Experiment And Simulation For Separation Of Cyclohexane-ethyl Acetate Azeotropic Mixture

Cyclohexane and ethyl acetate have been widely applied for chemical raw materials,solvents,and so on in many fields including pharmaceuticals,textile,spices and new energy,because of their good solubility and applicability.But the mixture of these two materials cannot be separated by conventional distillation in the field of industrial production due to existence of minimum azeotrope.In this study,we demonstrated that the extractive distillation can be used to separate the azeotrope with the solvent of DMSO.Firstly,solvents were selected preliminarily based on polarity and hydrogen bond theory.Compared with other extraction agents,DMSO and ethylene glycol have better selectivity according to the residue curve map,so it was chosen as the most suitable solvent after quantitative calculation based on UNIFAC group contribution method.Secondly,the gas-liquid equilibrium phase diagrams of azeotrope were measured with or without DMSO as solvent,and it was found that DMSO can cancel the azeotrope.According to batch extraction distillation experiment,operation parameters were set as follows: theoretical plate number 33,pressure drop of column about 300 Pa,reflux ratio 1.0 and solvent feed speed 10 mL/min.Under the conditions above mentioned,the production of 98.6%(mass fraction)cyclohexane was achieved and the yield was at least 81.2%.Thirdly,mass fraction curves with time of each component in top,bottom and each acceptor were analyzed by simulations of batch extraction distillation using Aspen Plus.Under the optimum operating condition,the operating cycle was 4.20 hours,at the same time,the purity that could be obtained of cyclohexane,ethyl acetate were approximately 98.9%,99.6%,separately.Finally,the influence of different parameters on continuous extractive distillation were researched by Aspen Plus.The operating parameters of two columns of continuous extractive distillation were determined by sensitivity analysis as follows: theoretical plate number of extractive distillation column 33,its solvent ratio 1.0,reflux ratio 0.6,solvent feed stage 7 and mixture raw material feed stage 25;theoretical plate number of solvent recovery column 10,feed stage 7 and reflux ratio 0.5.The result purity of cyclohexane,ethyl acetate and DMSO were up to 99.8%,99.7%,99.9%,respectively.