Separation Of Binary Azeotrope Tetrahydrofuran-Ethanol By Extractive Distillaton

Tetrahydrofuran and ethanol are very important intermediates and solvents, which are widely used in chemistry, pharmaceutical and so on. At atmospheric pressure, THF and ethanol form azeotrope, which can't be separated by conventional distillation.This paper studies the separation of such binary azeotrope by extractive distillation using ethylene-glycol as the solvent.Firstly, the vapor-liquid equilibrium is correlated using the UNIFAC method based on experimental data. Then the appropriate extractive solvent ethylene-glycol is chosen through qualitative estimation and quantitative calculation using group contribution method. The effectiveness of the solvent is validated though the VLE experiment. The effect on relative volatility with different solvent ratio is compared. When the solvent ratio is 3, the relative volatility is about 2.26.Secondly, the batch extractive distillation is done to separate the binary azeotrope of THF-ethanol. The hydrodynamics parameters of the distillation column are determined. Also the number of theoretical plates at total reflux and the range of the manipulateing reflux ratio are determined. The separation requirement can be achieved by BED with the extractive solvent ethylene-glycol. The curves of THF concentration in the distillate vs time are obtained. In these experiments, the solvent flowrate and the reflux ratio affect the separation obviously. The distillation curves at different reflux ratio and different solvent flowrate are compared.Thirdly, Aspen Plus is used to simulate the process of CED. The concentration profile cuves, the temperature profile curves and the vapor/liquid flowrate profile curves are obtained. The sensitivity analysis of the distillate concentration to reflux ratio and solvent ratio is done. ChemCAD is used to simulate the process of BED. The curves of concentration vs time in the distillate, the kettle and the liquid holdup of storage tank are obtained. The simulation results agree with the experiment data well. The simulation of the separation process is feasible.