Enhanced activity and stability of Al2O3-pillared layered manganese oxides for DME combustion

Abstract

Al2O3-pillared layered manganese oxides (Al2O3–MO), used as catalyst for the catalytic combustion of dimethyl ether (DME), were characterized by XRD, SEM-TEM, N2 adsorption and desorption, O2-TPD and XPS techniques. The Al2O3–MO shows a relative high thermal stability. The layered structure with a basal spacing of 0.67nm could be maintained up to 500°C. The O2-TPD technique showed that all the Al2O3-pillared layered manganese oxides catalysts have large amount of surface oxygen species and the Al2O3 pillars could promote the mobility of the active oxygen. Sample Al2O3–MO (300°C) with large amount of lattice oxygen species and higher oxygen mobility demonstrates excellent activity in the catalytic combustion of DME with a light-off temperature of 140°C and a complete combustion temperature of 149°C. The catalytic activity of the sample Al2O3–MO (300°C) was stable up to 200h. The transient response method was carried out to account for the participation of the lattice oxygen in the catalytic reaction. The results showed that the lattice oxygen of manganese oxide (MnO) was consumed in the combustion reaction and that reduced manganese oxide was reoxidized with O2.