两种铈锆-氧化铝载体对载Pd催化剂性能的影响  

Effect of Ce_xZr_(1-x)O_2/Al_2O_3 supports of two methods on performance of Pd catalysts

作　　者：房师平[1] 陈宏德[1] 田群[1] 

机构地区：[1]中国科学院生态环境研究中心大气污染控制研究室,北京100085

出　　处：《安全与环境学报》2005年第5期60-63,共4页Journal of Safety and Environment

摘　　要：分别以柠檬酸溶胶法和浸渍法制备了两种三氧化二铝负载的铈锆复合氧化物(CZ/A),考察了它们对载Pd三效催化剂性能的影响。发现柠檬酸法样品催化氧化CO和C3H6的活性大大优于浸渍法样品,NO的转化活性二者接近。表征结果显示,在柠檬酸法样品中,CZ以紧密的片层状结构覆盖在氧化铝上,而在浸渍法样品中,CZ呈疏松的颗粒状,这就导致在柠檬酸法样品样品上CZ具有更大的分散度,近而具有更多的Pd-CZ活性位。而且,对于柠檬酸法样品,高温老化后铈锆晶相稳定,无晶相分离,比表面积下降较小,催化剂自身的氧化还原性能更好。这些都使其表现出了更好的催化活性,特别是氧化活性。The present article aims to introduce the authors＇ study on the effect of CexZr1-xO2/Al2O3 supports of two methods （the citrate sol-gel method and incipient wet impregnation method） on the performance of Pd catalysts. To test the effect, we have prepared CeO2-ZrO2 mixed oxides supported on Al203 powder by using the citrate solgel method and the incipient wet impregnation method, and then began to prepare catalysts Pd. Our testing results indicate that the sample of the sol-gel method is more active in converting CO and C3H6, although they are nearly the same in converting NO no matter whether they were tested before or after the thermal aging. SEM results also show that CeO2-ZrO2 mixed oxides cover the surface of Al2O3 in the form of close-knit sandwich and loose granule in the sol-gel sample and the impregnation sample respectively, which makes sol-gel sample CeO2-ZrO2 disperse stronger. Thus, it can be said that the sol-gel sample is more reducible, which has been proved by the TPR results with more Pd-（CeO2-ZrO2） active sites for catalytic reaction. Furthermore, the XRD results seem to imply that the sol-gel sample has more stable crystal structure. After thermal ageing, most of CeO2-ZrO2 in the sol-gel sample proves to remain in the form of Ce0.5Zr0.5O2 with the largest oxygen storage capacity and the most active assistance to Pd/ CeO2-ZrO2 catalysts. All of the above results contribute to better catalytic activity of sol-gel sample, especially oxidative activity with CO and C3H6.

关 键 词：催化剂工程 氧化铝 铈锆复合氧化物 PD 三效催化剂 柠檬酸 

分 类 号：TQ426.97[化学工程]