Cu/Al-Ce-PILC在丙烯选择性催化还原NO反应中的失活研究  

Study on Deactivation of Cu/Al-Ce-PILC in the Selective Catalytic Reduction of NO by Propylene

作　　者：林绮纯[1] 郝吉明[1] 李俊华[1] 傅立新[1] 林维明[2] 

机构地区：[1]清华大学环境科学与工程系,北京100084 [2]广州大学化工系,广州510405

出　　处：《环境科学》2007年第3期489-493,共5页Environmental Science

基　　金：国家自然科学基金重点项目(20437010);中国博士后基金项目(2005037058)

摘　　要：采用聚合羟基复合阳离子合成交联黏土Al-Ce-PILC,经SO42-改性后,以浸渍法制备了铜基交联黏土催化剂Cu/Al-Ce-PILC,并将其应用于C3H6选择性催化还原NO的反应,350℃时NO转化率达到最大值56%,700℃时下降至22%.为探究催化剂高温失活的原因,采用XPS、TPR、TGA、Py-IR和DSC对反应前后催化剂的物化性能进行了表征.结果表明,经过H2预处理活化后活性组分Cu物种以Cu+形式存在,而高温反应后Cu物种除以Cu+和Cu2+2种形式存在外,还出现了少量CuO物种;高温反应过程中Al-Ce-PILC上结构羟基和SO42-流失导致催化剂表面酸性减弱;此外,还存在表面积炭覆盖了部分活性中心并堵塞了催化剂孔道的现象.这三者的共同影响促进了C3H6深度氧化,抑制了NO还原,从而导致催化剂的失活.New pillared clay catalysts were studied for NO removal by hydrocarbon in the presence of oxygen. The purpose of this work is to study the deactivation of Cu/A1-Ce-PILC in the SCR of NO. Montmorillonite was pillared by multi oligomeric hydroxyl cation to synthesize Al- Ce-PILC and treated by （NH4）2SO4, then it was used as catalyst support. Cu/A1-Ce-PILC catalyst was prepared by impregnation and applied to the SCR of NO by C3 H6. The NO conversion to N2 rehched its maximum of 56 % at 350℃ and decreased to 22 % at 700℃. To study the deactivation of Cu/A1-Ce-PILC in the SCR of NO at high temperature, the fresh and post-reaction catalysts were characterized by XPS, TPR, TGA, Py-IR and DSC. The results showed that only Cu^＋ species existed on the fresh catalyst pretreated in hydrogen, while another species CuO was detected on the post-reaction catalyst. The loss of structural hydroxyl and SO4^2- on A1-Ce-PILC weakened the surface acidity of the catalyst at high reaction temperature. Furthermore, the coke deposition on the catalyst covered part of the active sites and blocked the pores of the catalyst. The deactivation of Cu/A1-Ce-PILC may be due to the combined effects of CuO formation, the decrease on acidity and the coke deposition, which facilitated propylene combustion and inhibited NO reduction.

关 键 词：Cu/A1-Ce-PJLC 氮氧化物 丙烯 选择性催化还原 失活 

分 类 号：X511[环境科学与工程—环境工程]