Application Of Deep Eutectic Solvent For Separation Of Water-Ethanol-2-Propanol System

Ethanol and 2-propanol are basic chemical materials in daily life and industry,and are widely used as solvents or pharmaceutical intermediates.In some chemical production processes,ethanol and 2-propanol need to be introduced,and the mixture formed by the two needs to be separated in the post-treatment process.In this paper,with the solvent dehydration of ethanol,2-propanol and water as the research background,and the separation of the mixture of water,ethanol and 2-propanol by extractive distillation is studied.In order to separate the mixture by extractive distillation,the choice of entrainer is a key step.In this work,the performance of entrainers for ethylene glycol,glycerol,and some mixed solvents are evaluated.The isobaric vapor-liquid equilibrium data of quaternary and quinary systems are measured at p=101.3 k Pa,and the model is successfully established using the NRTL equation.The effects of ethylene glycol,glycerol and mixed solvents on the relative volatility and activity coefficient of key volatile components are discussed.Use Aspen Plus chemical simulation software to simulate the process of the system to provide a theoretical basis for industrialization.The vapor-liquid equilibrium data are correlated based on the NRTL equation,and the results show that the experimental values and calculated values are in good agreement.For the water?1?+ethanol?2?+2-propanol?3?+ethylene glycol?4?system,the temperature and vapor phase composition deviation are?T=0.28 K,?y₁=0.0008,?y₂=0.0031,?y₃=0.0057,for water?1?+ethanol?2?+2-propanol?3?+ethylene glycol?4?+choline chloride?5??T=0.18 K,?y₁=0.0007,?y₂=0.0017,?y₃=0.0043,for water?1?+ethanol?2?+2-propanol?3?+glycerol?4??T=0.20 K,?y₁=0.0005,?y₂=0.0030,?y₃=0.0034,for water?1?+ethanol?2?+2-propanol?3?+glycerol?4?+choline chloride?5??T=0.15 K,?y₁=0.0004,?y₂=0.0026,?y₃=0.0028.The experimental results show that the separation of water-ethanol-2-propanol system using deep eutectic solvent as entrainer shows better results compared with the use of ethylene glycol or glycerol alone.With the addition of choline chloride,it can be observed that the activity coefficient of water decreases faster and the activity coefficients of ethanol and 2-propanol increase,resulting in a faster increase in the relative volatility of ethanol and 2-propanol to water,which is more conducive to dehydration.A mixed solution with a mass fraction of 1.7%water,20%ethanol and 78.3%2-propanol,and a total flow rate of 1000 kg·h^-1 is used as the separation object.The deep eutectic solvent glycerol+choline chloride 2?1 and glycerol are used as entrainers,respectively.The NRTL activity coefficient model is used,and the binary interaction parameters optimized by experimental data are used as the model parameters.Aspen Plus chemical simulation software is used simulation and optimization of extractive distillation process for water-ethanol-2-propanol system.The simulation results show that when the same theoretical plate number,the same raw material feeding position,the same reflux ratio,and the same solvent feeding position are used,the use of glycerol+choline chloride 2?1 as the entrainer compared with the use of glycerol alone not only reduces the amount of entrainer but also saves 8.8%of energy consumption.Considering the separation performance of the entrainer and economic and environmental protection,it is better to use deep eutectic solvent glycerol+choline chloride 2?1 as the entrainer in the extractive distillation.This paper provides reliable basic data for the application of deep eutectic solvent in the separation of water-ethanol-2-propanol system.