Microscopic Structure, Interaction, and Properties of a Guanidinium-Based Ionic Liquid and Its Mixture with CO<sub>2</sub>

Zhang, Xiaochun; Liu, Xiaomin; Yao, Xiaoqian; Zhang, Suojiang

doi:10.1021/ie1025002

Cited by 32 publications

(12 citation statements)

References 52 publications

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“…Another mechanism proposed to explain CO2 solubility in ILs is the presence of a free volume that can accommodate CO2 molecules. There is, however, no agreement on the location of this free volume as two theories have been proposed: (i) on the one hand, it is thought that the free volume is near the alkyl chain of the cation and (ii) on the other hand, some studies showed that the free volume could be located in the space between the cation and anion (Babarao et al, 2011;Zhang et al, 2011;Lei et al, 2014). Despite the uncertainty, the free volume is considered to play a significant role in CO2 solubility.…”

Section: Conventional Ionic Liquidsmentioning

confidence: 99%

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

et al. 2015

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CO2 capture by amine scrubbing, which has a high CO2 capture capacity and a rapid reaction rate, is the most employed and investigated approach to date. There are a number of recent large-scale demonstrations including the Boundary Dam Carbon Capture Project by SaskPower in Canada that have reported successful implementations of aqueous amine solvent in CO2 capture from flue gases. The findings from these demonstrations will significantly advance the field of CO2 capture in the coming years. While the latest efforts in aqueous amine solvents are exciting and promising, there are still several drawbacks to amine-based CO2 capture solvents including high volatility and corrosiveness of the amine solutions as well as the high parasitic energy penalty during the solvent regeneration step. Thus, in a parallel effort, alternative CO2 capture solvents, which are often anhydrous, have been developed as the third-generation CO2 capture solvents. These novel classes of liquid materials include ionic liquids, CO2triggered switchable solvents (i.e., CO2-binding organic liquids, reversible ionic liquids), and nanoparticle organic hybrid materials. This paper provides a review of these various anhydrous solvents and their potential for CO2 capture. Particular attention is given to the mechanisms of CO2 absorption in these solvents, their regeneration and their processability-especially taking into account their viscosity. While not intended to provide a complete coverage of the existing literature, this review aims at pointing the major findings reported for these new classes of CO2 capture media.

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Section: Conventional Ionic Liquidsmentioning

confidence: 99%

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

et al. 2015

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“…Fluorination of the cation or anion, ,, along with the introduction of ether and carbonyl groups in the cation, has also yielded increased physical solubility of CO 2 . Regarding anions, the following trend has been observed for the solubility of CO 2 in ionic liquids for a given cation: nitrate [NO 3 ] − < thiocyanate [SCN] − < methylsulfate [MeSO 4 ] − < tetraborofluorate [BF 4 ] − < trifluoromethanesulfonate [OTF] − < trifluoroacetate [TFA] − < [PF 6 ] − < bis(trifluoromethanesulfonyl)imide [NTf 2 ] − < perfluoroheptaneacetate [C 7 F 15 COO] − < tris(pentafluoroethyl)trifluorophosphate [eFAP] − < tris(pentafluorobutyl)trifluorophosphate [bFAP] − . − An alternative theory for the high solubility of CO 2 in ionic liquids was proposed based on the results obtained from molecular dynamics (MD) and quantum mechanical calculations. − These studies aimed to explain the gas solubility in terms of the existence of free volume in the ionic liquidsthe void space between ions. Typically, fluorinated ionic liquids are characterized by weaker cation–anion interactions and possess high molar volumes and free volume, both favorable for CO 2 solubility.…”

Section: Introductionmentioning

confidence: 99%

Molecular Origins of the Apparent Ideal CO₂ Solubilities in Binary Ionic Liquid Mixtures

Kapoor

Shah

2018

J. Phys. Chem. B

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Molecular dynamics (MD) simulations were conducted to investigate the variation of Henry’s constant of CO2 in two binary ionic liquid mixtures. One of the mixtures is formed by pairing the cation 1-n-butyl-3-methylimidazolium [C4mim]+ with chloride Cl– and methylsulfate [MeSO4]−, whereas the other binary ionic liquid mixture contains [C4mim]+ in combination with the anions Cl– and bis(trifluoromethanesulfonyl)imide [NTf2]−. In order to provide a microscopic understanding of the behavior of the Henry’s constant with the anion composition, MD simulations of ionic liquid mixtures with and without CO2 saturation were performed at 353 K and 10 bar. Our calculations indicate that the Henry’s constant for CO2 follows a highly nonlinear, although expected based on ideal solubility, trend with respect to the increasing concentration of Cl– in [C4mim]Cl x [NTf2]1–x , whereas the Henry’s constant is almost independent of the anion composition in the [C4mim]Cl x [MeSO4]1–x system. Structural analyses presented in terms of radial, spatial, and angular distribution functions point to significant structural reorganization of the anions around cations in the [C4mim]Cl x [NTf2]1–x system. Because of the weakly coordinating ability of the [NTf2]− anion with the cation, the [NTf2]− anion is displaced from the equatorial plane of the imidazolium ring and occupies positions above and below the ring, enabling enhanced CO2–[NTf2]− association. The rearrangement also weakens the cation π–π interactions, resulting in the formation of increased local free volume aiding CO2 accommodation. On the contrary, such structural transitions are absent in the [C4mim]Cl x [MeSO4]1–x mixture system.

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“…Furthermore, CO 2 solubility has been explained in terms of molar volume or free volume of ILs with the help of molecular dynamic simulation, quantum, or simple calculations. The theory of free volume believes loosely held or weak ionic interactions create a space that is favorable for CO 2 solubility. ,− …”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide Solubility in Phosphonium-, Ammonium-, Sulfonyl-, and Pyrrolidinium-Based Ionic Liquids and their Mixtures at Moderate Pressures up to 10 bar

et al. 2017

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Carbon dioxide solubility in four ionic liquids (ILs) of different families with different cationic−anionic groups (tributylmethylphosphonium formate, butyltrimethylammonium bis(trifluoromethyl sulfonyl) imide, 1-methyl-1-propylpyrrolidinium dicyanamide, and 1ethyl-3-methylimidazolium acetate) at temperature of 298 K and a pressure range from vacuum to 10 bar were studied in this work using state of the art gravimetric sorption experiments. This work provides insight information regarding CO 2 solubility for IL−IL mixing effect pressures up to 10 bar and at 298 K. Density values were used to calculate molar volume of ionic liquids for further discussions on CO 2 solubility-molar volume relationship. Noticeably higher CO 2 solubility with IL−IL hybridized systems of different family is opening a new window for research on a molecular level by simulations and intellectually designed ILs. Chemisorption behavior has been observed for the ILs that contain acetate-based anions in the structure and relevant discussion is included in this work.

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Microscopic Structure, Interaction, and Properties of a Guanidinium-Based Ionic Liquid and Its Mixture with CO₂

Cited by 32 publications

References 52 publications

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

Molecular Origins of the Apparent Ideal CO₂ Solubilities in Binary Ionic Liquid Mixtures

Carbon Dioxide Solubility in Phosphonium-, Ammonium-, Sulfonyl-, and Pyrrolidinium-Based Ionic Liquids and their Mixtures at Moderate Pressures up to 10 bar

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Microscopic Structure, Interaction, and Properties of a Guanidinium-Based Ionic Liquid and Its Mixture with CO2

Cited by 32 publications

References 52 publications

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

Molecular Origins of the Apparent Ideal CO2 Solubilities in Binary Ionic Liquid Mixtures

Carbon Dioxide Solubility in Phosphonium-, Ammonium-, Sulfonyl-, and Pyrrolidinium-Based Ionic Liquids and their Mixtures at Moderate Pressures up to 10 bar

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Product

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Microscopic Structure, Interaction, and Properties of a Guanidinium-Based Ionic Liquid and Its Mixture with CO₂

Molecular Origins of the Apparent Ideal CO₂ Solubilities in Binary Ionic Liquid Mixtures