The catalytic performance of pure, doped, and reduced-doped SrTiO3 perovskite surfaces for oxidative coupling of methane

Abstract

DFT calculations can be a useful support in designing optimal catalysts for the oxidative coupling of methane (OCM) reaction. The capability of the surfaces to activate the methane is tested on pure, Al- or Mg-doped, and reduced Mg-doped SrTiO3(100) surfaces with a triad of parameters. They are generally accepted as robust descriptors of the catalyst performance in the OCM reaction: the C-H dissociation/association for activity, the CH3 adsorption for selectivity, and the oxygen vacancy formation for the reducibility. The results demonstrated a linear correlation between the parameters, even for the reduced doped surface. Comparison with experimental catalytic efficiency reveals the existence of optimal ranges for the CH3 adsorption and oxygen vacancy formation energies. Within these descriptors, the surfaces doped with Al at B-site and Mg at the A-site are shown to be performing catalysts for the OCM reaction. Furthermore, the good experimental performance for the Mg-doped surface at B-site can only be explained only by considering the presence of a percentage of oxygen vacancies (less than 25%) in the starting surface.