win德赢

Abstract: Oxidative coupling of methane (OCM) is one of the most promising approaches to produce ethylene and ethane (C2-hydrocarbons) in the post-oil era. The MnOx-Na2WO4/SiO2 system shows promising OCM performance, which can be further enhanced by cofed steam. However, the positive effect of steam on C2-hydrocarbons selectivity practically disappears above 800 °C. In the present study, we demonstrate that the use of SiC as a support for MnOx-Na2WO4 is beneficial for achieving high selectivity up to 850 °C. Our sophisticated kinetic tests using feeds without and with steam revealed that the steam-mediated improvement in selectivity to C2-hydrocarbons is due to the inhibition of the direct CH4 oxidation to carbon oxides because of the different enhancing effects of steam on the rates of CH4 conversion to C2H6 and CO/CO2. Other descriptors of the selectivity improvement are MnOx dispersion and the catalyst specific surface area. The knowledge gained herein may be useful for optimizing OCM performance through catalyst design and reactor operation.