Kinetics of methane oxidation over La-Sr-Ce-Fe-O mixed oxide solids

A kinetic study of methane combustion over La0.7Ce0.3FeO3, La0.7Sr0.3FeO3 and La0.7Sr0.1Ce0.2FeO3 mixed oxide solids has been carried out. From kinetic analyses of reaction rate, the combustion can be expressed by the Rideal-Eley mechanism, in which adsorbed oxygen, in dissociative form, is assumed to react with gaseous methane. True activation energies E-true in the range 63-75 kJ mol(-1), and heats of adsorption of oxygen lambda (O2), in the range 53-211 kJ mol(-1), have been determined. The large values of lambda (O2), are related to existence of a SrFeO3+x perovskite crystal phase, which is able to uptake large amounts of oxygen.