Reactivity and characterization of adsorbed oxygen on SrTi1-xMgxO3-δ catalysts for oxidative coupling of methane

Abstract

The reactivity of oxygen species adsorbed on SrTi_1-xMg_xO_3-δ catalysts with methane was investigated. Temperature programmed desorption of oxygen, temperature programmed surface reaction of methane, and electron spin resonance were used for the characterization of oxygen species. It is suggested that the adsorption site is formed by the substitution of Ti⁴⁺ in Sr–Ti perovskite-type oxides with added Mg²⁺. It was found that this oxygen species was able to convert methane to ethane at a temperature as low as 550 K. Without CO₂ on the surface, C₂ hydrocarbons were formed with high selectivity in the CH₄+O₂ reaction. On the other hand, CO and CO₂ were formed on the catalyst with CO₂ pre-adsorption.