Demonstrating the key role of kinetics over thermodynamics in the selection of ionic liquids for CO2 physical absorption

Palomar, José; Larriba, Marcos; Lemus, Jesús; Moreno, Daniel; Santiago, Rubén; Moya, Cristian; Riva, Juan de; Pedrosa, Graciela C.

doi:10.1016/j.seppur.2018.12.059

Cited by 65 publications

(66 citation statements)

References 53 publications

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“…36,40 Moreover, the absorption process in ILs is reported to be kinetically controlled so that using low-viscosity ILs would enhance gas diffusion coefficients and, consequently, lead to higher recoveries and more energy-efficient separations. 41 Thus, we present the experimental gas solubility and diffusion coefficients of refrigerants R32, R134a and…”

Section: Introductionmentioning

confidence: 99%

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

et al. 2020

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The phase-down of hydrofluorocarbons (HFCs) established by the Kigali Amendment to the Montreal Protocol is leading to the formulation and commercialization of new refrigerant blends containing hydrofluoroolefins (HFOs), such as 2,3,3,3-tetrafluoropropene (R1234yf), and HFCs with moderate global warming potential, namely, difluoromethane (R32 ) and 1,1,1,2tetrafluoroethane (R134a). Moreover, the recycling of refrigerants is attracting attention as a means to reduce the amount of new HFCs produced and their release to the environment. To that end, the use of ionic liquids has been proposed as entrainers to separate refrigerants with close-boiling points or azeotropic blends. Thus, the vapor-liquid equilibria and diffusion coefficients of the refrigerant-ionic liquid pairs formed by R32 +studied using an isochoric saturation method at temperatures ranging from 283.15 to 323.15 K and pressures up to 0.9 MPa. In addition, the solubility behavior is successfully modeled using the non-random two-liquid activity coefficient method, and the Henry's law constants at infinite dilution, solvation energies and infinite dilution activity coefficients are calculated.

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Section: Introductionmentioning

confidence: 99%

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

et al. 2020

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“…Previous process simulations revealed a determinant effect of the mass transport properties of ILs on the efficiency of H 2 S recovery 33 and CO 2 absorption processes. 36,44,63 In the case of H 2 S capture, all of the selected ILs (Table 2) present reasonably high solubilities (K Henry values between 8.8 and 18 bar), so the strategy in the process simulation was to combine the selected ILs with solvents of lower viscosity. Thus, the equimolar mixtures of 3).…”

Section: Is Observed That the Il-based Blends [Emim][(meo)po 2 H]− Tg...mentioning

confidence: 99%

“…29−35 However, one of the common drawbacks of ILs with high H 2 S solubility is their high viscosity, which leads to mass transfer limitations during absorption operations. 33,36 Less studied but thermodynamically much more attractive are ILs that chemically absorb H 2 S. It was reported that ILs containing carboxylate groups are a class with excellent affinity toward H 2 S because of their Lewis base features. 37−39 However, their higher viscosities make them difficult to be applied at a larger scale.…”

Section: ■ Introductionmentioning

confidence: 99%

Process Analysis of Ionic Liquid-Based Blends as H₂S Absorbents: Search for Thermodynamic/Kinetic Synergies

Lemus

Santiago

Hospital-Benito

et al. 2021

ACS Sustainable Chem. Eng.

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Acid gas absorption by ionic liquids (ILs) has arisen as a promising alternative technique for biogas or natural gas upgrading. In the present work, IL-based blends are evaluated for potential thermodynamic/ kinetic synergistic effects on hydrogen sulfide (H 2 S) capture through physical and/or chemical absorption. First, a molecular simulation analysis by means of COSMO-RS was used to select IL-based blends with enhanced H 2 S absorbent thermodynamic properties. Physical absorption parameters of reference (K Henry ) for H 2 S in several IL-based blends were calculated at 298 K, involving both IL mixtures and conventional industrial absorbents (tetraglyme (TGM)) with ILs at different compositions. A Henry's constant deviation parameter (ΔH K Henry H 2 S ) was employed to analyze the nonideal effects of the mixture on H 2 S gas solubility in IL-based blends. In addition, the viscosities and diffusivities of the IL-based blends were estimated as key parameters controlling H 2 S diffusion and absorbent uptake rates. From this analysis, a sample of IL-based blends with promising thermodynamic and kinetic properties was selected for H 2 S physical absorption. A process simulation analysis using the COSMO-based/Aspen Plus methodology was then carried out and the selected absorbents were evaluated by modeling H 2 S capture in an industrial-scale commercial packed column. One IL, 1-butyl-3-methylimidazoium acetate ([Bmim][OAc]), presenting high H 2 S chemical absorption and a low viscous industrial solvent (TGM) were also included. The strong kinetic control of H 2 S capture by physical absorption indicated the limited potential performance of IL-based blends or neat ILs in industrial equipment. In contrast, the COSMO/Aspen analysis revealed that adequate formulations based on [Bmim][OAc] and TGM present enhanced H 2 S absorbent properties compared to the neat compounds. These computational results may be used to guide future experimental research to design new H 2 S absorbents, reducing the highly demanding experimental input.

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“…For instance, the key role of absorption kinetics over thermodynamics in IL selection for CO2 capture has been revealed. [32][33][34] Ignoring kinetics can lead to sub-optimal or even poor solutions for absorption process development. To identify truly optimal solvent and absorption process, a rigorous rate-based absorption process model that incorporates absorption thermodynamics and kinetics should be used.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, absorption kinetics can dominate over the thermodynamics. For instance, the key role of absorption kinetics over thermodynamics in IL selection for CO 2 capture has been revealed 32–34 . Ignoring kinetics can lead to sub‐optimal or even poor solutions for absorption process development.…”

Section: Introductionmentioning

confidence: 99%

Integrated ionic liquid and rate‐based absorption process design for gas separation: Global optimization using hybrid models

et al. 2021

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A new method for integrated ionic liquid (IL) and absorption process design is proposed where a rigorous rate-based process model is used to incorporate absorption thermodynamics and kinetics. Different types of models including group contribution models and thermodynamic models are employed to predict the process-relevant physical, kinetic, and thermodynamic (gas solubility) properties of ILs. Combining the property models with process models, the integrated IL and process design problem is formulated as an MINLP optimization problem. Unfortunately, due to the model complexity, the problem is prone to convergence failure. To lower the computational difficulty, tractable surrogate models are used to replace the complex thermodynamic models while maintaining the prediction accuracy. This provides an opportunity to find the global optimum for the integrated design problem. A pre-combustion carbon capture case study is provided to demonstrate the applicability of the method. The obtained global optimum saves 14.8% cost compared to the Selexol process.

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Demonstrating the key role of kinetics over thermodynamics in the selection of ionic liquids for CO2 physical absorption

Cited by 65 publications

References 53 publications

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

Process Analysis of Ionic Liquid-Based Blends as H₂S Absorbents: Search for Thermodynamic/Kinetic Synergies

Integrated ionic liquid and rate‐based absorption process design for gas separation: Global optimization using hybrid models

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Demonstrating the key role of kinetics over thermodynamics in the selection of ionic liquids for CO2 physical absorption

Cited by 65 publications

References 53 publications

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

Vapor–Liquid Equilibria and Diffusion Coefficients of Difluoromethane, 1,1,1,2-Tetrafluoroethane, and 2,3,3,3-Tetrafluoropropene in Low-Viscosity Ionic Liquids

Process Analysis of Ionic Liquid-Based Blends as H2S Absorbents: Search for Thermodynamic/Kinetic Synergies

Integrated ionic liquid and rate‐based absorption process design for gas separation: Global optimization using hybrid models

Contact Info

Product

Resources

About

Process Analysis of Ionic Liquid-Based Blends as H₂S Absorbents: Search for Thermodynamic/Kinetic Synergies