Determination And Correlation Of Vapor Liquid Equilibrium Of Acetic Acid Association System Containing Ionic Liquid

Phase equilibrium is one of the important contents in the field of chemical thermodynamics.Phase equilibrium data are indispensable in distillation design,chemical process optimization and azeotrope separation.Therefore,it is of great significance to study the equilibrium of multiphase system in scientific research of chemical industry and chemical production.Ionic liquids,as a new type of green catalyst,have been gradually used in many processes because of their strong solubility,great thermal stability,extremely low vapor pressure and easy separation and recovery of products in recent years.With the application of ionic liquids in esterification,it is urgent to solve the problem of phase equilibrium.Due to the addition of ionic liquids,the vapor-liquid equilibrium of the esterification reaction distillation systems has changed.In the simulation and optimization of reactive distillation process,the binary interaction parameters fitted by vapor-liquid equilibrium data are deficiency.Therefore,supplementing the vapor-liquid equilibrium data of esterification reaction distillation system containing ionic liquids has become an instancy problem to be solved.In the previous work,our research group carried out the kinetic experiment of synthesis of TAG by vacuum distillation.In order to supplement the thermodynamic data,the influence of[HSO₃-BMPy][HSO₄]ionic liquid on the water+acetic acid system was investigated in this dissertation.The reasons of the influence were analyzed by COSMOlogic software.At the same time,because it is difficult to separate water from acetic acid system,the possibility of ionic liquid as extractant was discussed in this dissertation.The vapor-liquid equilibrium data of water+acetic acid binary system at101.3 k Pa were measured by Dvorak-Boublik vapor-liquid condensation double circulation equilibrium still.To check the reliability of the experimental equipment,the results were compared with the literature.The vapor-liquid equilibrium data of water（1）+acetic acid（2）binary system at 91.3,81.3,71.3,61.3 k Pa were measured.The effect of pressure on the vapor-liquid equilibrium of water+acetic acid system was explored.The vapor-liquid equilibrium data of water（1）+acetic acid（2）+3‰[HSO₃-BMPy][HSO₄]（3）ternary system at 91.3,81.3,71.3,61.3 k Pa were measured.The data needed in the simulation and optimization of reactive distillation were supplemented.The vapor-liquid equilibrium data of water（1）+acetic acid（2）+[HSO₃-BMPy][HSO₄]（3）with ionic liquid content of 1%,3%,5%at 101.3 k Pa were measured.The effect of the content of ionic liquid on the vapor-liquid equilibrium of water+acetic acid system was explored.The geometric structure of[HSO₃-BMPy]⁺cation was optimized by COSMOlogic software.And the screening charge densities of water,acetic acid,[HSO₃-BMPy]⁺cation and[HSO₄]^-anion were calculated respectively.The reasons for the change of vapor-liquid equilibrium curves of the above system were analyzed from the microscopic level.The simplified Hayden O′Connell model was used to correct the non ideality of vapor phase,and the NRTL equation suitable for electrolyte solution was used to correct the non ideality of liquid phase.The binary interaction parameters(g_ij-g_ii)of NRTL equation were obtained by correlating the experimental data of vapor-liquid equilibrium.According to the binary interaction parameters,the data of the corresponding system were predicted,and the binary prediction results are fitted with the experimental values.The prediction result of ternary system is average.In this dissertation,five phosphorous anions and twelve imidazole cations were combined to select the extractant suitable for the separation of water+acetic acid system by extractive distillation.The geometric structure of ions not included in COSMO software′s original database was optimized by TURBOMOLE quantitative calculation module.The extraction mechanism was analyzed byσ-profile diagram and molecular interaction energy.By analyzing the solubility of water in different ionic liquids,the selectivity of water to acetic acid,and the excess enthalpy when ionic liquids were mixed with water or acetic acid,the extraction effects of 60 kinds of ionic liquids were investigated.It is determined that[MIM][DBP]is a qualified extractant for separating water+acetic acid system.