【摘要】 采用等体积浸渍法制备了以改性氧化铝为载体材料的Pd/Al₂O₃密偶催化剂,并采用H₂程序升温还原（H₂-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C₃H₈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Pd⁰的产生。老化后,起燃温度(T₅₀)和完全转化温度(T₉₀)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H₂O对高温活性的促进作用。更多还原

【Abstract】 The Pd/Al₂O₃ close-coupled catalysts supported on modified alumina were prepared by an impregnation method,and then characterized by H₂-temperature programmed reduction（H₂-TPR）,CO chemisorption,and X-ray photoelectron spectroscopy（XPS）.Both total catalytic activity and single reactions in related to C₃H₈ conversion were tested in simulated exhaust gas.The results show that the amount of active PdO_x decreases and negative metallic Pd⁰ appears during aging treatment.The light-off temperature(T₅₀) and complete conversion temperature(T₉₀) increase by 76 ℃ and 64 ℃,respectively.After aging treatment,signifying that the low-temperature activity decreases more obviously than high temperature property.The results of comparison among single reactions indicate that the light-off activity of reactions which occur in atmosphere with the participation of NO but without H₂O injection decreases dramatically after the aging treatment.The inhibitive effect of NO on light-off activity and the positive effect of H₂O on high temperature property become obvious during the aging treatment.更多还原