Study On Separation Of Ethyl Acetate-Ethanol Azeotrope By Ionic Liquid Extractive Distillation

Both ethyl acetate and ethanol are chemical raw materials in great demand,and the crude product of ethyl acetate must be mixed with ethanol,and ethyl acetate and ethanol can form an azeotrope under normal pressure.The separation of azeotropes has always been a focus of research in the industry.Extractive distillation is widely used in the separation of azeotropes due to its simple operation and high product purity.As the currently popular new solvent ionic liquids,they not only have good physical and chemical properties and recyclability,but also can accurately select the chemical properties of anions and cations for specific system applications,so they have received extensive attention.Therefore,thesis selects ionic liquid as the entrainer to separate the azeotropic system of ethyl acetate and ethanol.The main research contents are as follows:（1）COSMOtherm X software was used to screen 300 ionic liquids consisting of a common combination of 20 anions and 15 cations,and three ionic liquids with acetate were screened according to the predicted solubility,selectivity,availability and price of ionic liquids,namely tetraethylammonium acetate[N_2,2,2,2][Ac],1-ethyl-2,3-dimethylimidazole acetate[EMMIM][Ac]and tributylmethylammonium acetate[N_4,4,4,1][Ac].（2）The vapor-liquid phase equilibrium data of ethyl acetate-ethanol binary system and ethyl acetate-ethanol-ionic liquid([N_2,2,2,2][Ac]、[N_4,4,4,1][Ac]、[BMMIM][Ac])ternary system were measured at atmospheric pressure.It can be seen from the experimental data that the addition of the three ionic liquids can make the ethyl acetate components aggregate in the gas phase,resulting in the phenomenon of salting out.As the concentration of the ionic liquid increases,the salting-out effect is more obvious.When the solution reaches a certain molar ratio,the ethyl acetate-ethanol azeotrope system will be broken.The NRTL model was selected to correlate the experimental data.The results showed that the data points of the experimental value fluctuated slightly around the calculated value of the NRTL model,indicating that the NRTL model equation could be used for the parameter calculation of the mixture system.The minimum mole fraction of three ionic liquids[N_2,2,2,2][Ac],[EMMIM][Ac],[N_4,4,4,1][Ac]to break the azeotrope can be obtained through the calculation of the NRTL model They are 0.015,0.020,and 0.022,respectively.The average relative volatility at 0.03 and 0.06 after breaking the azeotrope comprehensively shows that[EMMIM][Ac]shows the best separation in the separation of ethyl acetate-ethanol azeotrope ability.（3）Aspen Plus software was used to simulate the process of[N_4,4,4,1][Ac]extractive distillation for the separation of ethyl acetate-ethanol.The effects of parameters such as feedstock feed position,theoretical plate number,extractant feed position and reflux ratio on the extractive distillation process were investigated.Using the simulation results,the optimized operating conditions for the separation of ethyl acetate-ethanol azeotropes by extractive distillation were obtained.