Accurate thermodynamic modeling of ionic liquids/metal salt mixtures: Application to carbon monoxide reactive absorption

Abstract

For the first time, a theoretical semipredictive approach based on the soft‐Statistical Associating Fluid Theory equation of state is presented to model the complexation reaction between carbon monoxide (CO) in a combined ionic liquid (IL) plus a copper(I) metallic salt media in terms of the gas solubility as a function of temperature, pressure, and composition. Two different degrees of molecular approximation are tested. In the first approach, the IL‐metal salt mixture is treated as a single compound whose parameters are modified according to the concentration of the metallic salt. In the second approach, both compounds are treated as independent species, enhancing the predictive capability of the model. The complexation between CO molecules and the metal salt is reproduced by adding specific cross‐association interaction sites that simulate the reaction. The density of the doped IL and the CO solubility are described in quantitative agreement with the experimental data at different operating conditions. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3532–3543, 2017

Screening of Ionic Liquids and Deep Eutectic Solvents for Physical CO2 Absorption by Soft-SAFT Using Key Performance Indicators

“…In this section, we present the application of the soft-SAFT EoS for the screening of ILs and DESs, for the physical absorption of CO 2 . The soft-SAFT calculations for the thermophysical properties of the pure solvents and their phase equilibria with CO 2 are validated against experimental data with the molecular parameters of the pure solvents transferred from previous contributions. ,,,− ,,, The models are subsequently used in a predictive manner to assess the potentiality of these solvents in terms of KPIs such as cyclic working capacity, enthalpy of absorption, and diffusivity, capturing the trade-offs between these properties on the effectiveness of ILs and DESs for CO 2 capture.…”

“…The ILs were modeled using the pseudopure component approach as associating single chainlike fluids with the attractive interactions between the counterions mimicked through the addition of specific association sites (defined a priori ) dependent on the structure and charge distribution of the IL. For ILs with [BF 4 ] − , [PF 6 ] − , [Cl] − , [CF 3 SO 3 ] − , and [CF 3 CO 2 ] − anions, a single association site of type A was included in their models as the neutral counterions pair is quasi-spherical with a very localized charge, with A – A interactions allowed in the model due to the dual nature of the association site. ,, Alternatively, [C 4 mim]­[MeSO 4 ] and [C4mim]­[SCN] were modeled with two association sites, one site of type A representing the interaction between the anion and the cation, and one site of type B , mimicking the delocalized charge due to the oxygen molecule on the anion, with only A – B interactions allowed in the model. , In a similar fashion, ILs with [NTf 2 ] − , [C 4 F 9 SO 3 ] − , and [N­(C 2 F 5 SO 2 ) 2 ] − anions were modeled with three association sites, one site of type A and two sites of type B , as a consequence of a higher degree of charge delocalization in the anion, again only allowing A–B interactions in the model. ,, The soft-SAFT molecular parameters for the examined ILs were transferred from previous contributions, ,,,,, and are included in Table S1 in the Supporting Information for completeness.…”

Combining soft-SAFT and COSMO-RS modeling tools to assess the CO2–SO2 separation using phosphonium-based ionic liquids

“…4.1 Soft-SAFT parameter fitting and pure IL thermophysical data: Providing that ILs have a very low vapor pressure, the adjustable parameters of soft-SAFT EoS were fitted to single-phase liquid density data in a wide range of temperatures and pressures (i.e., T = 303 K -333 K, and P = 0.2 MPa -65 MPa). This is the common approach followed in previous contributions when dealing with ILs [13][14][15][16][17][18][19][20]46,[67][68][69]. Measured densities (𝜌) for the fitting of the ILs with [Cl]and…”

“…Molecular-based equations of state (EoS) such as the Statistical Associating Fluid Theory (SAFT) [10,11], and more specifically the soft-SAFT version [12], has been able to successfully describe the phase equilibria of different ILs with several gas molecules. Specifically, in the last years, the soft-SAFT EoS was used to study gas absorption in a wide variety of anions (e.g., [BF4] -, [NTf2] -, [DCA] -, [SCN] -, [Ac] -, [MeSO4] -) combined with imidazolium [13][14][15] and pyridinium [16,17] cations. Finally, CO2 and SO2 absorption have also been recently studied with tetraalkylammonium and choline chloride salts in deep eutectic solvents with CO2 and SO2 [18][19][20].…”

Molecular thermodynamic understanding of transport behavior of CO2 at the ionic liquids‐electrode interface

“…The detailed interfacial structure can affect the transport behaviors and thermodynamic properties of CO 2 , which will further regulate the entire performance of ILs in the process of CO 2 conversion. However, the special hydrogen bond and ionic nature within ILs lead to the interfacial structure and transport behaviors cannot be predicted well using the traditional models, [12][13][14] which restrains the applications of ILs in the field of CO 2 capture and reduction.…”