介孔载体负载的碱性离子液体催化合成碳酸丙烯酯

Basic ionic liquid supported catalyst for synthesis of propylene carbonate

采用后嫁接法将碱性离子液体1-丁基-3-甲基咪唑的氢氧化物([Bmim]OH)分别负载到介孔硅胶、MCM-41分子筛和SBA-15分子筛上制备了非均相负载型离子液体,采用傅立叶变换红外光谱、N2吸附-脱附、元素分析和热重分析等手段对其表征,发现离子液体以共价键嫁接到硅胶上,且有较好的热稳定性。在无溶剂和温和的条件下,以非均相负载型离子液体为催化剂,研究了环氧丙烷与CO2环加成合成碳酸丙烯酯的反应,结果表明,3种非均相负载型离子液体均具有较好的催化性能,其中,[Bmim]OH/SiO2的催化性能最好,在最优条件下,环氧丙烷转化率可达99.1%,反应后催化剂经过滤即可分离回收利用,多次使用仍保持较高的反应活性。

The heterogeneous supported ionic liquids were prepared by loading the ionic liquid 1-butyl-3- methylimidazolium hydroxide （[ Bmim ] OH ） on three mesoporous molecular sieves SiO2 （silica gel ）, MCM-41 and SBA-15 molecular sieves, and characterized by means of FT-IR, N2 adsorption-desorption, elemental analysis and TG. The results showed that the as-prepared supported ionic liquids with better thermal stability were successfully grafted on the support of silica gel via covalent bonds. The heterogeneous supported ionic liquids were effective catalysts for cycloaddition of propylene oxide and CO2 to propylene carbonate under solventless and mild conditions; the silica gel grafted 1-butyl-3-methylimidazolium hydroxide （[ Bmim ] OH/SiO2 ） exhibited the best catalytic performance. Propylene oxide conversion of 99.1% was attained under the optimal reaction condition. The catalyst could be recovered easily with filtration and recycled. In addition, the high catalytic performance of [ Bmim ] OH/SiO2 was remained after being reused several times. Key words：catalytic chemistry; mesoporous support; basic ionic liquid; propylene carbonate