Synthesis,Characterization And Application Of Functionalized Ionic Liquids Immobilized Mesoporous Materials

Recently, ionic liquids have been widely used in the fields of chemistry and chemical engineering, due to their properties such as extremely low volatility, nonflammable, wide electrochemical window, etc. Especially, functionalized ionic liquids show great potential in catalysis, which is one of the most important application regarding to ionic liquids. However, it is limited by some disadvantages, such as high cost, high viscosity, and difficulties of mass transfer and separation. In order to solve these problems, immobilization of ionic liquid was tried. To date, diverse materials could be used as carriers, including porous silica gel, mesoporous material, active carbon, etc. A variety of immobilization methods were developed, such as impregnation, grafting, sol-gel method, etc. Mesoporous materials as a kind of special carrier candidate, possesses uniform pore size, large specific surface areas and abundant suface OH group; Sol-gel technique and grafting method can make the organic substance be connected on the carriers with chemical bonds, and the loss of active component is not easy. At present, supported ionic liquid compounds containing metal ions were applied to catalysis, while reports on synthesis of supported functionalized ionic liquids are still rare. In this thesis, sol-gel technique and grafting method were used to immobilize functionalized ionic liquids on mesoporous molecular sieves. The resulting materials were characterized and applied as a catalyst.The main contents of this thesis are as following:1. Two kinds of functionalized ionic liquids precursors, N-(3-triethoxysilylpropyl)-N-(3-sulflopropyl)-amine (abbr.SNSA) and1-(3-triethoxysilylpropyl)-3-(3-sulflopropyl)-4,5-dihydroimidazole (abbr.SSHI) were designed and synthesized. The products were chara cterized by NMR, IR, UV, MS, etc.2. SNSA and SSHI ionic liquid precursors were immobilized on MCM-41and SBA-15mesoporous materials by using sol-gel and grafting methods respectively. And then, the materials were acidified and basified by using desirable acids or base solution to obtain the supported ionic liquid phase. Characterization of XRD, TEM, nitrogen adsorption and desorption showed that the materials have the characteristic mesoporous structure. Characterization of IR, UV, EA, CP MAS NMR demonstrated that the ionic liquids were successfully licked to the mesoporous materials.3. The basic ionic liquids supported materials were used as a catalyst in the aldol reaction of4-nitrobenzaldehyde and acetone. Compared with other organic solvents, n-hexane was most favorable solvent to the reaction. The highest conversion ratio was～89%; the selectivity to hydroxides is～92%; and the catalysts could be reused for three times without significant change of the catalytic activity.