The combustion of methane on platinum—alumina fibre catalysts—I: Kinetics and mechanism

As a part of a study of a convective—diffusive type catalytic combustor, the oxidation of methane has been studied over platinum supported on porous and non-porous alumina fibre. New and used catalysts have been carefully characterised, and the kinetics of the reaction have been measured at temperatures above and below 815 K, where a change in the apparent activation energy was found to occur. Comparison with Langmuir—Hinshelwood models suggests that the mechanism involves the reaction between adsorbed methane and oxygen adsorbed or in the gas phase. This mechanism is supported by the characterisation studies, which also suggest that the formation of carbonaceous intermediates may affect the reaction selectivity. Permanent catalyst deactivation occurs as a result of the sintering of platinum or of alumina; the latter effect is accelerated in the presence of steam.