Effect of high temperature pretreatment on the thermal resistance properties of Pd/CeO₂/Al₂O₃ close-coupled catalysts

【摘要】 Fresh Pd/CeO₂/Al₂O₃ close coupled catalyst was prepared by the stepwise impregnation method and calcined at 550 °C for 3 h, which was then pretreated at 700, 800, and 900 °C for 3 h, respectively. Finally, these pretreated catalysts were aged at 1000 °C for 3 h to study their anti-aging properties. The catalytic activities of the catalysts were investigated detailedly, and the results showed that the catalyst pretreated at 800 °C before aging treatment possessed the best anti-aging performance for C₃H₈ oxidation. XRD and XPS results indicated that well-crystallized CeO₂ particles were formed during calcinations at 800 °C, which made CeO₂ an effective promoter. HRTEM revealed that Pd particles found on the edge of CeO₂ over the aged catalyst pretreated at 800 °C were relatively smaller than those over the catalysts without pretreatment. H₂-TPR and XPS results also implied that the interaction between well-crystallized CeO₂ and Pd suppressed the deactivation of PdO sites and further enhanced the catalytic performance.更多还原

【Abstract】 Fresh Pd/CeO₂/Al₂O₃ close coupled catalyst was prepared by the stepwise impregnation method and calcined at 550 °C for 3 h, which was then pretreated at 700, 800, and 900 °C for 3 h, respectively. Finally, these pretreated catalysts were aged at 1000 °C for 3 h to study their anti-aging properties. The catalytic activities of the catalysts were investigated detailedly, and the results showed that the catalyst pretreated at 800 °C before aging treatment possessed the best anti-aging performance for C₃H₈ oxidation. XRD and XPS results indicated that well-crystallized CeO₂ particles were formed during calcinations at 800 °C, which made CeO₂ an effective promoter. HRTEM revealed that Pd particles found on the edge of CeO₂ over the aged catalyst pretreated at 800 °C were relatively smaller than those over the catalysts without pretreatment. H₂-TPR and XPS results also implied that the interaction between well-crystallized CeO₂ and Pd suppressed the deactivation of PdO sites and further enhanced the catalytic performance.更多还原