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

Abstract MnO x -CeO 2 oxides prepared by complexation-combustion method were used for soot oxidation. The highest conversion rate of soot was obtained on a MnO x -CeO 2 oxide prepared under mild acid condition of pH = 4, where the oxidation temperature corresponding to maximum activity was decreased more than 150 °C compared with that of un-catalytic soot oxidation. The structure and property of the catalysts were investigated by X-ray powder diffraction (XRD) and temperature programmed reduction (TPR). The results indicated that there were at least two kinds of Mn species present in MnO x -CeO 2 catalysts, i.e. Mn ions within CeO 2 lattice and high dispersion MnO x on the surface of CeO 2 . The presence of Mn ions in the CeO 2 lattice improved the oxygen vacancy due to the charge difference, and the CeO 2 considerably decreased the reduction temperature of MnO x . The capability to activate oxygen through the oxygen exchange between O 2 in gas phase and lattice oxygen species in MnO x -CeO 2 oxide contributed to the high catalytic activity for the reaction.