A mechanistic kinetic model for oxidative coupling of methane over Li/MgO catalysts

Abstract

A detailed mechanistic model has been developed to describe the methane oxidative coupling network over Li/MgO catalysts. The mechanism assumes that methane and other hydrocarbon species react directly from the gas phase with surface active oxygen centres (Eley- Rideal representation). The surface network comprises parallel and sequential elementary steps describing the following chemical processes: 1] hydrocarbon dehydrogenation, 2] non-selective partial oxidation of hydrocarbon species, 3] catalyst dehydration, 4] gaseous oxygen adsorption and active centre regeneration, 5] catalyst poisoning by carbon oxides, and 6] carbon monoxide oxidation. The surface kinetic parameters were estimated on the basis of scaling arguments and published experimental data. The surface network is combined with a homogeneous methane oxidation mechanism thus resulting in a detailed kinetic model which can account for the observed conversion levels and hydrocarbon product distributions.