Oxidative coupling of methane to C2-hydrocarbons over lithium-cerium-promoted MgO and MgO-CaO catalysts

The oxidative coupling of methane to ethylene and ethane was studied over lithium-cerium-promoted MgO and MgO-CaO catalysts in the presence of molecular oxygen at 730°C and at atmospheric pressure in a continuous flow, fixed bed quartz reactor. The catalysts were prepared by an impregnation method and finally calcined at 900°C. The surface area, pore size distribution and pore volume of the catalysts were determined. The feed consisted of only methane and oxygen in the molar ratio of 2:1. The results obtained over the catalyst systems, viz. (1) lithium-cerium-promoted MgO and (2) lithium-cerium-promoted MgO-CaO, have been compared. A relatively high C 2 -selectivity has been obtained with Li-Ce-promoted MgO-CaO catalysts. The optimum yield and selectivity for C 2 -hydrocarbons were found to be 21.5% and 76.8% respectively at a methane conversion of 28% over Li (7 wt%)-Ce (2 wt%)-doped MgO-CaO (3:1 wt ratio) catalyst. The various factors governing the activity and the selectivity of the catalyst systems have been discussed