Abstract: Pt/Al₂O₃ catalysts were prepared by impregnation method in which Pt loading was fixed at mass fraction 0.5%,and the Al₂O₃ carrier was prepared by sol-gel method. The activity for selective catalytic reduction of nitric oxide by propene in the presence of oxygen over Pt/Al₂O₃ catalyst was investigated and the bonding state of Pt in the samples pre-treated under different conditions was studied. It has been found that the activity window of the catalyst calcined in H₂ is the widest,and it changed little when the calcined temperature increased;the catalyst activity of the catalyst pretreated in O₂ at 523 K is the highest,the activity window shifted to a higher temperature when the calcined temperature increased. The reason of the activity difference is explained by the temperature programmed desorption. According to XPS measurements,the main bonding state of platinum supported on Al₂O₃ is Pt²⁺ calcined in O₂ at 523 K,and Pt⁰ calcined in N₂ and H₂ at 523 K,respectively.

Key words: Pretreatment, Pt/Al2O3, Catalytic reduction of NO