Separation Of Ethyl Acetate And Isopropanol By Using Ionic Liquids

The azeotropic system is usually separated by extractive distillation.Ionic liquid,as a molten salt,is used as an extractant for extractive distillation and has the advantages of both liquid solution(easy to operate)and solid salt(high separation capacity).The salting-out and salt-solving effects of ionic liquids can change the relative volatility of the components and eliminate azeotropic phenomena.This paper adopts the one-step synthesis of 1,3-dimethylimidazolium dimethylphosphate([MMIM][DMP]),1-ethyl-3-methylimidazolium diethylphosphate([EMIM][DEP])and1-butyl-3-methylimidazolium dibutylphosphate([BMIM][DBP]),and ~1H-NMR analysis and the moisture content determination of the three kinds of ionic liquids show that the structure of ionic liquid is right and its moisture content satisfies the requirement of experiment.The vapor-liquid equilibrium data of ethyl acetate-isopropanol-ionic liquid were measured at atmospheric pressure,and the changes of vapor-liquid equilibrium composition,equilibrium temperature,component activity coefficient and relative volatility were further studied.In the range of ionic liquids studied,the addition of the three kinds of ionic liquids breaks the azeotropic point of ethyl acetate-isopropanol.The addition of ionic liquid increases the equilibrium temperature of the system and the activity coefficient of ethyl acetate,but decreases the activity coefficient of isopropanol.In the high concentration area of ethyl acetate,the ionic liquid has a greater influence on the activity coefficient of isopropanol,while in the low concentration area ofethyl acetate,the ionic liquid has a greater influence on the activity coefficient of ethyl acetate.The separation ability of ionic liquids for ethyl acetate-isopropanol was[BMIM][DBP],[EMIM][DEP],[MMIM][DMP].Ethyl acetate(1)-isopropanol(2)-ionic liquids([MMIM][DMP]and[EMIM][DEP])(3)were measured at atmospheric pressure for T=298.15 K and T=318.15 K.The liquid-liquid equilibrium data of the ternary system was analyzed.The results showed that the increase of the isopropanol content in the system will reduce the selectivity coefficient S.For the ethyl acetate-isopropanol-[MMIM][DMP]system,the change in temperature has little effect on the solubility of[MMIM][DMP]and has little effect on the selectivity coefficient S.For the ethyl acetate-isopropanol-[EMIM][DEP]system,when the temperature increases,the solubility of[EMIM][DEP]increases and the selectivity coefficient S decreases.NRTL thermodynamic model was used to obtain the parameters of NRTL thermodynamic model by regression of vapor-liquid equilibrium data and liquid-liquid equilibrium data.The calculated values of the vapor-liquid equilibrium data and liquid-liquid equilibrium data compared with the experimental values,finding that the NRTL model can better correlate experimentally measured ternary isobaric vapor-liquid equilibrium data and liquid-liquid equilibrium data.