Solvent Screening Of Isopropanol-water System And Hexane-ethanol System Using LTTMs As Separation Agents

Extraction and extractive distillation technology are important separation technologies in chemical industry,in which the selection of sovents is crucial.Low Transition Temperature Mixtures(LTTMs)are composed of hydrogen bond acceptor and hydrogen bond donor in eutectic molar ratio,which possess advantages of low volatility,adjustable functions,wide liquid range,water compatibility,biodegradability,low price,easy preparation and so on.In view of this point,LTTMs are used as new extraction agents for the extraction and extractive distillation processes.Aiming at two typical different polar mixtures,LTTMs screening were conducted using COSMO-SAC predictive thermodynamic model.OC 1:1 and EC 2:1 are selected for isopropanol-water system,EC 2:1 is selected for hexane-ethanol system.The vapor-liquid equilibrium data of isopropanol-water-LTTMs system at 101.3 kPa shows that both OC 1:1 and EC 2:1 can separate isopropanol-water system,the ranking order of separation performance is OC 1:1 > EC 2:1.The liquid-liquid equilibrium data of hexane-ethanol-LTTMs system shows that EC 2:1 can separate hexane-ethanol system,the temperature has little effect on the extraction performance.The experimental data were regressed by activity coefficient model NRTL and binary interaction parameters of two ternary systems were obtained.The experimental and calculated results are consistent with each other.Based on simulation software Aspen Plus,the isopropanol dehydration extractive distillation process is simulated,when the number of plates is 19,the feed stage is 14,reflux ratio is 0.5,solvent feed stage is 5 and the ratio of solvent to feed is 0.3,the molar fraction of isopropanol can reach 0.99999;the hexane-ethanol extraction process are simulated,when the number of plate s is 3 and ratio of solvent to feed is 0.5,the mass fraction of hexane can reach 1.000.Based on two typical mixture systems with different polarities,the separation of azeotropic systems were achieved by solvent screening,phase equilibrium experiments and process simulation.This work is devoted to guiding the application of LTTMs in the extraction and extractive distillation processes.