Platinum Metals Review - Volume 32, Issue 4, 1988

There is a growing recognition of the opportunities that may exist for inorganic biochemistry to contribute to the solution of practical problems that occur in many quite different areas, ranging from mineral extraction to medicine. While most traditional applications of the platinum metals depend upon their ability to remain largely unchanged in highly reactive environments, compounds of these metals can be quite reactive and do react with biological materials. This paper reviews the present position and indicates potential applications.

The rhodium catalysed hydroformylation reaction is one of the most widely used industrial applications of homogenous catalysis to employ platinum group metals. Potential limitations in the application of this technology to molecules which are heat sensitive or have high boiling points are the stability of the catalyst and the ability to separate the catalyst from the products. A means of circumventing these limitations is described. This involves locating the catalyst in an aqueous liquid phase, and it enables viable reaction rates to be achieved at moderate temperatures and pressures.

Work on the electrolytic deposition of platinum and some platinum alloys is reviewed, and the results of our recent work on the deposition and the properties of the layers produced from some promising electrolytes are briefly discussed. In general, studies of plating solutions are restricted by the economic availability of the relevant platinum salts. On the other hand the hydrolysis of the platinum salts in solution, and the incorporation of decomposition products are also critical factors, especially for their influence on internal stress. Recent work has shown that it is possible to deposit platinum-cobalt alloys which have excellent magnetic and mechanical properties, and these alloy deposits look very promising for data storage applications and for small permanent magnet layers.

Molten carbonate fuel cells have the potential to succeed phosphoric acid fuel cells as systems for large scale electrical power generation. Their introduction, however, will depend on the wide acceptance of first generation phosphoric acid technology and on solutions being found to a number of significant technical problems, including corrosion of fuel cell components by the molten carbonate electrolyte. Ruthenium, rhodium, palladium, platinum, silver and gold have all been shown to exhibit resistance to corrosion by molten carbonates under the conditions experienced at the anode of a molten carbonate fuel cell. In addition, rhodium and ruthenium are not wetted significantly by the molten carbonate electrolyte.