Supported lithium tetraborate as a catalyst for the continuous oxidative dehydrogenation of methane

Abstract

Recent work from this laboratory has shown that quite extensive noncatalyzed gas-phase reactions take place between dilute methane and oxygen mixtures in the region 600-720{degree}C. The main products were found to be mostly CO and CO{sub 2}, together with some C{sub 2}H{sub 4} and C{sub 2}H{sub 6}. Since then, other workers have published detailed studies on the gas-phase oxidation of methane, in general agreement with this data. Furthermore, this work showed that one of the catalysts previously studied for this reaction, namely Li{sub 2}CO{sub 3} on MgO, while doubling the amount of C{sub 2}'s formed homogeneously, also oxidized almost all of the homogeneously formed CO to CO{sub 2}. Hence, if a catalyst that would not oxidize CO to CO{sub 2}, while still forming C{sub 2}H{sub 4} and C{sub 2}H{sub 6}, could be found, it would be of considerable importance. The authors have found that lithium tetraborate (LTB) supported on MgO does not oxidize CO, while showing activity for the formation of C{sub 2}'s. To investigate the effect of the support, catalysts have also been prepared using silica and alumina. Results are discussed.