Single-Site Catalysis of Li-MgO Catalysts for Oxidative Coupling of Methane Reaction

Li-MgO is a typical catalyst for the oxidative coupling of methane (OCM) reaction, one of the most challenging reactions in heterogeneous catalysis. Here, we report that the Li additive restructures MgO to enhance the surface density of the fourfold-coordinated Mg2+ site (Mg-4c(2+)) of MgO{110} facets, eventually leading to Li-MgO catalysts exclusively exposing the Mg-4c(2+) site. Such Li-MgO catalysts were observed to efficiently catalyze the OCM reaction by activating methane into a methyl radical intermediate with minimized further dissociations and consequent combustion reactions. These results demonstrate the presence of efficient single-site catalysis involving Mg-4c(2+) of MgO{110} facets in Li-MgO catalysts with high Li contents for the OCM reaction, which might provide some insights in developing industrially viable OCM catalysts.