Redox properties and metal-support interaction of Pd/Ce0.67Zro.3302-Al203 catalyst for CO, HC and NO elimination

Ce0.67Zr0.33 02, Ce0.67Zr0.3302-Al203 and -y-Al203 supported Pd catalysts (designated as Pd/CZ, Pd/CZA and Pd/Al2 03) have been characterized by XRD, CO chemisorption, in situ DRIFTS, XPS, HRTEM, H2-TPR, 02-TPSR and catalytic performance test. The results show that the small Pd0, particles dispersed in CZ would promote the conversion of HC, CO and NO2, while the Pd0, particles dispersed in Al203 promote the conversion of NO in the light-off process. Pd0, species mainly disperse on Al203-rich grains surface for fresh Pd/CZA catalyst, but easily migrate onto CZ-rich grains surface due to the strong interaction between Pd and ceria-based oxide under high temperature reaction conditions. And it promotes the thermal stability of Pd 0 species and resilience of Pd to Pd 0, therefore enhances the catalytic performance for HC, CO and NO elimination. Meanwhile, the interaction between CZ and Al203 can be enhanced after aging treatment, resulting in increasing the thermal stability of Pd/CZA catalyst. 2014 Elsevier B.V. All rights reserved.