INVESTIGATION OF REACTIVITY AND SELECTIVITY OF METHANE COUPLING CATALYSTS USING ISOTOPE EXCHANGE TECHNIQUES

The relationship between the activity and selectivity of four metal oxide catalysts for the oxidative coupling of methane has been compared with their basicity and their ability to effect the scission of C-H and O-O bonds. The rates of isotope exchange reactions (CH4-D2 and O-16(2-) O-18(2)) were used as a measure of catalyst's ability to activate both reactants. It is demonstrated that catalysts showing high C2 selectivity in the oxidative coupling reaction activate methane strongly and oxygen weakly. The lack of direct correlation between the rates of methane conversion and bonds' activation indicates that the formation of the methyl radical cannot be explained by a simple, one-step mechanism.