Preparation of CexZr1-xO2 by Different Methods and Its Catalytic Oxidation Activity for Diesel Soot

Novel CexZr1-xO2(x= 0.67, 0.8, 0.9, 1.0) catalysts were designed and synthesized by solvothermal, calcination, andsol-gel methods and were used to catalyze oxidation of soot from diesel vehicle exhaust. The influence of catalysts synthesized bydifferent methods and Ce/Zr molar ratios on the performance was investigated. These catalysts were characterized by XRD, N2adsorption-desorption, FT-IR, TEM, XPS, H2-temperature programmed reduction (TPR), and O2-temperature programmeddesorption (TPD) techniques. The results indicated that Ce0.8Zr0.2O2prepared by the calcination method has excellent activity andstability at low temperature. The soot ignition point is 322 degrees C, and the ratio of soot conversion reaches 90% at 497 degrees C, which islower than that from the solvothermal and sol-gel methods. The XRD, Raman, SEM, XPS and H2-TPR results reveal that thestructure and oxygen adsorption properties are crucial to soot oxidation activity, and Zr4+is successfully doped into the CeO2latticeand forms a homogeneous solid solution. Nanostructured Ce0.8Zr0.2O2with 110.2 m2/g surface areas is produced. The proportion ofchemical oxygen and surface adsorbed oxygen in the catalyst prepared from the calcination method is the highest at 23.18%. Thestructure may lead to charge imbalance, unsaturated bonds, and oxygen vacancies, thus increasing the adsorption of oxygen on thecatalyst surface.

Automated summary

Novel CexZr1-xO2 catalysts with different Ce/Zr molar ratios were synthesized using solvothermal, calcination, and sol-gel methods. The catalyst prepared by the calcination method with a Ce/Zr molar ratio of 0.8 exhibited excellent activity and stability at low temperature for soot oxidation. The structure and oxygen adsorption properties of the catalyst were crucial for its activity.