Effect of water vapor on the CO and CH4 catalytic oxidation over CeO2-MOx (M=Cu, Mn, Fe, Co, and Ni) mixed oxide

CeO2-MOx (M=Cu, Mn, Fe, Co, and Ni) mixed oxide catalysts were prepared by a citric acid complexation-combustion method. CeO2-MOx solid solutions could be formed with M cations doping into CeO2 lattice, while NiO and Co3O4 phases were detected on the surface of CeO2-NiO and CeO2-Co3O4 by Raman spectroscopy. The presence of M in CeO2 could obviously promote its catalytic activity for CH4 catalytic combustion and CO oxidation. Among the prepared samples, CeO2-CuO exhibited the best performance for CO oxidation. The addition of water vapor could obviously inhibit the catalytic performance of CeO2-MOx for CH4 combustion and CO oxidation, and CeO2-NiO showed good durability for CH4 wet combustion, that is, T-50 was 528 degrees C when 20% water vapor was added in the reaction stream.