Platinum Metals Rev., 1966, 10, (3), 93
Platinum as a Propane Fuel Cell Electrocatalyst
Comparison with Other Platinum Group Metals
The exceptional activity of the platinum metals as electrocatalysts in low-temperature fuel cells has been noted for some years. Numerous studies have been carried out to examine their behaviour in a variety of systems, and among recent published work in this field have been papers describing platinum black anodes operating in phosphoric acid at 110 to 200°C with hydrocarbon fuels (1, 2).
A more recent comparison of four platinum metals under similar conditions was carried out by W. T. Grubb of the General Electric Company, Schenectady, and confirmed the marked superiority of platinum over palladium, rhodium and iridium (3). The metals were Teflon-bonded to the anode structures in the form of their blacks, and their electrocatalytic performances compared at 150°C in an 85 per cent phosphoric acid electrolyte using propane as fuel. During test runs when hydrogen was employed as the fuel, both platinum and iridium gave very high current densities, exceeding 800 mA/cm2. Using propane, however, platinum proved very much more active than iridium, supporting more than 1000 times the current density although its surface area was substantially lower than that of iridium. Palladium and rhodium gave only marginally better results with propane than iridium.
The fact that the difference in catalytic activities between platinum and iridium is so large in hydrocarbon oxidation, whereas it is much less in the oxidation of hydrogen and other catalytic reactions, is remarkable, particularly in view of the close similarities in electronic and crystal structures of the two metals.
It is assumed that very specific catalytic properties are required for hydrocarbon electro-oxidation in the moderate temperature region.
- 1W. T. Grubb and C. J. Michaelske, J. Electrochem. Soc., 1964, 111, 1015
- 2H. Binder,, A. Kohling and G. Sandstede . Paper presented at the Washington Meeting of the Society, October 1964. Battery Division Extended Abstracts, 1964, 9, 25
- 3W. T. Grubb, J. Electrochem Soc., 1966, 113, ( 2 ), 191