Effects of Ce-Doping on the Structure and NH3-SCR Activity of Fe/Beta Catalyst

摘要:

用标准的离子交换法制备了Fe/Beta分子筛SCR催化剂，并将其涂覆在蜂窝陶瓷载体上进行氮氧化物转化率的性能评价。分子筛和Ce掺杂分子筛的结构采用如电感耦合等离子体原子发射光谱（ICP-AES），低温N2吸附，X射线衍射（XRD）仪，扫描电子显微镜（SEM），NH3程序升温脱附（NH3-TPD）和H2程序升温还原（H2-TPR）等进行表征。结果表明，不论催化剂是在新鲜状态还是经过水热/硫老化后，采用更好的沸石结构的Fe-Beta分子筛结构及铈掺杂的催化剂都具有更宽的NOx转化温度窗口。由实验结果可知，较大的比表面积、均匀的小颗粒分子筛、规则的沸石骨架以及表面分散的不饱和的Ce4+对NH3-SCR的性能均有促进作用。

Abstract:

Fe/Beta zeolite selective catalytic reduction (SCR) catalysts supported on honeycomb ceramic were prepared by a standard water ion exchange method and evaluated in NOx conversion process. The zeolite material characters and effects of Ce-doping on the zeolite were investigated by Inductively Coupled Plasma Atomic Emission Spectrum (ICP-AES), low temperature N2 adsorption, X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), NH3 Temperature-Programmed Desorption (NH3-TPD) and H2 Temperature-Programmed Reduction (H2-TPR). The results show that the Fe-Beta zeolite SCR catalysts with better zeolite structure and Ce-doping exhibit a more excellent catalytic ability on the NOx conversion temperature window, no matter for the fresh one or the one treated under hydrothermal or sulfur aged condition. It is deduced that the larger BET surface area, more uniform and smaller particles and more regular framework of zeolite as well as the unsaturated Ce4+ on zeolite have a great effect on the promotion of NH3-SCR performance.