CuCl改性对FeCl_3-氯化丁基甲基咪唑离子液体催化烷基化反应性能的影响

Effect of CuCl Modification on Catalytic Performances of FeCl_3-(Butyl-Methyl-Imidazolium) Ionic Liquid in Alkylation

将FeCl3-氯化丁基甲基咪唑(FeCl3-bmimCl)离子液体中加入少量CuCl改性后,用于催化苯与乙烯的烷基化反应。实验结果表明,在45℃、3.0MPa、苯与乙烯摩尔比10、反应时间2h的条件下,乙烯的转化率由改性前的89%增加到改性后的99%,乙苯的选择性由改性前的95%增加到改性后的99%。利用Raman光谱、快速原子轰击(FAB)和核磁共振氢谱(1HNMR)方法,对改性离子液体改善催化烷基化效果的原因进行研究。研究结果表明,改性后离子液体中主要的阴离子仍然是Fe2Cl-7,但形成的络合阴离子Fe3Cl11Cu-的电荷分布宽,成为不同种类正碳离子的良好接受体,从而改善了H+传递反应的活性,使其具有较高的催化活性和选择性。

Alkylation of benzene and ethylene catalyzed by FeCl3-bmimCl (bmim: butyl-methyl-imidazolium) ionic liquid modified with CuCl was studied. Ethylene conversion increased from 89% to 99% and ethylbenzene selectivity from 95% to 99% after CuCl was added to FeCl3-bmimCl ionic liquid when reaction conditions were:45°C, 3.0 MPa, n(benzene) : n(ethylene) 10 and reaction time 2 h. The structures and anions of ionic liquid before and after CuCl was added were studied by means of Raman spectrum, fast atom bombardment (FAB) and 1H NMR. Fe2Cl7 were still key anions in ionic liquid modified with CuCl. Newly formed anions Fe3Cl11Cu- in ionic liquid had wide charge distribution, which made it good acceptors of different kinds of carbonium ions. Consequently, the activity of H+ transfer reaction was improved. Thus, ionic liquid modified with CuCl had higher catalytic activity and selectivity in alkylation than the unmodified.