文摘
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.
