Synthesis of a homogeneous CeO2–ZrO2-Al2O3 composite material by a novel hydrothermal assisted precipitation method

Abstract

CeO2-ZrO2-Al2O3(CZA) composites, combining the advantages of CeO2-ZrO2 (CZ) and Al2O3, are widely used in three-way catalyst as an indispensable support material. However, due to the adverse Zr-Al interaction and the different precipitation conditions for Ce3+/Ce4+ and Zr4+, the CZA prepared by conventional co-precipitation method has poor compositional homogeneity, resulting in degradation of redox properties. In this study, a homogeneous CZA composite is synthesized by a novel hydrothermal assisted precipitation method, in which the CZ-precipitates and Al-precipitates will be controlled separately. A quantitative EDX points analysis reveals that the Ce/Zr ratio in the resulting CZA material exhibits slight fluctuations between 0.72 and 0.91, which is much narrow than that from conventional precipitation method (0.38∼0.83). As a result, the resulting CZA material exhibits the better redox property, higher specific surface area, and more importantly, its supported Pd/CZA catalyst exhibit superior three-way catalytic activity, the T50 (temperature for 50% conversion) for CO, NO, C3H6 and C3H8 over which is 41 ℃, 26 ℃, 28 ℃ and 12 ℃, respectively, lower than that from conventional method.