Thermodynamic modeling of aqueous ionic liquid solutions and prediction of methane hydrate dissociation conditions in the presence of ionic liquid (2023)

Chemical Engineering Science

Volume 102,

11 October 2013

, Pages 24-31

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Heterosegmented statistical associating fluid theory (SAFT) is developed to model the thermodynamic properties of aqueous imidazolium ionic liquid solutions. A set of transferable parameters is obtained, and in general, the model well represents the density, the activity coefficients, and the osmotic coefficients of aqueous ionic liquid solutions. This heterosegmented SAFT, coupled with the Van der Waals and Platteeuw theory for hydrate phase, is also found to well predict the methane hydrate dissociation conditions in the presence of imidazolium ionic liquids and well captures the roles of pressure, anion type, alkyl length of the cation, and ionic liquid concentration on the hydrate inhibition performance of the ionic liquids.


Ionic liquids (ILs), also known as liquid salts or ionic fluids, are organic salts with low melting point, which makes them liquids at ambient or relatively low temperature. ILs are promising chemicals or solvents for green chemical processes because of their unique physicochemical properties, such as low vapor pressure, low viscosity, high electric conductivity, excellent solvation behavior, non-flammability, and high selectivity.

Recently, ILs were also found to be a new class of dual function hydrate inhibitors, which not only shift the hydrate dissociation curve to higher pressures and lower temperatures, but also slow down the rate of hydrate formation (Xiao and Adidharma, 2009, Xiao et al., 2010); hydrate is clathrate solid formed by water and suitable gas molecules at high pressure and low temperature. Thus, IL could be a new effective hydrate inhibitor that is promising for the offshore oil and gas production process. The use of IL as inhibitor has been experimentally studied for both methane and carbon dioxide hydrates (Richard and Adidharma, 2013a, Li et al., 2011a, Li et al., 2011b, Chen et al., 2008). The huge combination of cations and anions that can be tailored to form ILs would enable us to find more effective gas hydrate inhibitors that are inexpensive and biodegradable. However, at the same time this also poses a real challenge. Due to the huge number of ILs potentially used as hydrate inhibitors, experimental study is not only inadequate but also expensive. Hence, it is extremely important to have thermodynamic models to describe their properties and behavior. It is the purpose of this work to introduce a thermodynamic model that can be used to describe the properties and the thermodynamic hydrate inhibition performance of this promising class of inhibitors.

Several thermodynamic models have been proposed to describe the properties of pure IL and fluid mixture containing IL. An early work on the thermodynamic modeling of IL by Shariati and Peters (2003) was based on Peng–Robison (PR) equation of state (Peng and Robinson, 1976). Carvalho et al. (2009) studied the solubility of CO2 in IL by combining the PR EOS and the UNIQUAC model, and Chen et al. (2008) modeled the liquid–liquid equilibrium of mixtures containing IL and organic solvent, such as alcohol and benzene, using NRTL model (Renon and Prausnitz, 1968). However, most of these models are empirical. Although the experimental data can be correlated, the predictive power of these models is limited.

Recently, models with theoretical basis were developed to describe the thermodynamic properties of ILs. Wang et al. (2006) developed a square-well chain fluid (SWCF) EOS and successfully described the density of pure IL and gas solubility in IL. In their model, IL was treated as a homosegmented chain molecule with a square-well potential. Wang et al. (2007) also proposed a heterosegmented SWCF EOS and modeled the binary vapor–liquid equilibria of systems containing IL. In this hetero-SWCF EOS, IL was modeled as a di-block molecule, with the alkyl chain as one block and the cation head-anion pair as the second block. Statistical associating fluid theory (SAFT) was also applied to the thermodynamic modeling of ILs. Kroon et al. (2006) developed a truncated perturbed chain polar statistical associating fluid theory (tPC-PSAFT) to model the CO2 solubility in IL, where the dipolar interactions between IL molecules and the Lewis acid-base type of association between the IL and the CO2 molecules were accounted for. Ji et al. (2012) used ePC-SAFT to correlate the density of pure IL and predict gas solubility in IL. They proposed and compared six different strategies for the IL modeling, and the one with the Debye–Huckle term to account for the Coulomb interaction was found to be the most predictive. In this strategy, the cation and anion of an IL were modeled as homosegmented chains without association. Heterosegmented SAFT models were also developed to describe the thermodynamic behavior of IL. Ji and Adidharma (2009) proposed a heterosegmented model to correlate and predict the density of pure IL. This heterosegmented SAFT EOS was then applied to correlate and predict the solubility and partial molar volume of CO2 in IL (Ji and Adidharma, 2010, Ji and Adidharma, 2012). In this model, the cation was treated as a chain molecule while the anion was represented as a spherical segment. The chain molecule of cation was composed of one effective segment representing the cation head and different groups of segments representing the alkyl chains. The cation head and anion each was assumed to have one association site, which could only cross associate to each other.

Although several theoretical thermodynamic models have been developed for IL, most of their applications focused on the description of pure IL properties and gas solubility in IL. The modeling work of aqueous IL solutions is quite rare although many ILs, as electrolytes, can totally or partially dissolve in water. This could be due to the fact that the modeling of these systems is even more challenging. Soft-SAFT was implemented to correlate the density of pure IL and predict the binary phase equilibria of IL and alcohol (or water) mixtures (Llovell et al., 2011). In their model, IL molecules were modeled as homosegmented chains with three associating sites to account for the interaction between cation and anion. Li et al. (2011a) used the SWCF EOS to model the thermodynamic properties of aqueous IL solutions. PC-SAFT was also implemented to describe the properties of aqueous solutions of IL (Reza et al., 2012). In these two models, cross association between cation and anion was also considered. The electrostatic interaction between cation and anion was described by using an electrostatic term based on the primitive model (PM) of the mean spherical approximation (MSA) (Blum, 1975). Their model parameters were obtained by fitting to the density and osmotic coefficients of aqueous IL solutions. Since these two works are based on a homosegmented model, the model parameters are not transferrable, which means that new parameters need to be fitted when new IL species having the same constituents are involved in the modeling.

Due to the complex molecular structure and thermodynamic behavior of IL, the modeling of IL as hydrate inhibitor is still very limited. Kaniki et al. (2011) studied the inhibition effect of tributhylmethylphosphonium methylsulfate on methane and carbon dioxide hydrates. In this model, the Peng–Robinson EOS (Peng and Robinson, 1976) and the NRTL model (Renon and Prausnitz, 1968) were used to describe the fluid phase while the Van der Waals and Platteeuw (1959) theory was applied to model the hydrate phase. Marziyeh et al. (2013) used the electrolyte cubic square well (ECSW) EOS (Haghtalab et al., 2012) and the Van der Waals and Platteeuw (1959) theory to predict the methane hydrate phase equilibria in the presence of IL. In their model, the parameters of the ECSW EOS were adjusted to the osmotic coefficients of aqueous IL solutions. A recent work by Partoon et al. (2013) implemented a Pitzer-type model to represent the methane hydrate dissociation conditions in the presence of ionic liquid. In our previous work, the heterosegmented SAFT EOS has been successfully applied to predict the n-alkane hydrate dissociation conditions in pure water and in solutions containing conventional inhibitors, including salt solutions (Jiang and Adidharma, 2011a, Jiang and Adidharma, 2011b, Jiang and Adidharma, 2012). In this work, we extend this heterosegmented SAFT to describing the thermodynamic properties of aqueous imidazolium IL solutions containing [CxMIM][Br] (2≤x≤6), [C4MIM][Cl], or [C4MIM][BF4], and apply it, coupled with the Van der Waals and Platteeuw (1959) theory, to predict the dissociation conditions of methane hydrate in the presence of imidazolium ILs.

Section snippets

Thermodynamic model

An IL consists of an organic cation and an organic or inorganic anion. The cation of the imidazolium IL is composed of an aromatic ring (imidazolium head/cation head) and several alkyls. In this heterosegmented SAFT model, the cation is treated as a chain with a spherical segment representing the cation head and different groups of segments representing the alkyls, as depicted in Fig. 1. The positive charge is assumed to be located on the head segment of the cation chain. The anion of the IL is

Parameter estimation

In a heterosegmented model, the parameters are assigned to each group of segments. The model parameters are transferrable and can be applied to other imidazolium ILs having ions that have been included in this work.

Some of the model parameters had been obtained in our previous works. The parameters for the alkyl groups, except voo, u/k, and λ of the ethyl group (C2−), are taken from the work of Ji and Adidharma (2009), in which the alkyl parameters were derived from those of the corresponding


Heterosegmented statistical associating fluid theory (SAFT) is developed to model the thermodynamic properties of aqueous IL solutions containing [C4MIM][Cl], [C4MIM][BF4], or [CxMIM][Br] (2≤x≤6). The cation of IL is treated as a chain with a spherical segment representing the cation head and different groups of segments representing the alkyls. The positive charge is assumed to be located on the head segment of the cation chain. The anion of the ionic liquid is modeled as a spherical segment

References (41)

  • Q. Chen et al.

    Effect of 1-butyl-3-methylimidazolium tetrafluoroborateonthe formation rate of CO2 hydrate

    Journal of Natural Gas Chemistry


  • B. Gonzalez et al.

    Osmotic coefficients of aqueous solutions of four ionic liquids at T=(313.15 and 333.15)K

    Journal of Chemical Thermodynamics


  • A. Haghtalab et al.

    Prediction of hydrate equilibrium conditions using electrolyte cubic square-well equation of state

    Fluid Phase Equilibria


  • X. Ji et al.

    Thermodynamic modeling of ionic liquid density with heterosegmented statistical associating fluid theory

    Chemical Engineering Science


  • X. Ji et al.

    Thermodynamic modeling of CO2 solubility in ionic liquid with heterosegmented statistical associating fluid theory

    Fluid Phase Equilibria


  • H. Jiang et al.

    Prediction of hydrate dissociation conditions for alkanes in the presence of alcohol and electrolyte solutions using ion-based statistical associating fluid theory

    Chemical Engineering Science


  • X. Ji et al.

    Modeling imidazolium-based ionic liquids with ePC-SAFT

    Fluid Phase Equilibria


  • X. Ji et al.

    Prediction of molar volume and partial molar volume for CO2/ionic liquid systems with heterosegmented statistical associating fluid theory

    Fluid Phase Equilibria


  • B. Partoon et al.

    A study on thermodynamics effect of [EMIM]-Cl and [OH-C2MIM]-Cl on methane hydrate equilibrium line

    Fluid Phase Equilibria


  • A. Richard et al.

    The performance of ionic liquids and their mixtures in inhibiting methane hydrate formation

    Chemical Engineering Science


  • A. Shariati et al.

    High-pressure phase behavior of systems with ionic liquids: measurements and modeling of the binary system fluoroform+1-ethyl-3-methylimidazolium hexafluorophosphate

    Journal of Supercritical Fluids


  • H. Shekaari et al.

    Osmotic coefficients of some imidazolium based ionic liquids in water and acetonitrile at temperature 318.15K

    Fluid Phase Equilibria


  • H. Shekaari et al.

    Influence of alkyl chain on the thermodynamic properties of aqueous solutions of ionic liquids 1-alkyl-3-methylimidazolium bromide at different temperatures

    Journal of Chemical Thermodynamics


  • T. Wang et al.

    Description of the PVT behavior of ionic liquids and the solubility of gases in ionic liquids using an equation of state

    Fluid Phase Equilibria


  • C. Xiao et al.

    Dual function inhibitors for methane hydrate

    Chemical Engineering Science


  • C. Xiao et al.

    Dialkyl imidazoliumhalide ionic liquids as dual function inhibitors for methane hydrate

    Chemical Engineering Science


  • L. Blum

    Mean spherical model for asymmetric electrolytes I. Method of solution

    Molecular Physics


  • L. Bhajan et al.

    Volumetric studies to examine the interactions of imidazolium based ionic liquids with water by means of density and speed of sound measurements

    Journal of Chemical Thermodynamics


  • C. Chen et al.

    Correlation and prediction of phase behavior of organic compounds in ionic liquids using the nonrandom two-liquid segment activity coefficient model

    Industrial & Engineering Chemistry Research


  • P. Carvalho et al.

    Specific solvation interactions of CO2 on acetate and trifluoroacetate imidazolium based ionic liquids at high pressures

    Journal of Physical Chemistry B


  • Cited by (19)

    • Thermodynamic modeling of methane hydrate equilibrium conditions in the presence of imidazolium based ionic liquids with the van der Waals-Platteeuw solid solution approach along with SRK and CPA EoS

      2023, Fluid Phase Equilibria

      Gas hydrates are solid solutions which cause flow assurance problems and risks to line integrity in the petroleum industry. Thermodynamic inhibitors are usually injected during production to avoid hydrate formation. In recent years, many authors have reported Ionic Liquids (ILs) as inhibitors. However, there are not many studies on thermodynamic modeling in the literature involving ILs as hydrate inhibitors, especially when it comes to the applicability of the Cubic Plus Association (CPA) and Soave-Redlich Kwong (SRK) Equation of State. In light of this, the aim of this work was to evaluate methane hydrate equilibrium in the presence of ILs as inhibitors using van der Waals-Platteeuw solid solution theory along with these Equations of State to describe liquid and gas phases. The commercial software Multiflash and its interface with excel were employed to calculate hydrate equilibrium pressures. Data from the literature on 12 imidazolium-based ILs were taken into account by varying carbon chain length and anion basicity. Both Equations of State resulted in accurate equilibrium predictions with similar deviations between calculated and experimental data (overall ARD 4.64% for CPA, and 4.49% for SRK) considering p and T conditions in the range of 2.5–35Mpa and 272–295K respectively. 2B association was considered for ILs, while 4C association was used for water. In general, longer cation carbon chain lengths and higher anion basicity resulted in lower accuracy.

    • Modeling stability conditions of methane Clathrate hydrate in ionic liquid aqueous solutions

      2021, Journal of Molecular Liquids

      Citation Excerpt :

      Hence, it can be concluded that these compounds are dual-function inhibitors for the methane hydrates. Using the heterosegmented statistical associating fluid theory (SAFT), Jiang and Adidharma [6] determined the thermodynamic properties of the imidazolium ILs. Furthermore, they predicted the dissociation conditions of methane hydrate in aqueous solutions of imidazolium ILs by employing the heterosegmented SAFT in conjunction with the solid solution theory of van der Waals and Platteeuw (vdWP) [7].

      Mixing ionic liquid (IL) and water can influence the thermodynamic characteristics such as water activity. Hence, some ILs can be utilized as inhibitors for hydrate systems. This work was intended to determine the three-phase equilibria of methane hydrate in aqueous solutions of 32 ILs using the least squares support vector machine (LSSVM), adaptive neuro-fuzzy inference system (ANFIS), and classification and regression tree (CART). The modeling studies on clathrate hydrates in aqueous solutions of ILs are also reviewed. The used databank contains anion groups such as sulphate, dicyanamide, tetrafluoroborate, and halides. The dissociation temperature of methane hydrate in aqueous solutions of ILs is modelled considering the ILs' critical pressure and critical temperature, the pressure of hydrate system, and the concentration of IL in aqueous phase as the independent parameters. All the developed models are found to well represent/predict the methane hydrate dissociation temperatures in aqueous solutions of ILs. The calculated values of average absolute relative deviation for the presented LSSVM, ANFIS, and CART models are equal to 0.08, 0.31, and 0.10, respectively. Hence, the results reveal that the introduced CART and ANFIS models cannot compete with the developed LSSVM approach in representing the dissociation temperatures of the methane + hydrate + IL + water systems studied in this research work. Using the proposed LSSVM model, all the investigated database equilibrium temperatures are within the absolute deviation percent of 0.0-1.0% except the data that show an absolute deviation percent of 1.35%. The findings of this study can help researchers and engineers to better understand the effects of ILs on methane hydrate stability conditions toward effective hydrate management.

    • PC-SAFT/UNIQUAC model assesses formation condition of methane hydrate in the presence of imidazolium-based ionic liquid systems

      2020, Fuel

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      Jiang and Adidharma developed a heterosegmented statistical associating fluid theory equation of state (SAFT EOS) to model the thermodynamic properties of different IL solutions including [C4MIM][Br], [C5MIM][Br], [C6MIM][Br], [C4MIM][Cl], [C2MIM][Br], [C3MIM][Br], and [C4MIM][BF4] [44]. They hybridized the SAFT model with the van der Waals and Platteeuw theory for the hydrate phase and effectively estimated the methane hydrate dissociation conditions in the presence of imidazolium IL solutions [44]. Chin et al. examined the impact of IL solutions on the gas hydrate dissociation conditions by using the thermodynamic model of the Peng−Robinson−Stryjek−Vera equation of state (PRSV EOS) integrated with the COSMO-SAC activity coefficient model and the first order modified Huron−Vidal (MHV1) mixing rule for the fluid phase; they also modified van der Waals and Platteeuw model for the solid phase [45].

      One of the major problems in flow assurance, especially in the case of deep subsea pipelines, is the accumulation of gas hydrates that leads to significant issues such as pipe plugging and cracking. Utilization of thermodynamic inhibitors is an effective method to prevent hydrate formation in pipelines. Recently, ionic liquids (ILs) have been recognized as new hydrate inhibitors due to their strong electrostatic charges, which form hydrogen bonds with water molecules. In this work, the capability of the PC-SAFT/UNIQUAC model combined with the van der Waals-Platteeuw theory is assessed for estimation of the methane hydrate dissociation temperatures in the presence of various IL solutions. Five pure-component parameters of PC-SAFT EOS for ILs are fitted by using experimental data of liquid density. Furthermore, vapour-liquid and hydrate equilibria experimental data are employed to adjust the binary interaction parameters of the PC-SAFT EOS (kij) and the UNIQUAC model (uij), respectively. Methane hydrate dissociation temperatures are successfully forecasted by using the proposed model for ten (10) IL systems with different concentrations in which the overall average absolute deviation for temperature (AADT %) of the model is lower than 1.5%. The results clearly demonstrate that the developed thermodynamic model is capable of precisely obtaining the methane hydrate dissociation temperatures in the presence of IL solutions, though, for [EMIM][Cl] solutions with a concentration of more than 30wt%, the model overestimates the methane hydrate conditions. The proposed thermodynamic modeling strategy can assist to screen suitable IL solutions with an optimal composition for hydrate formation inhibition in terms of technical, economic, and environmental prospectives.

    • Experimental study and thermodynamic modeling of the stability conditions of methane clathrate hydrate in the presence of TEACl and/or BMIM-BF<inf>4</inf> in aqueous solution

      2019, Journal of Chemical Thermodynamics

      In this work, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) and tetra ethyl-ammonium chloride (TEACl) were investigated to study their effects on thermodynamic stability conditions of methane clathrate hydrate. Different BMIM-BF4 and TEACl aqueous solutions (4.77 wt% (0.57 mol%) TEACl + 4.85 wt% (0.43 mol%) BMIM-BF4, 9.15 wt% (0.20 mol%) TEACl + 9.38 wt% (0.90 mol%) BMIM-BF4 and 11.82 wt% (1.63 mol%) TEACl + 11.82 wt% (1.20 mol%) BMIM-BF4) were used as thermodynamic inhibitors which have not been reported in literature. The experiments were conducted at constant volume from 274.6 K to 283.4 K and 3.18 MPa to 7.93 MPa. Moreover, methane hydrate phase equilibria in the aforementioned ioinic liquids (ILs) aqueous solutions were modeled. For this purpose, the chemical potential of water in hydrate phase is calculated using the van der Waals–Platteeuw (vdWP) theory. The Peng-Robinson (PR) equation of state (EoS) is used for calculation of fugacity in the gas phase. Water activity in the aqueous phase is determined by the NRTL activity coefficient model. Successful comparison of the experimental data with the modeling results confirms the model accuracy. It can also be observed that mixtures of the two aforementioned ionic liquids can inhibit methane hydrate formation more than each of single ILs. Furthermore, the studied ILs inhibit methane hydrate formation more at higher pressures.

    • COSMO-RS: An ionic liquid prescreening tool for gas hydrate mitigation

      2016, Chinese Journal of Chemical Engineering

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      Most recently, COSMO-RS was presented as a method for tuning ILs for natural gas dehydration [32], however there is no open literature regarding the use of COSMO-RS to screen ILs for gas hydrate studies. Claudio et al.[33] used COSMO-RS to predict the hydrogen bonding energies (EHB) of ILs, which is defined as the energy between IL accepter and donor in hydrogen-bonding interaction [34]; and reported that, COSMO-RS predicted EHB have a strong relationship with the experimental hydrogen bonding basicity ( ability of ILs to accept hydrogen atoms [35]) of ILs [20,21]. Klamt [36] described the interaction mechanism between water and solute compounds by determining their sigma-prolife and sigma-potentials in COSMO-RS and concluded that COSMO-RS effectively describes water-solvent interactions of compounds.

      Recently ionic liquids (ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial & error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies (EHB) of studied IL inhibitors and comparing the predicted EHB to the depression temperature (Ŧ) and induction time. Results show that, predicted EHB and chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately (R=0.70) with average induction time in literature. It is deduced from the results that, Ŧ increases with increasing IL EHB and/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection.

    • Effect of methylimidazolium-based ionic liquids on vapor-liquid equilibrium behavior of tert-butyl alcohol + water azeotropic mixture at 101.3 kPa

      2016, Chinese Journal of Chemical Engineering

      Citation Excerpt :

      A suitable solvent is very demanding for this purpose [4,5]. Ionic liquids (ILs), also known as liquid salts or ionic fluids, are a new chemical substances consisting of an organic cation and an inorganic or organic anion [6]. With the outstanding physicochemical properties of low vapor pressure and melting point, high stability, full of design ability, and environment-friendly, ILs are under intensive investigation to determine their potential as replacement solvents for extractive distillation [7,8].

      Three ionic liquids (ILs), 1-ethyl-3-methylimidazolium bromine ([EMIM]Br), 1-butyl-3-methylimidazolium bromine ([BMIM]Br), and 1-hexyl-3-methylimidazolium bromine ([HMIM]Br), were used as the solvent for separation of {tert-butyl alcohol (TBA)+water} azeotrope. Vapor–liquid equilibrium (VLE) data for {TBA+water+IL} ternary systems were measured at 101.3kPa. The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA+water} system and eliminate the azeotropy in the whole concentration range. [EMIM]Br is the best solvent for the separation of {TBA+water} system by extractive distillation among the three ILs. The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations. Explanations are given with activity coefficients of water and TBA, and the experimental VLE-temperature data for {TBA or water+IL} binary systems.

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