OXIDATIVE COUPLING OF METHANE AT 600-DEGREES-C ON CANIK OXIDE CATALYSTS

We are herewith reporting new data which modifies, explains and extends our earlier work on this subject. Previous observations of low CH4 conversion and high selectivity to C2 hydrocarbons were erroneous due to the formation of bulk CaCO3 in the catalyst. The carbonate was detected by powder X-ray diffraction and was shown to accumulate during the reaction and decompose during regeneration. Catalytic runs which incorporated an internal standard revealed a deficit in the C balance consistent with carbonate formation. Actual CH4 conversions were almost-equal-to 20% with almost-equal-to 15% selectivity to hydrocarbons. The effect of steam in promoting coupling over combustion was affirmed.