K修饰的CZA载体对全钯三效催化剂性能的影响  

Impact of Ce-Zr-Al Mixed Oxide Modified by Potassium on Pd-Only Three-Way Catalysts

作　　者：姚青[1] 田群[1] 陈宏德[1] 韩芸[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《中国科学院研究生院学报》2006年第3期331-336,共6页Journal of the Graduate School of the Chinese Academy of Sciences

摘　　要：采取柠檬酸溶胶凝胶法制备铈锆铝复合氧化物(CZA)载体,考察K对Pd/CZA催化剂性能的影响.实验结果表明,K的添加对此类催化剂具有明显劣化作用,其原因在于使用CZA作为载体时,K减弱Pd-Ce相互作用,降低催化剂活性,使之发生中毒;但随着K含量的增大,阻塞催化剂表面的活性位,促使Pd颗粒聚集长大,较大粒径的Pd颗粒有利于三效活性的提高,因而在一定程度上使活性有所恢复.相关的XRD和TPR实验也在一定程度上证明了这点.The Ce-Zr-Al mixed oxides were prepared by the sol-gel method with some special procedures. Pd-K/ CZA catalysts were characterized by TG-DTA, XRD, H2-TPR, O2-TPD and CO-TPD. The results showed that the activity of Pd-K/CZA catalysts with a small amount of potassium reduced, when it had been recovered with a large amount of potassium. It was shown by the calculation from CO uptake that the dispersion of Pd increased from 14.8%（K/CZA：ω（k） =0）to 22.3%（K/CZA：ω（k） = 1.5%）,then decreased to 8.6%（K/CZA：ω（k） = 14.6% ）. The light-off temperatures of the samples increased with increment of the amount of potassium, which is due to poisoning of potassium that weakens SMSI of Pd-Ce. For the sample K-4 with a big amount of potassium （K/CZA： ω（k） = 14.6% ） ,the poison was lightened because the particle size of Pd is beneficial to the three-way reaction.

关 键 词：钾 铈锆铝复合氧化物 程序升温反应 Pd—Ce相互作用 

分 类 号：X51[环境科学与工程—环境工程]