水热处理前后ZSM-5分子筛MTP反应催化性能研究

摘要

以粗孔硅胶为硅源经水热晶化制备了粒径约400nm~1μm的ZSM-5分子筛，并进行水热处理。采用SEM、XRD、NH3-TPD、N2物理吸附等方法对其结构进行了表征。比较研究了其水蒸气处理前后对甲醇制丙烯(MTP)反应的催化性能。结果表明，水热处理使ZSM-5分子筛酸中心数量减少，酸强度减弱，但孔容和孔径增大，从而使丙烯选择性及催化稳定性提高。%A ZSM-5 zeolite with the particle sizes of about 400nm~1μm was synthesized from macroporous silica gel by hy-drothermal crystallization, named as zeolite A, which was treated with steam to obtain zeolite B. The structural properties of both zeo-lites A and B were characterized by SEM, XRD, NH3-TPD and nitrogen adsorption, and their catalytic performances for methanol to propylene (MTP) reaction were comparatively investigated. Results show that steam treatment caused a decrease in the strength and amount of acidic sites and an increase in pore volume and average pore width. As a result, the propylene selectivity and life time of the catalyst were significantly improved.