Ternary liquid-liquid equilibria for systems containing (dimethyl carbonate or methyl acetate + methanol + 1-methylmidazole hydrogen sulfate) at 298.15 K and 318.15 K

doi:10.1016/j.jct.2018.02.012

The Journal of Chemical Thermodynamics

Volume 121, June 2018, Pages 49-54

https://doi.org/10.1016/j.jct.2018.02.012 Get rights and content

Highlights

•
Liquid-liquid equilibria data of methyl acetate/dimethyl carbonate + methanol + IL systems were measured.
•
Influence of temperature on the liquid-liquid equilibria was discussed.
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The NRTL and UNIQUAC models were applied to correlate the studied system with reasonable accuracy.

Abstract

The separation of methanol from its azeotropes is very important for the production process of vinyl alcohol and dimethyl carbonate. This work describes the feasibility of separating (methanol + methyl acetate) and (methanol + dimethyl carbonate) azeotropes by liquid-liquid extraction using ionic liquid as solvent. The ternary liquid-liquid equilibria (LLE) data for the systems of {methyl acetate + methanol + 1-methylmidazole hydrogen sulfate ([MIM]HSO₄]}, {dimethyl carbonate + methanol + [MIM][HSO₄]} were measured at 298.15 K and 318.15 K under atmospheric pressure. The separation factor and distribution coefficient were calculated from the experimental LLE results to evaluate the separation performance. The influence of temperature on the LLE was investigated and discussed. The experimental LLE data were satisfactorily correlated by NRTL and UNIQUAC models, the binary interaction parameters were obtained and the calculated LLE data were compared with the experimental results.

Introduction

As cleaner technology becomes a research priority for industry and academia, ionic liquids (ILs), a class of salts that are liquid at room temperature, have aroused widespread concern for their intrinsic advantages over organics. ILs show many attractive properties including chemical/thermal stability, ability to be recovered, negligible vapour pressure and especially their ability to be tuned for a specific task based on their fundamental properties [1], [2], [3], [4]. Ionic liquids can be used in many areas of science. Zhang et al. reported on their use as electrolytes for lithium ion batteries [5], Wasserscheid et al. explored the use of ILs for transition metal catalysis [6], Brandt et al. reviewed the application of ILs to the deconstruction of lignocellulosic biomass [7], and other scholars studied the application of ILs in azeotrope separation [8], [9], [10], [11], [12], [13], [14], [15]. ILs show great potential in separating azeotrope.

Methanol, methyl acetate are widely used solvents. Dimethyl carbonate is an important organic synthetic intermediate for the molecular structure contains functional groups such as carbonyl, methyl and methoxide. The (methanol + methyl acetate) [16] mixtures present in the industrial manufacturing process of vinyl alcohol and (methanol + dimethyl carbonate) [17] mixtures present in the industrial manufacturing process of dimethyl carbonate. The separation of these two mixtures is meaningful. However, the separation of these two mixtures is quite difficult due to the formation of an azeotrope. Ordinary distillation will consume a large amount of energy and cannot result in high purity. Special separation methods such as pressure-swing distillation [18], extractive distillation [19], liquid-liquid extraction [9], [20], membrane separation [21], are needed to separate these azeotropic mixtures. Among the separation technology, liquid-liquid extraction is an energy saving and environmentally friendly method, which is widely used in chemical industry. Solvent selection is the main consideration in the design a liquid-liquid extraction process [22], [23] and temperature may have an effect on the liquid-liquid equilibria (LLE) behaviour [24], [25], [26], [27].

In this work, the phase behaviour for systems of {dimethyl carbonate/methyl acetate (1) + methanol (2) + 1-methylmidazole hydrogen sulfate ([MIM][HSO₄])} (3) was studied. The LLE data for the two systems obtained at 298.15 K and 318.15 K under atmospheric pressure. Two important parameters, distribution coefficient (β) and separation factor (S), were calculated to assess the separation performance of [MIM][HSO₄] in the LLE. In addition, the experimental values for the ternary systems were correlated by the non-random two liquid (NRTL) and universal quasi-chemical (UNIQUAC) models [28], [29]. The UNIFAC-Lei model [30], [31], [32] was used to predict the LLE data of the systems studied.

Section snippets

Chemicals

Dimethyl carbonate, methyl acetate and methanol were purchased from Tianjin Kermel Chemical Reagent Co., Ltd. with mass fraction purity of 0.995, 0.990 and 0.998, respectively. [MIM][HSO₄] was supplied by Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (with a stated mass fraction purity of 0.98). The purities of all the organic reagents were checked by gas chromatography (GC-2014C) and all the chemicals were used without further purification. The detailed information

Experimental results

The LLE results for the systems of methyl acetate/dimethyl carbonate (1) + methanol (2) + [MIM][HSO₄] (3) were determined at 298.15 K and 318.15 K under atmospheric pressure. The experimental results are given in Table 2, and the experimental data and tie-lines of the ternary systems are shown in Fig. 1, Fig. 2, Fig. 3, Fig. 4. The ternary phase diagrams provided an intuitive visual for the phase behaviour. All the systems studied show Treybal type I behaviour. Methyl acetate and dimethyl

Conclusions

Experimental LLE data for the ternary systems {methyl acetate + methanol + [MIM][HSO₄]} and {dimethyl carbonate + methanol + [MIM][HSO₄]} were obtained at 298.15 K and 318.15 K under atmospheric pressure. The values of β and S were calculated from the experimental tie-lines. The values of β and S were greater than 1 over the whole concentration range studied. Therefore, [MIM][HSO₄] is a potential solvent for extracting methanol from methyl acetate/methanol and dimethyl carbonate/methanol

Acknowledgement

This work is supported by the National Natural Science Foundation of China (Project 21776145 and Project 21306093).

References (40)

K.N. Marsh et al.
Fluid Phase Equilibria
(2004)
F. Cai et al.
J. Chem. Thermodyn.
(2015)
N.M. Aranda et al.
J. Chem. Thermodyn.
(2014)
W. Liu et al.
Fluid Phase Equilibria
(2017)
D. Xu et al.
J. Chem. Thermodyn.
(2017)
G. Wen et al.
J. Chem. Thermodyn.
(2018)
X. Xu et al.
J. Chem. Thermodyn.
(2017)
S. Zhou et al.
Fluid Phase Equilibria
(2017)
G.W. Meindersma et al.
J. Chem. Thermodyn.
(2011)
Y. Chen et al.
J. Chem. Thermodyn.
(2017)

M. Männistö et al.

J. Chem. Thermodyn.

(2017)

J. Gao et al.

Fluid Phase Equilibria

(2016)

W. Liu et al.

Fluid Phase Equilibria

(2016)

A. Bharti et al.

Fluid Phase Equilibria

(2015)

Y. Zhou et al.

J. Chem. Thermodyn.

(2018)

T. Banerjee et al.

Fluid Phase Equilibria

(2005)

I.-C. Hwang et al.

Fluid Phase Equilibria

(2011)

R.S. Santiago et al.

Fluid Phase Equilibria

(2010)

J.P. Hallett et al.

Chem. Rev.

(2011)

K.R. Seddon

J. Chem. Tech. Biotechnol.

(1997)

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Ternary liquid-liquid equilibria for systems containing (dimethyl carbonate or methyl acetate + methanol + 1-methylmidazole hydrogen sulfate) at 298.15 K and 318.15 K

Highlights

Abstract

Introduction

Section snippets

Chemicals

Experimental results

Conclusions

Acknowledgement

Fluid Phase Equilibria

J. Chem. Thermodyn.

J. Chem. Thermodyn.

Fluid Phase Equilibria

J. Chem. Thermodyn.

J. Chem. Thermodyn.

J. Chem. Thermodyn.

Fluid Phase Equilibria

J. Chem. Thermodyn.

J. Chem. Thermodyn.

J. Chem. Thermodyn.

Fluid Phase Equilibria

Fluid Phase Equilibria

Fluid Phase Equilibria

J. Chem. Thermodyn.

Fluid Phase Equilibria

Fluid Phase Equilibria

Fluid Phase Equilibria

Chem. Rev.

J. Chem. Tech. Biotechnol.

Ternary liquid-liquid equilibria for systems containing (dimethyl carbonate or methyl acetate + methanol + 1-methylmidazole hydrogen sulfate) at 298.15 K and 318.15 K