复合型催化剂MIL-101@PIL催化CO_(2)环加成反应

CO_(2) CYCLOADDITION REACTION CATALYZED BY COMPOSITE CATALYST MIL-101@PIL

针对CO_(2)与环氧化物反应制备环碳酸盐需要高性能、低成本、易于回收的催化剂,制备了一种基于金属有机框架(MOF)的非均相催化剂(MIL-101@PIL)用于催化CO_(2)转化为环碳酸酯。首先采用水热法制备MIL-101-Cr,然后在其孔道中负载具有较大分子体积的双季鏻盐离子液体1,4-双三苯基膦基丁烷溴盐。通过一系列对比试验考察,结果表明,MIL-101@PIL催化剂在无溶剂和助催化剂的情况下,具有较高的催化环加成反应生成环碳酸酯的活性。以合成碳酸丙烯酯为例,在优化条件下(MIL-101@PIL加入量80 mg,CO_(2)压力1.4 MPa,环氧丙烷加入量17 mmol,反应温度90℃,反应时间3 h),可获得较高的碳酸丙烯酯收率(95%)和选择性(99%),MIL-101@PIL催化剂较高的催化活性主要是由于配位不饱和Cr与Br阴离子之间具有协同催化作用。基于此,提出了MIL-101@PIL催化剂催化环加成反应的可能机理。

The reaction of CO_(2) with epoxides to form cyclic carbonates requires a catalyst with high-performance,low-cost and easy recovery.A metal-organic frameworks(MOFs)-based heterogeneous catalyst(MIL-101@PIL)was prepared for catalytic conversion of CO_(2) to cyclic carbonates.Firstly,the MOF precursor MIL-101-Cr was prepared by hydrothermal synthesis,and then biquaternary phosphonium ionic liquid(1,4-bis-triphenylphosphonium butane bromide)with large molecular volume was loaded into its pore channel to form the catalyst MIL-101@PIL.A series of comparative experiments showed that the catalyst MIL-101@PIL had high activity in the synthesis of cyclocarbonate by cycloaddition reaction without solvent and co-catalyst.Under the optimum conditions(MIL-101@PIL mass of 80 mg,CO_(2) pressure of 1.4 MPa,propylene oxide amount of 17 mmol,reaction temperature of 90℃,reaction time of 3 h),higher yield(95%)and selectivity(99%)were obtained.The results showed that the catalyst(MIL-101@PIL)had high catalytic activity,which was mainly due to the synergistic catalysis between the coordination unsaturated Cr sites and the Br anions.Based on this,a possible mechanism of cycloaddition reaction catalyzed by catalyst MIL-101@PIL was proposed.