介孔HMS表面不同基团及孔口改性对固载Salen-Mn的影响

制备表面含-OH-、NH2-、CHO的三种HMS载体,研究这些载体表面功能团对Salen-Mn配合物的吸附固载作用,用FT-IR,TG-DSC表征配合物与载体表面基团的相互作用,并用配位滴定法测定了Mn的负载量。以E-二苯基乙烯环氧化反应考察其催化氧化性能和对环氧化物选择性的影响。结果表明,含表面-OH的HMS固载Salen-Mn的效果较差,而含表面-NH2,-CHO的HMS对Salen-Mn有较好的固载作用;对固载Salen-Mn的载体孔口改性可进一步提高环氧化物的选择性并减少Mn的流失。

Immobilization of Salen-Mn Complex over HMS with diffirent Surface's Groups and Modification of it's Outlet

Three hexagonal mesoporous silicas (HMS) with different surface's groups of -OH, -NH_(2), -CHO have been successfully prepared by grafting methods, and used to immobilize Salen Mn complex. The mutual interaction between Salen-Mn complex and the surface's groups of HMS were investigated by FT-IR and TG-DSC characterization technology. Mn loading was determined by coordinated titration. The effect of the surface's groups of HMS on the catalytic activity and selectivity of Salen Mn complex for E-stilbene epoxidation was investigated. The results indicated that the HMS with surface's NH_(2) or CHO could immobilize salen Mn complex more efficiently than that with surface's OH, therefore, the former possessed obvious higher salen Mn loading and conversion for E-stilbene epoxidation and with a concomitant lower Mn leaching than the latter in the catalytic reaction process. Furthermore, the outlet grafting some bulk large molecules of HMS absorbed salen Mn complex could efficiently reduce the Mn leaching and enhance the selectivity for the epoxides .