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Published by Johnson Matthey Plc
Vol 57 Issue 2
April 2013
www.platinummetalsreview.com
E-ISSN 1471-0676
A quarterly journal of research on the
science and technology of the platinum
group metals and developments in their
application in industry
© Copyright 2013 Johnson Matthey
http://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 sixplatinum group metals produced by Anglo American Platinum Ltd, South Africa.
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85 © 2013 Johnson Matthey
E-ISSN 1471-0676 • Platinum Metals Rev., 2013, 57, (2), 85•
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, UKEmail: jmpmr@matthey.com
Platinum Metals ReviewA quarterly journal of research on the platinum group metals
and developments in their application in industryhttp://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–PM2012 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
86 © 2013 Johnson Matthey
http://dx.doi.org/10.1595/147106713X665067 •Platinum Metals Rev., 2013, 57, (2), 86•
Editorial
Johnson Matthey and Alfa Aesar Support Academic ResearchAs many of our readers are no doubt aware, Alfa
Aesar is Johnson Matthey’s catalogue chemicals
business. As well as supplying research chemicals
to the fi ne chemicals and pharmaceuticals
industries, Alfa Aesar also supplies universities
and can deliver at any scale from bench to
pilot plant and through to commercial scale
production (1).
Platinum Metals Review has now teamed up
with Alfa Aesar to administer the “Johnson Matthey
Alfa Aesar Research Chemicals Scheme”, formerly
known as the “Loans Scheme”. Since the early years
of the 20th century, Johnson Matthey has used this
scheme to support fundamental research centred on
the platinum group metals (pgms) (2). Academics
and university groups can apply to receive small
amounts of pgm salts for use in their research, with a
focus on novel applications which may have future
commercial potential.
The scheme is currently well-subscribed. In the
past year we have supported projects in diverse areas
including anticancer drugs, asymmetric catalysis,
biomass conversion, nanoparticles, pharmaceuticals,
photovoltaics and renewable energy.
We are delighted to formally announce our
partnership with Alfa Aesar who from April 2013
will be supplying the chemicals from their stocks.
We look forward to working with our colleagues at
Alfa Aesar.
SARA COLES, Assistant Editor
Platinum Metals Review
References1 Alfa Aesar, A Johnson Matthey Company:
http://www.alfa.com/
2 D. T. Thompson, Platinum Metals Rev., 1987, 31, (4), 171
Contact InformationJohnson Matthey Precious Metals MarketingOrchard Road Royston HertfordshireSG8 5HEUK
Email: editorpmr@matthey.com
“PGMs in the Lab”From the next issue of Platinum Metals Review, in
July 2013, we will feature a new section called “PGMs
in the Lab” in which we will profi le one of the many
researchers whose work has benefi ted from the
support of Johnson Matthey and Alfa Aesar. This work
has expanded the boundaries of pgms research and
we hope that many new applications for the pgms
will arise from this exciting collaborative approach.
Look out for the new section and see if it inspires you
to try some new collaborations of your own.
Finally don’t forget that we are always interested
to hear from you about your research into new
areas of application for the pgms. So if you have
some new pgm research to report, a book that you
would like reviewed, or a conference that you have
organised or attended, please contact us at the
above address.
•Platinum Metals Rev., 2013, 57, (2), 87–100•
87 © 2013 Johnson Matthey
Platinum-Based and Platinum-Doped Layered Superconducting Materials: Synthesis, Properties and SimulationExperimental 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
Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg, Russia
Email: ivanovskii@ihim.uran.ru
In 2011, the newest group of layered high-temperature
superconductors were discovered: platinum-based
quaternary 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and 10-3-8
((CaFe1–xPtxAs)10Pt3As8) phases with superconducting
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.
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88 © 2013 Johnson Matthey
The face-centred cubic (fcc)-Pt metal remains non-
superconducting (1) even at the lowest accessible
temperatures of solid matter, T ~1.5 μK (4, 5). It is
believed that one of the obstacles to a possible
superconducting transition is the purity of the
metal, especially with regard to the concentration
of magnetic impurities (6). Strong electron-phonon
coupling, favourable for the formation of Cooper pairs
in fcc-Pt, may also be a factor. Enhanced electronic
susceptibility and the Sommerfeld coeffi cient (owing
to low-dispersive near-Fermi bands and high carrier
concentration) bring Pt close to magnetic instability
(Stoner factor ~4 (7)), when spin fl uctuations may
completely suppress superconductivity in this
metal (4). A very low-temperature superconducting
transition (at TC ~1.9 mK) was observed for compacted
high-purity Pt powder with average grain sizes of ~2
μm (6, 7); for Pt powders with nanosized grains (~100–
300 nm) TC increases to ~20 mK (8, 9). It is supposed that
the granular structure and the lattice strains related to
local inhomogeneity (which is incommensurate with
the Fermi surface nesting vectors (10)) are the key
factors for the occurrence of inter- and intragranular
superconductivity in granular Pt (8–10). In any case,
‘pure’ Pt as a superconductor seems unlikely.
However, a new set of Pt-based alloys and
compounds represent very attractive groups of modern
superconducting materials, and these have become
the subjects of much research interest, particularly
owing to clear evidence of unconventional pairing
mechanisms for these systems.
Traditional John Bardeen, Leon Cooper and Robert
Schrieffer (BCS)-like theories of superconductivity
hold that pairs of electrons within nonmagnetic
materials are coupled to phonons. In the case
of unconventional superconductors, various
mechanisms without phonons are suggested.
For example, the unusual properties of UPt3 (11)
including a heavy fermion state below T = 20 K,
dynamic antiferromagnetism (AFM) with onset at
magnetic transition temperature, TN = 6 K, and an
anisotropic superconducting state with three distinct
superconducting phases, provide strong evidence for
unconventional spin-triplet superconductivity. In turn,
CePt3Si is the fi rst heavy-fermion superconductor
without inversion symmetry, and its discovery (12)
has initiated widespread research activity in the fi eld
of so-called noncentrosymmetric superconductors
(13–15). Recently such superconductors lacking
a lattice inversion centre have been investigated
for the possibility of spin-triplet dominated pairing
symmetry. Related Pt-based noncentrosymmetric
superconductors are also known: BaPtSi3 (16), Li2Pt3B
(17) and LaPt3Si (18).
Another exciting material is platinum hydride
(PtH) (19–21), for which the superconducting
transition was predicted at TC ~12 K (19) – the
highest superconducting transition temperature
among known metal hydrides – at pressure P ~90 GPa.
Recent theoretical estimates confi rm that the critical
temperature of the two high-pressure phases of PtH
correlates with electron-phonon coupling (19).
Another group of low-TC (< 8.5 K) superconductors
include germanium-platinum compounds with the
skutterudite-like crystal structure MPt4Ge12 (where
M are alkaline earth metals (strontium or barium),
rare earth metals, thorium or uranium) (23–26).The
majority of the listed Pt-based materials (a) belong
to three-dimensional (3D)-like crystals; and (b) adopt
low-temperature superconductivity.
One of the most remarkable achievements in
physics and materials sciences was the discovery of
high-temperature superconductors with TC values
equal to or above the historical limit of TC ~23 K
for niobium-germanium (Nb3Ge). Starting with the
discovery of the superconducting transition at TC =
35 K in Ba-doped La2CuO4 in 1986 (27), several exciting
families of high-TC materials were subsequently found.
Among these are the discoveries of superconductivity
in layered materials: MgB2 (TC ~39 K) in 2000 (28)
and fl uorine-doped LaFeAsO (TC ~26 K) in 2008 (29).
These discoveries have inspired worldwide research
efforts and have been the subject of many reviews
(30–51). Most recently, phases with considerably
increased values of TC ~56 K were synthesised
(Gd1–xThxFeAsO (52), Sr1–xSmxFeAsF (53) and
Ca1–xNd1–xFeAsF (54)), and these form a new class of so-
called iron-based high-temperature superconductors.
The unconventional superconductivity of these
materials, including various types of pairing and the
coexistence of superconductivity with magnetism, has
been widely discussed.
Several groups in this class of Fe-based
superconductors are now known. The majority of them
are iron-pnictide (Pn) (or chalcogenide (Ch)) phases
(Fe-Pn or Fe-Ch, respectively). These materials can be
categorised into the following major groups. From
the chemical point of view, the simplest of them are
binaries: 11-like phases (such as FeSex (45, 55)); ternary
111-like (such as AFeAs, where A are alkali metals
(56)) and 122-like (such as BFe2Pn2, where B are alkali
earth metals (57), or AxFe2–yCh2 (58)) materials; and a
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89 © 2013 Johnson Matthey
wide group of quaternary 1111-like superconductors
including pnictide oxides or pnictide fl uorides such as
RFeAsO (R are rare earth metals) and BFeAsF.
Recently, more complex materials such as
B3Sc2Fe2As2O5 (32225 phases) (59) and B4M2Fe2Pn2O6
(M are d block metals) (42226 (or 21113) phases)
were proposed (60, 61) as parent phases for new high-
TC superconductors (46). For some of these, relatively
high transition temperatures were established, for
example TC ~17 K for Sr4Sc2Fe2P2O6 (60) and TC
~37 K for Sr4V2Fe2P2O6 (61). This family was further
expanded when new pnictide oxides such as Can+2(Al,
Ti)nFe2As2Oy (n = 2, 3, 4) (62), Ca4Al2Fe2(P,As)2O6–y (63),
Sr4(Sc,Ti)3Fe2As2O8, Ba4Sc3Fe2As2O7.5, Ba3Sc2Fe2As2O5
(64), Ca4(Mg,Ti)3Fe2As2Oy (65), Sr4MgTiFe2Pn2O6
(66, 67), and Ba4Sc2Fe2As2O6 (68) were successfully
prepared and studied (69–77).
For all the listed iron-based superconducting
materials:
(a) The crystal structure includes two-dimensional
(2D)-like (Fe-Pn) (or Fe-Ch) blocks, which are
separated by A or B atomic sheets (for 111- and
122-like phases, respectively) or by (RO), (B3M2O5)
or (B2MO3) blocks for more complex 1111, 32225
or 21113 phases; the simplest 11-like binaries
consist of stacked (Fe-Ch) blocks;
(b) The electronic bands in the window around the
Fermi level are formed mainly by the states of
(Fe-Pn) (or Fe-Ch) blocks, which are responsible
for superconductivity, whereas the A and B atomic
sheets or oxide blocks, which are often termed
also as spacer layers, serve as insulating ‘charge
reservoirs’; and
(c) These materials have high chemical fl exibility to
a large variety of constituent elements together
with high structural fl exibility, and atomic
substitution inside the blocks (electron or hole
doping) is one of the main strategies for designing
new superconducting systems with desirable
properties (30–51).
The next promising step in expanding of this
family of high-temperature superconductors was
made in 2011, when a unique group of Pt-based
materials: 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and 10-3-8
((CaFe1–xPtxAs)10Pt3As8) phases was discovered
(78–80) and intensive studies of their properties were
initiated (81–85). For these materials superconductivity
has been detected up to TC ~35–38 K, which is probably
induced either by Pt doping of the blocks (FeAs) in
the 10-3-8 phase or by indirect electron doping in the
10-4-8 phase owing to additional Pt2+ in the platinum
arsenide blocks (78–80). Thus, the role of Pt in the
formation of superconducting materials becomes
very intriguing.
Pt as a component of layered superconducting
materials has been investigated for a long time,
and Pt has been found to play a triple role: (a) as a
dopant, (b) as a component of non-superconducting
blocks (spacer layers), and (c) as a component of
superconducting blocks. Thus, all superconductors
with Pt can be divided onto two groups: Pt-based
materials (where Pt forms individual sub-lattices
inside blocks) and Pt-containing materials, where Pt
acts as a dopant.
The following sections will focus on the above
mentioned materials to cover the basic issues of their
synthesis, main properties and simulation.
2. Pt-Based Superconducting MaterialsBesides the 10-3-8 and 10-4-8 phases, some other Pt-
based superconductors are known, such as SrPtAs
(86), SrPt2As2 (87) and RPt2B2C (where R are rare earth
metals or Th) (88–94), see Table I.
2.1 1221 Phases (Borocarbides)Historically, the systematic study of layered Pt-based
superconducting materials began with borocarbides
RPt2B2C (1221 phases) in the mid-1990s and was
continued in the new millennium (87–99). These
phases crystallise in the tetragonal LuNi2B2C-type
structure, which is an interstitial modifi cation of the
ThCr2Si2-type, and attract attention mainly because of
the coexistence of various types of magnetic ordering
and superconductivity. Since data about the properties
of these materials are discussed in detail in a set of
available reviews (100–104), here only the structural
and superconducting parameters for known Pt-
based superconductors are listed (Table I). All these
materials belong to the class of low TC superconductors.
2.2 SrPtAsIn 2011, the hexagonal phase SrPtAs was discovered
(86) as a new low-temperature superconductor with
TC ~4.2 K. Polycrystalline samples of SrPtAs were
prepared (86) by a solid-state reaction with PtAs2 as a
precursor mixed with Sr and Pt powders using several
steps of heating. SrPtAs adopts a hexagonal structure
(space group P63/mmc, #194) derived from the well-
known AlB2-type structure and can be schematically
described as a sequence of two honeycomb planar
sheets, where one plane is formed by Sr atoms, and the
other (PtAs) by hexagonal Pt3As3, see Figure 1. The
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
90 © 2013 Johnson Matthey
atomic coordinates are Sr: 2a (0;0;0), Pt: 2c (⅓ ;⅔ ;¼),
and As: 2d (⅔ ;⅓ ;¼), the lattice constants are a = 4.244 Å
and c = 8.989 Å (86, 105).
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
(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
by two quasi-2D (cylindrical-like) sheets parallel to
the kz direction (along the Г-A direction) and by two
sheets at the zone corners (around K-H). All the Fermi
surfaces are hole-like. A very small closed electronic-
like pocket was found around K, see Figure 2.
Table I
Pt-Based Layered Superconducting Materials: Structural Properties and Critical Temperatures, TC
Type Material Space
group
Lattice constants, Å TC, K Refs.
a b c
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; -phase
P4/n 8.716 8.716 10.462 ~11–31 (80)
(CaFe1–xPtxAs)10Pt4–yAs8; -phase, x ~0.13
P1 8.7282 8.7287 11.049 ~30 (80)
(CaFe1–xPtxAs)10Pt4–yAs8; x ~0.36
P1 8.719 8.727 11.161 32.7–38 (88)
10-3-8 (CaFe1–xPtxAs)10Pt3As8; x ~0.05
P1 8.776 8.781 10.689 ~11–35 (80)
(CaFe1–xPtxAs)10Pt3As8; x ~0.16
P1 8.795 8.789 21.008 13.7 (83)
Fig. 1. Crystal structures of: (a) AlB2 and (b) SrPtAs. The structure of SrPtAs can be described as an ordered variant of the AlB2-type structure, where the Al sites are occupied by Sr and the boron sites are occupied either by Pt or As atoms so that they alternate in the honeycomb layer as well as along the c-axis (86)
(a)
B
A1(b)
As
Pt
Sr
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
91 © 2013 Johnson Matthey
(a)
A
H
K
L
M
(b) 4
2
0
–2
–4
–6
Ener
gy, e
V
A L M K H A
EF
Fig. 2. (a) Fermi surface; and (b) Electronic bands of SrPtAs (106)
Taking into account the relativistic effects, this
small electronic-like pocket disappears (102), and
the Fermi surface of SrPtAs becomes fully hole-like.
This feature distinguishes SrPtAs from other layered
pnictogen-containing superconductors. It was also
pointed out that SrPtAs provides a prime example
of a superconductor with locally broken inversion
symmetry (107). The calculated anisotropy in Fermi
velocity, conductivity and plasma frequency related
to the layered structure were found to be enhanced
owing to spin-orbit coupling; further, it was predicted
that electron doping would be favourable for an
increase in TC (108). Finally, SrPtAs was found (106)
as a mechanically stable and soft material with high
compressibility lying on the border of brittle/ductile
behaviour, and the parameter limiting its mechanical
stability is the shear modulus G, Table II.
2.3 SrPt2As2
For the chemically similar phase SrPt2As2 (110), low-
TC superconductivity (~5.2 K) has also been found
(87), and this phase seems very attractive as the fi rst
superconductor from the wide family of related Pt-
containing 122-like materials: for example, ThPt2Si2,
YbPt2Si2, UPt2Si2, RPt2Si2 (R = La, Nd, Er, Dy, Ce),
ThPt2Ge2, YbPt2Si2, UPt2Ge2 and RPt2Ge2 (112).
Polycrystalline samples of SrPt2As2 were
synthesised using stoichiometric amounts of Sr,
PtAs2 and Pt powders by a solid-state reaction (87).
SrPt2As2 adopts a tetragonal CaBe2Ge2-type structure
(space group P4/nmm, #129) (87, 110, 111). The atomic
positions are Sr: 2c (¼, ¼, zSr); 2a (¾, ¼, 0); Pt2: 2c
(¼, ¼, zPt); As1: 2b (¾, ¼, ½); and As2: 2c (¼, ¼, zAs),
where zSr,Pt,As are the internal coordinates. The lattice
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)
Phase/parameter SrPtAs SrPt2As2b SrPt2As2
c
BV,R,VRHa 79/10/44.5 101/99/100 71/71/71
0.023 0.010 0.014
GV,R,RVHa 30/15/22.5 27/25/26 29/5/17
G/B 0.51 0.26 0.24a 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
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92 © 2013 Johnson Matthey
schematically described as a sequence of Sr sheets
and [Pt2As2] and [As2Pt2] blocks consisting of {PtAs4}
and {AsPt4} tetrahedrons: …[Pt2As2]/Sr/[As2Pt2]/Sr/
[Pt2As2]/Sr/[As2Pt2]… as shown in Figure 3.
For SrPt2As2, superconductivity coexists with the
charge density wave (CDW) state (87) and this material
exhibits a CDW transition at about 470 K (110).
Theoretical probes (113, 114) predict that SrPt2As2
is essentially a multiple-band system, with the Fermi
level (EF) crossed by Pt 5d states with a rather strong
admixture of As 4p states, Figure 4. It was found (113)
that CaBe2Ge2-type SrPt2As2 is a unique system with an
‘intermediate’-type Fermi surface (Figure 3), which
consists of electronic pockets having a cylinder-like
(2D) topology (typical of 122 FeAs phases) together
with 3D-like electronic and hole pockets. The latest
are characteristic of ThCr2Si2-like iron-free low-TC
superconductors. The non-monotonic behaviour of
the density of states (DOS, see Figure 4) near the EF
suggests the possibility of signifi cant changes of TC
due to various (electron or hole) doping.
Analysis (113) revealed that other features of
CaBe2Ge2-like SrPt2As2 are as follows:
(a) Essential differences in contributions to the
near-Fermi region from the [Pt2As2] and [As2Pt2]
blocks when conduction is anisotropic and
occurs mainly in [Pt2As2] blocks;
(b) Formation of a 3D system of strong covalent Pt-As
bonds (inside and between [Pt2As2]/[As2Pt2]
blocks, see Figure 3), which is responsible
for enhanced stability of this polymorph – in
comparison with the competing ThCr2Si2-like
phase; and
(c) Essential charge anisotropy between adjacent
[Pt2As2] and [As2Pt2] blocks.
It has also been predicted that CaBe2Ge2-like
SrPt2As2 will be a mechanically stable and relatively
soft material with high compressibility, which will
behave in a ductile manner, Table II. However, the
ThCr2Si2-type SrPt2As2 polymorph, which contains
only [Pt2As2] blocks, is less stable and will be a ductile
material with high elastic anisotropy.
A family of higher-order polytypes has been
proposed (113), which can be formed as a result of
various stacking arrangements of the two main types
of building blocks ([Pt2As2] and [As2Pt2]) in different
combinations along the z axis. This may provide
an interesting platform for further theoretical and
experimental work in the search for new Pt-based
superconducting materials.
In 2012, a new family of related ternary platinum
phosphides APt3P (A = calcium (Ca), strontium (Sr)
or lanthanum (La)) was discovered (115). These
phases crystallise in a tetragonal structure, where
(a) (b)
AsPt
Sr
AsPt
PtAs
Sr
AsPt
ZR
XM
A
A
Z
P
X
N
As As
As
As
Sr Sr
Pt Pt
Pt
Pt
(c) (d)
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)
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
93 © 2013 Johnson Matthey
Den
sitie
s of
sta
tes,
eV
–1 f
orm
ula
unit–1 10
5
0
10
5
0–8 –6 –4 –2 0 2 4
Energy, eV
(a)
(b)
EFTotalPt1 5dPt2 5dAs1 4pAs2 4p
TotalPt 5dAs 4p
Fig. 4. Total and partial densities of states (DOSs) of SrPt2As2 polymorphs with structures of: (a) CaBe2Ge2-type; and (b) ThCr2Si2-type (113)
the anti-perovskite units Pt6P are placed between Sr
sheets. All three materials showed low-temperature
superconductivity. The highest TC ~8.4 K was found for
SrPt3P. Local-density approximation (LDA) calculations
(116) reveal the 3D-like multiple band structure of
APt3P phases. The increase of TC for SrPt3P with hole
doping (for example, by partial replacement of Sr with
potassium (K), rubidium (Rb) or caesium (Cs)) was
predicted.
2.4 Quaternary 10-4-8 and 10-3-8 Superconducting PhasesIn 2011, superconductivity with TC ~25 K was reported
for the tetragonal phase Ca10(Pt4As8)(Fe2As2)5 formed
in the quaternary Ca-Pt-Fe-As system (76). Very
soon, additional reports (78, 80) became available,
where the related Ca-Pt-Fe-As systems are examined
and enhanced superconductivity with transition
temperatures up to TC ~38 K, achieved by substitution
of Pt for Fe in the (Fe2As2) blocks, is reported.
One of the most intriguing features of these new Pt-
based materials (78–85) is the presence of (Fe2As2)
blocks, which are typical of the family of Fe-Pn
superconductors, together with oxygen-free blocks
[PtnAsm].
Based on Zintl’s chemical concept of ion electron
counting, it was proposed (79, 80) that [Pt4As8] and
[Fe2As2] blocks in the Ca10(Pt4As8)(Fe2As2)5 phase are
metallic-like (i.e. both blocks will give appreciable
contributions to the density of states at EF) leading
to enhanced inter-block coupling and thus to an
enhanced transition temperature of this system. It
has also been suggested that similar phases with
additional metallic-like blocks might provide an
interesting platform for the discovery of novel high-TC
superconducting materials.
Single crystals of Ca10(PtnAs8)(Fe2–xPtxAs2)5 were
grown (78) by heating a mixture of Ca, FeAs, Pt and
As powders. The mixture was placed in an alumina
crucible, sealed in an evacuated quartz tube, and
heated in one of two ways. Heating at 700ºC for 3 h
and then at 1000ºC for 72 h followed by slow cooling
to room temperature yielded an -phase with TC ~38 K,
whereas heating at 1100ºC and slow cooling to 1050ºC
for 40 h yielded a -phase with TC ~13 K (78).
The atomic structures of the -phase Ca10(Pt4As8)-
(Fe2–xPtxAs2)5 (termed also as 10-4-8 phase) and the
-phase Ca10(Pt3As8)(Fe2–xPtxAs2)5 (10-3-8 phase) are
depicted in Figure 5; the lattice parameters are listed
in Table I.These structures can be schematically described as
a sequence of 2D-like [Pt4As8]([Pt3As8]) and [Fe2As2]5
blocks separated by Ca sheets; in turn, platinum-
arsenide blocks [Pt4As8]([Pt3As8]) are formed by
corner-shared {PtAs4} squares, whereas iron-arsenide
blocks consist of {FeAs4} tetrahedrons. In both cases
[Pt4As8]([Pt3As8]) and [Fe2As2]5 blocks contain a set
of non-equivalent types of Fe, Pt and As atoms (78–85).
Further studies of superconducting gap anisotropy
(82), low energy electronic structure, and Fermi
surface topology (using angle resolved photoemission
spectroscopy, see Figure 5) (117), the critical magnetic
fi elds (118), and some transport properties (84, 119)
together with theoretical calculations of the electronic
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
94 © 2013 Johnson Matthey
band structure and parameters of interatomic bonds
(80, 81) reveal some interesting features of these
materials. In particular, Pt doping into FeAs blocks
was found to play a critical role for the occurrence of
superconductivity. This doping-dependent evolution
of the superconducting state is illustrated in Figure 6,
where the electronic phase diagram for Ca10(Pt3As8)-
(Fe2–xPtxAs2)5 is depicted. About 2 wt% Pt doping
produces superconductivity, and the superconducting
transition temperature reaches its maximum TC ~13.6 K
in the doping range 0.050 < x < 0.065. With further Pt
doping, TC slowly decreases.
The fi rst studies of electronic properties and
interatomic bonding (80, 81) reveal that for
Ca10(Pt4As8)(Fe2As2)5:
(a) The electronic bands in the window around the
Fermi level are formed mainly by the Fe 3d states
of [Fe2As2]5 blocks;
(b) The [Pt4As8] blocks will behave as semi-metals
with very low densities of states at the Fermi level;
(c) The near-Fermi bands adopt a ‘mixed’ character:
simultaneously with quasi-fl at bands, a series of
high-dispersive bands which intersect the Fermi
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-
like Fe-Fe bonds take place, whereas inside [Pt4As8]
blocks a system of covalent Pt-As and As-As bonds
emerges. Further, inside these blocks interatomic
ionic interactions occur owing to charge transfer
Fe As and Pt As. The inter-block charge transfer
occurs from the electropositive Ca ions to [Pt4As8]
and [Fe2As2]5 blocks. It is important that the charge
transfer Ca10 [Pt4As8] is much greater than the
transfer Ca10 [Fe2As2]5, i.e. in contrast to the
majority of known superconducting Fe-containing
materials (38–43, 51), the new phase Ca10(Pt4As8)-
(Fe2As2)5 includes two negatively charged blocks,
where the charge of the conducting [Fe2As2]5 blocks
is much smaller than for the Pt-As blocks. The
chemical modifi cation of PtnAs8 blocks may lead
(a) (b) (c)
Fe2As2
Ca
Pt4As8
Ca
Ca
CaFe2As2
Fe2As2
Fe2As2
Pt3As8
X0
Z0/
/Z0
M0kZ//kc//kc0
ky//kb0
kx//ka0
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)
Semiconducting
Superconducting
Metallic
0 0.02 0.04 0.06 0.08 0.10Platinum doping level, x
Tem
pera
ture
, K
100
10
Fig. 6. Electronic phase diagram for Ca10(Pt3As8)-(Fe2–xPtxAs2)5 (84) which illustrates the doping-dependent formation of semiconducting, metallic-like, and superconducting states for this material
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
95 © 2013 Johnson Matthey
to the discovery of similar materials with increased
TC (83).
3. Platinum-Doped Layered Superconducting MaterialsThe fi rst attempts to investigate Pt as a dopant
which can optimise the properties of layered
superconductors were undertaken as early as the
1990s when the high-temperature superconductor
cuprates were examined (120, 121). Next, the effects
induced by Pt doping of 1221 phases (borocarbides),
which exhibit a rich variety of phenomena associated
with superconductivity, magnetism, and their interplay,
were studied (122–131).
For non-magnetic superconductors such as YNi2B2C
and LuNi2B2C, the introduction of Pt atoms at the nickel
sites leads to modifi cations of their superconducting
properties. For series of single crystals of YNi2–xPtxB2C
(x = 0.02, 0.06, 0.1, 0.14 and 0.2), which were grown by
the travelling solvent fl oating zone method (125), with
an increase in the Pt content the critical temperature
decreases from TC ~15.9 K to TC ~13 K for x = 0.14,
Figure 8. The results were explained (125) assuming
the increase in inter-band scattering in the multi-band
superconductor YNi2B2C.
Pseudo-quaternary samples Y(Pd1–xPtx)2B2C were
prepared by mechanical alloying followed by a
thermal treatment (126). It was found that Pt stabilises
(a) (b) (c)
Fe 3dPt 5d
6
4
2
0
–2
–4
–6
Ener
gy, e
V
Pt-As
0.50
–0.5
Pt 5d
0 1
Densities of states, arbitrary units
Crystal orbital Hamilton population, arbitrary units
Bonding
Pt Pt
PtPtAs
As
As
AsAs
As
As
As6
4
2
0
–2
–4
–6En
ergy
, eV
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)
0
–0.2
–0.4
–0.6
–0.8
–1.0
(a) (b)
AC
susc
eptib
ility
, ‘
12 13 14 15 16Temperature, K
10
8
6
4
T C a
nd T
N, K
0 0.05 0.10 0.15 0.20Platinum concentration, x
TC
TN
x = 0x = 0.02
x = 0.06
x = 0.1
x = 0.14
x = 0.2
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)
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
96 © 2013 Johnson Matthey
the formation of the tetragonal superconducting
phase YPd2B2C (which adopts the highest TC ~23 K
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.
For magnetic superconductors such as ErNi2B2C,
the introduction of Pt atoms infl uences both TC and
TN (129–131). For example the measurements for
Er(Ni1–xPtx)2B2C (polycrystalline samples with
Pt content x = 0.0, 0.05, 0.10, 0.15 and 0.20 were
synthesised by standard arc melting under protective
argon atmosphere (131)) reveal that the variation of TC
as a function of x contains two intervals, see Figure 8.
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
observed with a further increase of x (131). The value
of TN, by contrast, decreases almost monotonically.
Thus, the Pt impurities in superconducting 1221
borocarbides usually lead to reduction of TC. The
explanation of the observed effects requires further
studies.
A different effect accompanies the introduction
of Pt inside layered 122-like Fe-based pnictides
such as BFe2Pn2 (132–136). It is known that ‘pure’
BFe2Pn2 phases (parent materials for Fe-based
superconductors) are located on the border
of magnetic instability and commonly exhibit
temperature-dependent structural and magnetic
transitions with the formation of collinear AFM spin
ordering, whereas superconductivity emerges either
as a result of hole or electron doping into these
parent compounds (38–43, 47). Accordingly, this effect
was observed for some Pt-doped 122-like phases.
Polycrystalline samples of SrFe2–xPtxAs2 (0 ≤ x ≤ 0.4)
were prepared by a solid-state reaction method using
SrAs, FeAs and metallic powders of Fe and Pt as
reagents. The mixture was pressed into a Ta capsule,
sealed in an evacuated quartz tube, and heated at
1000ºC for 48 h. The measurements demonstrated
that as a result of Pt doping, the magnetic order of the
parent phase SrFe2As2 is suppressed, superconductivity
for SrFe2–xPtxAs2 emerges at approximately x = 0.15,
and TC reaches a maximum of 16 K at x = 0.2 (132).
A similar effect was detected for the related system
BaFe2–xPtxAs2 (133), where at the doping level of x ~0.1
the maximum transition temperature TC ~25 K was
achieved. This situation is well illustrated in Figure 9,
where the electronic phase diagram of BaFe2–xPtxAs2
for the doping range x = 0–0.25 is depicted. In a
simplifi ed way, these effects can be interpreted in
terms of the difference in the number of valence
electrons between the doped transition metal (Pt) and
iron, i.e. the chemical scaling of the electronic phase
diagram (137, 138).
However, some exceptions can exist here: for
the related system CaFe2–xPtxAs2 it was established
(134) that the substitution of Pt is ineffective in the
reduction of AFM ordering as well as for inducing of
superconductivity up to a solubility limit at x ~0.08.
This challenge calls for further studies.
4. ConclusionsThis overview has covered the relatively little-known
role of platinum in design and modifi cation of modern
superconducting materials. The main goal was to
highlight recent experimental and theoretical results
that may give an insight into the current status and
possible development of layered superconducting
materials with Pt.
To date, two types of such materials have been
discovered: Pt-based materials (where Pt forms
individual sub-lattices inside building blocks of
corresponding phases such as SrPtAs, SrPt2As2, LaPt2B2C
and (CaFe1–xPtxAs)10Pt3As8) and Pt-containing materials
(such as Y(Pd1–xPtx)2B2C or SrFe2–xPtxAs2), where Pt acts
as a dopant. The role of Pt can be radically different. For
example, the Pt impurity in superconducting borocarbides
usually leads to a reduction of TC; whereas the
introduction of Pt inside layered Fe-based pnictides such
as BFe2Pn2 leads to the occurrence of superconductivity
(with high transition temperatures to TC ~25 K) in these
non-superconducting parent materials. A very promising
Fig. 9. Phase diagram of BaFe2–xPtxAs2 for the doping level x = 0–0.25 (133). At x < 0.02 a magnetic state with AF spin fl uctuations exists. Superconductivity appears at x = ~0.02, and TC reaches its maximum value (25 K) at x = 0.1
Tem
pera
ture
, K
150
100
50
0 0.05 0.10 0.15 0.20 0.25Platinum concentration, x
Antiferro-magnetic
Superconducting
http://dx.doi.org/10.1595/147106713X663780 •Platinum Metals Rev., 2013, 57, (2)•
97 © 2013 Johnson Matthey
step in expanding the family of superconducting
materials with Pt was made in 2011, when the unique
quaternary phases: 10-4-8 (Ca10(Pt4As8)(Fe2As2)5) and
10-3-8 ((CaFe1–xPtxAs)10Pt3As8) with highest TC ~35–38
K were discovered.
The author hopes that this overview will be useful as
a compendium to guide further research into layered
superconducting materials with Pt, which seem
interesting and challenging systems for providing new
and promising superconductors.
AcknowledgementsFinancial support from the Russian Foundation for
Basic Research (RFBR) (Grant 12-03-00038-a) is
gratefully acknowledged.
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The AuthorAlexander L. Ivanovskii completed his PhD in 1979 at the Institute of Solid State Chemistry in Ekaterinburg, Russia, and accomplished his habilitation in Chemistry at the same institute in 1988. He was promoted to Professor in 1992 and since 1994 he has been head of the Laboratory of Quantum Chemistry and Spectroscopy at the Institute of Solid State Chemistry at the Ural Branch of the Russian Academy of Sciences. Professor Ivanovskii is the author or coauthor of more than 470 research articles and 12 monographs. His main research interests are focused on the theory of electronic structure, chemical bonds, and computational materials science of superconductors, superhard materials and inorganic nanostructures.
•Platinum Metals Rev., 2013, 57, (2), 101–109•
101 © 2013 Johnson Matthey
CAT4BIO Conference: Advances in Catalysis for Biomass ValorizationHighlights 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
Laboratory of Environmental Fuels and Hydrocarbons, Chemical Process Engineering Research Institute, Centre for Research and Technology Hellas, 6th klm Charilaou – Thermi Road, PO Box 361, 57001 Thermi, Thessaloniki, Greece
Angeliki Lemonidou*
Laboratory of Petrochemical Technology, Department of Chemical Engineering, Aristotle Univerisity of Thessaloniki, 54124 Thessaloniki, Greece
*Email: alemonidou@cheng.auth.gr
Introduction The transformation of biomass into fuels and
chemicals is becoming increasingly popular as a
way to mitigate global warming and diversify energy
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
conferences complementing the 15th International
Congress on Catalysis 2012 (held 1st–6th July 2012,
in Munich, Germany), the Greek Catalysis Society
organised CAT4BIO, an international conference
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.
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102 © 2013 Johnson Matthey
Overall, there was excellent attendance with around
135 participants from both industry and academia from
28 countries worldwide. The conference succeeded in
serving as a platform for the presentation of the most
recent progress in fundamental and applied catalysis
research for the conversion of biomass. Presenters
shared their most up to date results on catalyst design,
synthesis and characterisation, surface and catalytic
reaction mechanisms and catalytic reaction processes
in the area of biomass valorisation. The conference
also provided ground for fruitful discussions among
catalysis experts from industry and academia. Selected
oral and poster contributions will be published as
full papers in a special issue of Applied Catalysis B:
Environmental (2).
This review focuses on the progress presented at the
conference on platinum group metal (pgm) catalysts
for the conversion of biomass to fuels and chemicals.
The main bulk of the pgm work reported at CAT4BIO
involved platinum catalysts, followed by papers on
ruthenium, palladium and rhodium. The highlights of
the pgm work presented in this review are categorised
based on the type of reaction employed for the
conversion of biomass and biomass-derived products
to high added value fuels and chemicals.
Hydrolysis of Cellulose/Hemicellulose to Platform ChemicalsThe catalytic conversion of cellulose to platform
chemicals has gained increasing research attention in
the past decade. Noble metal catalysts can be used to
achieve the one-pot synthesis of sorbitol from cellulose,
however commercial application is hindered by the
cost of the catalyst. The high stability of cellulose
presents another problem, as the reaction requires
harsh process conditions which degrade the fi nal
products and reduce selectivity. In a paper presented
by Jorge Beltramini and coworkers (University of
Queensland and Monash University, Australia), it
was shown that small amounts of Pt promote nickel
catalysts and signifi cantly improve their catalytic
activity. This synergistic effect was attributed to Pt and
Ni particles in close vicinity. Figure 1 shows sorbitol
and mannitol yields, as well as cellulose conversion,
from the aqueous phase hydrolysis and hydrogenation
of cellulose using supported alumina and alumina
nanofi bre (‘Alnf’) catalysts.
Hirokazu Kobayashi and colleagues (Hokkaido
University, Japan) showed that cellulose can also
be hydrolysed effectively to glucose by carbon-
supported Ru catalysts. 2 wt% Ru supported on
ordered mesoporous CMK-3 carbon gave a yield of
24% glucose and 16% cello-oligosaccharides at 503 K.
The conversion of cellulose was 56%, and thereby
the selectivity for glucose was 43%. The conversion
of cellulose was slightly improved by increasing
the content of Ru. This showed that the Ru species
hydrolyse both cellulose and oligosaccharides, and
show especially high activity for the latter substrate.
Results from X-ray absorption fi ne structure (XAFS)
Keynote LecturesProfessor 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’
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103 © 2013 Johnson Matthey
analysis for the Ru catalyst were also presented.
Characterisation showed that the Ru species on CMK-3
is not metal but RuO2·2H2O regardless of the hydrogen
reduction in its preparation. Accordingly, one possible
origin for the catalytic activity is that the Ru species
works as Brønsted acid by the heterolysis of water
molecules on Ru.
Hydrogen Production via Reforming of Biomass-Derived ProductsA good number of contributions dealt with the use
of pgms, mainly Pt, for the reforming of alcohols
and other oxygenates from biomass to hydrogen.
Leon Lefferts (University of Twente, The Netherlands)
presented interesting results on the aqueous phase
reforming of ethylene glycol in supercritical water over
Pt-based catalysts. Ethylene glycol was investigated as
a representative model compound for the aqueous
phase of bio-oil, derived from biomass pyrolysis. Pt/Al2O3
and Pt-Ni/Al2O3 catalysts, although active in the
reaction, were shown to deactivate rapidly with time
on stream. Acetic acid, an intermediate of the reaction,
was shown to be responsible for the deactivation of
Pt and Pt-Ni catalysts. The presenter explained that
acetic acid behaves as a strong acid in sub- and
supercritical water resulting in hydroxylation of the
Al2O3 surface. Redeposition of the dissolved Al2O3 on
the catalyst leads to blocking of catalytic Pt sites and
hence deactivation of the catalyst, as observed with
transmission electron microscopy (TEM) (Figure 2).
Taking their work one step further, the authors
reported the development of stable Pt catalysts for
ethylene glycol supercritical aqueous phase reforming
supported on carbon nanotubes (CNTs). CNTs were
found to be stable in hot compressed water. Moreover,
the Pt/CNT catalysts exhibited stable activity for the
reforming of both ethylene glycol and acetic acid,
confi rming that deactivation of Pt/Al2O3 is caused by
the support and demonstrating the great importance
of the type of support for reactions under supercritical
conditions. The aqueous phase reforming of ethylene
glycol and other polyols (glycerol and sorbitol) over
Pt supported on hollow-type ordered mesoporous
carbon (OMC) with three-dimensional (3D) pore
structure was also reported in a poster contribution
by Chul-Ung Kim and colleagues (Korean Research
Institute of Chemical Technology, Korea). Better
catalytic performance, including carbon conversion,
hydrogen selectivity, yield and production rate was
observed over these materials, implying that 3D
interconnected mesopore systems allow faster pore
diffusion of reactive molecules.
The steam reforming of bioethanol over Pt catalysts
was discussed in two oral presentations at the
Fig. 1. Sorbitol and mannitol yield and cellulose conversion from the aqueous phase hydrolysis and hydrogenation of cellulose using supported platinum and nickel on alumina and alumina nanofi bre (Alnf) catalysts (Courtesy of Jorge Beltramini, University of Queensland, Australia)
Catalysts
55
50
45
40
35
30
25
20
15
35
30
25
20
15
10
5
0
Conversion, %
Yiel
d, %
Ni/Alnf
Ni/Al 2O
3
Pt/Alnf
Pt/Al 2O
3
Ni-Pt/A
lnf
Ni-Pt/A
l 2O3
MannitolSorbitolCellulose
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104 © 2013 Johnson Matthey
conference. An especially interesting contribution,
reporting mechanistic aspects of the reaction over
Pt, came from the group of Professor Xenophon
Verykios (University of Patras, Greece). Paraskevi
Panagiotopoulou (University of Patras, Greece)
fi rst presented a very systematic work on ethanol
reforming over catalysts with different pgms (Pt, Pd, Rh
and Ru) and different supports (zirconia, Al2O3 and
ceria). Catalytic performance was found to depend
strongly on the nature of the dispersed metallic
phase employed, with Pt and Pd exhibiting good
activity and selectivity towards hydrogen. However,
the presenter showed that specifi c activity is defi ned
primarily by metal crystallites and secondarily by
metal/support interface. The normalised reaction rates
were found to increase with decreasing perimeter of
the metal/support interface and with increasing Pt
crystallite size, implying that active sites are terrace
sites and that ethanol adsorbs fl at on the Pt surface.
In situ diffuse refl ectance infrared Fourier transform
spectroscopy (DRIFTS) experiments also showed
that the oxidation state of Pt seems to affect catalytic
activity, which decreases with increasing population
of adsorbed carbon monoxide (CO) species on
partially oxidised (Pt+) sites. Moreover, the combined
results of temperature programmed surface reaction
(TPSR) and in situ DRIFTS experiments provided
evidence that the key step for ethanol reforming at low
temperatures is the ethanol dehydrogenation reaction,
producing surface ethoxy species and subsequently
acetaldehyde, which is further decomposed toward
methane, hydrogen and carbon oxides.
Similar conclusions were also reported in the
presentation of Filomena Castaldo et al. (University of
Salerno, Italy) who investigated the ethanol reforming
reaction over a 3 wt% Pt/10 wt% Ni/CeO2 catalyst.
Investigation of the reaction pathway by kinetic
experiments showed that ethanol steam reforming
is probably not the reaction that actually occurs at
370ºC. Instead, the involved reactions are most likely
to be the following: ethanol dehydrogenation; ethanol
and acetaldehyde decomposition and reforming;
water gas shift reaction; and methanation. The same
seems to apply for feedstocks other than ethanol,
based on the work that was presented by Ricardo
Reis Soares (Universidade Federal de Uberlândia,
Brazil). This contribution reported results on glycerol
reforming over Pt/C catalysts and also showed that
dehydrogenation is the key limiting step of the reaction.
Moreover, the reaction is sensitive to the structure of
the Pt/C catalysts, with the activity decreasing and the
selectivity shifting towards acetol and glycolaldehyde
as particles decrease in size. In other words, C–O
cleavage seems to occur preferentially on smaller
particles.
In a poster contribution by Weijie Cai and Pilar
Ramírez de la Piscina (University of Barcelona,
Spain) and Narcís Homs (University of Barcelona
and Catalonia Institute for Energy Research, Spain),
the importance of pgms for the effective oxidative
reforming of bio-butanol was reported. Doping
of cobalt/zinc oxide catalysts with Rh, Ru and Pd
signifi cantly improved the catalytic performance and
stability of the materials, with CoRh/ZnO exhibiting the
Al2O3 support
2.5×
0.71 nm
Pt particle covered by migrated Al2O3
2 nm
0.71 nm
2.5×
Fig. 2. TEM image of a deactivated platinum catalyst for the aqueous phase reforming of ethylene glycol in supercritical water (Reproduced from (3), Copyright 2012, with permission from Elsevier)
http://dx.doi.org/10.1595/147106713X663889 •Platinum Metals Rev., 2013, 57, (2)•
105 © 2013 Johnson Matthey
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 A B C
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 hb A: Lighter alkanes, B: 1-Hexadecanol, C: Palmityl palmitatec 0.25 g catalyst(Reproduced from (4), Copyright 2013, with permission from Wiley-VCH Verlag GmbH & Co KGaA)
best catalytic performance in bio-butanol oxidative
reforming.
Hydrodeoxygenation of Biomass and Biomass-Derived Products to Fuels and Chemicals Currently, there is considerable interest in investigating
the hydrodeoxygenation process, due to the high
oxygen content of the feedstocks used for the
production of renewable fuels. One of the main
advantages of the hydrodeoxygenation route relative
to other methods for making biomass-derived fuels
is that the corresponding renewable fuel product is
a high quality, oxygen free, hydrocarbon fuel which
can be readily blended with conventional petroleum-
based refi nery fuel blendstocks and components.
Johannes Lercher (Technical University of
Munich, Germany) reported exciting aspects of the
deoxygenation of components from both proteinaceous
biomass (grown in an aqueous environment) and
lignocellulose (grown terrestrially) during his keynote
lecture. Professor Lercher showed how detailed
knowledge of the elementary reaction steps and of
the surface chemistry of the catalyst components in
water allow suitable stable catalysts to be designed for
the aqueous phase hydrodeoxygenation of biomass
and biomass-derived components to alkanes. Results
relevant to pgms were shown on the kinetics of the
catalytic conversion of palmitic acid and intermediate
products, 1-hexadecanol and palmityl palmitate.
The impacts of the catalytically active metal (Pt, Pd
or Ni) and the support (C, ZrO2, Al2O3, silica, or the
zeolites HBEA or HZSM-5), as well as the role of H2,
were explored in order to elucidate the reaction
pathway. The speaker shared results on the conversion
of palmitic acid at 260ºC in the presence of H2 for
three monofunctional metal catalysts: Pt/C, Pd/C and
Raney Ni (Table I). High selectivity to n-pentadecane
was obtained on all three metals (70% on Ni; 98%
on Pt and Pd), but relatively low conversions were
attained on Pt and Pd at 31% and 20%, respectively.
A high selectivity to lighter hydrocarbons (16%)
through C–C bond hydrogenolysis together with a low
selectivity to palmityl palmitate (4.6%) was observed
over the Raney Ni catalyst. In a H2 atmosphere, the
direct decarboxylation or decarbonylation routes
http://dx.doi.org/10.1595/147106713X663889 •Platinum Metals Rev., 2013, 57, (2)•
106 © 2013 Johnson Matthey
proceeded in parallel to the hydrogenation pathway.
Direct decarboxylation and/or decarbonylation of fatty
acids were the major pathways on carbon supported
Pt or Pd, much faster than the hydrogenation of
the fatty acid. However, the hydrogenation route
took precedence over decarbonylation on the
pure metallic Ni, as the decarbonylation on Ni was
much slower than on Pt or Pd. When the support
was changed from carbon to ZrO2, the conversion
increased from 20–30% to 100% for supported 5 wt% Pt
and Pd catalysts under identical conditions, indicating
that the hydrogenation of fatty acids was promoted
by ZrO2. High selectivity for n-pentadecane (98%) was
observed on Pd/ZrO2, while Pt/ZrO2 led to a relatively
low selectivity towards C15 alkanes (61%) due to the
high concentrations of 1-hexadecanol (22%). Ni/ZrO2
also led to 90% selectivity towards n-pentadecane at
100% conversion. These results imply that by using
ZrO2 as support, the three metals (Pt, Pd and Ni)
varied the primary route from direct decarboxylation/
decarbonylation to hydrogenation-decarbonylation,
as large concentrations of alcohol intermediates were
observed during the reactions. Thus, support aided
hydrogenation became the primary route for reaction
on these ZrO2-based catalysts in H2. The three metals,
however, also led to different hydrogenolysis activities;
for example, Pt/ZrO2 or Pd/ZrO2 produced less than 1%
lighter alkanes, while Ni/ZrO2 led to 9%, in line with the
marked hydrogenolysis activity of Ni.
George Huber (University of Massachusetts,
USA) gave a comprehensive keynote lecture on the
aqueous phase hydrodeoxygenation of carbohydrates
to produce a wide range of products including C1–
C6 alkanes, C1–C6 primary and secondary alcohols,
cyclic ether and polyols. The lecture focused on the
hydrodeoxygenation of sorbitol, xylose and glucose,
as well as pyrolysis oils, and discussed several
aspects of the hydrodeoxygenation process, such
as catalytic challenges, chemistry, kinetic modelling
and reaction engineering. The reaction takes place
over Pt bifunctional catalysts that involve both metal
and acid sites. The presenter showed that three
classes of reactions occur during the aqueous phase
hydrodeoxygenation of carbohydrates: (a) C–C bond
cleavage on metal sites; (b) C–O cleavage reaction
on acid sites; and (c) hydrogenation on metal
sites. Figure 3 shows the rich reaction chemistry
involved in aqueous phase hydrodeoxygenation of
biomass derived oxygenates that according to the
speaker can be further tuned by adjusting the relative
reaction pathways through further catalyst design
and optimisation of reaction conditions. In terms of
catalyst design, Professor Huber showed that the Pt
metal sites and the acid sites can be atomically mixed
(as in the case of a Pt-ReOx/C catalyst) or atomically
separate (as in the case of a platinum/zirconium
phosphate catalyst). These differences in the catalyst
properties result in the formation of different products.
The product selectivity can be further adjusted by
tuning the metal to acid site ratio. The type of acid sites
is also important in this reaction to avoid undesired
coking reactions.
Another excellent keynote lecture was delivered by
Daniel Resasco (University of Oklahoma, USA) who
focused on the deoxygenation of phenolics, acids and
furfurals derived from biomass to monofunctional
compounds or hydrocarbons. Of interest to the progress
of pgms in the area of biomass valorisation were the
developed ruthenium/titania/carbon catalyst for the
liquid phase conversion of acetic acid to acetone and
the palladium-iron catalysts for the hydrogenation of
furfural. The novel Ru/TiO2/C catalyst proved to be very
effective at temperatures much lower than typically
needed for the reaction using existing catalysts. After
detailed characterisation of the material, Professor
Resasco proposed that the origins of this high activity
are the oxygen vacancies and the Ti3+ sites which
are promoted by the presence of Ru. Moreover, the
hydrophobicity of the carbon support is believed to
decelerate the inhibiting effect that water typically
has on catalysts with hydrophilic surfaces. Concerning
furfural conversion, the presenter showed that whereas
Pd is active for the decarbonylation of furfural
to furan and methylfuran, by alloying Fe with Pd
a dramatic change in selectivity occurs. It seems
that hydrogenolysis of the C–O bond is favoured on
Pd-Fe alloys, whereas on Pd the preferred reaction
is C–C bond breakage. Selectivity to methylfuran
was found to be a strong function of the degree
of Pd-Fe alloying. The extent of Pd-Fe interaction
also strongly depended on the type of support
(SiO2 > -Al2O3 > -Al2O3).
The pgm catalysts were also reported to be active
for the hydrodeoxygenation of fatty acids to renewable
diesel fuel. In an oral contribution from Bartosz
Rozmysłowicz (Åbo Akademi University, Finland),
Pd/C was shown to be an effective catalyst for the
deoxygenation of algae oil, tall oil fatty acids and
macauba oil, which were chosen as representative
renewable oils of different origins (algae, wood and
fruits). The presented work also included a set of kinetic
experiments which revealed the reaction pathway over
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107 © 2013 Johnson Matthey
H+
OH
OH
OH
OH
OH
OH
O
OO
H
OHH
+PtPt
OH
HO
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5
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108 © 2013 Johnson Matthey
Pd/C. The results showed that the catalyst deactivates
in a low hydrogen atmosphere due to unsaturation
of the feedstock. Moreover, deactivation is related to
feedstock purity and its production technology.
Worth mentioning is an interesting poster
contribution by the group of Regina Palkovits (RWTH
Aachen University, Germany) which demonstrated
the feasibility of using a heterogeneous Ru catalyst to
convert levulinic acid (LA), a versatile intermediate
that can be obtained directly from cellulose, to
-valerolactone (-VL), a compound that can be
utilised directly as a fuel additive. The contribution
investigated the effect of different supports (carbon,
TiO2, SiO2 and Al2O3) on 5 wt% Ru. Catalyst screening
demonstrated that variation of the catalyst support can
have a profound infl uence on the reaction outcome.
The Ru/C catalyst exhibited the highest -VL yield
(89.1%) when reacted with LA at 130ºC in an ethanol/
water solvent mixture.
Hydrogenolysis of Glycerol to ChemicalsGlycerol, a byproduct of biodiesel production, can be
converted by hydrogenolysis to different high value
added chemicals, such as 1,2-propanediol (1,2-PDO)
and 1,3-propanediol (1,3-PDO), which are promising
targets because of the high production cost using
conventional processes and the reasonably large
production scale. The production of propanediols
from glycerol, however, normally requires the use
of organic solvents and high hydrogen pressures.
Two contributions presented novel results on the
hydrogenolysis of glycerol to 1,2-PDO and 1,3-PDO
over Pd- and Pt-containing catalysts without the need
for externally added hydrogen. Gustavo Fuentes
(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
of external hydrogen and without the production of
appreciable amounts of ethylene glycol, the main
degradation product in basic medium, over a copper-
palladium/titania-5% sodium catalyst. It is important
to note that the highest selectivity reported so far
for 1,3-PDO using hydrogen pressure is 34%, a value
comparable to the authors’ results.
Another approach to alleviate the need for an
external hydrogen supply is the in situ formation and
consecutive consumption of H2, either by using a part
of the glycerol via a reforming reaction or by adding
a hydrogen donor molecule via dehydrogenation.
Efterpi Vasiliadou and Angeliki Lemonidou (Aristotle
University of Thessaloniki, Greece) presented a novel
one-pot catalytic route for effi cient 1,2-PDO production
using a crude glycerol stream as a feedstock under
inert conditions in the presence of Pt-based catalysts
(Pt/SiO2 and Pt/Al2O3). A European patent application
has been fi led (5). The H2 needed for glycerol
conversion was formed via a methanol reforming-
glycerol hydrogenolysis cycle taking advantage of
the unreacted methanol after biodiesel production
through transesterifi cation. The use of a Pt/SiO2
catalyst results in satisfactory 1,2-PDO yields (~22%) at
250ºC, 3.5 MPa nitrogen and 4 h reaction time.
Concluding RemarksThe conversion of biomass and biomass-derived
compounds to platform molecules and high added
value fuels and chemicals is a dynamic area of
research, which holds the attention of numerous
research groups worldwide. It is clear that catalysis
plays a key role in achieving effi cient and practical
biomass conversion routes to useful products. The
CAT4BIO conference on “Advances in Catalysis
for Biomass Valorization” was a successful event,
where groups from all over the world presented the
most recent progress in fundamental and applied
catalysis research for the conversion of biomass.
As demonstrated in the conference, pgm constitute
essential components of catalysis research for
biomass conversion reactions. Either as main active
components or as promoters, pgms fi nd use in a wide
range of chemical reactions. Their impact will render
them an essential component of future catalytic
processes for biomass valorisation.
References1 CAT4BIO: International conference on “Advances in
Catalysis for Biomass Valorization”, Thessaloniki, Greece, 8th–11th July, 2012: http://www.cat4bio2012.gr/ (Accessed on 31st January 2013)
2 Appl. Catal. B: Environ., Special Issue: CAT4BIO, to be published
3 D. J. M. de Vlieger, B. L. Mojet, L. Lefferts and K. Seshan, J. Catal., 2012, 292, 239
4 B. Peng, C. Zhao, S. Kasakov, S. Fortaita, J. A. Lercher, Chem. Eur. J., 2013, 19, (15), 4732
5 E. Vasiliadou and A. Lemonidou, Aristotle University of Thessaloniki, Greece, European Appl. 11179515.9; August 2011
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109 © 2013 Johnson Matthey
Angeliki Lemonidou is Professor of Chemical Engineering at Aristotle University of Thessaloniki, Greece, and Head of the Petrochemical Technology Laboratory. She holds a Bachelor’s degree in Chemistry and a PhD in Chemical Engineering from Aristotle University. Her research interests are in the area of catalysis and catalytic reaction engineering focusing on processes related to the valorisation of hydrocarbons and oxygenated compounds. Her expertise involves kinetic and mechanistic measurements of well-designed catalytic materials and their structural and morphological characterisation. She has extensively studied the performance of rhodium- and platinum-based catalysts in reforming and hydrogenolysis of biomass intermediates.
Eleni Heracleous is currently a Research Scientist at the Chemical Processes & Energy Resources Institute (CPERI) in the Centre for Research and Technology Hellas (CERTH) in Thessaloniki, Greece. She obtained her PhD in Chemical Engineering from Aristotle University of Thessaloniki in 2005, under the supervision of Professor Lemonidou. After her PhD she worked as a post-doc for two years in Shell Global Solutions in Hamburg, Germany. Since 2008, she works in CPERI and is involved in the development of tailor-made catalysts for the valorisation of hydrocarbons (mainly selective oxidation reactions) and the conversion of biomass to high added value ‘green’ chemicals and fuels, with a special focus on syngas conversion processes.
The Reviewers
•Platinum Metals Rev., 2013, 57, (2), 110–116•
110 © 2013 Johnson Matthey
Johnson, Matthey and the Chemical SocietyTwo hundred years of precious metals expertise
http://dx.doi.org/10.1595/147106713X664635 http://www.platinummetalsreview.com/
By William P. Griffi th
Department of Chemistry, Imperial College, London SW7 2AZ, UK
Email: w.griffi th@imperial.ac.uk
The founders of Johnson Matthey – Percival Johnson and
George Matthey – played important roles in the foundation
and running of the Chemical Society, which was founded in
1841. This tradition continues today with the Royal Society
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 SocietyAlthough 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
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111 © 2013 Johnson Matthey
and occupied a series of premises before its Jubilee
in 1891. The original accommodation at the Society
of Arts in John Street became too cramped for the
successful enterprise; having failed to rent rooms at
the newly instituted Royal College of Chemistry at
Hanover Square (3) it moved in 1849 to No. 142 Strand.
In 1851 it moved to share premises with the Polytechnic
Institution at 5 Cavendish Square and then in 1857
relocated to Old Burlington House (3, 6). The latter had
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
and palladium (13).
(a) (b)
Fig. 1. (a) Portrait of Percival Johnson (1792–1866); (b) Portrait of George Matthey (1825–1913)
Fig. 2. Portrait of William Cock (1813–1892)
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112 © 2013 Johnson Matthey
In 1807 John Johnson’s son Percival Norton
Johnson (1792–1866) (11, 12, 14) was apprenticed to
the fi rm – he already had good scientifi c credentials,
having published a paper on ‘Experiments which
prove Platina, when combined with Gold and Silver,
to be soluble in Nitric Acid’ (15) (reproduced in
(16)). This showed that small quantities of platinum
mixed with gold and silver in nitric acid facilitated
a separation of pure gold from the solution. He
became a partner in 1817, the year often regarded
as that in which the fi rm, later to become Johnson
Matthey, was established (11, 17).
By happy chance, 1817 was also the year in which Sir
Humphry Davy showed that a platinum wire catalysed
the combination of hydrogen with oxygen in the air
and became white-hot in the process (18) and he
observed a similar effect when a coil of platinum (or
palladium) was placed within his wire gauze safety
lamp (19). These were really the fi rst observations of
heterogeneous oxidation catalysis (20, 21). In 1822
the business moved to 79 Hatton Garden and in 1826
Percival Johnson employed an assayer, George Stokes,
taking him into partnership in 1832. The fi rm was now
called Johnson and Stokes. On the death of Stokes in
1835 another assayer, William John Cock (1813–1892)
(11, 22), the son of Johnson’s brother-in-law Thomas
Cock (also an expert in platinum metallurgy),
joined Johnson in 1837 and the fi rm was now called
Johnson and Cock (22). Like Johnson, William Cock
was a founding member of the Chemical Society in
1841 and had devised a process for making platinum
more malleable. He wrote a paper in the fi rst volume
of the Memoirs of the Chemical Society of London,
the Society’s fi rst journal, titled ‘On Palladium – Its
Extraction, Alloys, &c.’ (23), a remarkable summary of
the preparation and major properties of palladium.
The fi rm of Johnson and Cock, amongst much other
business, provided platinum for a commemorative
medal for Queen Victoria’s coronation (Figure 3)
and 100 ounces of the metal for the new Imperial
pound weight standards in 1844. Cock resigned in
1845 through ill-health, though he continued to help
Johnson until much later.
George Matthey (1825–1913) (11, 24, 25) was taken
on as an apprentice by Johnson and Cock in 1838 at
the age of thirteen and quickly became interested in
platinum refi ning, William Cock becoming his mentor.
Matthey was an excellent chemist, having spent some
time at the Royal College of Chemistry in the late 1840s
with August Wilhelm von Hofmann (26). His younger
brother Edward later studied chemistry and metallurgy
at the sister institution the Royal School of Mines and
later became a partner in the company (11). George
had a shrewd business mind and he persuaded
a rather reluctant Johnson to show samples of
platinum, palladium, rhodium and iridium at the Great
Exhibition of 1851: these exhibits were awarded a prize
(24). Johnson made him a partner in 1851 and thus the
fi rm of Johnson and Matthey was fi nally established
in that year (17, 27). It was very largely Matthey who
transformed the fi rm from a largely laboratory-based
enterprise into a fully commercial business.
Johnson and Matthey were elected Fellows of the
Royal Society in 1846 and 1879 respectively; Johnson’s
election was supported by Michael Faraday amongst
others. Faraday had many connections with Johnson
and, in particular, Matthey (28). Faraday mentions
having ingots of platinum, which he describes as
“this beautiful, magnifi cent and valuable metal” in his
celebrated lecture-demonstration ‘On Platinum’ at the
Friday Discourse at the Royal Institution in Albemarle
Street on 22nd February 1861. He acknowledged
“Messrs. Johnson and Matthey, to whose great kindness
I am indebted for these ingots…” (29). Matthey
published a number of papers, mainly in mining
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
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113 © 2013 Johnson Matthey
in a State of Purity of the Group of Metals Known as
the Platinum Series and Notes upon the Manufacture
of Iridio-Platinum’. This presented a new method of
refi ning the platinum group metals (pgms) in which
lead was used to remove rhodium and iridium (30).
The “New Oxford Dictionary of National Biography”
has articles on Johnson (14) and Matthey (25).
Obituaries of Johnson (31, 32), William Cock (33) and
George Matthey (34) were published; McDonald (12)
has established that both the Johnson obituaries (31,
32) were written by George Matthey, albeit in edited
forms. The full original version has been given (12).
Sir William Crookes was probably the author (22) of
Cock’s obituary (33).
Early Collaborations of Johnson, Matthey and the Chemical SocietyPercival Johnson (listed as of 38 Mecklenburgh
Square) appears in the list of the original members
of the Chemical Society of London in 1841, together
with other famous names (4). He was one of the
early members of the Council of the Society, serving
from 1842–1844 (Michael Faraday joined him on the
Council in 1843) (3, 5). William Cock also appears on
the list of founder members of 1841 (4) and was one
of the few who gathered informally, prior to the offi cial
formation of the Society, to consider setting up such an
institution. He served on the Council of the Society in
1845 (3), giving in that year a specimen of palladium to
the Society’s Museum. In 1868 the Society established
a Faraday medal and this was, for its fi rst six issues, cast
in palladium, donated by Johnson Matthey. An item in
the Society’s minutes says that “a letter was read from
Messrs. Johnson and Matthey containing an offer to
present to the Society an amount of palladium to form
the Faraday medals for the next ten years of the value
of £200. The offer was accepted and a vote of thanks to
Messrs. Johnson and Matthey carried by acclamation”
(3). The fi rst six recipients of this palladium medal
(later medals were cast in bronze after the palladium
had run out) were all still-famous chemists: Jean-
Baptiste Dumas, Stanislao Cannizzarro, August Wilhelm
von Hofmann, Charles-Adolphe Wurtz, Hermann von
Helmholtz and Dmitri Mendeleev (3).
George Matthey was prominent in the Society:
he joined in 1873 and served on its Council from
1877–1878 (3). He was present at the Jubilee dinner
of the Society on 25th February 1891 (at which eleven
courses, fi ve wines, brandy and port were served) and
gave a speech after the dinner in his capacity as Prime
Warden of the Goldsmiths’ Company. In the afternoon
preceding the dinner there was an exhibition at which
Matthey showed samples of all six pgms and other
related objects, including a platinum snuff-box made
by Percival Johnson in 1816 and used by Johnson until
his death (3).
The Royal Society of Chemistry in the Twentieth Century In 1972 the process of unifi cation began of the Chemical
Society, the Royal Institute of Chemistry (established
1877), the Faraday Society (established 1903) and the
Society of Analytical Chemistry (established 1874).
The Queen signed a Royal Charter for the new Royal
Society of Chemistry (RSC) on 15th May 1980 (9). That
and subsequent periods saw continued collaboration
with Johnson Matthey, as the following examples show.
The Badge of Offi ce of the President of the RSC
(Figure 4) was originally presented in 1979 to the
President of the Royal Institute of Chemistry (35) and
(a) (b)Fig. 4. (a) The badge worn 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
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114 © 2013 Johnson Matthey
the materials for it made and donated by Johnson
Matthey. The fi rm’s Chief Chemist at that time, A. R.
Powell FRS (1894–1975) (37), gave a detailed account
of the fabrication of this unique and remarkable
object (38). In the centre is an enamelled medallion
of Joseph Priestley, set within a hexagon to symbolise
benzene. In the circular rim of gold surrounding
the medallion are set, like spokes in a wheel, twelve
metals of catalytic importance. Four pgms mark the
cardinal points (north is palladium, south platinum,
east iridium and west is rhodium); in a clockwise
direction after palladium lie nickel and titanium; after
iridium there are niobium and tungsten; after platinum
we have molybdenum and tantalum; and fi nally after
rhodium lie zirconium and cobalt. The synthetic
fi bre ribbon of nylon, viscose and cellulose acetate is
dyed with mauveine, discovered by Sir William Perkin
(1838–1907) in 1856 (35, 36, 38).
Collaborations in the Twentieth and Twenty-First CenturiesIn 2001 Johnson Matthey received the fi rst RSC
National Historic Chemical Landmark award (Figure 5); it was unveiled at the Johnson Matthey Technology
Centre in Sonning Common, UK, on 21st March
2001, for “Pioneering Work in Platinum research…….
which led to the development of car exhaust catalysts
and the design of platinum-based, anti-cancer drugs”
(39). The manufacture of the fi rst autocatalysts is
also commemorated by a plaque at the company’s
manufacturing premises in Royston, UK (Figure 6). The company has sponsored or co-sponsored a
number of RSC events. Among these, the triennial
International Conferences on Platinum Group Metals
meetings from 1981 to 2002 were a major feature. They
were sponsored jointly by the Dalton Division of the
RSC and Johnson Matthey and brought together many
experts on pgm chemistry, dealing in particular with
aspects of organometallic, catalytic and coordination
chemistry. These were held in July at the following
universities and from 1981 were reviewed in Platinum
Metals Review (references given in parentheses):
Bristol, 1981 (40)
Edinburgh, 1984 (41)
Sheffi eld, 1987 (42)
Cambridge, 1990 (43)
St. Andrews, 1993 (44)
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. 6. A plaque commemorating the manufacture of autocatalysts by Johnson Matthey in Royston, UK
Fig. 5. The fi rst Royal Society of Chemistry National Historic Chemical Landmark award at Johnson Matthey Technology Centre, Sonning Common, UK
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115 © 2013 Johnson Matthey
In 2008 Johnson Matthey sponsored the new
biennial RSC Lord Lewis Prize, awarded “for distinctive
and distinguished chemical or scientifi c achievements,
together with signifi cant contributions to the
development of science policy” (49). The fi rst awardee
was Lord Robert May of Oxford, FRS, OM (born in
1938), President of the Royal Society from 2000 to
2005, former Government Chief Scientifi c Advisor,
Professor of Zoology at the University of Oxford and
Fellow of Merton College. In 2010 the Prize went to Sir
John Cadogan CBE, FRS (born in 1930), formerly Chief
Scientist at the BP Research Centre and President of
the RSC from 1982–1984. The most recent winner, in
2012, was Sir David King FRS (born in 1939), from
2000–2007 the Government’s Chief Scientifi c Advisor
and the founding Director (2008–2012) of the Smith
School of Enterprise and Environment at the University
of Oxford.
Other joint RSC–Johnson Matthey projects have
included a book and workshop on teaching of pgm
separations created in 1998 (50). Teachers spent two
to three days at the Johnson Matthey Technology
Centre in Sonning Common, UK, with the late Phil
Smith of the RSC at the invitation of David Boyd,
Technology Manager at the Centre. Boyd gave a series
of presentations and workshops on the chemistry,
extraction, refi ning and uses of platinum. These were
turned into teaching aids, with a variety of exercises,
games, questions and experiments.
Johnson Matthey also partnered with the RSC on its
‘Faces of Chemistry’ initiative, a series of short videos
aimed at bringing to life careers in industry for young
people (51). Johnson Matthey scientists explain the
chemistry of pgm-based emission control catalysis
in three short fi lms, which were made available via
website and social media links from 2011.
The company also contributed materially to the
RSC Roadmap objectives (‘Chemistry for Tomorrow’s
World’) prepared in 2009 (52). Dr David Prest,
Managing Director for the European Region in the
fi rm’s Emission Control Technologies division and a
member of the RSC Council, chaired the steering group
– a cross section from industry and academia – which
prepared the Roadmap. The aim of their report was to
identify the role of the chemical sciences in helping
to solve major global challenges. The Roadmap was
developed via expert workshops and extensive online
consultations; many challenges were identifi ed, with
specifi c objectives with timescales of up to 15 years.
In 2010 Dr Martyn Twigg, then Chief Scientist of the
fi rm, won the RSC Applied Catalysis award “for his
pivotal and innovative role in creating new catalysts
and catalytic processes for use in the automotive
industry” (53) and in 2012 Dr Thomas J. Colacot, of
Johnson Matthey Catalysis and Chiral Technologies,
USA, won the same award “for exceptional
contributions to the development and availability of
ligands and catalysts crucial for the advancement of
metal-catalysed synthetic organic chemistry” (54, 55).
Thus Johnson Matthey and the RSC have
collaborated over many years, continuing into
the twenty-first century, making use of the firm’s
expertise in chemistry and catalysis, with particular
emphasis on their unrivalled experience with the
precious metals.
ConclusionsThis article has sought to show that Percival Johnson
and George Matthey, in effect the founders of Johnson
Matthey Plc, were closely associated with the Chemical
Society (of which Johnson was a founder and Matthey
a prominent member) since its inception in 1841 and
that this tradition has been continued to the present
with Johnson Matthey Plc and the Royal Society of
Chemistry.
AcknowledgementsIt is a pleasure to thank David Allen and Pauline
Meakins from the RSC for their help; as well as David
Prest, David Boyd, Sally Jones, Haydn Boehm and
Richard Seymour from Johnson Matthey; and Martyn
Twigg, formerly of Johnson Matthey, for their help in
providing some of the source material for this article.
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http://dx.doi.org/10.1595/147106713X664635 •Platinum Metals Rev., 2013, 57, (2)•
116 © 2013 Johnson Matthey
8 P. Schmitt and O. Hopkins, “Burlington House: a Brief History”, Royal Academy of Arts, London, UK, 2010: http://static.royalacademy.org.uk/secure/fi les/architecture-guide-fi nal-785.pdf (Accessed on 14th February 2013)
9 D. H. Whiffen and D. H. Hey, “The Royal Society of Chemistry: the First 150 Years”, Royal Society of Chemistry, London, UK, 1991
10 D. McDonald, “The Johnsons of Maiden Lane”, Martins Publishers, London, UK, 1964
11 D. McDonald and L. B. Hunt, “A History of Platinum and its Allied Metals”, Johnson Matthey, London, UK, 1982
12 D. McDonald, “Percival Norton Johnson: The Biography of a Pioneer Metallurgist”, Johnson Matthey, London, UK, 1951
13 W. P. Griffi th, Platinum Metals Rev., 2003, 47, (4), 175
14 I. E. Cottington, ‘Johnson, Percival Norton (1792–1866), Metallurgist’, in “New Oxford Dictionary of National Biography”, Oxford University Press, Oxford, UK, 2004, Volume 30, p. 293
15 P. Johnson, Phil Mag., 1812, 40, (171), 3
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25 I. E. Cottington, ‘Matthey, George (1825–1913), Refi ner and Metallurgist’, in “New Oxford Dictionary of National Biography”, Oxford University Press, Oxford, UK, 2004, Volume 32, p. 372
26 H. Gay, Notes Rec. R. Soc., 2008, 62, (1), 51
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40 L. B. Hunt and B. A. Murrer, Platinum Metals Rev., 1981, 25, (4), 156
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44 O. J. Vaughan, Platinum Metals Rev., 1993, 37, (4), 212
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49 Lord Lewis Prize, RSC: http://www.rsc.org/ScienceAndTechnology/Awards/LordLewisPrize/Index.asp (Accessed on 14th February 2013)
50 “Learning About Materials: Three Workshop Exercises”, eds. E. Lister and C. Osborne, The Royal Society of Chemistry, London, UK, 1998
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The AuthorBill Griffi th is an Emeritus Professor of Chemistry at Imperial College (IC), London, UK. He has much experience with the platinum group metals, particularly ruthenium and osmium. He has published over 270 research papers, many describing complexes of these metals as catalysts for specifi c organic oxidations. He has written eight books on the platinum metals, and is currently writing, with Hannah Gay, a history of the 170-year old chemistry department at IC. He is responsible for Membership at the Historical Group of the Royal Society of Chemistry.
•Platinum Metals Rev., 2013, 57, (2), 117–122•
117 © 2013 Johnson Matthey
SAE 2012 World CongressVehicular 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
Corning Environmental Technologies, Corning Incorporated, HP-CB-2-4, Corning, NY 14831, USA
Email: johnsontv@corning.com
The annual SAE Congress is the vehicle industry’s
largest conference and covers all aspects of
automotive engineering. The 2012 congress took
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 TrapsThe 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
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118 © 2013 Johnson Matthey
the NOx desorption rate is considerably slower
than either adsorption or catalyst reactions at low
temperatures. The NOx desorption rate appears to be
increased by enhancing contact with CeO2 and baria,
the NOx trapping material. Work is continuing to verify
the effect.
Diesel Particulate Filters Although diesel particulate fi lters (DPFs) have been
in commercial production for original equipment
manufacturer (OEM) application for more than 10
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
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
et al. (Michigan Technological University, USA)
quantifi ed this effect for ultra-low sulfur diesel (ULSD)
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
and temperature to measure oxidation of the soot
with the NO2. They found that soot generated by
burning biodiesel oxidised slightly more slowly than
that from ULSD fuel, contradicting other studies
which have shown enhanced reactivity for biodiesel
soot in thermal regeneration. The Arrhenius plot did
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.
Interestingly, the investigators quantifi ed the internal
generation of NO2 in the catalysed fi lter, wherein
NO2 fi rst passes through and reacts with the soot;
the resulting nitric oxide (NO) is oxidised back to
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
were very high (each NO molecule recycled three to
four times) at 450ºC.
Carl Justin Kamp et al. (Massachusetts Institute of
Technology, USA) (6) looked at the recycling of the
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
away layers of material, ending up with a clean
cross-section of the substrate, washcoat, catalyst,
ash and soot. Figure 2 shows one such image. There
are voids between the soot and the catalyst that are
likely formed by the back diffusion of NO2 generated
by the catalyst. Other images show metal oxide ash
(from wear and burning lubricant oil) coating the
catalyst, but mostly not interfering with this recycling
phenomenon. Curiously, images were shown of ash
agglomerates measuring 20 μm in diameter that
mostly consisted of relatively large voids.
Ageing
Ageing
Conventional catalyst:
New concept catalyst:Pt
CeO2
Al2O3
Pt
CeO2 Al2O3
Fig. 1. Platinum is preferentially deposited on small ceria grains to minimise grain growth upon ageing of a new concept NOx trap catalyst (3)
Catalyst
Substrate
Soot
1 m
Fig. 2. Cross-section of the soot-catalyst layer in a platinum-catalysed diesel particulate fi lter made possible by a new ion milling technique (6)
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119 © 2013 Johnson Matthey
Particulate oxidation catalysts (POCs) are a
cross between a DPF and a DOC wherein the soot
is trapped by turbulence mechanisms, forcing
particles to make contact with the Pt-catalysed
fi lter. POCs are a leading approach to particulate
emissions control in developing countries because
they do not require active regeneration. However,
these countries might not have low-sulfur fuel. Piotr
Bielaczyc (BOSMAL Automotive R&D Institute Ltd,
Poland) et al. (7) looked at the effects of fuel sulfur
on the performance of these devices. Although the
dry soot coming from the engine was the same in
all tests, the total particulate matter (PM) coming
from the engine increased with increasing levels
of sulfate. Between 20 h and 40 h of operation the
fi ltration effi ciency using a high sulfur fuel (365 ppm)
dropped by about 10% across the particle size range,
while that of a clean (sulfur-free) fuel changed very
little. The loss of effi ciency seen in the high-sulfur
fuel is likely due to the reduced availability of NO2
for cleaning and maintaining the fi lter effi ciency,
since NO2 generation in the DOC is hampered by the
presence of sulfur.
An important emerging trend is to coat DPFs with
an SCR catalyst as a way of consolidating parts and
getting the SCR closer to the turbocharger for faster
heating. Friedemann Schrade et al. (IAV GmbH,
Germany) (8) showed that when soot is on the Cu-zeolite
coated fi lter, the change in NO2 levels across the
soot layer caused by soot oxidation can impact SCR
performance. If the NO2 level going into the fi lter is
higher than ideal for the ‘fast’ SCR reaction, the soot
can improve performance. Conversely, if the NO2 level
is at or below the optimum 50% (of total NOx) level,
the soot can impair the SCR performance.
Diesel Oxidation Catalysts DOCs are generally catalysed with platinum and/
or palladium. They play two primary roles in
commercial emissions control systems: (a) to
oxidise hydrocarbons (HCs) and carbon monoxide,
either to reduce emissions coming from the engine
or to create exothermic heat used to regenerate a
DPF; and (b) to oxidise NO to NO2, which is required
to continuously oxidise soot on a DPF and/or to
enhance the SCR deNOx reactions, particularly at
low temperatures.
Ageing of DOCs is a critical phenomenon to
understand. It can impact HC emissions, DPF
regeneration and SCR performance. Junhui Li et al.
(Cummins Inc, USA) (9) retrieved several fi eld-aged
DOCs from in-use vehicles, sectioned them and studied
the ageing characteristics of the segments. As shown
in Figure 3, irreversible ageing caused different types
of deterioration. Catalyst samples cut from the rear of
the DOC had a higher NO light-off temperature than
those taken from the front. The opposite was true for
HC (propene) oxidation, wherein the rear parts had
a lower light-off temperature. The front catalysts were
aged primarily by ash contamination, while the back
catalysts were generally thermally aged. The overall
light-off characteristics of the catalyst deteriorated due
to both effects as the mileage increased. The authors
also reported reversible deterioration caused by HC
Rear
100 120 140 160 180 200
ReferenceFront
310
290
270
250
230
210
190
170
Propene lightoff, T50, ºC
NO
ligh
toff
, T25
, ºC
Fig. 3. NO and hydrocarbon (propene) light-off properties for samples taken from the front and rear of fi eld-aged platinum-based diesel oxidation catalysts. The reference catalyst was laboratory aged (9)
http://dx.doi.org/10.1595/147106713X663933 •Platinum Metals Rev., 2013, 57, (2)•
120 © 2013 Johnson Matthey
and sulfur poisoning, which could be removed with a
thermal treatment.
A new type of DOC was reported by Federico Millo
and Davide Fezza (Politecnico de Torino, Italy). They
added a low-temperature NOx adsorber material
(probably an alkaline earth oxide) to the DOC (10).
The material stores NOx (presumably as a nitrate) at
low temperatures and then releases the NOx at higher
temperatures when the downstream SCR catalyst is
operative. The adsorber aged substantially, but could
still provide signifi cantly better NOx removal than an
SCR-only confi guration. This ‘passive NOx adsorber’
(PNA) concept is being developed by Cary Henry et al.
(Cummins Inc, USA) and Howard Hess et al. (Johnson
Matthey Inc, USA) with quite impressive results (11).
Gasoline Emissions ControlCatalytic gasoline emissions control has been
commercialised for more than 35 years and the three-
way catalyst (TWC) for more than 30 years. Yet, it is still
evolving and showing signifi cant improvements. Since
the mid-1990s, when the TWC was perhaps in its third
generation, emissions have dropped by more than 95%
and pgm loading is down by upwards of 70% of what it
was then. The progress is still continuing.
For example, Yoshiaki Matsuzono et al. (Honda
R&D Co, Japan) and Takashi Yamada et al. (Johnson
Matthey Japan Inc) described a new layered catalyst
for improving the performance of both close-coupled
and underbody catalysts (13). The improvements cut
pgm usage by 75% while meeting the new California
Low Emission Vehicle III, Super Ultralow Emission
Vehicle – 30 mg mile–1 non-methane HC+NOx (LEV
III SULEV30) standard. The close-coupled catalyst is
layered with higher activity Pd and a lower activity
oxygen storage capacity (OSC) on the top, to better
withstand phosphorous poisoning and to achieve
better HC conversion. The catalyst demonstrates that
Pd-only catalysts can have application for the lowest
emissions applications. The underbody catalyst utilises
a zirconia-based OSC, allowing 50% less Rh to be used
versus the current version of the catalyst.
System design and calibration are signifi cant
contributors to lowering emissions from gasoline
vehicles. Douglas Ball and David Moser (Umicore
Autocat Inc, USA) (14) benchmarked fi ve of the cleanest
gasoline engine vehicles on the market with a variety of
hardware calibration strategies, including port-fueled
and direct injection, with and without secondary air,
and with different injection timings, engine speeds
and air:fuel ratios. The light-off strategies used various
combinations of high idle speed, aggressive ignition
retard, secondary air and split injections. All designs
achieved catalyst light-off during idle before the fi rst
hill in the test cycle. Secondary air was not necessarily
needed, but helped the catalyst heat to 950ºC in the fi rst
idle. Only 500ºC was reached in the same time without
secondary air. Turbocharged direct injection engines
use split injection, secondary air and late injection to
aid cold start. The investigators ran emissions tests to
help estimate what volume of catalyst will be needed
to meet the new California regulations. Figure 4
shows the case for a highly calibrated, port-fuel injected,
naturally aspirated 2.0 l engine without secondary air.
100
49
35
21
14
10
Catalyst volume, l0 0.5 1 1.5 2 2.5 3
LEV70 Target
LEV50 Target
SULEV30 Target
SULEV20 Target
Non
-met
hane
hyd
roca
rbon
s +
NO
x (m
g m
ile–1
)
Relative pgm loading
1.33
1.25
1.17
1.08
1.00
Fig. 4. Estimated required amount of pgm catalyst to achieve various emissions levels on a 2.0 l port-injection fuelled engine without secondary air (14)
http://dx.doi.org/10.1595/147106713X663933 •Platinum Metals Rev., 2013, 57, (2)•
121 © 2013 Johnson Matthey
Approximately 2 l of catalyst will be needed to achieve
the SULEV 30 target, compared with about 2.5 l of
catalyst to achieve the same result on a 2.4 l engine
with secondary air.
In an entirely different approach to evaluating pgm
loadings and emissions, Michael Zammit (Chrysler
Group LLC, USA) et al. (15) changed the distance from
the engine of a close-coupled TWC and measured
the emissions. They made estimates of the increased
pgm loadings to offset the increased distance while
keeping the emissions the same: an additional 37–50 mg
Pd per cm of distance from the engine.
To meet the new gasoline particle number
regulations of the light-duty Euro 6 regulation in 2017,
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
fi lter. Joerg Michael Richter et al. (Umicore Autocat
Luxembourg) (16) evaluated two different coated
confi gurations with identical total pgm loadings. In
one confi guration the pgm was distributed evenly
between the close-coupled TWC and the GPF; in
another confi guration, the close-coupled catalyst was
optimised by zone-coating the Pd so that 80% of it is
on the front half. The investigators found that the NOx
emissions dropped by 20% in the fi rst coated GPF
confi guration compared to the baseline confi guration
without a GPF. With an optimised zone coating on
the close-coupled catalyst, 6% less pgm was used
compared to the baseline, NOx emissions remained
at the low level, but CO emissions were reduced by
30% compared to the other GPF confi guration. The
researchers reported that the TWC on the GPF aided
fi lter regeneration. No fuel penalty was observed when
the GPF was applied.
ConclusionWork is continuing on utilising Pt and other precious
metals more effectively to meet tightening tailpipe
emission regulations and reduce costs. Examples
highlighted in this Congress review include the more
effi cient use of Pt in LNTs by distributing it preferentially
on the CeO2 portion of the washcoat. In other work, Pt
was applied to a DPF resulting in the enhancement of
soot burn by NO2 by three or four times at 450ºC due
to the recycling of the NOx molecule in the vicinity
of the soot layer. Soot oxidation by NO2 was found to
be adversely impacted by sulfur in fuel and this could
impair the performance of POCs . The functionality
of Pt in fi eld-aged DOCs was impaired by ash in the
front portions, adversely impacting HC oxidation, and
by thermal ageing in the back, affecting NO oxidation.
The pgm loading of TWCs could be cut by 75% by
layering the catalyst, placing higher activity Pd and a
lower activity oxygen storage catalyst in the top layer.
Also, more is being learned on whole system design,
such as the effects of catalyst placement, turbocharging,
secondary air and fuel injection strategies, and the
impacts that these factors have on catalyst loadings.
Finally, this Congress featured catalysed GPFs for the
fi rst time, showing better system performance if some
pgm was moved from the close-coupled catalyst to
the GPF.
References 1 SAE International: http://www.sae.org/ (Accessed on
29th January 2013)
2 T. V. Johnson, ‘Vehicular Emissions in Review’, SAE Int. J. Engines, 2012, 5, (2), 216
3 K. Suga, T. Naito, Y. Hanaki, M. Nakamura, K. Shiratori, Y. Hiramoto and Y. Tanaka, ‘High-Effi ciency NOx Trap Catalyst with Highly Dispersed Precious Metal for Low Precious Metal Loading’, SAE Paper 2012-01-1246
4 Y. Tsukamoto, H. Nishioka, D. Imai, Y. Sobue, N. Takagi, T. Tanaka and T. Hamaguchi, ‘Development of New Concept Catalyst for Low CO2 Emission Diesel Engine Using NOx Adsorption at Low Temperatures’, SAE Paper 2012-01-0370
5 K. L. Shiel, J. Naber, J. Johnson and C. Hutton, ‘Catalyzed Particulate Filter Passive Oxidation Study with ULSD and Biodiesel Blended Fuel’, SAE Paper 2012-01-0837
6 C. J. Kamp, A. Sappok and V. Wong, ‘Soot and Ash Deposition Characteristics at the Catalyst-Substrate Interface and Intra-Layer Interactions in Aged Diesel Particulate Filters Illustrated Using Focused Ion Beam (FIB) Milling’, SAE Paper 2012-01-0836
7 P. Bielaczyc, J. Keskinen, J. Dzida, R. Sala, T. Ronkko, T. Kinnunen, P. Matilainen, P. Karjalainen and M. J. Happonen, ‘Performance of Particle Oxidation Catalyst and Particle Formation Studies with Sulphur Containing Fuels’, SAE Paper 2012-01-0366
8 F. Schrade, M. Brammer, J. Schaeffner, K. Langeheinecke and L. Kraemer, ‘Physico-Chemical Modeling of an Integrated SCR on DPF (SCR/DPF) System’, SAE Paper 2012-01-1083
9 J. Li, T. Szailer, A. Watts, N. Currier and A. Yezerets, ‘Investigation of the Impact of Real-World Aging on Diesel Oxidation Catalysts’, SAE Paper 2012-01-1094
10 F. Millo and D. Vezza, ‘Characterization of a New Advanced Diesel Oxidation Catalyst with Low Temperature NOx Storage Capability for LD Diesel’, SAE Paper 2012-01-0373
http://dx.doi.org/10.1595/147106713X663933 •Platinum Metals Rev., 2013, 57, (2)•
122 © 2013 Johnson Matthey
11 C. Henry, A. Gupta, N Currier, M. Ruth, H. Hess, M. Naseri, L. Cumaranatunge and H.-Y. Chen, ‘Advanced Technology Light Duty Diesel Aftertreatment System’, US Department of Energy 2012 Directions in Engine-Effi ciency and Emissions Research (DEER) Conference, Dearborn, Michigan, USA, 16th–19th October, 2012
12 K. Ishizaki, N. Mitsuda, N. Ohya, H. Ohno, T. Naka, A. Abe, H. Takagi and A. Sugimoto, ‘A Study of PGM-Free Oxidation Catalyst YMnO3 for Diesel Exhaust Aftertreatment’, SAE Paper 2012-01-0365
13 Y. Matsuzono, K. Kuroki, T. Nishi, N. Suzuki, T. Yamada, T. Hirota and G. Zhang, ‘Development of Advanced and Low PGM TWC System for LEV2 PZ EV and LEV3 SULEV30’, SAE Paper 2012-01-1242
14 D. Ball and D. Moser, ‘Cold Start Calibration of Current PZEV Vehicles and the Impact of LEV-III Emission Regulations’, SAE Paper 2012-01-1245
15 M. Zammit, J. Wuttke, P. Ravindran and S. Aaltonen, ‘The Effects of Catalytic Converter Location and Palladium Loading on Tailpipe Emissions’, SAE Paper 2012-01-1247
16 J. M. Richter, R. Klingmann, S. Spiess and K.-F. Wong, ‘Application of Catalyzed Gasoline Particulate Filters to GDI Vehicles’, SAE Paper 2012-01-1244
The ReviewerTimothy V. Johnson is Director – Emerging Regulations and Technologies for Corning Environmental Technologies, Corning Incorporated, USA. Dr Johnson is responsible for tracking emerging mobile emissions regulations and technologies and helps develop strategic positioning via new products.
•Platinum Metals Rev., 2013, 57, (2), 123–126•
123 © 2013 Johnson Matthey
“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
Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH, UK
Email: ashfi l@matthey.com
Introduction“Complex-shaped Metal Nanoparticles: Bottom-Up
Syntheses and Applications” offers a comprehensive
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 AspectsThe book opens with the most substantial chapter,
written by the editors, which gives a more general
http://dx.doi.org/10.1595/147106713X664617 •Platinum Metals Rev., 2013, 57, (2)•
124 © 2013 Johnson Matthey
introduction to complex-shaped noble metal
nanoparticles and is an essential read for those less
familiar with the subject. The brief discussion on
the classifi cation of different shaped nanoparticles
and accompanying fi gure of transmission electron
microscopy (TEM) images (Figure 1) serves to
emphasise the breadth of this topic. The synthesis
methodologies are introduced by the means of
reduction, with a heavy emphasis on chemical
reduction but also including electrochemical,
photochemical and biochemical routes. It does
omit other methods such as sonochemical and
hydrothermal reduction, but gives references to
alternative sources that cover these.
The chapter provides a useful introduction to
topics such as the use of hard templates, for example
aluminium oxide porous membranes, and soft
templates, for example micelles, to control the growth
of the particles. It also covers galvanic replacement
and seed-mediated synthesis. Many of these topics are
discussed in greater detail in subsequent chapters. In
addition to synthesis, the chapter also briefl y reviews
the many analytical methods that are commonly
used to characterise nanoparticles and discusses
the pros and cons of each method. It goes on to
address the mechanisms of morphology evolution
with comprehensive references to the academic
literature, for example, the growth of branched
platinum nanoparticles from twinned seed crystals or
the role of the common growth directing surfactant,
cetyltrimethylammonium bromide (CTAB), in the
formation of gold nanorods. The editors are pleasingly
frank about the limitations of the synthetic methods
and emphasise the need for post-synthesis separation
due to the prevalence of polydisperse particles in
many of the preparations. The chapter concludes
with an outlook on where research is lacking and
knowledge needs to be improved in order to progress
the applications for shaped nanoparticles.
A more in depth look at templating techniques is
described in the following chapter by Chun-Hua
Cui and Shu-Hong Yu (University of Science and
Technology of China). Templating covers a variety
of techniques including galvanic displacement,
such as the formation of platinum nanotubes from
the treatment of silver nanowires with platinum
acetate, the use of the porous membrane template
anodic aluminium oxide for the electrodeposition
of palladium nanowires, hard templates, such as
lithographically produced patterns or soft templates,
such as CTAB micelles.
Na Tian et al. (Xiamen University, China) provide a
well set out chapter on high surface energy nanoparticles
and their use in electrocatalysis. Nanoparticles with a
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)
(a)
1D
2D
3D
20 nm100 nm
100 nm 200 nm
100 nm 500 nm 1 μm
1 μm
100 nm 500 nm 100 nm 50 nm500 nm
(b) (c) (d) (e)
(f) (g) (h) (i)
(j) (k) (l) (m)(n)
(o)
500 nm
[111]
100 nm
http://dx.doi.org/10.1595/147106713X664617 •Platinum Metals Rev., 2013, 57, (2)•
125 © 2013 Johnson Matthey
high surface energy have an increased proportion of
active surface atoms, with obvious advantages in fuel
cells, electrooxidation of ethanol and other catalytic
applications. The pgm nanoparticles have a face-
centred cubic structure and under thermodynamic
equilibrium conditions are enclosed by low energy
facets {111} giving an octahedral or tetrahedral
shape. The authors describe electrochemical and wet
chemistry routes to alternative high energy shapes --
concave hexaoctahedrons, 5-fold twinned nanorods,
rhombic dodecahedrons and many more. They
provide a very useful table including pictures of the
shapes, the indices of their facets and references to the
literature.
Chapter 9, written by Christophe Petit and Caroline
Salzemann (Université Pierre et Marie Curie, Paris,
France) and Arnaud Demortiere (Argonne National
Laboratory, USA), is specifi c to platinum and palladium
nanoparticles, bringing together some of the more
general principles covered earlier in the book. It
illustrates the complexity of controlling the numerous
variables involved in defi ning particle morphology.
The authors compare the use of alkylamine capping
agents in the Brust and reverse micelle synthesis
methods, resulting in faceted platinum nanocrystals
and polycrystalline worms, respectively. They go on to
discuss the effect of reaction conditions, for example
the timing of capping agent addition or the presence
of dissolved gasses, on the resultant particle shape.
Platinum rods, cubes or tripods can be generated
by using a nitrogen atmosphere; in the presence
of hydrogen, platinum nanocubes are formed. The
chapter is completed by a short discussion on self-
assembled supercrystals, for example square-based
pyramidal or triangular superlattices made up of
truncated platinum nanocubes (Figure 2).
This leads nicely into a chapter on ordered and
non-ordered porous superstructures written by Anne-
Kristin Herrmann (Technische Universität Dresden,
Germany) et al. These have applications in a variety of
areas including gold substrates for surface-enhanced
Raman spectroscopy and ordered hollow palladium
spheres for use as catalysts in the Suzuki reaction. The
authors cover techniques including the use of artifi cial
opals or polystyrene spheres as templates, which can
be removed by acid etching leaving metal nanoparticle
shells. Biotemplates and non-ordered templates, such
as aerogels and hydrogels, are also discussed.
TheoryChapters 6--8 cover the theoretical aspects of complex-
shaped nanoparticles. Tulio C. R. Rocha (Fritz-Haber-
Institut der Max-Planck-Gesellschaft, Germany) et al.
discuss Monte Carlo simulations of growth kinetics with
an emphasis on defects, such as stacking faults and twin
planes, using the synthesis of shaped silver particles as
an illustration. Vladimir Privman (Clarkson University,
USA) looks at the modelling of nucleation and growth
and its application to shape selection and control of
the morphology of growth on surfaces. Amanda S.
Barnard (Commonwealth Scientifi c and Industrial
Research Organisation (CSIRO), Materials Science and
Engineering, Australia) takes a thermodynamic rather
than a kinetic approach with the emerging technique
of thermodynamic cartography. This involves mapping
the thermodynamically preferred structure within
specifi ed parameters such as temperature, pressure or
chemical environment.
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 with permission from Wiley-VCH)
(a)
(b)
(c)
(d)
5 μm
50 μm
20 μm
3 μm
http://dx.doi.org/10.1595/147106713X664617 •Platinum Metals Rev., 2013, 57, (2)•
126 © 2013 Johnson Matthey
No text on nanoparticles would be complete
without a section on surface plasmons and optical
responses. This is provided by Cecilia Noguez and
Ana L. González (Universidad Nacional Autónoma de
México, Mexico) in Chapter 11. It is quite a theoretical
chapter, illustrated by numerous equations, which at
fi rst appear a little daunting to the synthetic chemist.
However, the chapter provides a useful discussion
on how surface plasmon resonances are sensitive to
particle shape.
ApplicationsChapters 12 to 16 take a more detailed look at the
applications for complex-shaped nanoparticles. The
order of these chapters does appear to be a little
haphazard with chapters on biomedical applications
interspersed with other topics but as the book is
designed as a reference to be dipped into it does
not detract too much from the overall experience.
In Chapter 12 Thomas A. Klar (Johannes-Kepler-
Universität Linz, Austria and Center for NanoScience
(CeNS), Germany) and Jochen Feldmann (Ludwig-
Maximilians-Universität München, Germany) introduce
fl uorophore-metal interactions and their application
in biosensing. It begins by going through the
theories behind the subject, before moving on to the
applications, such as ion sensing or immunoassays,
but is written in an understandable way for those new
to the topic. The chapter would benefi t from some
concluding remarks on future trends in this area.
Chapter 13 deals with surface-enhanced Raman
spectroscopy (SERS) and is written by Frank
Jäckel and Jochen Feldmann (Ludwig-Maximilians-
Universität München). It gives a good overview of the
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
plasmonic photothermal effect with a small section
on applications and although it is of interest in the
more general context of nanoparticle applications, it
is not in keeping with the main theme of this book --
complex-shaped nanoparticles.
Jun Hui Soh (Institute of Bioengineering and
Nanotechnology, Singapore) and Zhiqiang Gao
(National University of Singapore) discuss the role
of metal nanoparticles in biomedical applications in
Chapter 15, covering subjects from diagnostics and
imaging to therapy. Some of these topics are discussed
in more detail in the preceding chapters, but this
chapter gives a well-written overview of all aspects
of biomedical applications. The only criticism is the
lack of real-world examples, as the references are all
based on academic literature. The fi nal chapter deals
with thermoelectric materials, which are generally
semiconductor materials.
SummaryIn conclusion “Complex-shaped Metal Nanoparticles:
Bottom-Up Syntheses and Applications” is an
extremely useful reference, whether the reader is
interested in synthesis, application or theory of
complex-shaped nanoparticles. Although there is
some repetition between chapters written by different
authors this serves to give the reader a choice of the
depth to which they wish to explore the subject and
I would recommend it as an informative resource to
anyone from students to experienced researchers.
The book clearly shows the potential for use of noble
metals in a broad spectrum of applications, including
catalysis, fuel cells, sensors, diagnostics and targeted
drug delivery. It becomes obvious that more research
into the reliable production of shaped nanoparticles
would be highly benefi cial.
The Reviewer Laura Ashfi eld received her DPhil in Inorganic Chemistry from the University of Oxford, UK, in 2005 and subsequently joined Johnson Matthey Technology Centre, Sonning Common, UK, where she is a Principal Scientist. Her work centres around the synthesis of nanomaterials with controlled morphology for a range of applications.
“Complex-shaped Metal Nanoparticles: Bottom-Up Syntheses and Applications”
•Platinum Metals Rev., 2013, 57, (2), 127–136•
127 © 2013 Johnson Matthey
Crystallographic Properties of RutheniumAssessment of properties from absolute zero to 2606 K
http://dx.doi.org/10.1595/147106713X665030 http://www.platinummetalsreview.com/
John W. Arblaster
Wombourne, West Midlands, UK
Email: jwarblaster@yahoo.co.uk
The crystallographic properties of ruthenium at
temperatures from absolute zero to the melting point at
2606 K are assessed following a review of the literature
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.
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
128 © 2013 Johnson Matthey
Thermal ExpansionHigh-Temperature RegionLength change values derived from the measurements
of Owen and Roberts (7, 8) and Ross and Hume-
Rothery (10) agree satisfactorily and were combined
to give Equations (i) and (ii) to represent the thermal
expansion from 293.15 K to the melting point. On the
basis ± 100L/L293.15 K Equation (i) for the a-axis has
an accuracy of ± 0.009 and Equation (ii) for the c-axis
an accuracy of ± 0.025. Crystallographic properties
derived from Equations (i) and (ii) are given in
Tables I and II.On the basis of the expression:
100 × (L/L293.15 K (experimental) – L/L293.15 K (calculated))
where L/L293.15 K (experimental) is the experimental length
change relative to 293.15 K and L/L293.15 K (calculated) is
the selected length change value, then length change
values derived from the measurements of Hall and
Crangle (9) deviate continuously from selected values
and both axes are 0.14 low at the experimental limit
1557 K. Above room temperature the a-axis values of
Schröder et al. (11) initially trend to be 0.080 low at
1300 K before increasing to 0.089 high at 1982 K. The
c-axis values behave similarly, initially trending to 0.072
low at 1100 K before increasing sharply to 0.35 high at
1982 K. The dilatometric measurements of Shirasu and
Minato (13) trend to 0.10 low. The deviations of these
three sets of values are shown in Figure 1.
Low-Temperature RegionThe lattice parameter measurements of Finkel’ et al.
(12), given as length change values by Touloukian
et al. (14), were fi tted to cubic Equations (v) and
(vi) for the a- and c-axes respectively. Derived
thermal expansion coeffi cients at 293.15 K of 6.5
× 10–6 K–1 for the a- axis and 11.5 × 10–6 K–1 for the
c-axis are notably higher than those derived from
Table I
High-Temperature Crystallographic Properties of Ruthenium
Temperature,
K
Thermal
expansion
coeffi cient,
a, 10–6 K–1
Thermal
expansion
coeffi cient,
c, 10–6 K–1
Thermal
expansion
coeffi cient,
avr, 10–6 K–1
Length
change,
a/a293.15 K
× 100, %
Length
change,
c/c293.15 K
× 100, %
Length
change,
avr/
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)
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
129 © 2013 Johnson Matthey
Temperature,
K
Thermal
expansion
coeffi cient,
a, 10–6 K–1
Thermal
expansion
coeffi cient,
c, 10–6 K–1
Thermal
expansion
coeffi cient,
avr, 10–6 K–1
Length
change,
a/a293.15 K
× 100, %
Length
change,
c/c293.15 K
× 100, %
Length
change,
avr/
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
Table I (Continued)
Table II
Further High-Temperature Crystallographic Properties of Ruthenium
Temperature,
K
Lattice
parameter,
a, nma
Lattice
parameter,
c, nm
c/a
ratio
Interatomic
distance,
d1, nm
Atomic
volume,
10–3 nm3
Molar
volume,
10–6 m3
mol–1
Density,
kg m–3
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)
a avr = average
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
130 © 2013 Johnson Matthey
Temperature,
K
Lattice
parameter,
a, nma
Lattice
parameter,
c, nm
c/a
ratio
Interatomic
distance,
d1, nm
Atomic
volume,
10–3 nm3
Molar
volume,
10–6 m3
mol–1
Density,
kg m–3
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
Table II (Continued)
100[L
/L29
3.15
K (e
xper
imen
tal)
– L
/L29
3.15
(cal
cula
ted)
]
0.36
0.31
0.26
0.21
0.16
0.11
0.06
0.01
–0.04
–0.09
–0.14
Ref. (9), a-axisRef. (9), c-axisRef. (11), a-axisRef. (11), c-axisRef. (13)
300 800 1300 1800 Temperature, K
Fig. 1. The difference between length change values derived from the measurements of Hall and Crangle (9), Schröder et al. (11) and Shirasu and Minato (13)
Equations (i) and (ii) as given in Tables II and III and
indicate the degree of incompatibility between the
high- and low-temperature data. Various manipulations
of subsets of the low-temperature measurements
to try and reconcile the differences proved to be
unsatisfactory and the measurements of Finkel’ et al.
were rejected. Therefore in order to extrapolate
below room temperature Equations (i) and (ii) were
differentiated and derived values of the thermal
expansion coeffi cient relative to 293.15 K, *, were
converted to thermodynamic thermal expansion, ,
using = */(1 + L/L293.15 K). The values obtained
a a = d2
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
131 © 2013 Johnson Matthey
Table III
Low-Temperature Crystallographic Properties of Ruthenium
Temperature,
K
Lattice
parameter,
a, nma
Lattice
parameter,
c, nm
c/a
ratio
Interatomic
distance,
d1, nm
Atomic
volume,
10–3 nm3
Molar
volume,
10–6 m3
mol–1
Density,
kg m–3
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 12364a
a = d2b Since all values below 293.15 K are estimated they are given in italics
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
132 © 2013 Johnson Matthey
at 293.15 K and over the range 300 K to 800 K at 50 K
intervals were then fi tted to Equations (iii) and (iv)
where the values of the specifi c heat used, Cp, are
given by Equation (vii). Equations (iii) and (iv) were
then extrapolated below the room temperature region
using specifi c heat values given in the Appendix in
order to represent the thermal expansion to absolute
zero, although a-axis thermal expansion coeffi cients
above 240 K were slightly adjusted in order to give a
smooth continuity with the high-temperature selected
values. Crystallographic properties derived from
Equations (iii) and (iv) are given in Tables III and IV.
There is the possibility of signifi cant uncertainty
in this procedure but it is noted that in comparison,
using the same procedure as for the high-temperature
data, the measurements of Finkel’ et al. (12) show a
maximum deviation of only 0.006 low at 80 K for the
a-axis and then converge towards the selected values.
For the c-axis, there is initially agreement with the
selected values and a maximum deviation of only
0.010 low at 220 K. These small differences would
actually suggest agreement between the high- and
low-temperature data; however, the fi tting procedure
is so sensitive that these differences represent
incompatibility. The low-temperature measurements
of Schröder et al. (11) are initially 0.027 low at 84 K
for the a-axis and then converge towards the selected
values, whilst for the c-axis the value is initially 0.026
low but there is agreement to better than 0.001 above
210 K.
Normally, as an alternative method of calculation,
Equations (iii) and (iv) would be fi tted to a series of
Table IV
Further Low-Temperature Crystallographic Properties of Ruthenium
Temperature,
K
Thermal
expansion
coeffi cient,
a, 10–6 K–1
Thermal
expansion
coeffi cient,
c, 10–6 K–1
Thermal
expansion
coeffi cient,
avr, 10–6 K–1
Length
change,
a/a293.15 K
× 100, %
Length
change,
c/c293.15 K
× 100, %
Length
change, avr/
avr293.15 K
× 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)
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
133 © 2013 Johnson Matthey
Temperature,
K
Thermal
expansion
coeffi cient,
a, 10–6 K–1
Thermal
expansion
coeffi cient,
c, 10–6 K–1
Thermal
expansion
coeffi cient,
avr, 10–6 K–1
Length
change,
a/a293.15 K
× 100, %
Length
change,
c/c293.15 K
× 100, %
Length
change, avr/
avr293.15 K
× 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 0a Since all values below 293.15 K are estimated they are given in italics
Table IV (Continued)
spline fi tted equations; however as there are two axes
this could involve a signifi cant number of equations
and therefore the much simpler procedure has
been adopted of substituting values of Cp from the
Appendix into the equations.
The Lattice Parameter at 293.15 KThe values of the lattice parameters, a and c,
given in Table V represent a combination of those
values selected by Donohue (15) and more recent
measurements. Values originally given in kX units
were converted to nanometres using the 2010
International Council for Science: Committee on Data
for Science and Technology (CODATA) Fundamental
Constants (16, 17) conversion factor for CuK1, which
is 0.100207697 ± 0.000000028 whilst values given in
angstroms (Å) were converted using the default ratio
0.100207697/1.00202 where the latter value represents
the old conversion factor from kX units to Å. Lattice
parameter values were corrected to 293.15 K using the
values of the thermal expansion coeffi cient selected
in the present review. Density values given in Tables II and III were calculated using the currently accepted
atomic weight of 101.07 ± 0.02 (18) and an Avogadro
Table V
Lattice Parameter Values at 293.15 Ka
Authors (Year) Reference Original
temperature,
K
Original
units
Lattice
parameter, a,
corrected to
293.15 K, nm
Lattice
parameter, c,
corrected to
293.15 K, nm
Notes
Owen et al. (1935)
(18) 291 kX 0.27044 0.42818 (a)
Owen and Roberts (1936)
(7) 291 kX 0.27042 0.42819 (a)
Owen and Roberts (1937)
(8) 293 kX 0.27040 0.42819 (a)
(Continued)
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
134 © 2013 Johnson Matthey
Authors (Year) Reference Original
temperature,
K
Original
units
Lattice
parameter, a,
corrected to
293.15 K, nm
Lattice
parameter, c,
corrected to
293.15 K, nm
Notes
Ross and Hume-Rothery
(10) 303 Å 0.27042 0.42799 (a), (b)
Finkel’ et al. (1971)
(12) 293 Å 0.27062 0.42815 (a), (b)
Hellawell and Hume-Rothery (1954)
(19) 298 kX 0.27058 0.42817
Swanson et al. (1955)
(20) 300 Å 0.27059 0.42819
Hall and Crangle (1957)
(9) rtb Å 0.27058 0.42805
Anderson and Hume-Rothery (1960)
(21) 293 kX 0.27058 0.42814
Černohorský (1960)
(22) 295 Å 0.27059 0.42812
Savitskii et al. (1962)
(23) rt kX 0.27059 0.42819
Schröder et al. (1972)
(11) 284 Å 0.27056 0.42826
aSelected values for the present paper are: a = 0.27058 ± 0.00002 and 0.42816 ± 0.00007brt = 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)
Table V (Continued)
constant (NA) of (6.02214129 ± 0.00000027) × 1023 mol–1
(16, 17). From the lattice parameter values at 293.15 K
selected in Table V as: a = 0.27058 ± 0.00002 nm
and c = 0.42816 ± 0.00007 nm, the derived selected
density is 12364 ± 3 kg m–3 and the molar volume is
(8.1743 ± 0.0018) × 10–6 m3 mol–1. In Tables II and III the interatomic distance d1 = (a2/3 + c2/4)½ and
d2 = a. The atomic volume is (√3 a2 c)/4 and the
molar volume is calculated as NA (√3 a2 c)/4 which
is equivalent to atomic weight divided by density.
Thermal expansion is avr = (2 a + c)/3 and length
change is avr/avr293.15 K = (2 a/a293.15 K + c/c293.15 K)/3
(avr = average).
SummaryBecause there is disagreement between the high-
and low-temperature measurements for ruthenium,
satisfactory thermal expansion data is only available
above 293.15 K with a novel approach being used to
extrapolate below this temperature to derive values
which must be considered to be tentative. Clearly
further measurements are required for this element.
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
135 © 2013 Johnson Matthey
High-Temperature Thermal Expansion Equations for Ruthenium (293.15 K to 2606 K)
a/a293.15 = –1.56642 × 10–3 + 4.93471 × 10–6 T + 1.34455 × 10–9 T 2 + 1.69158 × 10–13 T 3 (i)
c/c293.15 = –2.39045 × 10–3 + 7.52727 × 10–6 T + 2.06251 × 10–9 T 2 + 2.61425 × 10–13 T 3 (ii)
Low-Temperature Thermal Expansion Equations for Ruthenium (0 K to 293.15 K)
a (K–1) = Cp (1.92207 × 10–7 + 8.09046 × 10–11 T + 7.16082 × 10–6 / T) (iii)
c (K–1) = Cp (2.93088 × 10–7 + 1.24609 × 10–10 T + 1.09421 × 10–5 / T) (iv)
Thermal Expansion Equations Representing the Measurements of Finkel’ et al. (12)
a/a293.15 = –1.40337 × 10–3 + 3.25082 × 10–6 T + 4.63332 × 10–9 T 2 + 2.07266 × 10–12 T 3 (v)
c/c293.15 = –1.87652 × 10–3 + 3.44170 × 10–6 T + 2.91501 × 10–9 T 2 + 2.44946 × 10–11 T 3 (vi)
High-Temperature Specifi c Heat Equation (298.15 K to 2606 K)
Cp (J mol–1 K–1) = 23.1728 + 7.28378 × 10–3 T – 2.703021 × 10–6 T 2 + 1.50844 × 10–9 T 3 – 97572.6/T 2 (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,
K
Specifi c
heat, J
mol–1 K
Temperature,
K
Specifi c
heat, J
mol–1 K
Temperature,
K
Specifi c
heat, J
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)
http://dx.doi.org/10.1595/147106713X665030 •Platinum Metals Rev., 2013, 57, (2)•
136 © 2013 Johnson Matthey
Temperature,
K
Specifi c
heat, J
mol–1 K
Temperature,
K
Specifi c
heat, J
mol–1 K
Temperature,
K
Specifi c
heat, J
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
Table VI (Continued)
References 1 J. W. Arblaster, Platinum Metals Rev., 1997, 41, (1), 12
2 J. W. Arblaster, Platinum Metals Rev., 2006, 50, (3), 118
3 J. W. Arblaster, Platinum Metals Rev., 1997, 41, (4), 184
4 J. W. Arblaster, Platinum Metals Rev., 2010, 54, (2), 93
5 J. W. Arblaster, Platinum Metals Rev., 2012, 56, (3), 181
6 R. E. Bedford, G. Bonnier, H. Maas and F. Pavese, Metrologia, 1996, 33, (2), 133
7 E. A. Owen and E. W. Roberts, Philos. Mag., 1936, 22, (146), 290
8 E. A. Owen and E. W. Roberts, Z. Kristallogr., 1937, A96, 497
9 E. O. Hall and J. Crangle, Acta Cryst., 1957, 10, Part 3, 240
10 R. G. Ross and W. Hume-Rothery, J. Less Common Met., 1963, 5, (3), 258
11 R. H. Schröder, N. Schmitz-Pranghe and R. Kohlhaas, Z. 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
13 Y. Shirasu and K. Minato, J. Alloys Compd., 2002, 335, (1–2), 224
14 Y. S. Touloukian, R. K. Kirby, R. E. Taylor and P. D. Desai, “Thermal Expansion: Metallic Elements and Alloys”, Thermophysical Properties of Matter, The TPRC Data Series, Vol. 12, eds. Y. S. Touloukian and C. Y. Ho, IFI/Plenum Press, New York, USA, 1975
15 J. Donohue, “The Structure of the Elements”, John Wiley and Sons, New York, USA, 1974
16 P. J. Mohr, B. N. Taylor and D. B. Newell, Rev. Mod. Phys., 2012, 84, (4), 1527
17 P. J. Mohr, B. N. Taylor and D. B. Newell, J. Phys. Chem. Ref. Data, 2012, 41, (4), 043109
18 E. A. Owen, L. Pickup and I. O. Roberts, Z. Kristallogr., 1935, A91, 70
19 A. Hellawell and W. Hume-Rothery, Philos. Mag. Ser. 7, 1954, 45, (367), 797
20 H. E. Swanson, R. K. Fuyat and G. M. Ugrinic, “Standard X-Ray Diffraction Powder Patterns”, NBS Circular Natl. Bur. Stand. Circ. (US) 539, 1955, IV, 5
21 E. Anderson and W. Hume-Rothery. J. Less Common Met., 1960, 2, (6), 443
22 M. Černohorský, Acta Cryst., 1960, 13, (10), 823
23 E. M. Savitskii, M. A. Tylkina and V. P. Polyakova, Zh. Neorgan. Khim., 1962, 7, (2), 439; translated into English in Russ. J. Inorg. Chem., 1962, 7, (2), 224
24 J. W. Arblaster, CALPHAD, 1995, 19, (3), 339
The AuthorJohn W. Arblaster is interested in the history of science and the evaluation of the thermodynamic and crystallographic properties of the elements. Now retired, he previously worked as a metallurgical chemist in a number of commercial laboratories and was involved in the analysis of a wide range of ferrous and non-ferrous alloys.
•Platinum Metals Rev., 2013, 57, (2), 137–142•
137 © 2013 Johnson Matthey
“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
HySA Systems Competence Centre, SAIAMC, University of the Western Cape, Modderdam Road, Private Bag X17, Bellville 7535, Cape Town, South Africa
Email: bgpollet@hysasystems.org
IntroductionThis book set covers polymer electrolyte membrane
fuel cells (PEMFCs) and direct methanol fuel cells
(DMFCs). It is aimed at novice readers as well as
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 MaterialsPart 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
http://dx.doi.org/10.1595/147106713X664824 •Platinum Metals Rev., 2013, 57, (2)•
138 © 2013 Johnson Matthey
gives short overviews of fuel processing, fuel storage
methods and alternative sources of hydrogen. An
excellent diagram overview of fuel processing for
fuel cell systems (Figure 1) by Iain Staffell (Imperial
College, London, UK) (1) is given. Chapter 2: ‘Membrane
Materials and Technology for Low Temperature Fuel
Cells’ gives a very good overview of the most recent
investigations in PEM materials for low-temperature
PEMFCs with a section on PEM materials for high-
temperature applications. It reviews perfl uorosulfonic
acid PEMs and non-perfl uorinated PEMs including
sulfonic acid, phosphonic, heterocycle functionalised
and acid doped membrane materials. A short section
is specifi cally dedicated to the morphology and
microstructure of ionomer membranes.
ElectrocatalystsChapter 3: ‘Catalyst and Membrane for Low Temperature
Fuel Cells’ focuses on fuel cell electrocatalysis and
the importance of the type and loading of the
cathode catalyst. The current anode and cathode
catalyst loadings for low-temperature PEMFCs are ca.
0.2 mgPt cm–2 and 0.4 mgPt cm–2, respectively, with a
target for automotive applications of a total catalyst
loading of 0.2 mgPt cm–2 (with anode catalyst loading of
0.05 mgPt cm–2 and cathode catalyst loading of
0.15 mgPt cm–2) for a cell voltage of 0.85 V, assuming a
CO-free hydrogen supply. Figure 2 shows the evolution of
Pt loading and estimated fuel cell balance of plant from
2006 (2). Both carbonaceous and non-carbonaceous
electrocatalyst support materials are mentioned
MethodsNatural gas
Desulfuriser
Reformer
Shift reactor
CO removal
CO2 scrubber
Hydro-desulfurisation,
selective adsorption
Steam reforming, partial oxidation,
autothermal reforming
High-temperature (HT) and low-
temperature (LT) shift
Preferential oxidation, pressure swing adsorption,
methanisation
Soda lime adsorption, regenerative
amines, electrical swing adsorption
SOFC
PAFC
PEMFC
AFC
Output gas composition
95% CH4 , 4%
C2H
6 , 1% CO2
10% CO,10% CO2, 0.5–1% CH4
0.5–1% CO, 15% CO2
10 ppm CO, 15% CO2
10 ppm CO, 100 ppm CO2
Function
Remove the sulfur based odorants added to natural gas for safety reasons:
ZnO + H2S ZnS + H2OAl
25ºC
Catalytically process methane into hydrogen with steam and an absence of oxygen:
CH4 + H2O CO + 3H2Ni-Al/Pt-Pd
650–850ºC
Improve the hydrogen yield and reduce concentration of the waste carbon monoxide:
CO + H2O CO2 + H2Cu-Zn/Fe-Cr
350–450ºC (HT)175–300ºC (LT)
Reduce CO concentration to ppm levels:
CO + ½O2 CO2Pt-Ru/Rh-Al
150–200ºC
Reduce CO2 concentration to ppm levels:
CO2 + Ca(OH)2 CaCO3+ 25ºC H2O
Fig. 1. An overview of fuel processing for fuel cell systems (1) (Courtesy of Iain Staffell, University of Birmingham, UK, and Woodhead Publishing)
http://dx.doi.org/10.1595/147106713X664824 •Platinum Metals Rev., 2013, 57, (2)•
139 © 2013 Johnson Matthey
(including, for example, metal oxides (3)) for both
PEMFCs and direct methanol fuel cells (DMFCs).
The chapter also highlights some of the most
recent developments in anode and cathode catalysts
(including ultra-low Pt) used in low-temperature fuel
cells. These include core-shell and binary and ternary
alloy electrocatalysts – platinum alloyed with cobalt,
copper, iron, molybdenum, nickel and/or ruthenium.
The chapter also discusses new approaches in fuel
cell electrocatalysis research and development, for
example the reduction of the Pt content and the
investigation of Pt-free compounds (for example
Co and Fe incorporated in nitrogen macrocycle
structures) based upon either non-precious metals
or alloyed transition metals. However, the chapter
does not touch on advanced cathode catalysts such
as the famous 3M platinum nano-structured thin fi lm
(NSTF) (4), which is a bit of a disappointment. For
those who are interested in learning further about fuel
cell electrocatalysis, there are a number of additional
books which I would strongly recommend (4–6).
Gas Diffusion MediaChapter 4: ‘Gas Diffusion Media, Flow Fields and
System Aspects in Low Temperature Fuel Cells’ covers
the role and importance of gas diffusion media
(tefl onated/untefl onated woven and non-woven), fl ow
fi eld plate designs on performance and degradation
and system design criteria for low-temperature
applications. The chapter briefl y states characterisation
methods for gas diffusion layers, although it does not
highlight other ex situ characterisation methods for
bulk or contact resistance, surface morphology or fi bre
structure and mechanical strength measurements (7).
There is also little information on the possible thermal
conductivity effect of the microporous layer on cell
performance.
The chapter then broadly discusses the role of fl ow
fi eld design for both low-temperature PEMFC and DMFC
with some brief discussions around the importance
of fl ow fi eld plate material, especially its interaction
with the gas diffusion layer material under various
operating conditions and applications (7, 8). Perhaps
for completeness the authors could have added a short
section on ex situ characterisation and accelerated
ageing/accelerated stress tests for fl ow fi eld plate
materials. This chapter also discusses the importance
of the system layouts of the two low-temperature fuel
cells, i.e. balance of plant, including reactant supplies
and thermal management. For Chapter 4, perhaps
the section on system aspects of low-temperature
fuel cells could have been a separate chapter in the
book emphasising the correlation between the fl ow
fi eld plate design and material, the gas diffusion layer
material and the overall system design and layout.
Environmental AspectsChapter 5: ‘Recycling and Life Cycle Assessment of
Fuel Cell Materials’ focuses on the environmental
aspects of fuel, fuel cell components and fuel cell
stacks as well as recycling. The chapter highlights the
fact that pgms such as Pt, Pd and Rh are successfully
2015
2010
2009
2008
2007
2006
Year
0 0.2 0.4 0.6 0.8 1.0 1.2
US$30 kW–1 (US DOE target) 1 W cm–2
Key
Power density (W cm–2)Estimated balance of plant (US$ kW–1) (including assembly and testing)Platinum loading (mgPt cm–2) used in automotive PEMFC stacks at a cell voltage of 0.676 VPlatinum loading (gPt kW–1) used in automotive PEMFC stacks
Platinum loadings, gPt kW–1 or mgPt cm–2
US$51 kW–1
833 mW cm–2
US$61 kW–1
833 mW cm–2
US$94 kW–1
583 mW cm–2
US$73 kW–1
715 mW cm–2
US$108 kW–1 700 mW cm–2
Fig. 2. Evolution of platinum loadings and estimated fuel cell balance of plant (Reproduced from (2) by permission of Elsevier)
http://dx.doi.org/10.1595/147106713X664824 •Platinum Metals Rev., 2013, 57, (2)•
140 © 2013 Johnson Matthey
recycled from today’s vehicles (principally from
catalytic converters – modern vehicles may contain
around 1 g of Pt for petrol and around 8 g of Pt for
diesel (2)) and the technologies can be adopted to
recycle Pt from fuel cell systems. This chapter is very
interesting and well-written as recycling of fuel cell
components and systems and their impact on the
environment is often neglected, and a ‘zero-to-landfi ll’
approach is required in order to lead to long-term
cost savings. It also highlights that recycling in the fuel
cell manufacturing industry will become paramount
for mass-produced systems in which environmental
considerations will have to be taken into account
(for example, collection/separation systems, recycling
processes, component reuse, remanufacturability and
energy recovery). Life cycle assessment models of
fuels and fuel cell components are discussed in detail
and the standardised life cycle assessment protocol
(International Organization for Standardisation – ISO
14040 series) is briefl y mentioned.
Operation and AgeingPart II in Volume 1 consists of seven chapters:
Chapter 6: ‘Operation and Durability of Low
Temperature Fuel Cells’ gives an excellent overview
of the effects of low-temperature PEMFC operating
conditions (thermal, water and reactant management,
contamination types and levels and duty cycling) on
performance and durability (which is also correlated
to component material properties, their designs and
cycling abilities). The chapter highlights the major
degradation processes occurring in the pgm-based
cathode catalyst layer and PEM regions present for
all operating conditions and briefl y describes how
that degradation can be minimised, in turn increasing
performance and durability, by improving the overall
stack design at component material and operational
levels.
Chapter 7: ‘Catalyst Ageing and Degradation in
Polymer Electrolyte Membrane Fuel Cells’ focuses on
performance degradation of electrocatalysts affected
by the relatively harsh operating conditions within
low-temperature fuel cells and discusses catalyst
ageing mechanisms. For example, it explains the
three principal mechanisms attributed to the loss
of electrochemical surface area for pure Pt and Pt
alloys supported on carbon, i.e. dissolution (leading
to Pt redeposition or Pt precipitation), migration
with concomitant coalescence and detachment of
Pt nanoparticles from the carbonaceous support as
well as complete or incomplete carbon corrosion
of the support material. The discussion then focuses
on the main effects causing such mechanisms:
temperature, pH, anion types, water partial pressure,
Pt particle size and electrode potential variations
and for Pt alloy electrocatalysts, dealloying of the
non-precious metal (mainly transition metals as they
are not stable in acidic environments – for example
Pt-Co catalysts are known to exhibit poor performance
under intense cycling conditions). The chapter also
briefl y reviews ex situ and in situ catalyst degradation
characterisation methods with an emphasis on a very
useful, powerful and newly developed technique –
identical location transmission electron microscopy
(IL-TEM) – that was originally developed by the
chapter’s authors (Figure 3). The technique provides
(b)(a)
50 nm
50 nm
100 nm(c)
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)
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141 © 2013 Johnson Matthey
insights into electrocatalyst stability on the nanoscale
level under various regimes and thus allows a direct
(visual) observation of the effect of electrochemical
treatments on carbon-supported high surface area
electrocatalysts (9).
Durability TestsChapter 8: ‘Degradation and Durability Testing of
Low Temperature Fuel Cell Components’ is well-
written and well-structured. It discusses accelerated
durability test protocols (ex situ and in situ) mainly
for the critical low-temperature PEMFC components
which are the PEM, the electrocatalyst and the
electrocatalyst carbonaceous support materials.
The chapter also briefl y covers the effect of fuel
contaminants on durability. Chapter 8 nicely
highlights the main publications dealing with
degradation and durability studies and protocols for
the membrane electrode assembly (MEA) and its
subcomponents.
Chapter 9 is a very good and systematic discussion
of the stochastic microstructure techniques for the
determination of transport property parameters as well
as the study of the effect of porous structure materials
upon transport behaviours within the critical PEMFC
catalyst layer, gas diffusion layer and microporous
layer regions.
ModellingChapter 10: ‘Multi-scale Modelling of Two-Phase
Transport in Polymer Electrolyte Membrane Fuel
Cells’ discusses in detail the pore network model and
the lattice Boltzmann model for the modelling of
two-phase fl ow in porous PEMFC materials such as
gas diffusion layers and catalyst layers. The chapter
describes how pore-scale information (for example,
microstructure, transport and performance) can be
useful for more predictive macroscopic scale-up.
Chapter 11, entitled ‘Modelling and Analysis of
Degradation Phenomena in Polymer Electrolyte
Membrane Fuel Cells’, is an excellent review of
the various available models describing PEMFC
degradation phenomena and mechanisms. The
chapter highlights the most important work on
the subject in the last 20 years and also briefl y
introduces pioneering work by, for example, Springer
et al. (Los Alamos National Laboratory, New Mexico,
USA) (10), Bernardi and Verbrugge (General Motors
Research and Environmental Staff, USA) (11) and
Antoine (Université de Genève, Switzerland) et al.
(12). This chapter also describes systematically and
comprehensively the various modelling approaches
to elucidate ageing mechanisms and their possible
predictions. The author also discusses the newly
developed transient, multi-scale and multi-physics
single cell model MEMEPhys® (13) and emphasises
the need to generate representative accelerated testing
methods in the fi eld.
Finally, Volume 1 ends with Chapter 12 entitled
‘Experimental Monitoring Techniques for Polymer
Electrolyte Membrane Fuel Cells’. This chapter
describes the various techniques and methods
employed for on-line and off-line logging, monitoring
and diagnosis of important fuel cell parameters (for
example, temperature, humidity, current distribution,
local pressure distribution and pressure drop) during
operation.
Volume 2: “In Situ Characterization Techniques for Low Temperature Fuel Cells”Volume 2 consists of three parts: Part I entitled
‘Advanced Characterization Techniques for Polymer
Electrolyte Membrane and Direct Methanol Fuel
Cells’, Part II entitled ‘Characterization of Water
and Fuel Management in Polymer Electrolyte
Membrane and Direct Methanol Fuel Cells’ and Part
III entitled ‘Locally Resolved Methods for Polymer
Electrolyte Membrane and Direct Methanol Fuel
Cell Characterization’. I thoroughly enjoyed reading
Volume 2 as it covers comprehensively the important
and main (in situ) techniques and methods currently
employed in characterising in detail MEA and MEA
subcomponents (fuel cell electrocatalyst, catalyst
layer, membrane and gas diffusion medium) as
well as water and fuel management. It would have
been very useful to have included a summary table
showing the in situ and ex situ characterisation
techniques which help to elucidate the degradation
mechanisms for all MEA components and water
and fuel management (including extended X-ray
absorption fi ne structure (EXAFS), IL-TEM, three-
dimensional (3D)-TEM, in situ X-ray tomography
(XRT), small angle X-ray scattering (SAXS), X-ray
adsorption near edge structure (Δμ XANES),
neutron radiography, neutron tomography, magnetic
resonance imaging, synchrotron radiography,
Raman spectroscopy, scanning electron microscopy
(SEM) and laser optical methods).
ConclusionsThis two-volume set presents a fairly comprehensive
and detailed review of low-temperature PEMFCs and
DMFCs and their in situ characterisation methods
by reviewing in detail their fundamentals and
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142 © 2013 Johnson Matthey
performance as well as advanced in situ spectroscopic
techniques for their characterisation. I was impressed
by the content and breadth of this detailed work. There
are of course already books available covering similar
areas and there is some duplication between chapters
(for example, fuel cell descriptions), but this does not
detract from the overall experience. The book set also
highlights the key challenges for the commercialisation
of PEMFC-based systems, mainly related to life cycle
analysis of the overall systems and global research
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
6 “PEM Fuel Cell Electrocatalysts and Catalyst Layers: Fundamentals and Applications”, ed. J. Zhang, Springer-Verlag London Ltd, Guildford, Surrey, UK, 2008
7 A. El-kharouf and B. G. Pollet, ‘Gas Diffusion Media and Their Degradation’, in “Polymer Electrolyte Fuel Cell Degradation”, eds. M. M. Mench, E. C. Kumbur and T. N. Veziroglu, Elsevier Inc, Waltham, Massachusetts, USA, 2012, pp. 215-247
8 P. J. Hamilton and B. G. Pollet, Fuel Cells, 2010, 10, (4), 489
9 K. J. J. Mayrhofer, S. J. Ashton, J. C. Meier, G. K. H. Wiberg, M. Hanzlik and M. Arenz, J. Power Sources, 2008, 185, (2), 734
10 T. E. Springer, T. A. Zawodzinski and S. Gottesfeld, J. Electrochem. Soc., 1991, 138, (8), 2334
11 D. M. Bernardi and M. W. Verbrugge, J. Electrochem. Soc., 1992, 139, (9), 2477
12 O. Antoine, Y. Bultel and R. Durand, J. Electroanal. Chem., 2001, 499, (1), 85
13 A. A. Franco, ‘A Physical Multiscale Model of the Electrochemical Dynamics in a Polymer Electrolyte Fuel Cell – An Infi nite Dimensional Bond Graph Approach’, PhD Thesis, Université Claude Bernard Lyon-1, France, 2005
The ReviewerBruno G. Pollet FRSC recently joined Hydrogen South Africa (HySA) Systems Competence Centre at the University of the Western Cape as Director and Professor of Hydrogen and Fuel Cell Technologies. Pollet has extensive expertise in the research fi elds of PEMFC, fuel cell electrocatalysis and electrochemical engineering. Website: http://www.hysasystems.org/
“Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology”, Volumes 1 & 2
•Platinum Metals Rev., 2013, 57, (2), 143–147•
143 © 2013 Johnson Matthey
Kunming–PM’20125th 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*
Johnson Matthey Moscow Offi ce, Ilyinka 3/8, Building 5, Offi ce 301, 109012 Moscow, Russia
*Email: piskum@matthey.com
Carol Chiu**
Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH, UK
**Email: carol.chiu@matthey.com
The 5th international biennial conference in the series
“Platinum Metals in the Modern Industry, Hydrogen
Energy and Life Maintenance of the Future” was held
from 15th to 19th October 2012, in Kunming, China.
The conference was organised by the Kunming
Institute of Precious Metals under the patronage of
the International Organisation “Professor Ye. I. Rytvin
Foundation” and with the support of the Non-Ferrous
Metals Society of China and OJSC Supermetal, Russia.
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 MicroparticlesProfessor 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
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144 © 2013 Johnson Matthey
with commercial Pd black as well as unique optical
and photothermal effects. One of the proposed
applications is in near infrared photothermal cancer
therapy. Many other types of pgm nanostructures have
also been synthesised by the CO adsorption method,
such as tetrapod nanocrystals, nanocubes and
octapods. In the oxidation of ethanol, the activity of Pt
octapods was measured to be four times higher than
Pt black or Pt on carbon.
Professor Xudong Sun (Northeastern University,
Shenyang, China) presented a paper on ‘Controllable
Synthesis of Dispersed Precious Metal Powders’ which
reviewed achievements and problems related to
preparation of dispersed precious metals powders
by chemical reduction, more specifi cally synthesis
of various morphologies, such as monodispersed
spheres, single crystalline particles and nanowires.
In addition to nanoparticles, microparticles of silver,
gold, silver-palladium alloy, ruthenium and tungsten
also have a wide range of commercial applications,
such as electrode pastes and catalysts. Microparticles
have two representative categories, dispersed
crystalline particles and monodispersed spherical
particles. Formation of dispersed crystalline particles
is explained by the LaMer model (Figure 1) which
assumes that nucleation and growth are separate. By
adjusting the nucleation rate, the resulting particle sizes
can be controlled. The nucleation rate is controlled
by the pH while agglomeration is avoided by a high
stabiliser concentration. Monodispersed spherical
particles are formed by nucleation and growth to
subunits from a supersaturated solution, followed
by aggregation of the subunits into monodispersed
spheres. The aggregation of primary particles is affected
by changes in the ionic strength or pH. The presenter
concluded that research on structure control of noble
metal microparticles is at least as important as that on
the corresponding nanoparticles.
Tatjana Buslaeva (Lomonosov Moscow University
of Fine Chemical Technology, Russia) presented
joint work with the University of Eastern Finland
on ‘The Synthesis of Catalytic Systems Based
on Nanocomposites Containing Palladium and
Hydroxycarbonates of Rare-Earth Elements’. For this
work yttrium and cerium hydroxycarbonates were
used as the support and Pd nanoparticles were
directly reduced from solution. Nanocomposites
Pd/Y(OH)CO3 and Pd/Ce(OH)CO3 were synthesised
using two methods: (a) simultaneous production
of a nanoscale substrate and immobilisation of Pd
nanoparticles on its surface; or (b) prior synthesis
of polyvinylpyrrolidone stabilised Pd nanoparticles
followed by their immobilisation on the nanosized
substrate surface. The new systems synthesised
demonstrated high conversion effi ciency and can be
used for homogeneous catalyst production.
Applications of the Platinum Group Metals Professor Zhuangqi Hu (Institute of Metal Research
of the Chinese Academy of Sciences, Shenyang,
China) explained the role of Ru in nickel-based single
crystal superalloys. Over the last few years there has
been increasing research on superalloy materials
due to their high mechanical strength and oxidation
resistance at elevated temperatures. Ni-based
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
of superalloys is the third generation single crystal. By
adding a refractory element, such as rhenium, strength
is enhanced. However, over addition or segregation
of Re causes topologically close packed (tcp) phase
precipitation which damages the continuity of the
microstructure, promotes crack initiation and leads
to a decrease in strength of the superalloy. To prevent
this, tests were made with Ru-free alloy and with
alloys containing 1.5% and 3% Ru additions. Cast
microstructure, structural evolution, tensility and
rupture properties and oxidation behaviour were
studied. It was noted that the addition of Ru suppressed
tcp phase formation and hence improved the creep
properties, so that Ru-containing superalloys could be
used even under higher temperature conditions. There
Critical limiting supersaturation
Rapid self-nucleation
Growth Solubility
Time
Cmax
Cmin
CsConc
entr
atio
n
I II III
Fig. 1. LaMer model of dispersed crystalline particle formation (Cmax = maximum concentration for nucleation, Cmin = minimum concentration for nucleation, Cs = concentration for solubility, I = prenucleation period, II = nucleation period, III = growth period) (Image courtesy of Professor Xudong Sun, Northeastern University, China)
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145 © 2013 Johnson Matthey
was a strengthening effect on tensility, but no obvious
effect on stress rupture life, and a weakening effect on
heat/corrosion resistance. A higher oxidation rate was
also observed when the Ru-containing superalloys
were heated to 1000ºC or 1100ºC. The conclusion was
that in future Ru might play an important commercial
role in such superalloys.
Professor Yizhou Zhou (Institute of Metals Research
of the Chinese Academy of Sciences, Xi’an, China)
presented a paper entitled ‘Effects of Platinum on
the Micro-Segregation Behaviour and Phase Stability
in Nickel-Base Single Crystal Superalloys’. In addition
to the work on Ru discussed above, Pt has also
been examined as a potential alloying addition to a
third generation single crystal superalloy. However,
experimental work on such materials has shown
that the incipient melting point, solidus and liquidus
temperatures are decreased. Pt segregates to the
interdendritic region and intensifi es the segregation
of refractory elements such as Re and tungsten.
Formation of a tcp phase is also promoted under
extended thermal exposure at 1100ºC. Although Pt
additions enhance tensile strength at high temperature,
it is unable to enhance rupture life. It was concluded
that Pt additions to single crystal superalloys do not
have a benefi cial effect on phase stability.
Professor Guang Ma (Northwest Institute for Non-
Ferrous Metal Research, China) spoke on the topic of
Pd alloy membranes in hydrogen energy. Hydrogen
is an alternative energy source which could reduce
our dependence on fossil fuels in the future. For
many commercial applications hydrogen must be
purifi ed and the use of Pd-based alloy membranes
for purifi cation is very attractive. Pd-rare earth alloys
have improved hydrogen permeability compared to
other alloys used for this purpose (1). This is because
the rare earth elements not only expand the Pd lattice
but also readily adsorb hydrogen onto the membrane
surface. Hydrogen separation rates increase with
hydrogen permeability of the membrane. Improved
mechanical strength, heat resistance and hydrogen
diffusion rates, as well as the development of low cost
manufacturing routes, are seen as important research
and development targets for Pd-based hydrogen
separation membranes.
Wei Li (General Motors, USA) reported on such
issues as catalyst deactivation due to pgm sintering
and poisoning, recent trends in the use of pgms in
diesel catalysts (in particular the diesel oxidation
catalyst (DOC), lean NOx trap (LNT) and diesel
particulate fi lter (DPF)), different factors affecting
catalyst performance, and the impact of future global
emissions regulations on pgm usage in automotive
emissions control catalysts.
Junjun He (Sino-Platinum Metals Co Ltd, China)
presented a review of the metal–support interaction
in automotive catalysts. The support can improve the
dispersion of Pt, Pd and Rh and suppress the sintering
of the pgms at high temperatures. The pgms can also
enhance the redox performance and oxygen storage
capacity of the support. The presentation reviewed the
reaction phenomena and mechanism of pgms and
supports such as Al2O3 and CeO2-based composite oxides.
Vitaly Parunov (Moscow State University of
Medicine and Dentistry, Russia) made a report on the
biocompatibility of different denture materials based
on research carried out amongst 109 patients. The noble
metal-based alloys Plagodent and Palladent (fabricated
by Supermetal, Russia) showed the best results when
compared to other types of metal-based materials.
PGM Refi ning TechnologiesJoseph L. Thomas (Metals Recovery Technology Inc
(MRTI), USA) explained MRTI’s commercial precious
metal recovery technologies. Recently, four different
types of pgm-containing waste feedstock have been
treated:
(a) Pd was recovered from various supported Pd
catalysts (100–5000 ppm Pd) by chlorine leaching.
After addition of chlorine and polyamine resin, a
Pd-loaded polyamine composite resin (2) was
produced, while other metals (e.g. Ni, copper
and iron) remained in solution. The capacity
was 20 Mt per batch with a fi ve day cycle and a
recovery rate of 99% Pd.
(b) Pt, Pd or gold were recovered from Cu alloys
containing these metals. After adding Cu metal
to Pt, Pd or Au ores or spent catalysts, the mixture
was melted by induction to give the Cu alloy.
Then sodium chloride and chlorine gas were
added. The dissolved precious metals were then
reduced to insoluble solids and separated from
the solution.
(c) Pd, Pt, rhodium and Au were recovered from
spent autocatalysts. The reaction again involved
the addition of chlorine together with resin to
the autocatalysts. Only Pd, Pt, Rh and Au were
absorbed onto the resin while other metals,
including Group I and Group II chalcogens
and other transition metals, were not. The
metal resins were then burned to yield metal of
98–99% purity.
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146 © 2013 Johnson Matthey
(d) The pgms were recovered from a complex
mixture of pgms and other transition metals. The
pgms were refi ned using a substituted quaternary
ammonium salt (2) giving more than 99.9% pgm
recovery with a typical purity of 99.97% to 99.99%
in six days. The procedure relied on precipitation,
fi ltration and washing and did not involve ion
exchange or solvent extraction. This is based
on the fact that only pgms will precipitate with
tetramethylammonium chloride. The reagent may
be recycled after use.
Professor Jinhui Peng (Kunming University of
Science and Technology, China) reviewed the recovery
of pgms from secondary resources using microwave
technology. This is believed to be more effi cient,
energy-saving and environmentally friendly than
conventional metallurgical process. Three different
approaches were discussed:
(a) Microwave-assisted leaching improved the yield
and process time for the recovery of pgms from
spent catalysts. After microwave heating at 600ºC
for 60 minutes, the leaching effi ciencies of Pd and
Rh were 99.8% and 97.4%, respectively (3).
(b) Microwave pyrolysis was used to recycle pgms
from waste printed circuit boards. The waste
circuit boards were initially crushed into small
pieces and microwave heated to decompose
organic compounds. Subsequent heating to
1100ºC allowed the pgms to be separated and
recovered.
(c) Microwave augmented ashing was used to reduce
the length of time required for the activation
process for recovery of Pt and Rh from scrap
fi rebricks from the glass industry.
Although microwave assisted pgm recovery was
still at the laboratory stage, it has potential to be a
next generation pgm refi ning technology due to its
environmental benefi ts.
Market Trends and the PGM IndustryMikhail Piskulov (Johnson Matthey Moscow,
Russia) reported on recent trends in industrial pgm
applications. It was noted that industrial applications
play an important role in the pgm markets,
accounting for 25–30% of the gross total demand for
Pt and Pd and close to 100% for such minor pgms
as Ru and Ir. In the last 10 years industrial demand
has been on the increase over the entire pgm range.
However, there is a constant need for new research
and development to fully explore and develop new
areas which can benefit from the unique properties
of pgms.
Alexander Andreev (Ekaterinburg Non-Ferrous
Metals Processing Plant, Russia) outlined in his paper
the role of Russia in the global pgm markets and the
problems faced by Russian exporters due to internal
regulations. Andreev estimates that in 2011, the
Russian share of global pgm supply amounted to 13%
(26 tonnes) Pt, 47% (108 tonnes) Pd and 8.9% (2.12
tonnes) Rh. However, the Russian share of world pgm
trade was much lower. The discrepancy was explained
by a lack of metal trading activities in Russia, compared
to the European and Asian markets, largely due to
concentration of demand (end users for sectors like
electronics and automotive) in these regions, but also
due to issues related to the limitations and shortcomings
of Russian customs and currency regulations.
Mariya Goltsova (Donetsk National Technical
University, Ukraine) presented the ‘Hydrogen
Civilization (HyCi) Doctrine’, which describes a vision
of sustainable development, starting with a gradual
change to the use of hydrogen energy, followed by
a more integrated hydrogen economy and fi nally
what the HyCi doctrine calls a ‘hydrogen civilisation’.
The authors anticipate that this will lead to global
transformation in all aspects of life, society, the
environment and industrial development.
Jurgen Leyrer (Umicore AG & Co, Belgium) outlined
Umicore’s ‘Process Exellence Model’ for the special
glass and chemical industries. Umicore defi nes
process excellence as any achievement related to Pt
components before, during or after use in a customer’s
production process. They claim to offer cost savings,
for example by reductions in pgm inventory and pgm
losses in operation and during refi ning, reduction
of Rh requirements, energy and raw materials and
increase in the service time of pgm components.
Liudmila Morozova (Supermetal) made a
presentation on this Russian fabricator’s pgm product
manufacturing activities. The company has been
active for 50 years, and for the last 25 years it has
been fabricating equipment for the production of
high-quality glass and monocrystals as well as other
pgm products for technical and medical applications.
They use pyrometallurgical processing of scrap with
high pgm content, which allows scrap alloys to be
refi ned without dealloying, substantially accelerating
processing time and reducing costs. They also use
electrophysical fabrication technologies to produce
dispersion strengthened materials (DSMs) based
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147 © 2013 Johnson Matthey
on Pt and its alloys with Rh. DSMs allow the use of
manufacturing techniques such as rolling, stamping,
drawing and welding, while the heat resistance of
DSMs (as measured by the creep rate and long-term
strength under operational temperatures and stresses)
is tens of times higher than that of traditional Pt-Rh
alloys. Laminar composite materials (LCM) combine
the properties of regular Pt-Rh alloys with the improved
heat resistance and thermal stability of DSMs. In
combination with a new technology for producing
solid stamped bushing base plates, bushings can be
made 20–30% lighter with increased service life. The
company also manufactures thermocouple wire and
catalyst systems and catchment packs for the nitric
acid industry.
Pavel Khorikov (Krasnoyarsk Non-Ferrous Metals
Plant, Russia) reported on the company’s fabrication
of bushings and other glass making manufacturing
units. The current bushing production range is
200–4000 tips. Materials include dispersion stabilised
Pt10Rh DS. They also make combination bushings,
where a bushing body manufactured from Pt20Rh
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
products for the glass industry made by the company
was in excess of 160 kg.
Conclusions
A number of pgm topics were covered during
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
the world’s leading platinum consuming country
(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.
References1 G. Ma, J. Li, Y. Li, X. Sun, Q. Cao and Z. Jia, Precious Met.
(Chin.), 2012, 33, (S1), 208
2 J. L. Thomas and G. F. Brem, Metals Recovery Technology Inc, ‘Process for Recovery of Precious Metals’, US Patent 7,935,173; 2011
3 S. Wang, J. Peng, A. Chen and Z. Zhang, Precious Met. (Chin.), 2012, 33, (S1), 33
4 J. Butler, “Platinum 2012 Interim Review”, Johnson Matthey, Royston, UK, 2012
5 Precious Met. (Chin.), 2012, 33, (S1), 1–304
The ReviewersDr Mikhail Piskulov is General Manager of Johnson Matthey Moscow, Russia, where he is involved in market analysis, sales and new business development. Dr Piskulov graduated from Moscow State University of International Relations with a degree in International Business. Before joining Johnson Matthey in 1993, he worked for the USSR Ministry of Foreign Trade. He holds a PhD in Economics, obtained in 2002, on the competitive advantages of foreign direct investment for the receiving country.
Carol Chiu works in Technology Forecasting and Information at Johnson Matthey Technology Centre. She specialises in the provision of technical and commercial information to Johnson Matthey businesses in Asia. Since she joined Johnson Matthey in 2011, she has worked on many different projects involving usage of pgms in the region.
“Precious Metals Blue Book” 《贵金属蓝皮书》
http://dx.doi.org/10.1595/147106713X666561 •Platinum Metals Rev., 2013, 57, (2), 148–150•
148 © 2013 Johnson Matthey
BOOKS“Applied Cross-Coupling Reactions”
Edited by Y. Nishihara (Department of Chemistry, Okayama University, Japan), Series: Lecture Notes in Chemistry, Vol. 80, Springer-Verlag, Berlin, Heidelberg, Germany, 2013, 245 pages, ISBN: 978-3-642-32367-6, £90.00, €106.95, US$129.00
Since the discovery of transition
metal-catalysed cross-coupling
reactions in 1972, various synthetic
uses and industrial applications have been developed.
Cross-coupling reactions catalysed by pgms such
as palladium can produce natural products,
pharmaceuticals, liquid crystals and conjugate
polymers for use in electronic devices. The Nobel
Prize in Chemistry 2010 was awarded jointly to
Richard F. Heck, Ei-ichi Negishi and Akira Suzuki “for
palladium-catalyzed cross couplings in organic
synthesis”. In this book, recent trends in synthesis
and catalytic activities of transition metal catalysts,
mainly palladium, for cross-coupling reactions
are presented.
“How to Invent and Protect Your Invention: A Guide to Patents for Scientists and Engineers”
J. P. Kennedy (The University of Akron, USA), W. H. Watkins with E. N. Ball (University of Akron Research Foundation, USA), John Wiley & Sons, Inc, Hoboken, New Jersey, USA, 2012, 248 pages, ISBN: 978-1-1183-6937-1 (Paperback), £40.50, €48.60, US$59.95
This book is based on lecture notes
developed over twenty-fi ve years at
The University of Akron, USA. It provides a clear, jargon-
free and comprehensive overview of the patenting
process tailored specifi cally to the needs of scientists
and engineers, including:
(a) Requirements for a patentable invention;
(b) How to invent;
(c) New laws created by President Obama’s 2011
America Invents Act;
(d) The process of applying for and obtaining a patent
in the USA and in other countries;
(e) Commercialising inventions and the importance
of innovation.
“Inventing Reactions”Edited by L. J. Gooßen (TU Kaiserslautern, FB Chemie - Organische Chemie, Germany), Series: Topics in Organometallic Chemistry, Vol. 44, Springer-Verlag, Berlin, Heidelberg, Germany, 2013, 354 pages, ISBN: 978-3-642-34285-1, £206.50, €245.03, US$309.00
This book analyses the creative
process associated with some recent
inventions of chemical reactions.
Leading academics describe their
creative solutions to longstanding problems in organic
chemistry. Each chapter provides short overviews of
the context and subsequent developments of their
respective transformations. The book includes a chapter
by Professor Keith Fagnou (posthumously) and David
Stuart (University of Ottawa, Canada) on the discovery
and development of a Pd(II)-catalysed oxidative cross-
coupling of two unactivated arenes.
“Modern Tools for the Synthesis of Complex Bioactive Molecules”
Edited by J. Cossy and S. Arseniyadis (Laboratoire de Chimie Organique, ESPCI ParisTech, Paris, France), John Wiley & Sons, Inc, Hoboken, New Jersey, USA, 2012, 596 pages, ISBN: 978-0-470-61618-5, £100.00, €120.00, US$149.95
Focusing on organic, organometallic
and bio-oriented processes, this book
covers the use of the latest synthetic
tools for the synthesis of complex
biologically active compounds. Innovative methods
are described that make it possible to control the
exact connectivity of atoms within a molecule in
order to set precise three-dimensional arrangements.
Many of the transformations rely on palladium,
rhodium, ruthenium or other pgm catalysts. Chapters
of interest include: ‘C--H Functionalization: A New
Strategy for the Synthesis of Biologically Active Natural
Products’, ‘Metal-Catalyzed C--Heteroatom Cross-
Coupling Reactions’ and ‘Metathesis-Based Synthesis
of Complex Bioactives’.
“Sustainable Preparation of Metal Nanoparticles: Methods and Applications”Edited by R. Luque (Departamento de Química Orgánica, Universidad de Córdoba, Spain) and R. S. Varma (National Risk Management Research Laboratory, US Environmental Protection Agency, USA), RSC Green Chemistry No. 19, The
Publications in Brief
http://dx.doi.org/10.1595/147106713X666561 •Platinum Metals Rev., 2013, 57, (2)•
149 © 2013 Johnson Matthey
Royal Society of Chemistry, Cambridge, UK, 2013, 230 pages, ISBN: 978-1-84973-428-8, £109.99
This book provides the state-of-the-
art as well as current challenges
and advances in the sustainable
preparation of metal nanoparticles
for a variety of applications. For
example, wet chemistry methods
are frequently used for biomedical applications,
while gas phase deposition on solid supports is
commonly employed in the preparation of catalysts
and electrocatalysts. Platinum, palladium, iridium
and ruthenium are featured. Researchers interested
in the green and environmentally safe production of
nanoparticles will fi nd this book useful.
JOURNALSJournal of Environmental Chemical Engineering
Editors: D. Fatta-Kassinos (University of Cyprus, Nicosia, Cyprus), Y. Lee (Gwangju Institute of Science & Technology (GIST), Gwangju, Republic of Korea), T.-T. Lim (Nanyang Technological University, Singapore) and E. C. Lima (Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil); Elsevier; e-ISSN: 2213-3437
The new online-only journal
Journal of Environmental Chemical Engineering
(JECE) from Elsevier focuses on environmental
sustainability in engineering and chemistry. Published
four times per year, JECE will provide a forum for the
publication of original research on the development
of alternative sustainable technologies for water and
wastewater treatment and reuse; treatment, reuse and
disposal of waste; pollution prevention; sustainability
and environmental safety; green chemistry; and
remediation of environmental accidents.
Materials HorizonsEditor: L. Dunn; Royal Society of Chemistry; ISSN: 2051-6347; e-ISSN: 2051-6355
Materials Horizons from the Royal
Society of Chemistry is a new
peer-reviewed journal publishing
primary research on materials
science. Seth Marder (Georgia
Institute of Technology, USA),
chair of the Editorial Board, said “while published by
a chemical society, the journal will seek to serve the
broader materials community by welcoming papers
that cover the gamut of materials research”. It will
include content specifi cally aimed at educating and
engaging younger researchers. Due to launch late in
2013, access will be free until December 2015.
Special Issue: Asymmetric Gold SynthesisChin. J. Chem., 2012, 30, (11), 2601–2725
Asymmetric synthesis, particularly
utilising catalysts, is very
important for providing chiral
compounds in an enantiopure
form. Contributions dealing with
recent progress in homogeneous
asymmetric catalysis are collected
here. This special issue contains 19 selected papers
including: ‘Enantioselective and -Regioselective
Allylic Amination of Morita-Baylis-Hillman Acetates
with Simple Aromatic Amines Catalyzed by Planarly
Chiral Ligand/Palladium Catalyst’, ‘Iridium-Catalyzed
Allylic Alkylations of Sodium Phenyl Selenide’
and ‘Stereoselective Synthesis of Optically Active
Hydrobenzoins via Asymmetric Hydrogenation of
Benzils with Ru(OTf)(TsDPEN)(6-cymene) as the
Pre-catalyst’.
Special Issue: ElectrocatalysisCatal. Today, 2013, 202, 1–210
A number of European universities
(Alicante, Birmingham, Gothenburg,
Leiden, Liverpool and Ulm), one
research institute (Heyrovsky
Ins t i tu te , P rague) and two
companies (Johnson Matthey, UK,
and Permascand, Sweden) were
involved in the EU-funded ‘ELCAT’
network. The aim was to train young researchers
in theoretical and experimental research methods
and to provide theoretical and synthetic tools to
design new electrocatalysts. The collection of papers
in this special issue, many from groups outside the
ELCAT network, refl ects these aims and strategies.
ELCAT: http://www.elcat.org.gu.se/
Special Issue: Fuel Cells 2012 Science & Technology – A Grove Fuel Cell EventEnergy Procedia, 2012, 28, 1–198
The Fuel Cells 2012 Science and Technology
conference took pace in Berlin, Germany, from 11th–
12th April 2012. It included the award of the 2012
Grove Medal to Professor Dr Hubert Gasteiger, Chair
http://dx.doi.org/10.1595/147106713X666561 •Platinum Metals Rev., 2013, 57, (2)•
150 © 2013 Johnson Matthey
of Technical Electrochemistry
at the Technical University
of Munich, Germany. Both as
industrial and university scientist,
Professor Gasteiger has made
remarkable contributions
to the understanding of fuel
cell related electrochemistry
and to the vitally important
task of translating application requirements
into fundamental parameters. His interests
include electrocatalysts for low-temperature
fuel cells and electrolysers as well as materials
degradation mechanisms. Twenty articles from
this conference are included in this special
issue. Fuel Cells 2012 Science & Technology:
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
is an anthology of the topics
addressed over the last fi ve years
of The Netherlands Catalysis and
Chemistry Conference (NCCC). It
refl ects the development of new
or renewed catalysis research
from heterogeneous catalysis, homogeneous catalysis
and biocatalysis. Items of interest include: ‘Pt/Al2O3
Catalyzed 1,3-Propanediol Formation from Glycerol
Using Tungsten Additives’, ‘Stable and Effi cient Pt–Re/
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
[Ru(bpy)3]2+ Persulfate System’.
ON THE WEB2012 Fuel Cell Patent Review
The “2012 Fuel Cell Patent Review” is the second Fuel
Cell Today report on annual fuel cell patent activity. It
analyses both granted patents and patent applications
published in 2011, by comparison with publications
in 2010. The number of granted fuel cell patents
increased by 51% between 2010 and 2011. Fuel cell
patent applications also continue to grow, with a 58%
increase in 2011 versus 2010. The emergence of Asia as
a dominant patenting force has also been identifi ed,
with the World Intellectual Property Organization
observing double-digit growth in applications from
Japan and China. Fuel Cell Today has tracked the
emergence of China as a named country in the fuel
cell patent literature and this is discussed in the 2012
Patent Review.
Find this at: http://www.fuelcelltoday.com/analysis/
patents/2012/2012-fuel-cell-patent-review
Global Emissions Management
Latest issue: Volume 3, Issue 05 (January 2013)
The latest update of Global Emissions Management
(GEM) from Johnson Matthey Emission Control
Technologies includes:
(a) Advanced Emission Control Concepts for Gasoline
Engines;
(b) Renault Awards for Johnson Matthey;
(c) Johnson Matthey Acquires the Axeon Group.
Find this at: http://www.jm-gem.com/
Platinum Today
Platinum Today has been redesigned. Its new
simplifi ed homepage presents easy access to all of
its most frequently visited areas such as prices, news
and publications. An upgraded price charting system
allows comparison pricing between all the platinum
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/
http://dx.doi.org/10.1595/147106713X666895 •Platinum Metals Rev., 2013, 57, (2), 151–153•
151 © 2013 Johnson Matthey
CATALYSIS – APPLIED AND PHYSICAL ASPECTSOn the Key Role of Hydroxyl Groups in Platinum-Catalysed Alcohol Oxidation in Aqueous MediumS. Chibani, C. Michel, F. Delbecq, C. Pinel and M. Besson, Catal. Sci. Technol., 2013, 3, (2), 339–350
In the aerobic selective oxidation of alcohols in
aqueous medium in a batch reactor, the addition of
H2O to dioxane solvent (10–50 vol%) substantially
increased the activity of a Pt/C catalyst. Periodic
DFT calculations were performed to compare the
reactivity of alcohols on the bare Pt(111) surface and
in the presence of adsorbed H2O or OH groups. The
calculations were found to indicate that the presence
of adsorbed OH groups promotes catalytic activity by
participating directly in the catalytic pathways and
reducing the activation barrier. Decarbonylation of
acetaldehyde at 373 K is thought to be the cause of
deactivation of the catalyst.
Recyclable Pd-Incorporated Perovskite-Titanate Catalysts Synthesized in Molten Salts for the Liquid-Phase Oxidation of Alcohols with Molecular OxygenI. B. Adilina, T. Hara, N. Ichikuni, N. Kumada and S. Shimazu, Bull. Chem. Soc. Jpn., 2013, 86, (1), 146–152
Pd-incorporated titanate catalysts (Pd/KSTO) were
prepared by the intercalation of Pd(NO3)2 into layered
potassium titanate (KTO), which proceeded via a
cation-exchange reaction in molten salts. Perovskite
phases of Pd/KSTO were obtained at 600ºC and above,
whereas a lepidocrocite-type layered titanate structure,
similar to that of KTO, was retained at 400ºC. The
Pd/KSTO catalysts were then investigated for the
liquid-phase oxidation of alcohols using molecular
O2. The perovskite-type Pd/KSTO catalyst, exhibited
superior activity, giving a high TON of 800 in the
aerobic oxidation of 1-phenylethanol with no loss of
catalytic activity after three runs.
CATALYSIS – INDUSTRIAL PROCESSApplication of Precious Metal Catalysts in Drug SynthesisQ. Meng, Q. Ye, W. Liu and Y. Wang, Precious Met. (Chin.), 2012, 33, (3), 78–82
Supported pgm catalysts (e.g. Pd/Al2O3, Pd/C, Pd-Co/C
and Ru/C) with high activity and high selectivity are
widely used in the pharmaceutical as well as the fi ne
chemicals industry. The application of these catalysts
in drug synthetic reactions including coupling,
hydroformylation, hydrogenolysis, hydrosilylation,
isomerisation and transfer hydrogenation is described.
(Contains 25 references.)
CATALYSIS – REACTIONSAqueous Phase Transfer Hydrogenation of Aryl Ketones Catalysed by Achiral Ruthenium(II) and Rhodium(III) Complexes and Their Papain ConjugatesN. Madern, B. Talbi and M. Salmain, Appl. Organomet. Chem., 2013, 27, (1), 6–12
Ru and Rh complexes having 2,2-dipyridylamine
ligands substituted at the central N atom by an
alkyl chain terminated by a maleimide functional
group were evaluated along with a Rh(III) complex
of unsubstituted 2,2-dipyridylamine as catalysts
in the transfer hydrogenation of aryl ketones in
H2O with formate as hydrogen donor. All of the
complexes except one led to secondary alcohol
products. Site-specifi c anchoring of the N-maleimide
complexes to the single free cysteine residue of
the cysteine endoproteinase papain endowed this
protein with transfer hydrogenase properties towards
2,2,2-trifl uoroacetophenone.
EMISSIONS CONTROLEffect of Barium Sulfate on Sulfur Resistance of Pt/Ce0.4Zr0.6O2 CatalystY. Zheng, Y. Zheng, Y. Xiao, G. Cai and K.-M. Wei, Catal. Commun., 2012, 27, 189–192
BaSO4-doped ceria zirconia (CZ) solid solution
was prepared using a coprecipitation method. The
synthesised samples were used as supports for
preparing Pt catalysts. BaSO4 was evenly distributed
in the irregular mesoporous structure of the CZ.
Furthermore, the addition of BaSO4 to the CZ improved
Abstracts
NO2
N N
NH2
N N
+ [H] Pd/C
Q. Meng et al., Precious Met. (Chin.), 2012, 33, (3), 78–82
http://dx.doi.org/10.1595/147106713X666895 •Platinum Metals Rev., 2013, 57, (2)•
152 © 2013 Johnson Matthey
the desorption of sulfur species under a reducing
atmosphere, which could decrease the accumulation
of sulfur species in the catalyst. The sulfur poisoning
resistance of the catalyst was thereby improved.
FUEL CELLSPlatinum Catalysts Supported on Nafi on Functionalized Carbon Black for Fuel Cell ApplicationF. Luo, S. Liao and D. Chen, J. Energy Chem., 2013, 22, (1), 87–92
A Pt/Nafi on functionalised C black catalyst was
characterised by IR spectroscopy, TEM and XRD. TEM
showed that the active Pt component was in the form
of NPs and highly dispersed on the carbon black. The
catalyst showed improved activity towards methanol
anodic oxidation and the ORR, resulting from the high
dispersion of the active Pt component. The catalyst
produced an increase in the electrochemically
accessible surface area and ion channels, as well
as easier charge-transfer at the polymer/electrolyte
interface.
Three-Dimensional Tracking and Visualization of Hundreds of Pt−Co Fuel Cell Nanocatalysts during Electrochemical AgingY. Yu, H. L. Xin, R. Hovden, D. Wang, E. D. Rus, J. A. Mundy, D. A. Muller and H. D. Abruña, Nano Lett., 2012, 12, (9), 4417–4423
A 3D tomographic method for tracking the trajectories
and morphological changes of individual Pt-Co
nanocatalyst particles on a fuel cell C support, before
and after electrochemical ageing via potential sweeps,
was developed. The growth in the Pt shell thickness
and observation of coalescence in 3D are proposed
to explain the decrease in electrochemically
active surface area and the loss of activity of
Pt-Co nanocatalysts in PEMFC cathodes. Along with
atomic-scale EELS imaging, the experiment enables
the correlation of catalyst performance degradation
with changes in particle/interparticle morphologies,
particle–support interactions and the near-surface
chemical composition.
SiO2–RuO2: A Stable Electrocatalyst SupportC.-P. Lo and V. Ramani, ACS Appl. Mater. Interfaces, 2012, 4, (11), 6109–6116
High surface area SiO2–RuO2 (SRO) supports
were obtained using a wet chemical method. Pt
NPs were deposited on their surface. The optimal
1:1 mol ratio of SiO2–RuO2 (SRO-1) had a BET
surface area of 305 m2 g–1 and an electrical
conductivity of 24 S cm–1. SRO-1 demonstrated
10-fold higher electrochemical stability than Vulcan
XC-72R C when subjected to an aggressive accelerated
stability test. The mass activity of Pt-doped SRO-1 was
54 mA mgPt–1, whereas its specific activity was
115 μA cmPt–2. The fuel cell performance obtained
with this catalyst was lower, but compared
favourably against commercial Pt/C.
APPARATUS AND TECHNIQUEPreparation of Pd–Pt Co-Loaded TiO2 Thin Films by Sol-Gel Method for Hydrogen Gas SensingS. Yanagida, M. Makino, T. Ogaki and A. Yasumori, J. Electrochem. Soc., 2012, 159, (12), B845–B849
Pd-, Pt- and Pd–Pt-loaded TiO2 thin films were
prepared and their respective capabilities as H2
gas combustion sensors were investigated. H2 gas
sensing was assessed at 300ºC by measuring the
sample resistance under H2 gas (3%–100%) and
air flow conditions. The Pd–Pt step-by-step loaded
sample showed higher sensitivity than either the Pd
or Pt single-loaded sample for H2 concentrations
of less than 30 vol%. STEM revealed its structure:
Pt fine particles deposited selectively on the Pd
particles predeposited on the TiO2 surface.
ELECTROCHEMISTRYA Kinetic Description of Pd Electrodeposition under Mixed Control of Charge Transfer and DiffusionM. Rezaei, S. H. Tabaian and D. F. Haghshenas, J. Electroanal. Chem., 2012, 687, 95–101
The electrodeposition of Pd from an aqueous
solution containing PdCl2 (0.001 M) and H2SO4
(0.5 M) was studied by CV and potentiostatic current-
time transients (CTTs). From the polarisation curves,
regions corresponding to charge transfer control,
mixed control and diffusion control were identifi ed.
In the mixed control region, the CTTs results suggested
processes involving adsorption, the ion transfer
reaction and 3D progressive nucleation with mixed
charge transfer-diffusion controlled growth. The
analysis of CTTs at short times was performed with
the model proposed by Milchev and Zapryanova.
The reduction reaction of Pd(II) Pd(I), as an ion
transfer reaction, occurs before the formation of the
Pd nucleus.
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153 © 2013 Johnson Matthey
PHOTOCONVERSIONPorous, Platinum Nanoparticle-Adsorbed Carbon Nanotube Yarns for Effi cient Fiber Solar CellsS. Zhang, C. Ji, Z. Bian, P. Yu, L. Zhang, D. Liu, E. Shi, Y. Shang, H. Peng, Q. Cheng, D. Wang, C. Huang and A. Cao, ACS Nano, 2012, 6, (8), 7191–7198
A Pt NP-adsorbed C nanotube yarn was obtained by
solution adsorption and yarn spinning processes, with
uniformly dispersed Pt NPs throughout the porous
nanotube network. TiO2-based dye-sensitised fi bre
solar cells with a Pt--nanotube hybrid yarn as counter
electrode were fabricated. A power conversion
effi ciency of 4.85% under standard illumination
(AM1.5, 100 mW cm–2) was achieved, comparable to
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 TransferR. 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 RECOVERYSelective Recovery of Precious Metals from Acidic Leach Liquor of Circuit Boards of Spent Mobile Phones Using Chemically Modifi ed Persimmon Tannin GelM. 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
for the acidic leach liquor of PCBs from spent mobile
phones.
In Situ Platinum Recovery and Color Removal from Organosilicon StreamsH. Bai, Ind. Eng. Chem. Res., 2012, 51, (50), 16457–16466
The recovery of Pt from organosilicon hydrosilylation
streams is a potential source of cost savings. Here in situ
fi xed-bed adsorption technology was demonstrated
to be effective for Pt recovery and product colour
removal. With the in situ Pt recovery process and
using a functionalised silica gel scavenging material,
a Pt recovery >90% was achieved both from silane
distillation heavy wastes (with initial Pt concentration
of ~50 ppm) and from organosilicon products (with
initial Pt concentration of ~5 ppm).
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154 © 2013 Johnson Matthey
CATALYSIS – APPLIED AND PHYSICAL ASPECTSPalladium-Gold CatalystLyondell Chemical Technology, US Appl. 2012/0,302,784
A Pd-Au catalyst is prepared by the following method:
(a) mixing TiO2, a carboxyalkyl cellulose and a
hydroxyalkyl cellulose to form a dough; (b) extruding
the dough to produce an extrudate; (c) calcining
the extrudate to produce a calcined extrudate; (d)
impregnating the calcined extrudate with Pd and Au
compounds to produce an impregnated extrudate;
and (e) calcining the impregnated extrudate to
produce the Pd-Au catalyst. This catalyst is used in
producing vinyl acetate by oxidising ethylene with
oxygen in the presence of acetic acid.
CATALYSIS – REACTIONSReusable Hydroformylation CatalystUmicore AG & Co KG, World Appl. 2012/163,831
A novel process for producing 4-hydroxybutyraldehyde
is claimed, where an allyl alcohol is reacted in polar
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)-
cyclobutanes, 1, where R1 is alkyl, preferably methyl,
ethyl or propyl; R2 is H or an alkoxy group; R3 and R4,
independently of one another, are H, CH2OR1, CH2O-
aralkyl, CH2OH, CH2-[P(3,5-R1,R1-4-R2-phenyl)2], or
CH2O-(CH2-CH2-O)m-H; where m is 1–1000. The
hydroformylation takes place in a membrane reactor
and the catalyst used is separated off from the reaction
mixture, optionally after adding water, by extraction
with hydrophobic solvents and is reused.
R3 CH2-[P(3,5-R1,R1-4-R2-phenyl)2]
CH2-[P(3,5-R1,R1-4-R2-phenyl)2]R4
World Appl. 2012/163,831
1
Catalyst for Alkylation of Aromatic CompoundsStamicarbon BV, European Appl. 2,540,691; 2013
A method for the alkylation of an aromatic
compound involves the aromatic compound making
contact with an alkane of 1–12 C atoms at 200–500ºC,
preferably 320–400ºC, in the presence of a catalyst
composition consisting of a catalytically active metal
selected from Pt, Pd, Rh, Os, Ir, Ru or a combination
and a promoter metal, e.g. Zn, on a zeolite support. The
molar ratio of the promoter metal to the catalytically
active metal is between 0.01 and 5, preferably
between 0.1 and 0.5.
Catalyst for Naphtha ReformingOOO Nauchno-Proizvodstvennaya Firma, Russian Patent 2,471,854; 2013
A catalyst for reforming gasoline fractions comprises
(in wt%): 0.1–1.0 Pt; 0.1–1.0 Cl; 0.5–3.9 zeolite; 1–2
amorphous Al2SiO5; -Al2O3; and optionally 0.1–0.5
Re. Al(OH)3 powder is mixed with zeolite, this mixture
is peptised with 0.5–20% organic acid, e.g. citric acid,
it is then granulated, heat treated at 630–700ºC and
this is followed by the addition of Pt in the form of
an aqueous solution of chloroplatinic acid and
chlorine in the form of HCl. The catalyst is then
dried and annealed.
EMISSIONS CONTROLPlatinum Group Metal CatalystJohnson Matthey Plc, World Appl. 2012/170,421
A catalyst for treating exhaust gas consists of an
aluminosilicate molecular sieve comprising crystals
with a porous network and at least one pgm with the
majority of the selected pgm embedded in the porous
network relative to the pgm disposed on the surface
in a ratio of ~4:1 to ~99:1. The catalyst comprises
~0.01–10 wt% pgm relative to the weight of the
molecular sieve and the crystals have a mean
crystalline size of ~0.01–10 μm. A method for treating
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
portion of NH3 at ~300ºC–650ºC.
Cold Start CatalystJohnson Matthey Plc, US Appl. 2012/0,308,439
A cold start catalyst consists of: (a) a zeolite catalyst
comprising a base metal, a noble metal and a zeolite;
Patents
http://dx.doi.org/10.1595/147106713X664644 •Platinum Metals Rev., 2013, 57, (2)•
155 © 2013 Johnson Matthey
and (b) a supported pgm catalyst comprising one or
more pgms and one or more inorganic oxide carriers.
The noble metal is selected from Pt, Pd, Rh or a
mixture. The zeolite catalyst and the supported pgm
catalyst are coated onto a fl ow-through substrate in an
exhaust system.
Three-Way Catalyst Microwave DryingX. 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
of its internal pores with a catalyst slurry which
contains H2O, composite Al2O3, CeO2-ZrO2 oxygen
storage material and Pd or Rh. The catalyst slurry
coated support is then introduced through
microwave devices and dried at 1400–2500 MHz
microwave to have a water content <7%. The
advantages of the microwave drying technique
include rapid heating speed, high production
efficiency, good working environment, reduced
energy consumption and an increase of catalytic
performance of the catalyst.
FUEL CELLSNanostructured Platinum CatalystAtomic Energy and Alternative Energies Commission, World Appl. 2013/017,772
The process for producing a catalyst PtxMy for PEMFC,
where M is a transition metal selected from Ni, Fe, Co
and Cr, involves: (a) deposition of PtxMy nanostructures
on a support by sputtering; (b) annealing the
nanostructures at 600–1200ºC preferably for 1 h; and
(c) depositing a layer of PtxMy onto the surface of the
nanostructures; and (d) then leaching the metal M.
The catalyst is made with Pt3Ni. The support is the
GDL and the thickness is preferably 200 μm.
Microbial Fuel CellGwangju Institute of Science and Technology, US Appl. 2012/0,315,506
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
which accommodates electrochemically active
microorganisms and an ion exchange membrane is
interposed between the two electrodes. The cathode
consists of a carbon electrode treated with Pt, Pd, Os
or Ru. The unit cells are arranged vertically and are
electrically connected to each other in series through
a conductive fi lm to form a module.
Platinum-Rhodium CatalystTokuyama Corp, Japanese Appl. 2013-037,891
A Pt-Rh catalyst for DMFCs consists of a ratio of
0.10–2.00 mol Rh to 1 mol Pt. The catalysts show a high
MeOH oxidation current at a low voltage in an alkaline
environment. Electrodes containing the title catalysts
can be bonded to anion-exchange membranes and
used in MEAs.
METALLURGY AND MATERIALSBlack Fire Retardant Silicone RubberShanghai University of Engineering Science, Chinese Appl. 102,643,552; 2012
A black fi re retardant silicone rubber is prepared
with (in wt%): 50–60 vinyl- or allyl-capped silicone
rubber; 5–10 hydrogen-containing polysiloxane; 0.1–
0.3 soluble Pt catalyst; and 29.7–44.9 fi re retardant
which is a mixture of carbonised residue of waste tyre
pyrolysis and (NH4)2HPO4. The method of preparing
the black fi re retardant silicone rubber involves adding
the carbonisation residue of waste tyre pyrolysis and
(NH4)2HPO4 into the vinyl- or allyl-capped silicone
rubber, stirring, adding the hydrogen-containing
polysiloxane and the Pt catalyst, stirring, ball milling,
vacuum air exhausting and fi nally curing at 20–40ºC.
MEDICAL AND DENTALPalladium Braze Boston Scientifi c Neuromodulation Corp, US Patent 8,329,314; 2012
An implantable microstimulator comprising a component
assembly housing which consists of a ceramic part, a
metal part selected from Ti and Ti alloys and a Pd interface
layer is claimed. The interface layer comprises Pd which
is combined with a portion of one or both of the metal
part or the ceramic part, forming a bond between the
two parts and further comprising an electrode contact. A
second Pd interface layer bonds the electrode contact to
the ceramic part of the component assembly housing.
REFINING AND RECOVERYSeparation of Pure OsmiumThe Curators of the University of Missouri, World Appl. 2013/020,030
A process for separating Os including from an
irradiated Os-191 mixture, involves: (a) the mixture is
put into contact with an aqueous solution of NaClO at
a concentration of ~12% available Cl2 to form a volatile
http://dx.doi.org/10.1595/147106713X664644 •Platinum Metals Rev., 2013, 57, (2)•
156 © 2013 Johnson Matthey
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 COATINGSElectroless Plating of IridiumJapan 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.
157 © 2013 Johnson Matthey
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FINAL ANALYSIS
NOx Emissions Control for Euro 6
The control of oxides of nitrogen (NOx) emissions to
meet more stringent motor vehicle emission legislation
has been enabled by the development of various
exhaust gas aftertreatment technologies, notably those
that employ platinum group metals (pgms).
Technology DevelopmentsFor gasoline engines the most common aftertreatment
for the control of NOx, as well as the other major
regulated pollutants, carbon monoxide (CO) and
unburnt hydrocarbons (HCs), is the three-way
catalyst (TWC). This technology was developed
in the late 1970s (1). It allows the oxidation of CO
and HC over platinum-palladium or just palladium
during lean (excess oxygen) conditions to form
carbon dioxide and water, while rhodium performs
the reduction of NOx to N2 under rich (oxygen
depleted) conditions. This technology relies on
the engine operating around the stoichiometric
point (air:fuel ratio of 14.7:1) where maximum
simultaneous reduction of NOx and oxidation of
CO and HCs can take place. Emissions standards
for European gasoline vehicles which have been in
force since 2009 (2) specify NOx emissions must not
exceed 0.06 g km–1 (Table I), a limit that is met by
TWC technology.
For diesel engines, which operate under lean
conditions, NOx is harder to deal with. Previous
diesel vehicles used advanced engine technologies
to signifi cantly lower NOx emissions. For example,
exhaust gas recirculation (EGR) is used to recirculate
a proportion of the exhaust gas back into the engine
cylinders to reduce the cylinder temperature during
combustion and thereby reduce formation of NOx.
A disadvantage of this method is that it increases
emissions of particulate matter (PM). Tighter
PM limits have now been enforced across many
jurisdictions and are met by using a pgm-coated
diesel particulate fi lter (also known as a catalysed
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, g km–1
Number of 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 modelsb 2013.01 for all modelsc Applicable only to vehicles using direct injection enginesd 0.0045 g km–1 using the particulate measurement proceduree 6.0×1012 km–1 within fi rst three years from Euro 6 effective dates
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158 © 2013 Johnson Matthey
New Legislation Challenges New legislation in force for European heavy-duty
diesel vehicles from 2013, light-duty diesels from
2014 and some non-road diesel engines from 2014
requires a further reduction of NOx emissions.
As shown in Table I, NOx emissions for light-duty
diesel passenger cars reduce from the current Euro
5 limit of 0.18 g km–1 to the Euro 6 limit of 0.08 g km–1
from 2014. PM emissions are already regulated
to the extremely low level of 0.005 g km–1 by the
current Euro 5 legislation. The development of fuel
effi cient lean-burn gasoline engines also presents
new challenges – NOx levels typically generated in
the engine cylinder, whilst lower than conventional
gasoline engines, are nevertheless still well above
the Euro 6 limits and therefore some form of catalytic
aftertreatment is required.
The two leading catalyst technologies used to
remove NOx in a lean-burn engine to meet the above
legislation are lean NOx trap (LNT) or selective
catalytic reduction (SCR). LNT catalysts remove NOx
from a lean exhaust stream by oxidation of NO to NO2
over a platinum catalyst, followed by adsorption of
NO2 onto the catalyst surface and further oxidation
and reaction with metal species incorporated in the
catalyst, for example barium, to form a solid nitrate
phase. Once the catalyst is fi lled with the solid
nitrate phase, the engine is then run rich for a short
period to release the NOx from its adsorbed state.
The released NOx is then converted during the rich
period to N2 over a rhodium catalyst. SCR systems use
a platinum-based diesel oxidation catalyst (DOC)
or a combination of a DOC and a platinum-based
CSF to oxidise a proportion of the NOx into NO2 and
remove HC/CO. A NOx reductant, usually in the form
of aqueous urea, is then injected into the exhaust gas
after the oxidation catalyst and the NO/NO2 mixture
is then selectively reduced over the downstream SCR
catalyst.
The decision whether to use LNT or SCR on a
vehicle involves many factors. SCR requires space
on the vehicle to fi t the urea tank and dosing system,
which is less of a constraint on heavy-duty and larger
light-duty vehicles. Furthermore, the need to run
the engine rich for LNT systems is more technically
demanding for larger engines so LNT systems are
more suited to smaller light-duty vehicles. SCR
systems are impractical for use on gasoline vehicles
as their NOx output is signifi cantly higher than from
diesel, and hence unfeasibly large urea tanks would
be required.
The FutureNOx and other pollutant levels emitted from vehicles
are assessed by use of a standardised driving cycle
for Europe. The current driving cycle which is used
to measure emissions from light-duty vehicles may be
changed in the future to include an even wider range
of driving conditions, for example further extended
low speed driving conditions such as common in
congested city driving or much higher speed driving
conditions than used in the current drive cycle.
For diesel LNTs the future challenge is to maximise
NOx conversion at low speed driving conditions as
well as providing high NOx conversion during high
speed driving. For diesel SCR systems, the future
challenge is also to boost NOx conversion when
the engine is operating at very low speeds. This low
speed challenge may be helped by moving the SCR
closer to the engine where it can benefi t from higher
temperatures, but there are space and system layout
considerations. There is currently a good deal of
research ongoing into diesel powertrain optimisation
for a wide range of driving scenarios.
The proposed enforcement of a particulate number
limit (3) for gasoline engines in Europe also presents
challenges by requiring control of PM to extremely
low levels in addition to keeping emissions of other
pollutants at minimal levels. One possibility is to use a
fi lter coated with similar material to a TWC as part of
the overall aftertreatment system.
For gasoline engines, new on-board diagnostic limits
that come into force at Euro 6 part 2 in 2017 (3) reduce
by 70% the threshold amount of NOx emitted before
the driver is notifi ed of a problem with the catalyst.
Some manufacturers are therefore looking at ways of
further improving the durability of catalysts, including
by increasing the relative loadings of rhodium. Due to
the excellent NOx reduction capability of rhodium, it
may be possible to substitute palladium with small
quantities of rhodium to give a cost- and performance-
optimised system.
ConclusionsThere remains a good deal that can be done on
controlling NOx emissions from vehicles using pgms.
As regulations tighten, cover more vehicle types and are
adopted by more jurisdictions around the world, greater
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159 © 2013 Johnson Matthey
use of pgm-containing emissions control systems can be
anticipated. Good progress has been made on the control
of NOx from gasoline engines and developments are
being made on lowering NOx emissions from diesels to
meet upcoming emissions limits.
JONATHAN COOPER* and PAUL PHILLIPS**
Johnson Matthey Emission Control Technologies, Orchard Road, Royston, Hertfordshire SG8 5HE, UK
Email: *jonathan.cooper@matthey.com; **paul.phillips@matthey.com
References 1 B. Harrison, B. J. Cooper and A. J. J. Wilkins, Platinum
Metals Rev., 1981, 25, (1), 14
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 from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information (Text with EEA relevance)’, The
European Parliament and the Council of the European Union, Offi cial Journal of the European Union, L 171/1, 29th June, 2007
3 ‘Commission Regulation (EU) No 459/2012 of 29 May 2012 amending Regulation (EC) No 715/2007 of the European Parliament and of the Council and Commission Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) (Text with EEA relevance)’, The European Commission, Offi cial Journal of the European Union, L 142/16, 1st June, 2012
The AuthorsJonathan Cooper is Gasoline Development Manager at Johnson Matthey Emission Control Technologies and has over 13 years’ experience in global gasoline aftertreatment systems research at Johnson Matthey. He holds a degree and DPhil in Chemistry from the University of Oxford, UK.
Paul Phillips is European Diesel Development Director at Johnson Matthey Emission Control Technologies. He has 17 years’ experience at Johnson Matthey aiding the development of emission control systems. Paul has a BSc in Chemistry and a PhD in Organometallic Chemistry from the University of Warwick, UK.
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EDITORIAL TEAM
Jonathan ButlerPublications Manager
Sara ColesAssistant Editor
Ming ChungEditorial Assistant
Keith WhitePrincipal Information Scientist
Email: jmpmr@matthey.com
Platinum Metals Review is Johnson Matthey’s quarterly journal of research on the science and technologyof the platinum group metals and developments in their application in industry
http://www.platinummetalsreview.com/
www.platinummetalsreview.com
Platinum Metals ReviewJohnson Matthey PlcOrchard Road RoystonSG8 5HE UK
%: +44 (0)1763 256 325@: jmpmr@matthey.com
Editorial Team
Jonathan Butler Publications Manager
Sara Coles Assistant Editor
Ming Chung Editorial Assistant
Keith White Principal Information Scientist