CIESC Journal ›› 2009, Vol. 60 ›› Issue (6): 1452-1458.
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WEI Zuojun;LI Yan;LI Feijin;CHEN Chuanjie;LIU Yingxin;REN Qilong
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魏作君;李艳;李斐瑾;陈传杰;刘迎新;任其龙
Abstract: Three designed and synthesized Brnsted acidic ionic liquids(ILs)[(n-Bu-SO3H)MIm][HSO4],[(n-Bu-SO3H)MIm][p-CH3C6H4SO3]and [Et3NH][HSO4],as well as another commercial ionic liquid [HBIm][CF3SO3]were used to catalyze the esterification reaction of hexanoic acid and ethanol.Among them(n-Bu-SO3H)MIm][HSO4]exhibited the highest activity,which was later selected to be immobilized on the silica gel by both impregnation and sol-gel methods.The immobilized ILs were then characterized by 1H NMR,elemental analysis,FTIR and activity test.The results showed that the loading amounts of ionic liquid by the impregnation method A,B and sol-gel methods were 15.5%,20.5 % and 40.5 %(mass),respectively.For the first time the three immobilized ILs were used to catalyze the esterification of hexanoic acid and ethanol,and the yields of ethyl hexanoate were 75.3%,92.6%and 92.6%,respectively.However,the activity of the ionic liquid immobilized impregnation decreased rapidly with recycle runs since the load amount of ionic liquid dropped to 3.0 %(mass)after 4 recycle runs for method A and dropped to 7.0 %(mass)after 8 cycle runs for method B.By contrast,the ionic liquid immobilized by the sol-gel method was much stable,and could be reused for 10 times with only little decrease in activity.Moreover,the sol-gel method immobilized ionic liquid also showed acceptable activity(ester yields>90.0%)for the esterification of other carboxylic acid with ethanol.Therefore,the sol-gel method is an excellent method for the immobilization of ionic liquid to catalyze esterification reactions..
Key words: 离子液体, 酸催化剂, 固定化, 酯化反应, 浸渍法, 溶胶-凝胶法
离子液体,
摘要:
设计合成了1-甲基-3-丁烷磺酸咪唑硫酸氢盐([(n-Bu-SO3H)MIm][HSO4])、1-甲基-3-丁烷磺酸咪唑对甲苯磺酸盐([(n-Bu-SO3H)MIm][p-CH3C6H4SO3])和硫酸三乙胺([Et3NH][HSO4])3种Bronsted酸性离子液体,考察了其催化正己酸与乙醇酯化反应的活性,分别采用浸渍法和溶胶-凝胶法将活性最佳的离子液体[(n-Bu-SO3H)MIm][HSO4]固定在硅胶上,对固定化离子液体催化正己酸与乙醇酯化反应的性能及重复使用性能进行了比较,并采用1H NMR、元素分析和FTIR等方法对其进行了表征。研究结果表明:采用浸渍法A、浸渍法B和溶胶-凝胶法固定的离子液体的负载量(质量分数)分别为15.5 %、20.5 %和40.5 %,催化正己酸与乙醇酯化反应所得正己酸乙酯的产率分别为75.3%、92.6%和92.6%。但浸渍法制备的固定化离子液体不稳定,重复使用4次(浸渍法A)和8次(浸渍法B)后离子液体负载量分别下降到3.0 %和7.0 %,正己酸乙酯产率分别降为24.2%和64.5%;而采用溶胶-凝胶法制备的固定化离子液体重复使用10次后,离子液体的负载量为39.0%,流失很少,正己酸乙酯产率依然高达92.7%。将溶胶-凝胶法制备的固定化离子液体进一步应用于其他脂肪酸与乙醇的酯化反应,乙酯产率均在90.0%左右,表明采用溶胶-凝胶法是制备固定化离子液体催化剂的有效方法。
关键词: 离子液体, 酸催化剂, 固定化, 酯化反应, 浸渍法, 溶胶-凝胶法
WEI Zuojun, LI Yan, LI Feijin, CHEN Chuanjie, LIU Yingxin, REN Qilong. Catalytic esterification reactions over immobilized Bronsted ionic liquid[J]. CIESC Journal, 2009, 60(6): 1452-1458.
魏作君, 李艳, 李斐瑾, 陈传杰, 刘迎新, 任其龙. 固定化Bronsted酸性离子液体催化酯化反应 [J]. 化工学报, 2009, 60(6): 1452-1458.
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