Highly efficient Pt catalyst on newly designed CeO2-ZrO2-Al2O3 support for catalytic removal of pollutants from vehicle exhaust

Abstract

Pt-CeO2 catalysts have been widely studied for the vehicle emission control. Designing novel CeO2 based supports with improved physical-chemical properties has become a research hotspot to further promote the catalytic performance and stability of Pt-CeO2 catalysts. In this work, through utilizing a unique, two-step incipient wetness impregnation (T-IWI) method for ceria-zirconia-alumina (CZA-T) support preparation, a Pt single site catalyst (Pt/CZA-T) with excellent thermal stability was synthesized. Higher oxidation activity and Oxygen storage capacity (OSC) were achieved on activated Pt/CZA-T, comparing to Pt catalysts on regular CeO2/Al2O3 (Pt/CA) and one-step prepared CeZrOx/Al2O3 (Pt/CZA). Via the modification of hydrophilic/hydrophobic properties of γ-Al2O3 by this unique T-IWI method, finer Ce0.9Zr0.1O2 particles with higher density of surface defects were formed on CZA-T, on which a higher Pt dispersion and stronger Pt-O-Ce interaction were achieved. Upon activation, smaller, well-dispersed Pt clusters on CZA-T were generated. It was concluded that the CO oxidation performance and OSC were highly related to the size of Pt clusters on different supports that we have developed. More Pt sites located at Pt cluster-CeZrOx interfaces, which were the real active sites, were responsible for the highest OSC function and CO oxidation activity of activated Pt/CZA-T catalyst.