Catalytic activity of perovskite-type doped La0.08Sr0.92Ti1−xMxO3−δ (M = Mn, Fe, and Co) oxides for methane oxidation

Transition metal doped La0.08Sr0.92M0.20Ti0.80O3−δ (M = Mn, Fe, and Co) perovskite oxides were synthesized by the Pechini method. The methane oxidation behavior and the polarization resistance of the solid oxide fuel cells (SOFCs) with the perovskite oxides as anode was subsequently measured as a function of operation temperature. Surface atomic concentrations of the perovskite oxides were evaluated using X-ray photoelectron spectroscopy (XPS) and their relationship to the catalytic activity were discussed with respect to the transition metal dopant. The complete oxidation of methane was predominant in the low-temperature region, while the partial oxidation of methane occurred at high temperatures. Fe- and Co-doped perovskites showed better catalytic activity for the methane oxidation reaction than Mn-doped powder. This phenomenon could be explained by the high atomic concentration with low oxidation states and the resulting high oxygen vacancy concentration in the Fe- and Co-doped perovskite powder samples.