Influence of Zr Content on Stability of (CeMn)1-xZrxO2 Catalysts for Catalytic Combustion of Diesel Soot

(CeMn)(1-x)ZrxO2 catalysts were prepared by co-precipitation, where 0 <= x <= 0.3 and the molar ratio of CeO2 to MnO2 was 6:4. The catalytic activities of these catalysts for the catalytic combustion of diesel soot were investigated. The catalysts were further characterized by a series of characterization methods. The results of X-ray diffraction(XRD) and low temperature nitrogen adsorption-desorption measurements indicated that the addition of ZrO2 improved the structure properties and textural properties of aged catalysts. When x >= 0.2, the catalysts exhibited optimum structure properties while improved textural properties could be observed for the catalysts with x >= 0.1. The results of H-2-temperature programmed reduction (H-2-TPR) measurements revealed that, among the ZrO2-doped aged catalysts, the one with x = 0.2 exhibited the best low-temperature reduction ability. The results of O-2-temperature programmed desorption (O-2-TPD) measurements suggested that the adding of ZrO2 increased the anion vacant sites on the surface of the catalysts and improved the catalyst's ability to adsorb and activate O-2. The results of catalytic activities of these catalysts discolsed that T-m (T-m is the temperature at which the maximal mass loss can be observed in the combustion process of soot) of the fresh catalysts decreased by about 270 degrees C. After aged, the adding of ZrO2 increased the stability. When x=0.2, the catalyst exhibited excellent thermal resistance performance, the gap of T-m before and after aging was only 6 degrees C. These catalysts suggested potential application in diesel soot catalytic combustion.