The high activity of Co-Mn-based solid solution catalysts for lean methane combustion

Abstract

Developing non-noble metal-based catalysts for methane combustion with high catalytic activity and stability is important in the new context of a changing global energy landscape. In this study, we reported an Co5Mn1-O catalyst achieved 90% conversion of methane to CO2 at 305 °C, which was about 60 ℃ lower than the catalysts reported. The synthetic strategy via lattice distortion that inhibits the deep oxidation of Mn2+ with prepared a highly catalytic reactive Co-Mn-based solid solution material. The results show that introduction of Mn atoms into the Co3O4 spinel structure caused lattice distortion, which modulated the oxygen coordination environment and oxygen vacancies of the catalyst, and the Co5Mn1-O (Optimum) catalyst prepared under optimized conditions obtained excellent methane activation capacity and lattice oxygen mobility. The higher lattice oxygen mobility of the Co5Mn1-O catalyst facilitated the adsorption, activation, and oxidation of methane, especially the rate-determining step of methane oxidation, the conversion of CH4 to CH3-. The conversion rate decreases slightly in the presence of 5 vol% or 10 vol% H2O, but it also still maintained good catalytic activity and stability under high temperatures and long-term reactions. In addition, in situ infrared specra was used to explore the reaction mechanism of methane combustion under real reaction conditions.