Extractive Distillation For Azeotropic Mixture Of Tert-butyl Alcohol And Water With Ionic Liquids As Solvent

Extractive distillation with ionic liquid as entrainer is a novel green process for the separation of azeotropic mixture.The vapor liquid equilibria and extractive distillation process for the separation of tert-butanol and water using single ionic liquid and mixed ionic liquids as entrainer were studied in this paper.Thevapor-liquidequilibriafortert-butanol+water+1-ethyl-3-methyl-imidazolium dicyanamide?[C₂mim][DCA]?were measured at 101.3 kPa.The NRTL model was used to correlate the experimental vapor-liquid equilibrium data of the ternary systems,and the binary interaction parameters of tert-butanol-[C₂mim][DCA],water-[C₂mim][DCA]were obtained.The correlation results were in good agreement with the experimental results.The experimental results show that ionic liquid[C₂mim][DCA]can improve the relative volatility of tert-butanol to water,and the azeotropic point of tert-butanol–water can be eliminated if the mole fraction of[C₂mim][DCA]is greater than 0.2.The vapor-liquid equilibrium data of tert-butanol-water-[C₂mim][DCA]-1-ethyl-3-methylimidazolium acetate?[C₂mim][OAc]?were determined by experiments at 101.3 kPa.The results indicate that mixed ionic liquids?[C₂mim][DCA]+[C₂mim][OAc]?can completely destroy the azeotrope of tert-butanol-water.The binary interaction parameters of tert-butanol-[C₂mim][OAc],water-[C₂mim][OAc]and[C₂mim][DCA]-[C₂mim][OAc]for NRTL equation were obtained by correlation of the experimental vapor-liquid equilibrium data.There is no synergistic effects between[C₂mim][DCA]and[C₂mim][OAc],and the selectivity of[C₂mim][OAc]is higher than that of[C₂mim][DCA].The extractive distillation processes for the separation of tert-butanol and water using single ionic liquid entrainer[C₂mim][DCA]and mixed entrainer?[C₂mim][DCA]+[C₂mim][OAc]?were simulated by simulation software Aspen Plus.The effects of entrainer temperature,entrainer position,feed position,reflux ratio and solvent ratio on the extractive distillation processes with single ionic liquid entrainer and mixed ionic liquid entrainer were investigated by the simulation results.