The oxidative coupling of methane on Mn/SiO2 and the effect of Solid- and gas-phase doping

The presence of a small quantity of tetrachloromethane in the reactant stream promotes the oxidative coupling of methane over silica-supported alkali-added manganese oxide catalysts. The choice of the alkali metal and of the anion employed to introduce the alkali metal to the catalyst was found to affect considerably the extent of TCM promotion. Mn/SiO2 catalyst heavily doped with Na or K behaves as a promising catalyst for the coupling reaction in the presence of TCM, producing 20–22% yield of C2 hydrocarbons with a selectivity of 75–80%. The formation of an active chlorine species on the surface of the solid is suggested to alter its catalytic properties, which generates a new route, in addition to that occurring in the absence of chlorine species, for the coupling of methane.