LAUSR

Abstract The effects of Mn/Na2WO4, Li, and CaO loading on the monoclinic Sm2O3 catalyst were investigated for the oxidative coupling of methane using O2 or N2O as an oxidant. The catalysts were prepared by wet impregnation method and characterized by XRD, BET, CO2-TPD, and XPS analysis. Impregnation of Mn/Na2WO4 on monoclinic Sm2O3 resulted in the formation of Sm2−xMnxO3 phase, decreasing the catalytic performance. Li impregnation increased the C2 selectivity but decreased the catalytic activity. The SmLiO2 formation increased the catalytic activity and selectivity. High amounts of CaO impregnation increased the C2 selectivity of monoclinic Sm2O3 without a loss in catalytic activity. 6Li/m-Sm2O3 were found unstable due to the Li loss from the catalyst. The 15CaO/m-Sm2O3 was quite stable and showed 8.2% ethylene yield with N2O use, much higher than that was obtained with the well-known 2Mn/5Na2WO4/SiO2 and 4Li/MgO catalysts. N2O was more selective than O2 as an oxidant and enhanced ethylene formation.