Isobaric VLE data for the system of butan-1-ol + butyl ethanoate + 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

doi:10.1016/j.fluid.2013.05.020

Fluid Phase Equilibria

Volume 352, 25 August 2013, Pages 75-79

https://doi.org/10.1016/j.fluid.2013.05.020 Get rights and content

Highlights

•
Vapor–liquid equilibrium (VLE) for the azeotropic mixture with ionic liquid.
•
The addition of ionic liquid enhanced the relative volatility.
•
Use the NRTL activity coefficient model to correlate the experimental VLE data.
•
The correlated results and the experimental data agreed well.

Abstract

Vapor–liquid equilibrium (VLE) for the ternary system of butan-1-ol + butyl ethanoate + 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM][NTf₂]) and the binary system of butan-1-ol + [BMIM][NTf₂], as well as butyl ethanoate + [BMIM][NTf₂] were measured at 101.3 kPa. The experimental VLE data were correlated by the nonrandom two-liquid (NRTL) activity coefficient model, and the correlated results agreed well with the experimental data. The results showed that the addition of ionic liquid ([BMIM][NTf₂]) to the azeotropic mixture produced a notable salting-out effect, which enhanced the relative volatility of butan-1-ol to butyl ethanoate. The ionic liquid entrainer [BMIM][NTf₂] was compared with the conventional entrainer ethylene glycol, and [BMIM][NTf₂] is more effective for the separation of the azeotropic mixture of butan-1-ol + butyl ethanoate via extractive distillation.

Introduction

Extractive distillation is widely used to separate azeotropic or close-boiling mixtures, and the entrainer plays a significant role in the application of extractive distillation [1], [2], [3], [4], [5]. However, the conventional entrainers are usually volatile and they will cause environmental problem. Ionic liquids (ILs) are chemicals composed entirely of ions. They have excellent properties such as: nonvolatility, less causticity, and good performance in improving the separation efficiency [6], [7], [8]. Because of these merits, ILs have attracted increasing attentions in the separation process in the past ten years. Many authors studied the effects of ionic liquids to azeotropic mixtures or close boiling mixtures [9], [10], [11], [12], [13], [14], [15], [16]. The phase equilibria data are essential for separation processes, but the phase equilibria data for the IL-containing systems are still insufficient up to now.

A minimum-boiling azeotrope can be formed by butyl ethanoate and butan-1-ol, and an enhanced distillation (such as extractive distillation) can be used to separate the azeotrope [17], [18]. Recently, ionic liquids are often used as mass-separating agents for the azeotropic mixture due to their particular properties. Vapor–liquid equilibrium data are essential for the development of the new enhanced distillation process.

To find a suitable ionic liquid solvent for the separation of butan-1-ol and butyl ethanoate, we calculated the infinite dilution activity coefficients of butan-1-ol and butyl ethanoate in hundreds of ILs using COSMO-SAC model [19], [20]. We found 1-butyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl] imide ([BMIM][NTf₂]) was a promising solvent for the separation of the azeotropic mixture butan-1-ol + butyl ethanoate. In this paper, vapor-liquid equilibrium data for the ternary system butan-1-ol + butyl ethanoate + [BMIM][NTf₂] and binary system of butan-1-ol + [BMIM][NTf₂] as well as butyl ethanoate + [BMIM][NTf₂] are presented, and the vapor-liquid equilibrium (VLE) data were correlated by the nonrandom two-liquid (NRTL) model.

Section snippets

Materials

The ionic liquid ([BMIM][NTf₂]) was purchased from Chengjie Chemical Reagents Co., Shanghai, China, with a minimum mass fraction of 0.99 (observed by liquid chromatography). The water mass fraction in ionic liquid determined by Karl Fischer titration was less than 0.001. Butyl ethanoate and butan-1-ol were purchased from Jiangtian Chemical Reagents Co., Tianjin, China.

Their purities checked by gas chromatography were greater than 0.997 in mass fraction. All chemicals were used without further

Experimental data

Equilibria temperatures for the binary systems of butan-1-ol + [BMIM][NTf₂] and butyl ethanoate + [BMIM][NTf₂] were measured at 101.3 kPa and the results are shown in Table 1, Table 2, respectively. Where x₃ presents the mole fraction of ionic liquid in the liquid phase, T^exp presents the experimental equilibrium temperature and T^cal presents the calculated equilibrium temperature.

Vapor–liquid equilibrium for the ternary system of butan-1-ol (1) + butyl ethanoate (2) + [BMIM][NTf₂] (3) was measured at

Conclusions

The vapor–liquid equilibrium for the ternary system of butan-1-ol + butyl ethanoate + [BMIM][NTf₂] and the binary systems of butan-1-ol + [BMIM][NTf₂] and butyl ethanoate + [BMIM][NTf₂] were measured at 101.3 kPa. The NRTL model was used to correlate the VLE data for the ternary mixture, and the correlated results agreed well with the experimental results. The results indicate that the relative volatility of butan-1-ol to butyl ethanoate can be greatly enhanced by IL ([BMIM][NTf₂]), and the azeotropic

Acknowledgments

The authors are grateful to the Innovation Fund of Tianjin University for the financial support of this work.

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Isobaric VLE data for the system of butan-1-ol + butyl ethanoate + 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

Highlights

Abstract

Introduction

Section snippets

Materials

Experimental data

Conclusions

Acknowledgments

Fluid Phase Equilibr.

Chem. Eng. J.

Fluid Phase Equilib.

Fluid Phase Equilib.

Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures

Ind. Eng. Chem. Res.

Azeotropic distillation

AIChE J.

Em Perry's Chemical Engineers’ Handbook. Distillation

Distillation: Principles and Practice

Conceptual Design of Distillation Systems

Ionic liquids in separations

Acc. Chem. Res.

Ionic liquids show promise for clean separation technology

Chem. Eng. News

Structure and solvation in ionic liquids

Acc. Chem. Res.

Separation of azeotropic mixtures using hyperbranched polymers or ionic liquids

AIChE J.

Extractive distillation with ionic fluids

Chem. Ing. Tech.