In this work, the extractive methanol removal from C4hydrocarbon using ionic liquids(ILs)as extractants was studied. Firstly, the effect of structure of ionic liquid on extraction process was investigated. The results show that 1-butyl-3-methyl imidazole dibutyl phosphate([Bmim][DBP])performs the best ex-traction. According to the selected ionic liquid[Bmim][DBP], quantum chemistry calculation method was used to explain the mechanism between ionic liquid[Bmim][DBP]and methanol. The results show that sta-ble hydrogen bonds not only exist between cation and anion in ionic liquid[Bmim][DBP],but also exist be-tween methanol and ionic liquid[Bmim][DBP]. The hydrogen bonds strengthen the interaction among the molecules. The anion[DBP]ˉin[Bmim][DBP]and—OH in methanol form a hydrogen bond of 0.1711 nm and the interaction energy isˉ62.08 kJ/mol. A series of experiments was carried out to determine the effect of ILs/C4mass ratio,extraction time and recycle times on the performance of ionic liquid[Bmim][DBP]. The results show that the extraction rate reaches 99.65% under the conditions of ILs/C4mass ratio of 1:2,extrac-tion time of 60 min,temperature of 25℃. Furthermore,the extration rate would not decrease after 5 recycles.%研究了用离子液体(ILs)萃取分离混合C4烃(C4)中微量甲醇的过程.考察了不同组成的离子液体的萃取性能,发现1-丁基-3-甲基咪唑磷酸二丁酯([Bmim][DBP])具有最佳的萃取性能.采用量子化学方法,研究了[Bmim][DBP]与甲醇的作用机理.结果表明,在离子液体阴、阳离子以及离子液体与甲醇之间均存在稳定的氢键,并且氢键加强了分子间的相互作用.[Bmim][DBP]的阴离子[DBP]ˉ与甲醇中的—OH形成了键长为0.171 nm的氢键,其相互作用能为ˉ62.08 kJ/mol,强于其它阴离子与甲醇的相互作用能.还探讨了[Bmim][DBP]离子液体与混合C4烃的比例、萃取时间及离子液体循环次数等因素对萃取效果的影响,结果表明,当m(ILs):m(C4)=1:2,于25 ℃萃取60 min时,萃取率为99.65%,离子液体循环使用5次后萃取率仍保持稳定.
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