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Title: A Computational Study of Dicationic Ionic Liquids/CO 2 Interfaces

Abstract

Our recent studies on CO 2 capture using dicationic ionic liquids (DILs) demonstrated that DILs are promising absorbents for CO 2 uptake especially compared with monocationic ionic liquids (MILs) analogues, in which each cation carries single positive charge in contrast to two unit charges of a dication. However, DILs/CO 2 interfacial properties at the molecular level are still unknown. This work investigated the CO 2 absorption properties of representative DILs, 1-alkyl-3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [C n(mim) 2](Tf 2N) 2 (n = 3, 6, 12), using molecular dynamics (MD) simulations. The higher interfacial CO 2 density at DIL than that at MIL interfaces suggests the increased CO 2 interaction sites in DILs. The interfacial CO 2 density also exhibits an alkyl chain length dependence which decreases with the elongation of alkyl chain and proportionally correlates with the content of fluorine atoms at interfaces. Different alkyl chain orientations in DILs were illustrated in contrast to those of MILs; both DILs and CO2 inside DILs exhibit lower diffusivity than MILs, in agreement with the stronger cation–anion binding energy of DILs. Moreover, DILs show a lower H2O and N2 uptake from flue gas compared with MILs, implicating the higher CO 2/H 2O and CO 2/N 2more » selectivity.« less

Authors:
 [1];  [1];  [1];  [2]
  1. Huazhong Univ. of Science and Technology, Wuhan (China). School of Energy and Power Engineering
  2. Vanderbilt Univ., Nashville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1265425
DOE Contract Number:  
AC05-00OR22725; AC02- 05CH11231; 2014CFA089; 51406060
Resource Type:
Journal Article
Resource Relation:
Journal Name: Langmuir; Journal Volume: 31; Journal Issue: 8
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 97 MATHEMATICS AND COMPUTING

Citation Formats

Li, Song, Zhao, Wei, Feng, Guang, and Cummings, Peter T. A Computational Study of Dicationic Ionic Liquids/CO2 Interfaces. United States: N. p., 2015. Web. doi:10.1021/la5048563.
Li, Song, Zhao, Wei, Feng, Guang, & Cummings, Peter T. A Computational Study of Dicationic Ionic Liquids/CO2 Interfaces. United States. doi:10.1021/la5048563.
Li, Song, Zhao, Wei, Feng, Guang, and Cummings, Peter T. Mon . "A Computational Study of Dicationic Ionic Liquids/CO2 Interfaces". United States. doi:10.1021/la5048563.
@article{osti_1265425,
title = {A Computational Study of Dicationic Ionic Liquids/CO2 Interfaces},
author = {Li, Song and Zhao, Wei and Feng, Guang and Cummings, Peter T.},
abstractNote = {Our recent studies on CO2 capture using dicationic ionic liquids (DILs) demonstrated that DILs are promising absorbents for CO2 uptake especially compared with monocationic ionic liquids (MILs) analogues, in which each cation carries single positive charge in contrast to two unit charges of a dication. However, DILs/CO2 interfacial properties at the molecular level are still unknown. This work investigated the CO2 absorption properties of representative DILs, 1-alkyl-3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [Cn(mim)2](Tf2N)2 (n = 3, 6, 12), using molecular dynamics (MD) simulations. The higher interfacial CO2 density at DIL than that at MIL interfaces suggests the increased CO2 interaction sites in DILs. The interfacial CO2 density also exhibits an alkyl chain length dependence which decreases with the elongation of alkyl chain and proportionally correlates with the content of fluorine atoms at interfaces. Different alkyl chain orientations in DILs were illustrated in contrast to those of MILs; both DILs and CO2 inside DILs exhibit lower diffusivity than MILs, in agreement with the stronger cation–anion binding energy of DILs. Moreover, DILs show a lower H2O and N2 uptake from flue gas compared with MILs, implicating the higher CO2/H2O and CO2/N2 selectivity.},
doi = {10.1021/la5048563},
journal = {Langmuir},
number = 8,
volume = 31,
place = {United States},
year = {Mon Feb 09 00:00:00 EST 2015},
month = {Mon Feb 09 00:00:00 EST 2015}
}