Although oxidative coupling of methane (OCM) has been investigated for many years, lack of C2 hydrocarbon yield essentially hinders its practical application. A reaction mechanism involved in the oxidative coupling of methane (OCM) has been long described with oxygen species that are activated on the oxide catalyst surface, which react to subtract one hydrogen from methane molecule, leaving methyl radicals in the gas phase. Recently, the rigorous kinetic measurements found out that a reaction mechanism is consistent with the OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. Consistent with this reaction mechanism and a known gas-phase radical chemistry, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable using Na2WO4/SiO2 which selectively catalyzes the OH-mediated pathway.

Methane coupling reaction in an oxysteam stream via an OH radical pathway

249th National Meeting (2015)

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