Modeling imidazolium-based ionic liquids with ePC-SAFT

Abstract

a b s t r a c t ePC-SAFT was used to investigate the density and gas solubilities in imidazolium-based ionic liquids (ILs) applying different modeling strategies. The ion-based strategy including a Debye-Hückel Helmholtzenergy term to represent the ionic interactions describes the experimental data best. For this strategy, the IL was considered to be completely dissociated into a cation and an anion. Each ion was modeled as non-spherical species exerting repulsive, dispersive, and Coulomb forces. A set of ePC-SAFT parameters for seven ions was obtained by fitting to reliable density data of pure ILs up to 1000 bar with a fitting error of 0.14% on average. The model can be used to quantitatively extrapolate the density of pure ILs at temperatures from 283 to 473 K and pressures up to 3000 bar. Moreover, this strategy allows predicting CO 2 solubilities in ILs between 293 and 450 K and up to 950 bar. Applying the same set of IL parameters, the much lower solubility of CH 4 compared to CO 2 can also be predicted with ePC-SAFT.

Measurement and PC-SAFT modeling of solid-liquid equilibrium of deep eutectic solvents of quaternary ammonium chlorides and carboxylic acids

“…Ji et al [38], Nann et al [39] and Passos et al [40] reported the use of PC-SAFT to model IL solutions while Zubeir et al [28] used this EoS to model the CO 2 solubilities in DES with [Ch]Cl, and different symmetrical quaternary ammonium chlorides serving as HBA. The various authors treated ILs as molecules with associative behavior by using a 2B association scheme (according to Huang and Radosz [41]), where to each molecule two association sites (mimicking the cation and the anion) are assigned and association interactions between unlike sites are allowed.…”

Modeling imidazolium-based ionic liquids with ePC-SAFT. Part II. Application to H2S and synthesis-gas components

“…As described in our previous work [6], polar interactions can be neglected for modeling gas solubilities in imidazolium-based ILs, and thus the Helmholtz-energy contributions considered within ePC-SAFT in this work are:…”

“…In addition, the removal of H 2 S from industrial gas and oil streams is an essential step because of its undesirably high toxicity and corrosiveness [5]; thus, the application of ILs for H 2 S removal purposes requires knowledge of the H 2 S solubility in ILs. Although experimental measurements are broadly available and can already provide some insights into the understanding of gas solubility in ILs [5][6][7][8][9][10][11][12][13][14][15], such measurements are often difficult, time-consuming and expensive. It is thus desirable to develop theoretical models that are able to estimate the gas solubility in ILs over a wide range of system conditions.…”

“…Several SAFT-type models have been developed to represent the gas solubility in imidazolium-based ILs, for example, truncated Perturbed-Chain Polar SAFT (tPC-PSAFT) [17,18], PC-SAFT [19], soft-SAFT [20][21][22], heterosegmented SAFT [23][24][25], SAFT-␥ [26] as well as ePC-SAFT [6]. Most of them require binary fitting parameters, which are usually adjusted to gas-solubility data in order to represent gas solubilities quantitatively.…”

“…In contrast, the modeling strategy within ePC-SAFT developed in our previous work [6] could be used to predict CO 2 solubilities Table 1 ePC-SAFT parameters of IL-ions determined in [6] and used in this work. …”