Identification and control of the total oxidation sites in the reaction of oxidative coupling of methane over sulfated lanthana catalysts

Abstract

The addition of potassium sulfate, subject to an optimum content, is proposed as an effective way to improve the catalytic performances of lanthana-based catalysts for the reaction of oxidative coupling of methane. The promoting effect is ascribed to the decrease in the concentration of specific oxidation sites of the lanthana surface. Thus, the thermal decomposition of potassium sulfate under the reaction conditions leads to a partial neutralization of localized low-coordination oxygen anions associated with anionic vacancies, through formation of stable sulfate ions.