Oxidative Coupling of CH4+CD4 Mixture Over Manganese Oxide Catalysts

Abstract

The oxidative coupling of methane—the major constituent of natural gas—to C 2 hydrocarbons or to transportable liquid hydrocarbon fuel is the subject of catalytic research. The enhancement of the selectivity formation of C 2 -products, mainly ethylene as the more desirable product of methane oxidative coupling over metal oxide catalysts, is a rather difficult problem as the reaction is radical in nature and non-selectivity is inherent in it. Currently, a few reaction routes from CH 4 to C 2 -hydrocarbons are under consideration that involve CH 3 and CH 2 radicals as the primary species. The chapter discusses the composition and structure of isotopic ethanes and ethylenes—the products of oxidative coupling of a CH 4 /CD 4 equimolecular mixture over a complex manganese oxide catalyst to provide mechanistic information about the primary C 2 -hydrocarbons. If only CH 3 and CD 3 radicals are generated in an oxidative coupling of methane (OCM) reaction, the products will have to contain three isotopic (HD) ethanes: (1) H 3 CCH 3 , (2) H 3 CCD 3 , and (3) D 3 CCD 3 , the result of CH 3 and species dimerization. If both CH 3 and CH 2 species are involved in %-hydrocarbon formation, the reaction products will contain full-set deuterated molecules.