Influence of la on CeO2-ZrO2 catalyst for oxidation of soluble organic fraction from diesel exhaust

Abstract

CeO2-ZrO2 and CeO2-ZrO2-La2O3 catalysts with mass ratios of 60:40 and 60:30:10 were prepared by co-precipitation method, respectively. The catalytic activity in oxidation of the soluble organic fraction (SOF) in diesel exhausts was studied using thermogravimetric-differential thermal analysis (TGDTA). The results indicate that the catalytic activity of the La-modified CeO2-ZrO2 catalyst is better than that of the CeO2-ZrO2 catalyst; the light-off temperature of SOF is 164 °C, and the weightlessness fastest point temperature is 212 °C, whereas for CeO2-ZrO2, these temperatures are 168 and 221 °C, respectively. X-ray diffraction (XRD) shows that modification with La is beneficial to decrease the growth rate of the crystallite size relative to that of CeO2-ZrO2 after high-temperature ageing. N2 adsorption-desorption results suggest that the addition of La enlarges the surface area. O2-temperature-programmed desorption (O2-TPD) and X-ray photoelectron spectroscopy (XPS) show that modification with La increases the amount of chemisorbed oxygen on the CeO2-ZrO2 catalyst. The CeO2-ZrO2-La2O3 catalyst shows better activity and ageing resistance than the CeO2-ZrO2 catalyst.