A novel Ce3Zr5O16 composite with gradient distribution of elements and its application in Pd-only three-way catalyst

摘要

To equilibrate the conflict between the thermal stability and redox property of ceria-zirconia mixed oxide (CZ), a novel Ce3Zr5O16 composite with gradient distribution of elements (CZ-tcp) was prepared by twostep coprecipitation and compared with the sample (CZ-cp) obtained from conventional coprecipitation method. The distribution of elements, structural and textural properties, and redox properties of samples were investigated by HAADF-STEM equipped with EDS, XPS, XRD, Raman, SEM, N-2 physisorption, oxygen storage capacity and H-2-TPR systematically. The results revealed that, with respect to CZ-cp, CZ-tcp exhibits more stable phase structure, and less attenuation rates of pore volume (40.1% vs 67.9%) and oxygen storage capacity (1.0% vs 18.7%) after ageing treatment, which is on account of Zr enriched in the core of the grains and Ce enriched at the surface layer of the grains. Based on this, the catalytic performance evaluation results revealed that the catalyst supported on CZ-tcp (Pd@CZ-tcp) presents improved catalytic activity of HC and NO, and better thermal stability of CO catalytic activity compared with Pd@CZ-cp. Therefore, this designed CZ-tcp shows enhanced thermal stability and redox property at the same time and can be used as a competitive oxygen storage support for three-way catalyst. (C) 2021 Elsevier B.V. All rights reserved.