Design Synthesis And Application Of Bifunctional Catalysts Based On MWW Zeolite

Conventional homogeneous catalysts have many disadvantages,such as bad selectivity,low yield,difficulty in separation and recovery,serious environment pollution etc.Whereas the discovery of zeolites exploited a new area of catalysts, because zeolites not only have regular structures which causing shape-selectivity,but also can be loaded,modified to introduce new functions,moreover,they are always robust and recyclable.In this study,we made some noble bifunctional catalysts through grafting,loading functional groups or metals on MWW type zeolites,using them to one-pot catalyze complex reactions.First,we grafted basic group on MCM-22 or delaminated MCM-22 to prepare acid-base bifunctional catalysts,using them to catalyze Knoevenagel reaction and Nitroaldol condensation.Second,mercaptopropyl triethoxy silane reacted with delaminated Ti-MWW's terminal Si-OH,obtained a SH modified catalyst,SH was then further oxidized by H₂O₂ to finally prepare Del-Ti-MWW-SO₃H,which appeared both catalytic oxidative and acidic abilities.We tried it in catalyzing one-pot synthesis e-Caprolactam from cyclohexanone.A new kind of bifunctional catalyst Rh(OH)x/Ti-MWW was prepared by the impregnation method.Rh(OH)x/Ti-MWW possessed two kinds of metals which can simultaneously catalyze ammoximation and rearrangement reactions.So it proved to be successful in catalyzing one-pot synthesis amide from aldehyde.This amide synthesis method breaks with the convention,is a green,convenient approach.