Platinum Metals Review - Volume 8, Issue 2, 1964

The high catalytic activity exhibited by some of the platinum group metals, together with their excellent resistance to corrosion, form the basis of their applications in fuel cells. In this article the author describes the use of these metals in cells fuelled by hydrogen/oxygen, ammonia, hydrazine and hydrocarbons. The kinetics of the electro-chemical oxidation of hydrocarbons are examined, a mechanism of electrode poisoning is discussed, and finally the author comments on the likely usage of platinum metals in fuel cell technology.

This paper has been written to provide a framework for the observed facts relating to the reactions between platinum and oxygen at temperatures up to the melting point. A thin film of feebly -stable solid platinum oxide is believed to form on platinum surfaces in air or oxygen at room temperatures and to thicken as the temperature is raised to about 500°C, when it decomposes. The loss of weight of platinum at higher temperatures is attributed to the formation of gaseous PtO2, and deposition of platinum on cooler surfaces (above about 500°C) to its disproportionation. A succeeding paper will deal with the oxidation of the other platinum metals.

In the electrodeposition of rhodium from the sulphate bath normally employed highly stressed deposits are produced. In this paper the author describes an investigation of the effects of contamination by organic compounds contained in masking paints on these stresses, and shows that the results of earlier studies on internal stress may have been vitiated by the employment of a method relying on such paints for masking one side of the cathode. An apparatus completely avoiding the use of paint was designed in the course of the present investigation, and an improved paint, giving markedly less contamination and lower stresses in the deposit, was formulated for use in commercial rhodium plating practice.

It has been shown in a previous article in this journal that the hitherto little studied metals ruthenium and osmium possess catalytic activities which are comparable with those of the other noble Group VIII metals for the hydrogenation of the n-butenes, buta-1,3-diene and acetylene. Further studies have now been made using alumina-supported ruthenium and osmium catalysts for the hydrogenation and deuteration of dimethylacetylene and for the deuteration of ethylene and acetylene. Some of the results from these more recent studies are given in this article and the catalytic properties of ruthenium and osmium are discussed in relation to their position in the periodic table.