Studies On The Heterogeneous Catalysts For The Cycloaddtion Of Carbon Dioxide And Epoxides

CO2 is a major greenhouse gas in the atmosphere. There is a growing awareness that anthropogenic CO2 emissions should be reduced. The chemical fixation of CO2 into cyclic carbonates is of great interests in terms of "green and sustainable chemistry" because CO2 can be considered as a renewable carbon resource and these cyclic carbonates can be widely used for various purposes.In this study, we have focused on the developing an efficient and environmentally benign catalyst for cyclic carbonate synthesis. The main contents of this thesis are described as follows:1. A series of the montmorillonites modified with different ionic liquids was synthesized, and the modified montmorillonite catalysts were utilized for the addition reaction. Then the recyclability and the generality of the catalyst were investigated systemically.2. A series of inorganic oxides, coupling with a quaternary ammonium salt constituted an efficient binary catalyst system which can convert CO2 and epoxides into cyclic carbonates. The binary catalysts offered higher activity, in comparison with sole TBAB or inorganic oxides. This demonstrated that the inorganic oxides and TBAB showed a strong synergetic effect for the cycloaddition reaction. Especially, the silica has been chosen as model oxide to study the role of the surface hydroxyl groups in the reaction. It was found that when the surface of silica was silylated, the catalytic activity decreased sharply due to surface silylation, which indicated clearly that the surface hydroxyl groups on the silica played a decisive role in influencing the catalytic activity.