负载Pd催化剂的表面碱性和NO吸附关系

Correlation of the Basicity with the Adsorption of NO on Supporte Pd Catalysts

The adsorption of CO2 and NO on supported Pd catalysts has been studied by using TPD-MS method and the adsorbed surface species were discussed based on literatures. The amount and intensity of basic sites increase when promoter Li is added, whereas the amount of basic sites decreases when Ce is added. It is found that there are three kinds of basic sites with different intensity on the catalyst surface. On sample Pd/Al2O3 and Pd/Al2O3-Li2O, large amount of CO desorption species is detected, this shows some CO2 on the surface being decomposed. There is no such effect on the sample Pd/Al2O3-CeO2. After analyzing the TPD profiles of NO adsorption on catalysts, it is found that both the NO desorption amount and the shapes of desorption peaks change remarkably when promoter Li or Ce is added. In the case of Li, the γ-peak （nitrate and nitrite species on surface） of NO desorption increases, the intermediate N2O desorbs at higher temperature. In the case of Ce, the α-peak （species on the Bronstesd acidic sites ） of NO desorption decreases, and N2O desorbs at lower temperature.