Effect of surface tension on the properties of a doped CeO2-ZrO2 composite and its application in a Pd-only three-way catalyst

La and Pr modified ceria-zirconia solid solution materials CeO2-ZrO2-La2O3-Pr6O11 (CZLP) were synthesized through a co-precipitation method, in which the influence of surface tension during the drying process on the textural/structural properties, reduction behavior and oxygen storage capacity of the materials was investigated. The difference in catalytic performance of the supported Pd-only thee-way catalysts was further studied. The results revealed that CZLP3 obtained through a supercritical ethanol drying method which eliminated the surface tension in the drying process exhibited a texture with a larger pore size and wider pore size distribution. Such texture is crucial to improve the thermal stability and anti-aging ability of materials. After calcining at 1000 °C, the specific surface area, cumulative pore volume and average pore radius of CZLP3-a were 52 m2 g-1, 0.52 cm3 g-1 and 20.3 nm, respectively. The XRD and Raman results revealed that a more homogeneous solid solution of Ce, Zr, La and Pr was formed, and the aging-treatment-induced segregation of phases was inhibited for CZLP3. Besides, the slightest grain growth after the aging treatment shown in TEM images indicated the superior anti-aging ability of CZLP3. The Raman and XPS analysis demonstrated the highest concentration of oxygen vacancies and surface Ce3+ species for CZLP3 both before and after the aging treatment, which contributed to the enhancement of its reduction properties and oxygen storage capacity. Consequently, Pd/CZLP3 exhibited outstanding three-way catalytic activity compared with the others both before and after the thermal aging treatment, indicating its tremendous potential possibilities.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology