Separation of ethyl acetate-isopropanol using low transition temperature mixtures: Vapor-liquid equilibrium experiments and quantum chemical calculation

Abstract

Ethyl acetate and isopropanol, as essential chemical ingredients and organic solvents, play an important role in the industry. At atmospheric pressure, ethyl acetate and isopropanol form an azeotrope, which can be separated by extractive distillation. The choice of extractant is critical in extractive distillation. Low transition temperature mixtures (LTTMs), which are emerging as efficient green solvents, are used as extractants in this work. The effect of type and structure on separation performance were studied, and three LTTMs were selected for the separation of the ethyl acetate-isopropanol system. The vapor–liquid equilibrium (VLE) data of ethyl acetate-isopropanol-LTTMs was measured by experiments, and the results showed that when the mole fraction of LTTMs was 0.1, all three LTTMs could break the azeotrope of ethyl acetate and isopropanol, especially LTTM1 (tetrabutylammonium bromide: ethanolamine = 1:2) having the best selectivity. To acquire the binary interaction parameters, the NRTL model was used to fit the experimental data, and the regression data was in good agreement with the experimental data. In addition, a quantum chemical method was used to investigate the interactions between molecules to gain insights into the microscopic mechanism. Results showed that the weak hydrogen bonding and van der Waals forces are formed between ethyl acetate and other systems, while moderate or weak hydrogen bonding are formed between isopropanol and other systems.