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采用等体积浸渍法制备了以改性氧化铝为载体材料的Pd/Al_2O_3密偶催化剂,并采用H_2程序升温还原(H_2-TPR),CO化学吸附和X射线光电子能谱(XPS)对催化剂进行了表征。在模拟尾气条件下对催化剂的总包反应及与C_3H_8相关的单反应活性进行了测试。结果表明,老化处理后活性PdO_x数量下降,并伴随有金属态Pd~0的产生。老化后,起燃温度(T_(50))和完全转化温度(T_(90))分别提高了76和64℃,即催化剂低温活性比高温活性下降明显。对比新鲜和老化催化剂上单反应活性,结果表明,老化后无水条件下有NO参与的反应的低温活性下降显著。老化处理过程突出了NO对低温活性的抑制作用和H_2O对高温活性的促进作用。
The Pd / Al 2 O 3 close-coupled catalysts with modified alumina as support material were prepared by the same volume impregnation method. The catalysts were characterized by H 2 -programmed temperature reduction (H 2 -TPR), CO chemisorption and X-ray photoelectron spectroscopy Characterization. The total reaction of the catalyst and the single reaction activity related to C_3H_8 were tested under simulated tail gas conditions. The results showed that the amount of active PdO_x decreased after aging, accompanied by the formation of metal Pd ~ 0. After aging, the light-off temperature (T_ (50)) and complete conversion temperature (T_ (90)) increased by 76 and 64 ℃, respectively. Comparison of fresh and aged catalysts showed that there was a significant decrease in the low temperature activity of the reaction with NO under anhydrous conditions after aging. The aging process highlights the inhibitory effect of NO on low temperature activity and the promotion effect of H 2 O on high temperature activity.