Abstract
The separation of benzene and cyclohexane azeotrope is one of the most challenging processes in the petrochemical industry. In this paper, deep eutectic solvents (DES) were used as solvents for the separation of benzene and cyclohexane. DES1 (1:2 mix of tetrabutylammonium bromide (TBAB) and levulinic acid (LA)), DES2 (1:2 mix of TBAB and ethylene glycol (EG)) and DES3 (1:2 mix of ChCl (choline chloride) and LA) were used as entrainers, and vapor-liquid equilibrium (VLE) measurements at atmospheric pressure revealed that a DES comprised of a 2:1 ratio of LA and TBAB could break this azeotrope with relative volatility (αij) up to 4.763. Correlation index suggested that the NRTL modelling approach fitted the experimental data very well. Mechanism of extractive distillation gained from FT-IR revealed that with hydrogen bonding and π–π bond interactions between levulinic acid and benzene could be responsible for the ability of this entrainer to break the azeotrope.
Highlights
IntroductionThese solvents are typically toxic, flammable, volatile, and difficult to recover
Some researchers believed that azeotropic phenomenon was broken because hydrogen bond sites which exist in deep eutectic solvents (DES) have strong solvation with polar substances, changing the relative volatility [26,27,28,29,30]
A continuous extraction process for separating benzene from cyclohexane was preliminarily simulated in Aspen Plus V8.4
Summary
These solvents are typically toxic, flammable, volatile, and difficult to recover In this respect, ionic liquids (ILs) have been employed as effective entrainers for separations in the fine chemical industry. Deep eutectic solvents (DESs) as novel entrainers can be used for the separation of azeotropic mixture, and have received much attention in recent years [21,22,23]. Some researchers believed that azeotropic phenomenon was broken because hydrogen bond sites which exist in DES have strong solvation with polar substances, changing the relative volatility [26,27,28,29,30] Many of these extractive processes have not been fully optimized. A cheap and prepared DES as an entrainer in benzene-cyclohexane azeotropes extractive distillation processes was reported. The mechanism of extractive distillation was explored by FT-IR
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