Extractive rectification using DES for benzene-cyclohexane-cyclohexene ternary azeotropic system

BACKGROUND

Benzene, cyclohexane, and cyclohexene are ternary azeotropic systems, which cannot achieve high-purity separation by ordinary distillation, but this issue can be solved by extractive distillation. Deep Eutectic Solvents (DES) is a ‘green solvent’ that has emerged in recent years and is often used as an extractant.

RESULTS

In this study, the COSMO-SAC solvation model was used to calculate the infinite dilution activity coefficients (γ∞) of DES with different compositions to screen suitable DES, and the effect was demonstrated by vapor–liquid equilibrium experiment (VLE). In addition, the effect of intermolecular interactions was explored in this study by means of independent gradient (IGM) equivalence plot, and process simulations were carried out by means of Aspen Plus software.

CONCLUSION

VLE experiments showed that the combination of DES extractants tetrabutylphosphonium bromide: levulinic acid (1:4) and tetrabutylammonium bromide: cyclobutyl sulfone (1:4) could break the azeotropic relationship of benzene, cyclohexane, and cyclohexene ternary systems. In addition, using Aspen process simulation to compare the screened DES extractant with the industrially used dimethylacetamide (DMAC) extractant, the use of the screened DES extractant was able to reduce the condenser and reboiler energy consumption by 14.93%. © 2024 Society of Chemical Industry (SCI).