummetalsreview.com/ Editorial Team Jonathan Butler Publications Manager Sara Coles Assistant Editor Ming Chung Editorial Assistant Keith White Principal Information Scientist

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