Effect of B Site Substitution on the Catalytic Activity of La-Based Perovskite for Oxidative Coupling of Methane

Abstract

The effect of B site element in LaBO3 (B = Al, Ga, In, Yb, Co, Mn, Fe) perovskites on the catalytic performance for the oxidative coupling of methane (OCM) reaction is investigated. Among the catalysts tested, LaAlO3, LaGaO3, LaInO3, and LaYbO3 show higher activity for the formation of C2 hydrocarbons in the OCM reaction. From the kinetic study on LaAlO3 and LaCoO3, which are the highest and lowest active catalysts, the CH3• formation, as the first step in the OCM reaction, via the reaction of CH4 with oxygen is strongly affected by the B site element. X-ray photoelectron spectroscopy analysis and the 16O/18O isotopic exchange reaction suggest that the role of the B site element in LaBO3 perovskite is to create enough amount of surficial mobile oxygen species.