Preparation And Application Of Hydrophobic Functionalized Ionic Liquids In Separation Of Butanol

Biobutanol,as a new type of biofuel,has high energy density,good intersolubility with gasoline and does not cause environmental pollution.Thus,biobutanol is an ideal substitute for gasoline.Since biobutanol is generally obtained through ABE fermentation,efficient separation of butanol from the ABE fermentation product is one of the important research topics.Ionic liquids have good physicochemical properties and can be used as extractants under mild conditions.Furthermore,hydrogen bonds can be formed between functionalized ionic liquids and butanol,which improves the extraction performance.Therefore,the functionalized ionic liquids can be widely applied in the extraction and separation of butanol.Based on the designability of ionic liquids,there hydrophobic ionic liquids were prepared.First,amine-based ionic liquid was synthesized by introducing amine group into imidazoles cation and with bis(trifluoromethylsulfonyl)imide[NTf2]' as anion.The extraction of butanol with amine-based ionic liquid mainly depends on the hydrophobic effect.Then the hydroxyl ionic liquid was synthesized by introducing hydroxyl group into the DBU cation and the extraction of butanol with this hydroxyl ionic liquid mainly depends on the hydrogen bonding effect between ionic liquid and butanol.Finally,the imidazolium anion-based ionic liquid was synthesized by combining hydroxyl with imidazole.The extraction of butanol mainly depends on the hydrogen bonding effect between hydroxyl and imidazole.The structures of these three ionic liquids were verified by NMR and FT-IR spectra,the results of which confirmed the high purity of prepared ionic liquids.The binding energies between prepared ionic liquids and butanol,acetone,ethanol and other substances were calculated by using density functional theory with Gaussian software,the results of which indicates that all the interaction energies between ionic liquids and butanol,acetone and ethanol were larger than that between ionic liquids and water.In addition,the interaction energies follow the sequence:butanol>acetone>ethanol>H2O.The three prepared ionic liquids were used as extractants for the separation of bicomponent systems of butanol/water,acetone/water and ethanol/water.Effects of extraction temperature,extraction time,ionic liquid dosage and regeneration times on extraction performances were stuied.The results showed that the imidazole anion-based ionic liquid had the best extraction ability for butanol and the extraction performance was stable after 10 cycles of regeneration.Then the imidazole anion-based ionic liquid was used for the separation of simulated butanol fermentation products.Effects of extraction temperature,extraction time and the dosage of ionic liquid on extraction performance were investigated.The results showed that the extraction efficiencies of butanol,acetone and ethanol with the imidazolium anoin-based ionic liquid as extractant were78%,34%and 6%,respectively.After 10 cycles of regeneration,the extraction efficiencies remained stable.Finally,the technology route of the extraction process was studied.The number of extraction stages was calculated and the extraction process flow diagram was determined.Aspen software was used to simulate the extraction process and analyze energy consumption.The feasibility of the extraction process was confirmed through technical feasibility analysis.