CATALYTIC COMBUSTION OF METHANE

Palladium-based catalysts have been found to be the most efficient cat alysts for the catalytic oxidation of methane to carbon dioxide and wa ter. The catalytic oxidation is dependent on factors such as the oxyge n:methane feed ratio, the loading of precious metal on the support, th e nature of the support, the particle size of the precious metal and t he extent and nature of catalyst pretreatment. The reaction rate is fo und to be dependent on methane concentration, generally to the first o rder or less. The dependence of rate on oxygen pressure is found to de pend on the operating conditions. Because of overheating as a result o f high conversions of methane, chemical kinetics are often affected by mass and heat transfer. Deactivation of the catalyst can involve sint ering or poisoning. The thermal stability of the catalyst is strongly dependent on the support and the extent of overheating induced by oxid ation of methane. Sulphur oxides deactivate most noble metal catalysts with the exception of platinum.