Among items appearing in this issue are the following:

The last in a series of papers on catalysis for low temperature fuel cells, from Johnson Matthey scientists, is published in this issue. The direct methanol fuel cell (DMFC) is powered by methanol - a convenient transportable fuel - and operates at temperatures of 30 to 130°C. These features are often cited in identifying the DMFC as the ideal fuel cell system. In this paper, Martin Hogarth and Tom Ralph of the Johnson Matthey Technology Centre compare various aspects of the DMFC with those of the hydrogen-fuelled proton exchange membrane fuel cell (PEMFC) and describe work undertaken to improve the materials of the electrocatalysts and membrane electrode assemblies. Although the improved DMFC is still less efficient than the PEMFC, the improvements have much enhanced its performance and make its commercial use more feasible. Some sizes and operating parameters of the DMFC for portable use are also considered.

The Eighth International Conference on the Chemistry of the Platinum Group Metals, held at the University of Southampton in July 2002, is reviewed by Professor John Evans of the University of Southampton. Included in the wide range of topics covered at the conference were: organometallic chemistry; coordination and supramolecular chemistry; biological and medicinal chemistry; surfaces, materials and crystal engineering; photochemistry and electrochemistry; and catalysis and organic syntheses. Reviews written by the joint winners of the Student Competition: Matt Hall of the University of Sydney, Australia, and Gareth Owen of Imperial College, London, are also included.

The hydrogen economy continues to create interest, based on the benefits of using hydrogen as the main fuel. Storing hydrogen is, however, a concern. One storage method is to absorb the hydrogen into a metal that will ‘hold’ it until it is required. Palladium is well known to have excellent hydrogen storage properties and a capacity for frequent reuse. Clearly it is important to understand the processes that occur in palladium as hydrogen is taken in, stored and then emitted. These issues are considered in a paper by V. M. Avdjukhina, A. A. Katsnelson and G. P. Revkevich of Moscow State University, Russia, who examine the responses, in terms of structural changes and phase transformation kinetics, that take place in palladium, palladium-tungsten and palladium-erbium on repeated use. The changes appear to occur in stages and the materials have been observed over periods of up to tens of thousands of hours. Thermodynamic and hydrogen interactions between matrix defects and atoms in the palladium systems are proposed to explain the phenomena.

Professor Grant Cawthorn, the Platinum Industry’s Professor of Igneous Petrology at the University of the Witwatersrand, South Africa, reviews the 9th International Platinum Symposium, which was held in Billings, Montana, U.S.A., in July 2002. These meetings are primarily intended for the exchange of geological information and ideas, with less emphasis being placed on mining, metallurgy, and extraction. Professor Cawthorn also describes the various routes by which the platinum metals came to be located in the earth.

The high quality optical perfection now expected in the glass used for LCD screens and in high-quality glassware requires glass producers to be very confident of their glass-making equipment. Molten glass is highly corrosive and damaging to furnace refractory ceramics and other glass-making equipment, which traditionally have been protected by sheet claddings of platinum and platinum alloys. As these are costly, Johnson Matthey developed thermally deposited ACT^TM coatings, which evolved to cope with progressively more arduous conditions. Now, a further enhancement to the platinum coatings called Power Coatings^TM is described by Paul Williams of Johnson Matthey Noble Metals, Royston, U.K. Power CoatingsTM involves electrical resistance heating of ACT^TM platinum coated systems, and the glass contained by it. The system gives enhanced responsiveness, accurate temperature control and high power capability.

Three short items give a flavour of the way that platinum catalyst materials are presently being combined with polymers and the new effects, new materials and possible uses that can be obtained.

A long-lasting pink glow was recently seen - electrically induced phosphorescence - when a team of researchers in Germany (from Mainz and Potsdam) and Austria (from Graz and Weiz) switched off the voltage while testing a newly synthesised poly(para-phenylene) ladder-type polymer. They had expected to see a short-lived blue-green fluorescence. The polymer was found to contain (~ 80 ppm) palladium left over from the catalyst. It is thought that the palladium atoms, which are bound to the polymer backbone, are responsible for this new effect.

Researchers at Texas A & M University, U.S.A., have developed a homogeneous metal-polymer catalyst that is soluble in supercritical carbon dioxide solvent. They synthesised a fluoroacrylate copolymer, then attached a homogeneous rhodium catalyst to its backbone. Catalyst hydrogenation activity was evaluated using 1-octene and cyclohexene at different temperatures and molar ratios of substrate:rhodium. The synthesis route for this rhodium-polymer catalyst is reproducible.

Scientists from the Chinese Academy of Sciences, Beijing, and Hong Kong Polytechnic University describe synthesising dendritic Ru-BINAP catalysts that are peripherally alkyl-functionalised. The catalysts can be used for asymmetric hydrogenation in an ethanol/hexane reaction medium. Phase separation is induced by a small amount of water. The hexane catalyst-containing layer can be removed for reuse.

The issue also contains a selection of abstracts of the most recently published literature and patents and the annual Name and Subject Indexes.

Platinum Metals Review is available on the internet from the publications section of the Platinum Today site or from the host site Ingenta Select.

Susan V. Ashton
Editor

Anyone with an active interest in the platinum group metals and their uses who does not have ready access to a copy of Platinum Metals Review and who may benefit from reading it, is invited to request a specimen copy from:

The Editor, Johnson Matthey PLC, Orchard Road, Royston, Hertfordshire SG8 5HE, United Kingdom; Fax +44 (0) 1763 256359; Email jmpmr@matthey.com