CONVERSION OF METHANE WITH CARBON-DIOXIDE INTO C-2 HYDROCARBONS OVER METAL-OXIDES

Conversion of methane with carbon dioxide has been performed over seventeen metal oxides using a flow reaction system at 1123 K. The conversion ratio of carbon dioxide to methane is approximately two in most cases, Ethane and ethene (C-2 hydrocarbons) are formed over many oxides, and C-2 yield is higher over yttrium and manganese oxides. Rare earth catalysts such as yttrium, lanthanum, and samarium show higher C-2 selectivities of about 30%. C-2 selectivity is almost unchanged over yttrium and zirconium oxides during reaction while it decreases over samarium oxide. X-ray diffraction analysis reveals that some oxides such as manganese and iron oxides are reduced during reaction. The reaction mechanism for C-2 formation is discussed in terms of both adsorbed oxygen species dissociated from carbon dioxide and the lattice oxygen in metal oxides.