Catalytic Combustion of Low-Concentration Methane over M_x-Cu/-Al₂O₃ (M = Mn/Ce) Catalysts

Cu/Al2O3 modified by Mn and Ce catalysts for the catalytic combustion of low-concentration methane was studied by catalytic activity experiment and characterization. The results indicate that Mn improves the low-temperature (450-600 degrees C) catalytic activity. Compared with 10Cu/Al2O3, CH4 conversion of 3Mn-10Cu/Al2O3 is increased by 7% at 550 degrees C. This is because the interaction between Cu-Mn promotes the formation of CuMn2O4 and the dispersion of Cu, and increases the proportion of surface oxygen. Ce improves the high-temperature (600-700 degrees C) catalytic activity. Compared with 10Cu/Al2O3, CH2 conversion of 5Ce-10Cu/Al2O3 is increased by 8% at 700 degrees C. It is because Ce reduces Cu2+ to Cu+ with higher catalytic activity and inhibits CuAl2O4 production by Cu-support interaction. Cu-Mn-Ce three-component catalysts have the best catalytic activity. CH4 conversion of 3Mn-5Ce-10Cu/Al2O3 is increased by 11% at 600 degrees C. The synergy between Mn-Ce increases the proportion of surface oxygen and promotes the formation of the MnCeOx solid solution.