Phase states of Li(Na,K,Rb,Cs)/W/Mn/SiO2 composite catalysts for oxidative coupling of methane

Abstract

This survey analyzes the results of studies into Li(Na,K,Rb,Cs)/W/Mn/SiO2 composites, which are used as catalysts for oxidative coupling of methane (OCM). The focus is on phase states. Our analysis shows that the SiO2 matrix is an active constituent of the composites and not an inert carrier of additives and the OCM heterogeneous process involves alkali-metal tungstate melts, along with polycrystalline manganese oxides. The effects of the cation ratio and synthetic routes on the phase composition of Li(Na,K,Rb,Cs)/W/Mn/SiO2 are assessed.