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 a nd La0.7Sr0.1Ce0.2FeO3 mixed oxide solids has been carried out. From kineti c 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 ra nge 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 i s able to uptake large amounts of oxygen.