Measurement and correlation of isobaric vapor-liquid equilibrium for binary system 1, 2-butanediol+ethylene glycol under vacuum

In order to separate 1,2-butanediol and ethylene glycol,the method of only vapor phase circulation was used to measure the vapor-liquid equilibrium(VLE) values of the binary system 1,2-butanediol +ethylene glycol at 6.67kPa.Azeotropic behavior was found for this system: the azeotropic temperature is 395.67K and the azeotropic composition is 0.457 mole fraction 1,2butanediol.The measured VLE data of the binary system could pass the thermodynamic consistency test according to Herington area method,and were correlated by Wilson,NRTL and UNIQUAC activity coefficient models.And all the models showed rather small deviation from the experimental results,indicating that the experimental data could be suitable for use in the industrial process design.