Mechanistic aspects of oxidative coupling of methane over LaAlO3

Abstract

Mechanistic aspects of the oxidative coupling reaction of methane over an LaAlO₃ catalyst (La:Al = 1 : 1) prepared by the mist decomposition method have been studied, using both continuous-flow and pulsed-flow techniques. The delayed pulse technique together with temperature-programmed desorption reveal that an adsorbed oxygen species is effective in the formation of the C₂ compounds, while a gaseous or weakly adsorbed oxygen species is involved in the combustion reaction. Methane cannot stay on the surface stably. Comparing these results with those obtained using the continuous flow reactor, mechanistic aspects are considered from the viewpoint of oxygen activity. The stability of this catalyst is also discussed.