The Study On Separation For Ethyl Acetate-ethanol By Ionic Liquid Compound Extractent

Traditional organic solvents in the extraction distillation existed some shortcomings,such as large amount of use,high cost of solvent recovery,high energy consumption.At present,ionic liquid(IL)as extractant separating azeotrope had become a hot research topic.But its viscosity and the costs of production was high.This paper presented ionic liquid compound extractant,which consisted of ionic liquid and DMSO.The effect of ionic liquid compound extractant on the azeotropic system was studied.Firstly,σ-map library of 22 kinds of anions and 176 kinds of cationic was established,in the Material Studio software.Python language was used to write the program of molecular design process.The 1-octyl-3-methylimidazolium tetrafluoroborate was selected as the single extractant with the aim of the selectivity and solubility.The vapor-liquid equilibrium(VLE)datas of ethyl acetate-ethanol-DMSO,ethyl acetateethanol-IL,ethyl acetate-ethanol-DMSO + IL were measured at 101.32 kPa.The results showed that DMSO had a great influence on the relative volatility of the system,when the concentration of ethyl acetate was large.IL had a great influence on the relative volatility of the system,when the ethyl acetate concentration was low.Ionic liquid compound extractant(DMSO + IL)could significantly change the relative volatility of the binary azeotrope system over the entire concentration range.It could improve the effect of separation.Experimental data was fitted by NRTL equation model,and the parameters of NRTL equation were regressed.The VLE data of ternary and quaternary systems are predicted,which was consistent with the experimental data.The GC-PT state equation model was used to predict the critical properties of ionic liquids,the parameters of vapor pressure and heat capacity.The extraction process of quaternary system was simulated by Aspen Plus software.The results of optimization showed that the theoretical stage number of the distillation column was 36,the feed stage of the ionic liquid compound extractant was 4,the feed stage of raw material was 26,the molar reflux ratio was 1.2.Finally,the energy consumption of the three extractant processes was compared.The results showed that compared the processes in which IL was extractant,the amount of ionic liquid decreased by 46.15%;and the duty of reboiler reduced 10.95% in the processes of Ionic liquid compound extractant.Compared the processes in which DMSO was extractant,the number of theoretical stage reduced by 10%.The amount of extractant is reduced by 68.89%,and the duty of reboiler reduced 23.40% in the processes of Ionic liquid compound extractant.In summary,the ionic liquid compound extractant could separate the azeotropic mixture of ethyl acetate and ethanol with low cost.The optimized process of separating the crude ester material with the ionic liquid compound extractant was optimized,and the effect of separation was better.