The Research On The Separation Of Isoamyl Alcohol And Isoamyl Acetate By Extractive Distillation

Isoamyl alcohol and isoamyl acetate are important chemical raw materials and organic solvents.Isoamyl alcohol and isoamyl acetate formed pseudo azeotropic mixture at atmospheric pressure.When the mole purity of isoamyl alcohol is beyond 0.85,the relative volatility of isoamyl alcohol and isoamyl acetate is close to 1,which means that they cannot be effectively separated by ordinary distillation.In this paper,the separation of isoamyl alcohol and isoamyl acetate by extraction distillation with dimethyl sulfoxide(DMSO)as solvent was researched.Firstly,the vapor-liquid equilibrium data of isoamyl alcohol and isoamyl acetate system at atmosphere pressure was measured,and the difficulty of conventional separation was analyzed.The extractive solvent was preliminarily selected by qualitative judgment according to the property of isoamyl alcohol and isoamyl acetate,and then the appropriate extraction agent for the binary system was determined using the UNIFAC group contribution method.The effectiveness of extractive solvent DMSO was verified by measured the vapor-liquid equilibrium data of isoamyl alcohol + isoamyl acetate + DMSO.The measured vapor-liquid equilibrium data was tested thermodynamic consistency using Herington method and Van Ness method.The experimental VLE data were correlated with NRTL,Wilson and UNIQUAC models,then the binary interaction parameters of these models were obtained.The ternary vapor-liquid equilibrium was predicted by Wilson model and compared with the ternary vapor-liquid equilibrium experimental data to verify the accuracy of the experiment.The results indicated that the relative volatility of isoamyl alcohol and isoamyl acetate was significantly changed and reversal after the addition of DMSO.Intermittent extraction distillation experiment using DMSO as extractive solvent were conducted to separated isoamyl alcohol and isoamyl acetate.The hydrodynamic parameters of the distillation column were calibrated and the number of theoretical plates of the distillation column was determined.It can achieve separation requirement by intermittent extraction distillation using DMSO as extractive solvent for the mixture of isoamyl alcohol and isoamyl acetate.The relationship between the mole composition of isoamyl acetate and time was obtained.In the experiment,the influence of the solvent ratio on the separation requirement was significant,and the product purity curves at different solvent ratios were compared.The chemical simulation software Chem CAD was used to calculate the batch extractive distillation process.The results coincided well with the experimental data.The chemical simulation software Aspen Plus was used to calculate the continuous extractive distillation process.The binary interaction parameters of Aspen Plus were modified by the VLE data corrected results.The process of conventional extractive distillation is proposed.The optimization scheme of the process was carried out and the annual total cost TAC is minimized,then the specific parameters of distillation column were obtained.The concentration distribution curves and temperature distribution curves in the distillation column were obtained and analyzed.