Double perovskite oxides Sr2Mg1-xFexMoO6-δ for catalytic oxidation of methane

The double perovskite oxides Sr2Mg1-xFexMoO6-δ were investigated as catalysts for the methane oxidation. The structural properties of catalysts were characterized in detail by X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The catalytic property was strongly influenced by the Fe substitution. The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides. The Fe-containing catalysts exhibited higher activity attributable to the possible (Fe2+, Mo6+) and (Fe3+, Mo5+) valency pairs, and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ. The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.