Abstract
The effects of CO2, steam, C2H6, and C2H4 partial pressures on oxidative methane coupling over a Li/MgO catalyst were studied under low conversion conditions in a fixed bed catalytic reactor. CH4:O2 ratios from 0.5 to 35 and temperatures from 973 K to 1073 K were used in the experiments and modeling. Results indicate CO2 has a poisoning effect on both COx and C2 formation rates, while selectivity to the C2 hydrocarbon was not significantly affected. Rate expressions rigorously derived from proposed mechanisms were obtained. The rate expressions agree well with the measured rates and predict well the high conversion experimental results under various reaction conditions. Results also indicated that addition of H2O to the feed enhanced the deactivation rate. The deactivation rate increased with increasing PH2O in the feed, and/or with increasing temperature. The deactivation rate was decreased by adding small amounts of CO2 to the reaction mixture. Results indicate that both CH4 conversion and C2 selectivity decrease with increasing C2H6 and C2H4 partial pressures in the feed.