Ce-promoted Mn/Na_2WO_4/SiO_2 catalyst for oxidative coupling of methane at atmospheric pressure

A series of Ce-promoted Mn-Na_2WO_4/SiO_2 catalysts were prepared by incipient wetness impregnation method,and their catalytic performance for oxidative coupling of methane(OCM)was investigated at atmospheric pressure in a micro-quartz-tube reactor.The catalysts were characterized by X-ray diffraction(XRD),temperature program reduction(TPR)and BET surface area.Ce promoter increased surface area and Na_2WO_4 species dispersion,which enriched the amount of the surface species.In addition,Ce promoter increased the Na/W species reduction,but the reduction peak shifted to higher temperature.Stability test of 5wt%Ce catalyst indicated suitable performance and stability.The selectivity and yield of C_(2+) hydrocarbons after 50 h operation reached 65.5% and 19.6%,respectively,at 840℃ over 5wt%Ce-2wt%Mn-5wt%Na_2WO_4/SiO_2 catalyst.