Different valent ions-doped cerium oxides and their catalytic performances for soot oxidation

The nmCeO2 and Ce0.8M0.2O2 (M = Sm, Zr, V) nanoparticles were prepared by the method of microwave-assisted heating decomposition. Their catalytic performances for diesel soot oxidation were investigated with temperature-programmed oxidation reaction (TPO). Spectroscopic techniques (XRD, Raman, UV-Vis DRS and FT-IR) were utilized to characterize the structures of nmCeO2 and Ce0.8M0.2O2 catalysts. The results show that the structures of the catalysts depend on the different doped ions. Ce0.8Sm0.2O2 and Ce0.8Zr0.2O2 still preserved a face-centered cubic fluorite structure of CeO2. However, CeVO4 crystallite was formed as V doping (Ce0.8V0.2O2). Nanometer CeO2, Ce0.8Sm0.2O2 and Ce0.8Zr0.2O2 exhibited higher catalytic activity than conventional CeO2 and Ce0.8V0.2O2 for soot combustion due to the nanometer effect and the good contact between the catalyst and soot. For soot oxidation, nmCeO2 is mainly active components. However, the doping of Sm or Zr could remarkably improve the thermal stability of nmCeO2, and the doping of Sm or V could enhance the ability to resist SO2 poison of catalysts.