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

Abstract

A kinetic study of methane combustion over La_0.7Ce_0.3FeO₃, La_0.7Sr_0.3FeO₃ and La_0.7Sr_0.1Ce_0.2FeO₃ 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 λ_O2, in the range 53–211 kJ mol⁻¹, have been determined. The large values of λ_O2, are related to existence of a SrFeO_3±x perovskite crystal phase, which is able to uptake large amounts of oxygen.