柴油车尾气NOx控制是目前大气污染控制领域的重要研究内容,对改善城市大气污染现状有着极其重要的作用。NH3选择性催化还原NOx(NH3-SCR)是应用于该领域的主流技术之一。近年来,以具有菱沸石(chabazite,CHA)结构的分子筛为载体负载Cu制备的Cu-CHA(Cu-SSZ-13和Cu-SAPO-34)系列催化剂,因其优秀的NH3-SCR活性和良好的水热稳定性,成为学者们关注的热点。本文首先从制备方法及反应条件对Cu-CHA催化性能的影响和NH3-SCR反应机理这几个方面系统阐述Cu基菱沸石在柴油车尾气NOx催化净化领域的研究进展;然后总结了负载其他过渡金属和稀土金属制备的M-CHA分子筛催化剂在NH3-SCR反应中的应用,指出双活性中心菱沸石催化剂在NH3-SCR领域表现出的优势;在此基础上对菱沸石NH3-SCR催化剂的进一步改良做出展望。
The purification of NOx from diesel engine exhaust is an important topic in the field of air pollution control,which is significant for the improvement of current unban air quality. The selective catalytic reduction of NOx with NH3( NH3-SCR) is one of the most promising technologies for the control of NOx emission from diesel engine exhaust. In recent years,Cu-CHA catalysts,which are obtained from loading transition metal Cu on zeolites with chabazite( CHA) structure,have attracted much attention in the field of NH3-SCR reaction,due to their excellent NH3-SCR activity and hydrothermal stability. Cu-SSZ-13 and Cu-SAPO-34 are the two typical Cu-CHA catalysts. In this review,the progress of NOxcontrol in the field of diesel engine exhaust with Cu-CHA catalysts is stated from three aspects firstly,including the influences of preparation method,the effects of reaction condition and the NH3-SCR reaction mechanism. Then,the application of M-CHA catalysts in NH3-SCR reaction are elaborated,where M is limited as some other transition metal and rare earth metal. Meanwhile,theadvantages of bimetallic-based CHA zeolites in NH3-SCR reaction are identified. Based on these results,the possible improvement orientations for NH3-SCR catalysts with CHA zeolites structure are also prospected.