Ti-MCM-41分子筛催化剂的合成、表征及催化性能  

Synthesis,characterization and catalytic performance of Ti-MCM-41 catalyst

作　　者：刘红梅[1] 亢宇[1] 徐向亚[1] Liu Hongmei;Kang Yu;Xu Xiangya(Beijing Research Institute of Chemical Industry,SINOPEC,Beijing 100013,China)

机构地区：[1]中国石油化工股份有限公司北京化工研究院

出　　处：《工业催化》2019年第9期36-42,共7页Industrial Catalysis

摘　　要：以正硅酸四甲酯为硅源,钛酸四异丙酯为钛源,在异丙醇和水的混合溶液中室温下合成了Ti-MCM-41介孔分子筛,采用TEM、N 2吸附-脱附、XRD、UV-Vis和Raman等研究了分子筛的结构特性。并以过氧化氢异丙苯为氧化剂,考察了硅烷化处理后的Ti-MCM-41分子筛催化剂在丙烯环氧化反应中的催化性能。结果表明,与骨架外六配位钛物种相比,骨架内四配位钛物种活化有机过氧化物的能力更强,速率更快;四配位钛物种是环氧丙烷生成的活性物种,而六配位钛物种的存在则会导致反应副产物的生成。合成时添加适量的异丁醇可有效促进钛物种进入分子筛骨架中,并增大比表面积和孔体积,进而改善Ti-MCM-41催化剂的丙烯环氧化催化性能。性能最佳的催化剂上过氧化氢异丙苯转化率可达94.7%,环氧丙烷选择性可达95.8%。Ti-MCM-41 mesoporous molecular sieves were prepared at room temperature in a mixture of isopropyl alcohol and water,with tetramethyl orthosilicate as Si source and tetraisopropyl titanate as Ti source.The structure properties of Ti-MCM-41 mesoporous molecular sieves were characterized by TEM,N 2 adsorption,XRD,UV-Vis and Raman techniques.The catalytic performances for propylene epoxidation of the silylated Ti-MCM-41 catalysts were investigated,using cumene hydroperoxide(CHP)as the oxidant.It is found that,compared with the hexa-coordinated Ti atoms,the tetra-coordinated Ti atoms introduced into the framework of MCM-41 are better active sites for the conversion of cumene hydroperoxide.The tetra-coordinated Ti species play an important role in the formation of propylene oxide,and the hexa-coordinated Ti species favor the formation of by-products.A proper addition of isobutanol could improve the formation of Ti species in framework,and increase the surface area and pore volume,therefore enhance the catalytic activity for epoxidative reactions.Cumene hydroperoxide conversion of 94.7%and propylene oxide selectivity of 95.8%can be obtained over the best Ti-MCM-41 catalyst.

关 键 词：催化化学 TI-MCM-41 介孔分子筛 丙烯环氧化 

分 类 号：TQ426.94[化学工程] O643.36[理学—物理化学]