Mechanism analysis of extractive distillation for separation of acetic acid and water based on quantum chemical calculation and molecular dynamics simulation

Abstract

The selection of high efficiency and environmental protection entrainer is the inevitable requirement of extractive distillation sustainable development. According to the extraction mechanism, the σ-profile was drawn by COSMO-SAC model. Based on the quantum chemistry method, the interaction energy, deformation charge density and total charge density of different organic solvent, ionic liquids and acetic acid-water system were calculated. The binding energy between organic solvents, ionic liquids and acetic acid-water system was further analyzed by Gaussian software. The binding energies of organic solvent tetramethylene sulfone and 1-butyl-3-methylimidazolium dibutyl phosphate ([BMIM][BDP]) ionic liquid with acetic acid were - 934.9622 a.u., − 1610.6557 a.u., respectively. Through molecular dynamics simulation, the radial distribution functions of organic solvents and ionic liquids were calculated and compared at the molecular level, and the interaction between different molecules was analyzed. The cation plays a leading role. When Å = 4.5, ionic liquid and solvent interact strongly with acetic acid, respectively. The comprehensive results showed that tetramethylene sulfone and [BMIM][BDP] had better extraction effect. Finally, the self-diffusion coefficient of [BMIM][BDP] and HAc is 0.0105 cm2 / s. The combination of quantum chemical calculation and molecular dynamics simulation provides theoretical guidance for the effective separation of acetic acid-water system, which provides a certain reference for the selection of the best entrainer.