Search

The recovery of refrigerant blends and the subsequent separation of value-added hydrofluorocarbons (HFCs) for reuse would help to meet the phase-down in the production of virgin HFCs established by the Kigali Amendment to the Montreal Protocol. The use of ionic liquids (ILs) in extractive distillation processes has become particularly relevant. In this process, the selection of the IL is the core element for a technically and economically feasible design. For this purpose, the absorption of the HFCs difluoromethane (R-32) and pentafluoroethane (R-125), components of the equimassic mixture R-410A, in 1-alkyl-3-methylimidazolium tricyanomethanide ILs was studied. The isochoric saturation method was applied to report vapor-liquid equilibrium data over a temperature range of 283.15–323.15 K and up to 0.9 MPa. These data were fitted accurately to the NRTL activity coefficient model and the Henry's law constants, the activity coefficients at infinite dilution, the enthalpies and entropies of solvation and the thermodynamic mixing properties were calculated. Finally, [C 2 C 1 im][tcm] ranked as one of the most selective ILs to date, exhibiting a good R-32 absorption capacity that could make it a valuable solvent for the separation of R-410A by extractive distillation. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([C 2 mim][DCA]) and a mixture of ionic liquids [C 2 mim][DCA] + 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]) were used as extractive distillation solvents to separate tert -Butyl alcohol (TBA) + water. The vapor-liquid equilibria for TBA + water + [C 2 mim][DCA] and TBA + water + [C 2 mim][DCA] + [C 2 mim][OAc] were measured at 101.3 kPa. The NRTL model was employed to correlate the vapor-liquid equilibrium data, and the binary interaction parameters were obtained. The experimental results show that both of the solvents can improve the relative volatility of TBA to water, and completely destroy the azeotropic point of TBA-water. There is no synergistic effects between [C 2 mim][DCA] and [C 2 mim][OAc], and the selectivity of [C 2 mim][OAc] is higher than that of [C 2 mim][DCA], but the viscosity of [C 2 mim][DCA] is lower. [ABSTRACT FROM AUTHOR]

• DPD in the calculation of the interfacial tension of organic solvent-hydrocarbon systems. • Phase correlation length in binary systems near the critical temperature. • Potential organic solvents to separate cyclohexane-benzene and hexane-benzene. The interfacial tension (IFT) and its dependence on temperature play an important role in organic solvents employed to purify hydrocarbons using extractive distillation. IFT between organic solvents (formamide, ethylene glycol, glycerol, and sulfolane) and hydrocarbons (hexane, cyclohexane, and benzene) was calculated at mesoscopic scales in temperature ranges from 298.15 K to 338.15 K, applying the Dissipative Particle Dynamics (DPD) simulation method. The effect of the external temperature was introduced to calculate the DPD interaction parameters (a i j), which is directly related to the Flory-Huggins solubility parameters (χ i j). The results show that ethylene glycol and sulfolane are potential organic solvents in the purification of systems consisting of benzene-hexane and cyclohexane-benzene by extractive distillation process. [Display omitted] [ABSTRACT FROM AUTHOR]

Ethylene glycol (EG) is proposed as an entrainer for the separation of methylal and methanol by extractive distillation. The COSMO-RS model was used to screen the suitable entrainer in terms of selectivity and solvent capacity. EG is a suitable entrainer with a low environmental impact. Vapor–liquid equilibrium (VLE) experiments demonstrated that the relative volatility of methylal to methanol is significantly improved using EG as an entrainer. The new corresponding interaction parameters were obtained by correlating the VLE data using the UNIFAC model, and then they were introduced into the process simulation software. The extractive distillation process was simulated using the rigorous equilibrium stage model. The optimal operating conditions were obtained by sensitivity analysis. The simulation results showed that EG is effective and efficient for the separation of methylal and methanol. In addition, the COSMO-RS model provides some theoretical insights into the separation mechanism. [ABSTRACT FROM AUTHOR]

Process simulators depend on models for estimating basic thermodynamic properties. The parameters of these models are subject to uncertainties due to measurement errors in the experimental data and the uncertainties are typically assumed to be insignificant in process simulation. This work shows the effect of model parameter uncertainty in the process simulation of extractive distillation for the separation of a diisopropyl ether – isopropyl alcohol minimum boiling azeotrope with entrainer 2-methoxyethanol. This is achieved by extending the application of the uncertainty quantification framework used by Hajipour and Satyro to an extractive distillation process. The approach used was to obtain the best fit of experimentally available literature data and then perform uncertainty quantification based on the combined experimental and model uncertainties using a Monte Carlo simulation for the uncertainty propagation and Aspen Plus ® for process simulation. This systematic analysis of model uncertainty provides quantitative insight into the propagation of thermodynamic model errors to the various unit operations. It was found that while the propagated model parameters are able to predict the phase behaviour with a 95% certainty, significant deviations may occur for the process simulation. The approach can be used to improve the confidence with which appropriate safe design margins are assigned to columns and identify the risk areas in the design. [ABSTRACT FROM AUTHOR]

• The contribution of atomic pairs to the interaction is quantitatively analyzed. • The effects of 12 solvents on the relative volatility of azeotropes were studied. • Applying experimental binary interaction parameters to distillation process. Sufficient and accurate physical property data is the basis for thermodynamic analysis and process simulation analysis. Reliable thermodynamic model data is essential for the study of extractive distillation separation of azeotropic mixtures. The vapor-liquid equilibrium data of 2-butanol alcohol-ethylene glycol and cyclohexane-butyl butyrate were measured by using a reliable experimental device, namely a modified Rose vapor-recirculating-type equilibrium still. The effects of 12 solvents on the relative volatility of the azeotrope of cyclohexane, 2-butanol alcohol and water were calculated, and ethylene glycol was selected as the best solvent. On this basis, the contribution of different atom pairs and atoms to the interaction between ethylene glycol and cyclohexane/2-butyl alcohol/water was compared and studied, and the reason why ethylene glycol can separate cyclohexane-2-butyl alcohol-water was analyzed. The thermodynamic model parameters obtained from the vapor-liquid equilibrium experiment were used to simulate the extractive distillation process, and total annual cost optimization was performed to improve the process accuracy. Overall, this study improves the application potential of phase equilibrium data in azeotropic separation technology, and establishes a reliable data and model foundation for the sustainable development of 2-butyl alcohol and cyclohexane. [ABSTRACT FROM AUTHOR]

In order to avoid the disadvantages of common organic solvent in extractive distillation, such as low selectivity, high volatility and poor molecular design capability, ionic liquids (ILs) were selected as entrainers for the separation of 2-butanone + ethanol azeotropic mixture. The isobaric vapor-liquid equilibrium (VLE) data were measured for the ternary systems of 2-butanone + ethanol + ILs (1-ethyl-3-methylimidazolium diethylphosohate [EMIM][DEP], 1-butyl-3-methylimidazolium diethylphosphate [BMIM][DEP] or 1-butyl-3-methylimidazolium dibutylphosphate [BMIM][DBP]) at 101.3 kPa. A remarkable salting-out effect was produced by the addition of IL. After the content of ILs was increased to a specific value, the azeotropic phenomenon of 2-butanone-ethanol system could be completely eliminated. The separation ability of the three ILs follows this order: [EMIM][DEP] > [BMIM][DEP] > [BMIM][DBP]. The VLE data are well correlated with the nonrandom two-liquid (NRTL) model. [ABSTRACT FROM AUTHOR]

The distillation of azeotropic mixtures is commonly and widely performed in the pharmaceutical, petroleum, and chemical industries. Deep eutectic solvents (DESs) are environmentally-friendly entrainers that have many properties similar to ionic liquids (ILs) but are also simple in preparation and cheap in price. Also, the ethanol/water system is a typical industrial azeotropic mixture. In this work, the relative volatility of ethanol and water at the azeotropic point was increased from 1.00 to 4.70 with 0–51.0 mass % ChCl/urea (1:2, mol/mol), with ChCl/urea showing a remarkable entrainer performance in this separation. Isobaric vapor–liquid equilibrium (VLE) data of four systems, water + ethanol, water + ChCl/urea, ethanol + ChCl/urea, and water + ethanol + ChCl/urea (at 10, 20, and 30 mass%), were determined using a modified Othmer equilibrium still at 101.32 kPa. After addition of ChCl/urea, the ethanol + water mixture’s azeotropic point was eliminated. The parameters of the nonrandom two-liquid (NRTL) model for these systems were calculated and the predicted values for these systems were found to fit the experimental VLE data quite well. [ABSTRACT FROM AUTHOR]

The ionic liquid (IL) 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] was studied as an agent for the separation of the methanol + dimethyl carbonate (DMC) azeotropic mixture by extractive distillation. Isothermal vapor-liquid equilibria of the methanol + DMC binary system and the ternary system with the IL were measured by headspace gas chromatography (HSGC) to examine the effect of the IL additive on the separation factor. The measurements were conducted at 336.2 K, a temperature close to the normal boiling point of the methanol + DMC azeotropic mixture, and at various compositions keeping constant IL mole fractions x 3 = (0.05, 0.10, 0.50). The new binary and ternary VLE data together with previously measured infinite dilution activity coefficients of methanol and DMC in [EMIM][TCB] were correlated well by the NRTL excess Gibbs energy model yielding their description at the level of experimental uncertainty. We found that [EMIM][TCB] increases the methanol/DMC separation factor considerably, thus eliminating the isovolatility behavior at quite low IL contents ( x 3 > 0.080 at 101.325 kPa). Compared to other IL and non-IL entrainers studied for the purpose in the literature, [EMIM][TCB] ranks among the best performing ones, though its prohibitively high price would certainly hinder the process application at present. [ABSTRACT FROM AUTHOR]

Vapor pressure data for water, 1-propanol, 2-propanol, as well as the mixtures of {water + 1-propanol} and {water + 2-propanol}, were measured by a quasi-static ebulliometric method, in the presence of an alkylsulfate-based IL, namely, 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MS]) or 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ES]). The experimental vapor pressure data for binary systems containing IL were correlated by NRTL model with an overall relative root mean square deviation (rRMSD) of 0.0053, and the obtained binary NRTL parameters were employed to predict the vapor pressure for two ternary systems with an overall rRMSD of 0.0196. In addition, isobaric vapor–liquid equilibria were predicted for the ternary systems containing [EMIM][MS], [EMIM][ES], 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]), and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate [EMIM][OTf], respectively, with IL mole fraction of 0.05, 0.15, and 0.25 at 101.325 kPa. It was found that the addition of IL can enhance the relative volatility of propanol to water, and the separation ability follows the order of [MMIM][MS] > [EMIM][MS] > [EMIM][ES] > [EMIM][BF 4 ] > [EMIM][OTf], which was further explained at electronic level with quantum chemical calculation. Therefore, the azeotropic mixtures of {water + 1-propanol}, and {water + 2-propanol} might be separated effectively by the addition of the alkylsulfate-based ILs in extractive distillation. [ABSTRACT FROM AUTHOR]

In this study, a mixture of N -methyl-2-pyrrolidinone (NMP) and ionic liquid (IL) was proposed as the entrainer for the separation of benzene and thiophene by extractive distillation. [EMIM] + [BF 4 ] − might be a suitable IL for investigating the selectivity and capacity together using the COSMO-RS model. The experimental vapor–liquid equilibrium (VLE) results indicated that the addition of IL did not obviously improve the relative volatility of benzene to thiophene; however, the content of NMP in the vapor phase could be significantly reduced using the combination of NMP and [EMIM] + [BF 4 ] − in comparison to the benchmark solvent NMP. Moreover, the UNIFAC model was extended and the corresponding interaction parameters were obtained by correlating the ternary (benzene + thiophene + NMP) and quaternary (benzene + thiophene + NMP + [EMIM] + [BF 4 ] − ) VLE equilibrium data obtained in this work at ambient pressure. [ABSTRACT FROM AUTHOR]

The close-boiling and azeotropic nature of the tetrafluoromethane and nitrogen trifluoride binary mixture complicates its separation. Extractive distillation using 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether as an entrainer is investigated for the separation of tetrafluoromethane and nitrogen trifluoride. Isothermal phase equilibrium data were measured for the binary systems of tetrafluoromethane + 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether and nitrogen trifluoride + 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether between temperatures of (283.15 to 303.15) K. The binary phase equilibrium data reveal that the proposed solvent has an affinity for nitrogen trifluoride. The data were modeled using the Peng-Robinson equation of state. The theoretical design and optimization of the extractive distillation process was performed in Aspen Plus. The optimal operating parameters were found by minimizing the total annual cost of the process. The new solvent was benchmarked against the processes proposed in the literature. [Display omitted]. [ABSTRACT FROM AUTHOR]

Low transition temperature mixtures (LTTMs) are evaluated as potential entrainers for extractive distillation for the first time. The selected LTTMs were lactic acid–choline chloride 2:1 (LC 2:1), malic acid–choline chloride 1:1 (MC 1:1), glycolic acid–choline chloride 3:1 (GC 3:1) and glycolic acid–choline chloride 1:1 (GC 1:1). Vapour–liquid equilibrium (VLE) data for the pseudo-binary mixtures of water–LTTM and ethanol–LTTM were measured and fitted with the NRLT model to calculate the interaction parameters. These parameters were used to predict the pseudo-ternary VLE data using the same model. The prediction was compared with new experimental data for the water–ethanol–LTTM system and the prediction was found to be adequate. It was found that the ethanol–water azeotrope can be broken by MC 1:1, GC 1:1 and GC 3:1 and it can be moved to the pure ethanol side with LC 2:1. [ABSTRACT FROM AUTHOR]

Vapor pressure data for water, ethanol, 1-propanol, and 2-propanol, as well as the mixtures of {water + 1-propanol} and {water + 2-propanol}, were experimentally measured in the presence of an ionic liquid (IL) 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]) at varying IL-contents and temperatures using a quasi-static ebulliometric method. The experimental vapor pressure data for binary systems containing IL were correlated using NRTL model with an overall relative root mean square deviation (rRMSD) of 0.0055, and the obtained binary NRTL parameters were employed to predict the vapor pressure for two ternary systems with an overall rRMSD less than 0.0234. Moreover, the inter-molecular interaction between [MMIM][MS] and volatile solvent was assessed theoretically in terms of the predicted activity coefficients of solvents for binary systems and quantum chemical calculations with polarizable continuum model. Finally, isobaric VLE data were predicted for three ternary systems containing [MMIM][MS] with IL mole fraction of 0.05, 0.15, and 0.25 at 101.325 kPa, respectively. The results indicate that [MMIM][MS] might be applied as a promising entrainer to separate the azeotropic mixtures of {water + ethanol}, {water + 1-propanol}, and {water + 2-propanol} by extractive distillation. [ABSTRACT FROM AUTHOR]

• The thermodynamic behavior of [Hpy]Br was measured by IGC technology. • Obtained the VLE data of [Hpy]Br with solvents and correlated with the NRTL. • The potential of [Hpy]Br as an extractive distillation entrainer was evaluated. A series of thermodynamic parameters of N-hexylpyridinium bromide ([Hpy]Br) ionic liquid (IL) were investigated by inverse gas chromatography (IGC) technique. These parameters included the Flory-Huggins interaction parameters (χ 12), activity coefficients at infinite dilution (γ 12 ∞), molar heat (enthalpy) of probe absorption in the [Hpy]Br (Δ H 1 S), molar heat of mixing at infinite dilution between [Hpy]Br and probe (Δ H 1 ∞), and Hildebrand solubility parameters (δ 2). The isothermal vapor-liquid equilibrium (VLE) data of [Hpy]Br and solvents with good solubility at 353.15K were determined from χ 12 and correlated with the NRTL model. The potential of [Hpy]Br as an entrainer for separating benzene (1)/ethanol (2), benzene (1)/isopropanol (2), and benzene (1)/thiophene (2) azeotropic mixture by extractive distillation was explored using the y - x ′ diagram. Results showed that the azeotropy of three binary systems could be broken by adding [Hpy]Br and the reliability of thermodynamic analyses was verified. [Display omitted] [ABSTRACT FROM AUTHOR]

Experimental VLE data for binary systems of ethanol or water with three 1-ethyl-3-methylimidazolium ionic liquids (ILs) containing different anions were measured at normal pressure using the Siwoloboff procedure. ILs selected in this study were those that appear to be suitable for the ethanol−water mixture separation by extractive distillation. Measured vapor–liquid equilibria were described by the extended Raoult's law with components activity coefficients calculated using the NRTL equation. Detailed analysis of the VLE data is presented in form of equilibrium diagrams, variation of activity coefficients with mixture composition and thermodynamic consistency tests. Experimental t – x data were measured within a wider range of the binary mixture compositions and compared to those found in literature. Boiling point temperature measurement of binary mixtures (adapted Siwoloboff procedure) provided comparable results to those obtained applying conventional methods of VLE estimation (circulation method, ebulliometric measurement, etc.). Reliability and thermodynamic consistency of experimental data obtained using the adapted Siwoloboff procedure for high ILs' content (high temperature) were affected by the accuracy of the temperature measurement. However, the trend of these experimental data is useful for VLE description in concentration regions where usually only coarse extrapolation is applied. Experimental data obtained for a wide binary mixture composition range (IL content of more than 70 mole%) seem to be more suitable for binary and ternary VLE description in separation equipment simulations, e.g. extractive distillation columns. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is the selection of a suitable entrainer for the separation of the binary azeotropic mixture, namely methanol+dimethyl carbonate (DMC) by extractive distillation. In this study, 2-ethoxyethanol and 4-methyl-2-pentanone were considered as entrainer candidates for the separation of methanol and DMC. Isobaric vapor–liquid equilibria (VLE) were measured for the ternary mixtures methanol+DMC+2-ethoxyethanol and methanol+DMC+4-methyl-2-pentanone, and for their constituent binary mixtures, under reduced pressures of 66.66kPa and 93.32kPa. Experimental VLE data for the constituent binary mixtures were represented by the Wilson and the NRTL model. The VLE predictions for two ternary mixtures were compared with the experimental VLE data on the basis of the Wilson or NRTL parameters obtained from the constituent binary VLE data. The modified UNIFAC (Dortmund) model was also used for the prediction of the binary and ternary mixtures. The solvent effects of the two entrainer candidates investigated are discussed using the predicted results for the ternary mixtures and both 2-ethoxyethanol and 4-methyl-2-pentanone were found to be suitable entrainers for the separation of methanol and DMC. When the selectivity of 2-ethoxyethanol and 4-methyl-2-pentanone are compared, it could be concluded from the separation factors that 4-methyl-2-pentanone shows a higher selectivity. [Copyright &y& Elsevier]

Abstract: Vapor–liquid equilibria (VLE) for the binary systems benzene–cyclohexane, 1-hexene–n-hexane and 2-propanol–water and the ternary systems with the ionic liquids 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [HMIM]+[BTI]− and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [BMPYR]+[BTI]− as entrainers were measured, to investigate the influence of ionic liquids on the separation factors. The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data. [Copyright &y& Elsevier]

Abstract: This work focuses on the extension of the numbers of group parameters and application of the group-contribution lattice-fluid equation of state (GCLF EOS). The new group parameters of the GCLF EOS were evaluated by means of the volume translated Peng–Robinson equation of state (VTPR EOS) and the UNIFAC model. Values for 20 main groups and 33 subgroups are added into the current parameter matrix. The procedure used in this work can also be used to evaluate group parameters for the groups not present in the current matrix. Some examples are given to show the reliability of the new group parameters. Two new applications of the GCLF EOS are present: the effect of polymeric additive to solvents in extractive distillation and prediction of the crystallinity of polymers in the presence of gas. [Copyright &y& Elsevier]

Abstract: Activity coefficients at infinite dilution, , have been determined for organic solutes in the phosphonium-based ionic liquid, tributylmethylphosphonium methylsulphate at T =308.15K, 318.15K and 328.15K. The experimental activity coefficient data presented are the first to be reported for this ionic liquid, through the use of the technique of steady-state gas–liquid chromatography. The organic solutes that were investigated were normal alkanes (pentane, hexane, heptane and octane), alkenes (1-hexene, 1-heptene and 1-octene), alkynes (1-hexyne, 1-heptyne and 1-octyne), cycloalkanes (cyclopentane, cyclohexane and cycloheptane) and benzene. The partial molar excess enthalpies at infinite dilution, , were also determined for the solutes from the temperature dependency of the values. The data obtained for tributylmethylphosphonium methylsulphate in this investigation have been compared to those obtained for other ionic liquids available in literature; most notably that of trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate. This comparison allows for an assessment of the potential for the use of different ionic liquids as solvents in industrial solvent-enhanced separation processes such as extractive distillation. [Copyright &y& Elsevier]

Abstract: This work deals with the separation of 1-hexene and n-hexane as the representation of olefins and paraffins with ionic liquids, as well as N-methyl-2-pyrrolidone (NMP) screened by computer-aided molecular design (CAMD). On the basis of conformation analysis of solvents and ionic liquids, the conductor-like screening model for real solvents (COSMO-RS) was used to make a priori prediction for suitable ionic liquids. It was found that the suitable ionic liquids should have small molecular volume, unbranched group and sterical shielding effect around anion charge center. Headspace-gas chromatography (HSGC) experiments were done at 313.15 and 333.15K. It was verified that the anion with sterical shielding effect around anion charge center is favorable for increasing the selectivity, and [C8Chin]+[BTA]− is the best among all the ionic liquids investigated. The separation mechanism of olefins and paraffins with ionic liquids can be explained by the theory of Prausnitz and Anderson''s solution thermodynamics. This work also can be extended to the separation of other hydrocarbons with ionic liquids since the separation mechanism between n-hexane/1-hexene and other hydrocarbons is consistent. [Copyright &y& Elsevier]

Abstract: Activity coefficients at infinite dilution, , have been determined for polar and non-polar organic solutes in the high molecular weight ionic liquid, trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate at T =308.15, 318.15 and 328.15K. The experimental activity coefficient data presented are the first to be reported for the phosphonium-based ionic liquid. For the measurement of , the technique of steady-state gas–liquid chromatography has been employed. The organic solutes that were investigated were normal alkanes (pentane, hexane, heptane and octane), alkenes (1-hexene, 1-heptene and 1-octene), alkynes (1-hexyne, 1-heptyne and 1-octyne), cycloalkanes (cyclopentane, cyclohexane and cycloheptane), alcohols (methanol, ethanol and propanol) and benzene. The partial molar excess enthalpies at infinite dilution, , were also determined for the solutes from the temperature dependency of the values. The data obtained for trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate in this investigation have been compared to that obtained for other ionic liquids available in literature and the potential for the use of ionic liquids as solvents in industrial solvent-enhanced separation processes such as extractive distillation has been discussed. [Copyright &y& Elsevier]

Reliable P–x and enthalpy of mixing data have been measured for the ternary systems 1-hexene+water+N-methyl-2-pyrrolidone (NMP), 3-methylcyclopentene+water+NMP, 3-methylpentane+water+NMP, 1-pentene+water+NMP, and 2-methylbutane+water+NMP at 90 °C, and for 1-hexene+water+NMP also at 140 °C using a static apparatus and an isothermal flow calorimeter, respectively. Activity coefficients at infinite dilution for the different hydrocarbons in the solvent have been derived from the P–x data in the dilute composition range, where the water content of NMP ranged between 0 and 6 wt.%. NRTL parameters have been fitted to the experimental data. [Copyright &y& Elsevier]

With the help of the dilutor technique activity coefficients at infinite dilution have been measured for 24 solutes (alkanes, alkenes, cyclic hydrocarbons, aromatic hydrocarbons, ketones, ethers and alcohols) in N-methyl-2-pyrrolidone (NMP), N-formylmorpholine (NFM) and their mixtures with water in the temperature range between 303.15 and 333.15 K (in a few cases for temperatures up to 423.15 K). The influence of water on the activity coefficient at infinite dilution is presented for different solutes. Furthermore, the selectivities at infinite dilution (Sij∞=γi∞/γj∞) for the separation of aliphatics from aromatics are discussed. [Copyright &y& Elsevier]

Hyperbranched polyglycerol (PG) samples of different molecular weight were synthesized by ring-opening polymerization. Vapor–liquid equilibria (VLE) and liquid–liquid equilibria (LLE) of PG solutions were measured in order to evaluate the potential of hyperbranched polymers for process engineering applications such as extractive distillation and solvent extraction. The VLE experiments focused on the polyglycerol–ethanol–water system, which was contrasted with VLE results for the systems poly(vinyl alcohol) (PVA)–ethanol–water and ethanediol–ethanol–water in order to discuss the impact of polymer branching, functional groups, molecular weight and selective interactions on the phase behavior of the azeotropic ethanol–water mixture. Furthermore, weight activity coefficients and Flory-Huggins parameters for PG in ethanol and in water were determined. For the system acetylated PG–tetrahydrofuran (THF)–water LLE results were reported and distribution coefficients as well as selectivities were discussed. For the analyzed polymer solutions, the extent of inter- and intramolecular hydrogen bond formation is the dominating impact factor on solvent activity and therefore determines partition coefficients and separation factors. Due to their remarkable solution properties, hyperbranched polymers, such as PG can be used for the separation of azeotropic mixtures in the field of process engineering. [Copyright &y& Elsevier]

Salt effect on the extractive distillation was discussed thoroughly in terms of scaled particle theory. A relationship of salting coefficient and relative volatilities at infinite dilution with salt and no salt was obtained. For the non-polar solute systems DMF/C4 and ACN/C3, we have calculated relative volatilities at infinite dilution with salt which were in agreement with experimental values. But the theory is unsatisfactory for the polar solute systems, glycol/ethanol/water and ethylene glycol/acetone/methanol, because in this case the interactions between polar solutes and solvents are very complicated. The salt effect on the relative volatilities can only be qualitatively analyzed in terms of scaled particle theory for the polar solute systems. But for separating non-polar systems or polar systems by extractive distillation, it is possible to optimize the solvents with salt. A set of experimental apparatus has been set-up to test the effect of adding salts. This work provides a way to optimize the solvents. [Copyright &y& Elsevier]

n -Hexane and 1-hexene are highly valued compounds within the petrochemical industry because of their wide range of applications. These compounds are generally found together in the same stream. Their separation is difficult to accomplish by conventional distillation due to their close boiling points. Technologies currently used to separate n -hexane and 1-hexene at industrial scale range from membrane processes to extractive distillation and liquid-liquid extraction with organic solvents. However, these processes present several technical and environmental drawbacks. A promising alternative is extractive distillation with ionic liquids as entrainers. In this work, a screening of ten ionic liquids was made to check their potential in the extractive distillation of n -hexane and 1-hexene mixtures. Firstly, the ionic liquids' extractive properties were determined to establish which ionic liquids are suitable for the n -hexane/1-hexene extractive distillation. Five ionic liquids, namely [4bmpy][TCM], [4bmpy][Tf 2 N], [bmim] 2 [Co(SCN) 4 ], [P 66614 ][TCM] and [P 66614 ][DCA] were selected. Secondly, vapor-liquid equilibrium experiments for the binary systems { n -hexane or 1-hexene + ionic liquid} were conducted at 343.2, 363.2 and 383.2 K to select the minimum solvent-to-feed ratio that guarantees homogenous ternary systems { n -hexane + 1-hexene + ionic liquid}. Then, the vapor-liquid equilibria for the ternary systems { n -hexane + 1-hexene + ionic liquid} were determined at the same three temperatures with a solvent-to-feed ratio on a mass basis of 10. Besides, solvent-to-feed ratios of 7.5 and 5 were also used for those systems containing [P 66614 ]-based ionic liquids. n -Hexane/1-hexene relative volatilities up to 2.3 were obtained, overcoming those provided by other ionic liquids and organic solvents. Finally, the NRTL model was used to adjust the ternary data accuracy. [ABSTRACT FROM AUTHOR]

The accurate prediction of activity coefficients of electrolyte solutions is of great importance for many engineering applications. The electrolyte non-random two-liquid (eNRTL) model is a commonly used semi-empirical activity coefficient model for electrolyte solutions. This work presents a modified version of the eNRTL model, which aims to extend its predictive capabilities. An ion-specific parameterization scheme is developed to replace the conventionally used salt-specific parameterization scheme. Consequently, this new method allows for the prediction of the properties of electrolytes consisting of ions for which optimal ion-specific parameter values have been determined, which is inherently not possible when using salt-specific parameters. In order to capture the features of solvent-ion interactions, a segment-based local composition term is used and experimental activity data of both the salt and the solvent are utilized for parameter fitting. The modified eNRTL model with optimal ion-specific parameters is applied to aqueous electrolyte solutions and shows satisfying prediction performance. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have found application in wide range of areas including petroleum industry, extractive distillation, raw material processing, additives for lubricants, functional materials, and catalyst for organic processes. Despite their applications in various fields of science, the use of ILs has been of questionable existence due to their induced toxic effects. To study the phase behavior of these ILs, various methods of obtaining data have been proposed. Notably, the main source of data comes from the laboratory experiments. Despite the existence of experimental methods to quantify the vapor-liquid equilibrium behavior of a fluid – IL system, it is necessary to build a model that can predict the behavior of the system at various states such as, changing temperature, pressure, and volume. Notwithstanding the huge cost and time required during experiments, thermodynamic model has found increasing use for modeling complex mixtures and/or compounds. One of the key parameters of the various thermodynamic models is the acentric factor, which dictates the level of sphericity of a molecule. In this study, the authors explored two different intelligent systems to estimate this key property for binary and ternary mixtures. The algorithm considered in this study include the least square support vector machine and artificial neural network. The input parameters considered include the critical temperature and volume, mole fraction of the solvent(s) and ionic liquid, molecular weight, density of the mixture, and temperature of the fluid. The comparison between the best model and experimental data point indicates very low root mean square error of 0.0164 and 0.0005 for the binary and ternary mixtures respectively. Similarly, the best model produced a very high correlation coefficient of 0.9826 and 1.0000 for the binary and ternary mixtures respectively. Image 1 • The use of intelligent system to estimate acentric factor of Ionic liquids is presented. • The model is a non-complicated function of critical properties, mole fractions, molecular weight, and density of the mixture. • The proposed model outperforms existing data-driven approach. • The proposed model is computationally time efficient. • Open-source model to estimate the property is presented. [ABSTRACT FROM AUTHOR]