Research On Thermodynamic Model Of Extractive Distillation For Alcohol + Water System With Deep Etectic Solvents

The thermodynamics model was established for six quaternary systems of(1)water + ethanol + glycerol + choline chloride,(2)water + 2-propanol + glycerol + choline chloride,(3)water + 1-propanol + glycerol + choline chloride,(4)water + ethanol + ethylene glycol + choline chloride,(5)water + 2-propanol + ethylene glycol + choline chloride,and(6)water + 1-propanol + ethylene glycol + choline chloride.Binary parameters were obtained.Using binary parameters calculated VLE data of corresponding system.Mean absolute deviations for six quaternary systems were,respectively,(1)?T/K = 0.40,?y = 0.0044,(2)?T/K = 0.15,?y = 0.0035,(3)?T/K = 0.16,?y = 0.0043,(4)?T/K = 0.15,?y1 = 0.0014,?y2 = 0.0025,(5)?T/K = 0.25,?y1 = 0.0032,?y2 = 0.0031,and(6)?T/K = 0.25,?y1 = 0.0047,?y2 = 0.0051,showing good agreement.The established NRTL model and binary parameters provide the basis for the design of potential applications.The correlation showed that the azeotrope of water + alcohol can be removed by mass fraction of choline chloride,glycerol + choline chloride,and glycerol from less to more;the equilibrium temperature was arranged,from high to low,by solvent of choline chloride,glycerol,and glycerol + choline chloride.With the increase of the ratio of choline chloride,breaking azeotrope of water + alcohol used less solvent of ethylene glycol + choline chloride;the equilibrium temperature was reduced.Glycerol + choline chloride and ethylene glycol + choline chloride are potentially solvents.The study unified binary parameters,and established an unified thermodynamics model.The model has a certain ability to predict.During the process,ten systems(1)water + ethanol + glycerol,(2)water + 2-propanol + glycerol,(3)water + 1-propanol + glycerol,(4)water + ethanol + glycerol + choline chloride,(5)water + 2-propanol + glycerol + choline chloride,(6)water + 1-propanol + glycerol + choline chloride,(7)water + ethanol + ethylene glycol,(8)water + 2-propanol + ethylene glycol,(9)water + 1-propanol + ethylene glycol,and(10)water + 2-propanol + ethylene glycol + choline chloride,were correlated.Due to the lack of activity coefficient of choline chloride,and the poor accuracy of activity coefficient of glycerol,unified binary parameters limited accuracy of modeling.The quaternary system(11)water + ethanol + ethylene glycol + choline chloride and(12)water + 1-propanol + ethylene glycol + choline chloride were predicted.The experimental results were compared graphically with those of calculations,(11)?T/K = 0.52,?y1 = 0.0085,?y2 = 0.0096,and(12)?T/K = 0.31,?y1 = 0.0051,?y2 = 0.0057,showing good agreement.During the dehydration process,the solvent moisture has an important effect on product purity.The key to the extractive distillation's successful application is whether the solvent is easy to regenerate.In this article,isobaric vapor-liquid equilibrium data were reported for the ternary system water + ethylene glycol + choline chloride at 5.0,5.5 kPa and binary system water + ethylene glycol at 5.5,6.2 kPa.The NRTL equation was used for the modeling of ternary VLE.The ternary VLE data,together with binary VLE,were used for the modeling.Binary parameters,water + ethylene glycol,water + choline chloride,and ethylene glycol + choline chloride,were obtained.The calculated results are in good agreement with experimental values,with ?T/K = 0.61 and ?y = 0.0038.At low temperature condition,bubble point is low,significantly different with the bubble point at atmospheric pressure,and activity coefficient of water is generally small.With the increase of the amount of choline chloride,the activity coefficient of water was gradually decreased,and relative volatility in extractive distillation column was enhanced,however,the reduction of activity coefficient of water is unfavorable for regeneration tower.Aspen was used to simulate and optimize the process of extractive distillation and solvent dehydration.The ethylene glycol + choline chloride were solvent;ethanol,2-propanol and 1-propanol + water were feed.The simulation made the alcohol reached the electronic grade 99.9 %wt.The sum of reboilor duty of extractive distillation and solvent dehydration was used to compare ethylene glycol + choline chloride in different proportions.The best solvent for ethanol + water is 2:1,and is 4:3 for 2-propanol or 1-propanol + water.