Separation abilities of three acetate-based ionic liquids for benzene-methanol mixture through vapor-liquid equilibrium experiment at 101.3 kPa
Introduction
Benzene and methanol are important solvents. The mixture of benzene and methanol is common in fine chemical industries [1,2]. However, benzene and/or methanol can't be completely recovered from their waste mixture by traditional distillation method because of the formation of benzene-methanol azeotrope. A few special distillation methods have been utilized to separate the azeotrope such as azeotropic distillation, extractive distillation, and pressure swing distillation [[3], [4], [5], [6], [7], [8], [9]]. Extractive distillation is widely used because of its advantages of simple operation, high separation ability, and flexible selection of entrainer. Entrainer is the core of extractive distillation. More and more attentions are paid to the selection of entrainer [[10], [11], [12]]. Compared with the traditional entrainer (solid salt [13,14] and organic solvent [15,16]), ionic liquids (ILs) have many advantages such as stable property, negligible vapor pressure, and easy recovery [[17], [18], [19]]. In recent years, many publications have been devoted to ILs for the application as entrainer of extractive distillation [17,[19], [20], [21], [22], [23]].
In the reports on the inorganic or organic salt entrainers [1,[24], [25], [26], [27]], the benzene-methanol system could only be completely separated by LiI [27]. The separation effect of IL on the benzene + methanol mixture was investigated through a series of isobaric VLE experiments by Li Q. S et al. [2,28,29]. 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM][BF4]) showed the best salting out effect. The azeotropy was eliminated by increasing the mole concentration of [OMIM][BF4] to 0.3. The isothermal VLE data of benzene and methanol containing tetraphenylphosphonium chloride ([PH4P]Cl) IL were studied by Kurzin, A. V. et al. [30]. The azeotropy was eliminated when the concentration of [PH4P]Cl was 0.5 mol kg−1.
The purpose of this study is to obtain some useful data for the separation of the benzene-methanol mixtures. Three acetate-based ILs (1-hexyl-3-methylimidazolium acetate [HMIM][OAC], 1-octyl-3-methylimidazolium acetate [OMIM][OAC], and 1-decyl-3-methylimidazolium acetate [DMIM][OAC]) were selected by a molecular design method. The VLE data for the ternary systems of the benzene + methanol + IL were measured at 101.3 kPa. The VLE data were correlated by NRTL model. The separation abilities of the three ILs for the benzene-methanol system were analyzed.
Section snippets
Chemicals
[HMIM][OAC], [OMIM][OAC], and [DMIM][OAC] were provided by Yulu Group with claimed purity ≥99.0 (wt)%. Prior to the experiment, IL was dried at 353 K and 2 kPa for 36 h to remove the volatile compounds. The ILs were checked by liquid chromatography. Benzene and methanol were purchased from Sinopharm group with claimed purity ≥ 99.9 (wt)%. The water contents in IL, benzene, and methanol were measured by Karl Fischer titration. The specifications of all the chemicals are shown in Table 1.
Apparatus and procedure
The VLE
Binary data
To test the dependability of the equilibrium apparatus, the binary VLE data of the benzene (1) + methanol (2) mixture were measured at 101.3 kPa and are shown in Table 3 and Fig. 1. The correlated curve and the reported data [2] are also listed in Fig. 1. Where T presents the VLE temperature. The ARD between the correlated curve and the experimental data is 0.73% and that between the correlated curve and the reported data is 2.0%. In addition, the experimental data are consistent with
Conclusions
Isobaric VLE data for benzene + methanol + ILs ([HMIM][OAC], [OMIM][OAC], or [DMIM][OAC]) systems were obtained at 101.3 kPa. The relative volatility of benzene to methanol can be enhanced by rising the IL mole fraction. The minimum mole fractions of [HMIM][OAC], [OMIM][OAC] and [DMIM][OAC] needed to eliminate azeotropy are 0.145, 0.136, and 0.132 on the basis of the NRTL model. The minimum mass fractions of [HMIM][OAC], [OMIM][OAC], or [DMIM][OAC] needed to eliminate azeotropy are 0.329,
Acknowledgments
This work is financially supported by the National Science Foundation of China (Project No. 21576166), Program for Liaoning Excellent Talents in University (LR2012013) and Liaoning Province Science Foundation of China (Project No. 2014020140).
References (44)
- et al.
Design and control of methyl acetate-methanol separation via heat-integrated pressure-swing distillation
Chin. J. Chem. Eng.
(2016) - et al.
Application of a simulated annealing algorithm to design and optimize a pressure-swing distillation process
Comput. Chem. Eng.
(2016) - et al.
Insight into pressure-swing distillation from azeotropic phenomenon to dynamic control
Chem. Eng. Res. Des.
(2017) - et al.
Separation of azeotrope (2,2,3,3-tetrafluoro-1-propanol + water) via heterogeneous azeotropic distillation by energy-saving dividing-wall column: process design and control strategies
Chem. Eng. Res. Des.
(2018) - et al.
Isobaric vapor–liquid equilibrium for ternary mixtures of acetone + methanol + ionic liquids at 101.3 kPa
Fluid Phase Equilib.
(2017) - et al.
Application of scaled particle theory in extractive distillation with salt
Fluid Phase Equilib.
(2002) - et al.
Control of an extractive distillation process to dehydrate ethanol using glycerol as entrainer
Comput. Chem. Eng.
(2012) - et al.
Isobaric vapor–liquid equilibria for the binary and ternary mixtures of 2-propanol, water, and 1,3-propanediol at P=101.3kPa: effect of the 1,3-propanediol addition
Fluid Phase Equilib.
(2014) - et al.
Ionic liquids in separations of azeotropic systems-a review
J. Chem. Thermodyn.
(2012) - et al.
Isobaric vapor-liquid equilibrium for 2-butanone + ethanol + phosphate-based ionic liquids at 101.3 kPa
Fluid Phase Equilib.
(2018)
Effect of bis(trifluoromethylsulfonyl)imide-based ionic liquids on the isobaric vapor - liquid equilibrium behavior of ethanol + dimethyl carbonate at 101.3 kPa
Fluid Phase Equilib.
Isobaric vapor-liquid equilibrium for acetone + methanol system containing different ionic liquids at 101.3 kPa
Fluid Phase Equilib.
Isobaric vapor-liquid equilibrium for methanol+dimethyl carbonate+phosphoric-based ionic liquids
Fluid Phase Equilib.
Study of activity coefficients for sodium iodide in (methanol + benzene) system by (vapour + liquid) equilibrium measurements
J. Chem. Thermodyn.
Effect of imidazolium-based ionic liquid on vapor-liquid equilibria of 2-propanol + acetonitrile binary system at 101.3 kPa
Fluid Phase Equilib.
Separation of ethyl acetate and 2-propanol azeotropic mixture using ionic liquids as entrainers
Fluid Phase Equilib.
Designing new mass-separating agents based on piperazine-containing good's buffers for separation of propanols and water azeotropic mixtures using COSMO-RS method
Fluid Phase Equilib.
Separation of ethyl acetate and ethanol azeotrope mixture using dialkylphosphates-based ionic liquids as entrainers
Fluid Phase Equilib.
Isothermal vapor–liquid equilibrium data for the methanol + benzene + sodium tetraphenylborate
J. Chem. Eng. Data
Isobaric vapor-liquid equilibrium for methanol+benzene+1-octyl-3-methylimidazolium tetrafluoroborate
Kor. J. Chem. Eng.
Energy-efficient extractive distillation process by combining preconcentration column and entrainer recovery column
Ind. Eng. Chem. Res.
Measurement and correlation of isobaric vapor-liquid equilibrium for binary systems of allyl alcohol with isobutyl acetate, butyl acetate, and butyl propionate at 101.3 kPa
J. Chem. Eng. Data
Cited by (20)
Isobaric vapor-liquid equilibrium for 2-butanone + ethanol + acetate-based ionic liquids at 101.3 kPa
2022, Fluid Phase EquilibriaCitation Excerpt :ILs are innovative solvents entirely consisted of different anions and cations with good solubility, very low vapor pressure, a wide range of applicable temperature, adjustable structure and more advantages [18–22]. Up to now, ILs as entrainers in extractive distillation have been extensively reported in a large number of publications [23–25]. Three kinds of acetic acid ILs (1-ethyl-3-methylimidazolium acetate [EMIM][OAC], 1‑butyl‑3-methylimidazolium acetate [BMIM][OAC], and 1-hexyl-3-methylimidazolium acetate [HMIM][OAC]) were used to separate the 2-butanone + ethanol azeotrope [4].
Fast and non-destructive determination of water content in ionic liquids at varying temperatures by Raman spectroscopy and multivariate regression analysis
2021, Analytica Chimica ActaCitation Excerpt :Since the first investigation by Walden in 1914, ILs have been shown to have many desirable properties that include low vapor pressure [2], excellent thermal stability [3], high conductivity [4], and anion-dependent miscibility with various solvents and substrates [5–7]. The hydrophilic imidazolium acetate ILs possess relatively low melting points and viscosities compared with other common ILs [8], which makes them very useful in greenhouse gas sorption [9–11], biomass processing [12–14], separations [15–17], as well as other applications [18–20]. For many applications using imidazolium acetate ILs, the water content and temperature of the IL may fluctuate over a large range, and many studies have focused on the simultaneous optimization of water content and temperature in these applications.
Isobaric vapour-liquid equilibrium of methanol + tetrahydrofuran + imidazolium-based ionic liquids at 101.3 kPa
2020, Journal of Molecular LiquidsCitation Excerpt :Therefore, the effect of [HMIM][OTF] on methanol + tetrahydrofuran system was more influential than that of [HMIM][BF4] (Fig. 5a), which may be attributed to their σ-Profiles. According to the σ-Profiles of methanol [17], tetrahydrofuran [18], [HMIM]+ [19], [BF4]− [17] and [OTF]− [18] as illustrated in Fig. 5b (Reprinted with Permission from Elsevier & CIESC, Ref. [17], Fluid Phase Equilibria, 477, 12–18; Ref. [18], CIESC Journal, 71(4), 1676–1682; Ref. [19], Fluid Phase Equilibria, 492, 80–87). There were distinct peaks in the hydrogen bond donator region, non-polar region and hydrogen bond acceptor region for methanol, respectively.
Isobaric vapor-liquid equilibrium for toluene-methanol system including three ionic liquids with acetate anion at 101.3 kPa
2020, Fluid Phase EquilibriaCitation Excerpt :The abilities of [DMIM][OAC] and [C14MIM][OAC] to eliminate azeotropy are very close. It is not sufficient to evaluate the separation abilities of the two ILs by only using their abilities to eliminate azeotropy [41]. Further research is needed.
Separation of ethyl formate and ethanol azeotrope by extractive distillation using phosphate salt ionic liquid as extractant
2024, Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering