分子筛固载席夫碱过渡金属配合物催化丙烯环氧化

Epoxidations of Propylene Catalyzed by Transition Metal Schiff Base Complex Immobilized on Molecular Sieve

采用硅溶胶、氨水等廉价原料水热法合成Ti-MCM-41介孔分子筛,用γ-氨丙基三乙氧基硅烷对分子筛表面改性,与水杨醛反应得到表面固载席夫碱的分子筛催化剂前体,利用浸渍法分别制得分子筛固载席夫碱过渡金属Cu^(2+)、Mn^(2+)、Ag^+、Fe^(3+)、Co^(2+)配合物催化剂,并将此催化剂用于丙烯环氧化反应。采用X射线衍射、红外光谱、扫描电子显微镜等对催化剂结构和组成进行表征。结果表明,分子筛表面改性后原有的介孔结构保持不变;分子筛表面弱碱性能够抑制副反应的发生;分子筛固载锰配合物的催化丙烯环氧化反应性能最好,H_2O_2的转化率达42.5%,环氧丙烷选择性92.6%。

Ti -MCM-41 mesoporous molecular sieve was synthesized under hydmthermal condition with sili- ca, ammonia and other low - cost raw materials. The molecular sieve was modified using T - aminopropyltriethoxysilane and reacted with salicylaldehyde and the precursors of zeolite catalyst was synthesized. The ultimate catalysts of zeolite immobilizing Schiff base transition metal Cu^2＋ , Mn^2＋ , Ag ^＋ , Fe^3 ＋ , Co^2 ＋ were obtained by impregnation method and the catalyst was used in the reaction of the epoxidafion of propylene. The structures and composition of the catalysts were characterized by X - ray diffraction, infrared spectroscopy, scanning electron microscopy. The results showed that the modification of zeolite surface did not destroy its original mesoporous structure; zeolite surface with weak alkaline inhibited the occurrence of side effects; zeolite immobilizing manganese complex had the best performance with 42.5% conversion rate of H202 and 92.6% selectivity of propylene oxide.