Catalytic oxidation of soot particulates over MnOx-CeO2 oxides prepared by complexation-combustion method

MnOx-CeO2 oxides prepared by complexation-combustion method were used for soot oxidation. The highest conversion rate of soot wasobtained on aMnOx-CeO2(4) oxide prepared under mild acid condition of pH = 4, where the oxidation temperature corresponding to maximumactivity was decreased more than 150 ◦C compared with that of un-catalytic soot oxidation. The structure and property of the catalysts wereinvestigated by X-ray powder diffraction (XRD) and temperature programmed reduction (TPR). The results indicated that there were at leasttwo kinds of Mn species present in MnOx-CeO2 catalysts, i.e. Mn ions within CeO2 lattice and high dispersion MnOx on the surface of CeO2.The presence of Mn ions in the CeO2 lattice improved the oxygen vacancy due to the charge difference, and the CeO2 considerably decreasedthe reduction temperature of MnOx. The capability to activate oxygen by the oxygen exchange between gas phase O2 and oxygen into theoxide contributed to the high catalytic activity for the reaction.