A comparative study of substituted perovskite-type solids of oxidic La1−xSrxFeO3±δ and chlorinated La1−xSrxFeO3±δClσ form: Catalytic performance for CH4 oxidation by O2 or N2O

A comparative study between two groups of substituted perovskite-type solids, one oxidic and another chlorinated with general formulas La1−xSrxFeO3±δ and La1−xSrxFeO3±δClσ (x=0.0,0.4,0.6x=0.0,0.4,0.6 and 0.8), was carried out for the oxidation of CH4 by O2 and N2O. For stoichiometric feeding compositions CH4:O2 = 1:2 and CH4:N2O = 1:4, the catalysts were active in the temperature range 400–760 °C. The oxidic solids were more active than the chlorinated ones. Catalysts of both groups, containing Sr, exhibited a drop in activity for the above reactions, related to an increased amount of desorbed oxygen from the solids. The amount of desorbed oxygen is linearly correlated with the Fe4+ content in the solid. The lower activity of the chlorinated samples can be attributed to a poisoning effect by chlorine, the quantity of which was estimated using proper deactivation kinetics.