Perovskite catalysts for oxidative coupling of methane improved by Y-doping

Oxidative coupling of methane (OCM) is an effective route for methane direct conversion to ethylene. Perovskite oxides (ABO(3)) with variable properties are potential catalysts for OCM by adjusting the compositions. In this study, four perovskite catalysts, BaMO3-delta and BaM1-xYxO3-delta (M = Zr, Ce; x = 0.2), were prepared by the sol-gel method to explore their catalytic performance of OCM. All catalysts are active toward OCM and reach the highest catalytic performance at 800 degrees C. The OCM performance of Ce-based catalysts is higher than that of Zr-based catalysts. The selectivity of C-2 compounds is significantly improved by Y-doping. At CH4/O-2 mol ratio of 8, a C-2 selectivity of 67% was achieved on BaCe0.8Y0.2O3-delta. Compared with Zr-based catalysts, more amounts of active oxygen species, which are beneficial to OCM, were observed on BaCeO3-delta and BaCe0.8Y0.2O3-delta. Meanwhile, higher contents of moderate and strong basic sites, which are beneficial to OCM, were found on the Y-doped catalysts. This is attributed to the generation of oxygen vacancies caused by Y-doping in the B-site. Therefore, BaCe0.8Y0.2O3-delta with more active oxygen species and stronger basicity exhibits the highest performance among the four catalysts.