A mechanistic study on the oxidative coupling of methane over lithium doped magnesium oxide catalysts

To elucidate the importance of various reaction steps in the oxidative convers ion of methane, experiments were carried out with three reaction products: ethane, ethylene and carbon monoxide. These products were studied seperately, in oxidation experiments with and without a catalyst. Moreover , the effect of admixing them to a methane/oxygen feed was investigated. All experiments were carried out in a micro flow tubular quartz reactor, which was empty or filled with catalyst. The temperature was 800 C. The ethane and ethylene experiments have learnt that: - ethane to ethylene convers ion is much more rapid than ethane combustion, irrespective of the presence of a catalyst. The main path of combustion leads via ethylene -ethane is converted much more rapid than methane. This imposes serious constraints to maximum attainable yields. - The principal combustion product in absence of a catalyst is CO. With a catalyst C02 is dominating. This agrees well with the rapid catalytic oxidation observed with CO/02 feeds. The conclusions can be summarized in a simplified overall reaction scheme.