Separation Of Methyl Acetate-Methanol By Batch Extractive Distillation

Methly acetate is an important chemical raw material.Methyl acetate and methanol form an azeotrope which is produced in many industrial processes.At present,extractive distillation using water or inorganic salt aqueous solution as extraction solvent is widely adopted in industry,leading to the water content in methyl acetate.Therefore,it is important to seek a nonaqueous solvent for separatiing the azeotrope.In this paper,the process of separating methyl acetate-methanol by batch extractive distillation with dimethyl sulfoxide(DMSO)was studied in detail.Isobaric vaporeliquid equilibrium(VLE)data for the systems of methyl acetate-dimethyl sulfoxide,methanol-DMSO and methyl acetate-methanol-DMSO were determined with a modified Othmer still at 101.3 kPa.And all experimental VLE data have passed the Herington and Van Ness thermodynamic consistency tests.The experimental binary VLE data were correlated by NRTL,Wilson and UNIQUAC models and the binary interaction parameters were obtained.And the VLE data predicted by the obtained parameters agree well with the experimental data.The results show that DMSO can significantly alter the relative volatility of methyl acetate-methanol system.Therefore,DMSO is a promising extractive agent for the separation of the binary azeotrope of methanol and methyl acetate in extractive distillation.A simplified model was established to describe the process of separating methyl acetate-methanol azeotrope by batch extractive distillation.Then,the feasibility and limiting values of the most important operational parameters(number of stages,flow rate of entrainer,and reflux ratio)were determined for different steps of the batch extractive distillation by calculating feasible profiles of extractive and rectifying sections and figuring them in the triangular diagram.The process of batch extractive distillation was simulated with PRO/II 7.1 software.The effects of the process parameters(solvent ratio to vapor,reflux ratio,number of theoretical plates,extracting agent feed location and temperature,reflux tank liquid holdup and initial incharge amount)on the yield of methyl acetate were analysised.And the optimum conditions were determined.To verify the feasibility of process and the credibility of simulation results,the batch extractive distillation of seperating methyl acetate-methanol azeotrope was carried out.The experiment results validate the feasibility of process and reveal fine agreement with the simulation ones.