Cu-Ce-Zr-O复合氧化物催化剂的制备与三效催化性能

Preparation and Three-Way Catalytic Performance of Cu-Ce-Zr-O Mixed Oxide Catalysts

采用柠檬酸溶胶凝胶法制备了Cu-Ce-Zr-O复合氧化物催化剂.当Ce∶Zr∶Cu摩尔比为2∶8∶5时,制得的Ce0.2Zr0.8Cu0.5-O2-λ催化剂具有较佳的三效催化性能和较宽的工作窗口.当空燃比为1.33(富氧)时,CO,C3H6和NO的起燃温度分别为183,257和236℃,并且当温度高于340℃时都能完全转化;催化剂经高温老化后CO,C3H6和NO的起燃温度仍较低,分别为225,350和350℃.X射线衍射、X射线光电子能谱和程序升温还原的结果表明,部分Cu进入Ce-Zr固溶体形成Cu-Ce-Zr固溶体;Cu与Ce产生协同效应使Ce0.2Zr0.8Cu0.5O2-λ催化剂的低温活性明显提高,并且在贫燃情况下具有更高的三效催化性能.

A series of Cu-Ce-Zr-O mixed oxide catalysts were prepared by the citric acid sol-gel method. The Ce0.2Zr0.8Cu0.5O2-λ catalyst with Ce： Zr： Cu molar ratio of 2：8：5 showed high three-way catalytic performance. When the air/fuel ratio was 1.33, under the condition of excess oxygen, the light-off temperatures for CO, C3H6, and NO were 183, 257, and 236℃ , respectively, and the three gases could be completely converted above 340℃. After undergoing high temperature aging, their light-off temperature changed to 225, 350, and 350℃, respectively, which still remained lower. The results of XRD, XPS, and TPR characterization showed that some Cu entered the Ce-Zr solid solution to form a Cu-Ce-Zr solid solution. There was synergistic effect between Cu and Ce, which increased the catalytic activity of the Ce0.2Zr0.8Cu0.5O2-λ catalyst at low temperature and resulted in the higher three-way catalytic performance under lean-fuel conditions.