Study On Ternary Vapor-Liquid Equilibrium In The Ethyl Propionate Synthesis System

Ethyl propionate can be widely used in food processing,perfumery,solvents,organic synthesis reaction intermediates,but also can be used in the production of biofuels.It is of great significance to study the synthesis and purification of ethyl propionate.The separation and purification of ethyl propionate is inseparable from the distillation,and the vapor-liquid equilibrium data for the ethyl propionate synthesis system is the basis of distillation operations.In this paper,the synthesis reaction of ethyl propionate was studied and found the best reaction conditions:the ratio of ethanol and propionic acid is 2:1,0.2 mol ethanol,0.1 mol propionic acid,with 5 mL cyclohexane,0.1 mL concentrated sulfuric acid and catalyzed the reaction for 2 h.The esterification rate of the product was97.74%,and the reaction yield was 92.49%.The vapor-liquid data for seven atmospheric?101.3 kPa?binary systems:ethanol?1?+cyclohexane?2?,ethanol?1?+n-hexane?2?,ethanol?1?+n-octane?2?,cyclohexane?1?+ethyl propionate?2?,n-hexane?1?+ethyl propionate?2?,n-octane?1?+ethyl propionate?2?and ethanol?1?+ethyl propionate?2?was measured.Samples were analyzed using the gas chromatograph,and the vapor-liquid phase composition was determined by area calibration normalized quantitative analysis.Wilson,NRTL and UNIQUAC models were used to perform correlation calculations on seven binary systems.It was found that the UNIQUAC model is not suitable for our seven binary systems.Wilson and NRTL models have better correlation effects and the RMSD_y1 calculated by the NRTL model correlation.The minimum calculated by the NRTL model was 0.0103,and the minimum RMSD_y1 calculated by the Wilson model was 0.0104.The vapor-liquid data for three atmospheric?101.3 kPa?ternary systems:ethanol?1?+cyclohexane?2?+ethyl propionate?3?,ethanol?1?+n-hexane?2?+ethyl propionate?3?and ethanol?1?+n-octane?2?+ethyl propionate?3?was measured.The samples were analyzed by gas chromatography,and the vapor-liquid phase composition was determined by area calibration normalized quantitative analysis.Wilson,NRTL and UNIQUAC models were used to perform correlation calculations on three ternary systems.It was found that the UNIQUAC model is not suitable for our three ternary systems.The Wilson and NRTL models reproduced the experimental values very well,while the UNIQUAC model provided a bad result.And the interaction parameters of ternary VLE data can be not obtained by UNIQUAC model.And the RMSD_y1 calculated by NRTL model correlation reaches a minimum of0.0103,RMSD_y2 reaches a minimum of 0.0050,and RMSD_y3 reaches a minimum of0.0127.The RMSD_y1 calculated by the Wilson model reaches a minimum of 0.0197.The RMSD_y2 reaches a minimum of 0.0130,and the RMSD_y3 reaches a minimum of0.0295.Moreover,the NRTL model has a better correlation than the Wilson model.The reliability of the binary system vapor-liquid equilibrium data was verified.The results are:the value of D-J in system ethanol?1?+cyclohexane?2?was-6.0527,the value of D-J in system ethanol?1?+n-hexane?2?was-8.2780,the value of D-J in system ethanol?1?+n-octane?2?was-21.1228,the value of D-J in system cyclohexane?1?+ethyl propionate?2?was-7.0637,the value of D-J in system n-hexane?1?+ethyl propionate?2?was-5.7891,the value of D-J in system n-octane?1?+ethyl propionate?2?was-9.5990 and the value of D-J in system ethanol?1?+ethyl propionate?2?was-8.5722.It can be found that D-J<10 for all systems,all data was consistent with the thermodynamic consistency test and the experimental data was reliable.The experiment data can be directly used to design chemical unit operations and provided the basic data for vapor-liquid equilibrium studies.