New insights into the structure of a CeO2-ZrO2-Al2O3 composite and its influence on the performance of the supported Pd-only three-way catalyst

In this work, a Ce0.5Zr0.5O2-Al2O3 (CZA) mixed oxide prepared by a coprecipitation method was deeply investigated and some new insights into the microstructure were obtained. The XRD, Raman, TEM and XPS results revealed that compositional inhomogeneity existed in fresh CZA; some Zr-rich species were in close contact with Al2O3, leading to the observed CZ nanocrystallites being richer in Ce, which was detrimental to the oxygen mobility, and consequently an undesirable redox property was obtained. During thermal treatment from 600 °C to 900 °C, atomic rearrangement took place, giving rise to the enhanced homogeneity of CZ solid solutions, accompanied by a weakened interaction between CZ and Al2O3, and a homogeneous CZ solid solution with a Ce/Zr ratio approaching the theoretical value of 1 was obtained for CZA treated at 900 °C. The TPR and OSC results indicated that the enhanced homogeneity of the CZ solid solution could facilitate the improvement of the redox property. However, further treatment at 1000 °C brought about the phase segregation of CZ, which led to significantly deteriorated textural and structural properties as well as a worse redox property. As a result, the catalyst Pd/CZA900 (CZA was treated at 900 °C) exhibited the best redox and catalytic performances, as well as excellent thermal stability.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology