Synthesis of mesoporous CeO2-MnOx binary oxides and their catalytic performances for CO oxidation

Mesoporous CeO2-MnOx binary oxides with different Mn/Ce molar ratios were prepared by hydrothermal synthesis and characterized by scanning electron microscopy(SEM),N2 sorption,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and H2 temperature-programmed reduction(H2-TPR).The characterization results indicated that the CeO2-MnOx catalysts exhibited flower-like microspheres with high specific surface areas,and partial Mn cations could be incorporated into CeO2 lattice to form solid solution.The CeO2-MnOx catalysts showed better catalytic activity for CO oxidation than that prepared by the coprecipitation method.Furthermore,the CeO2-MnOx catalyst with Mn/Ce molar ratio of 1 in the synthesis gel(Ce-Mn-1) exhibited the best catalytic activity,over which the conversion of CO could achieve 90% at 135 oC.This was ascribed to presence of more Mn species with higher oxidation state on the surface and the better reducibility over the Ce-Mn-1 catalyst than other CeO2-MnOx catalysts.