A Rational Approach to CO2 Capture by Imidazolium Ionic Liquids: Tuning CO2 Solubility by Cation Alkyl Branching.
Branching at the alkyl side chain of the imidazolium cation in ionic liquids (ILs) was evaluated towards its effect on carbon dioxide (CO2 ) solubilization at 10 and 80 bar (1 bar=1×10(5)  Pa). By combining high-pressure NMR spectroscopy measurements with molecular dynamics simulations, a full description of the molecular interactions that take place in the IL-CO2 mixtures can be obtained. The introduction of a methyl group has a significant effect on CO2 solubility in comparison with linear or fluorinated analogues. The differences in CO2 solubility arise from differences in liquid organization caused by structural changes in the cation. ILs with branched cations have similar short-range cation-anion orientations as those in ILs with linear side chains, but present differences in the long-range order. The introduction of CO2 does not cause perturbations in the former and benefits from the differences in the latter. Branching at the cation results in sponge-like ILs with enhanced capabilities for CO2 capture.
REQUIMTE, UCIBIO, LAQV, Dep. Química, Fac. Ciências e Tecnologia, UNL, 2829-516 Caparica (Portugal). marta.corvo@fct.unl.pt.
Marta C
MC
Corvo
REQUIMTE, UCIBIO, LAQV, Dep. Química, Fac. Ciências e Tecnologia, UNL, 2829-516 Caparica (Portugal).
João
J
Sardinha
REQUIMTE, UCIBIO, LAQV, Dep. Química, Fac. Ciências e Tecnologia, UNL, 2829-516 Caparica (Portugal).
Teresa
T
Casimiro
Institute of Chemistry, UFRGS, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil).
Graciane
G
Marin
PUCRS, Fac. Química, BR-90619900 Porto Alegre, RS (Brazil).
Marcus
M
Seferin
PUCRS, Fac. Química, BR-90619900 Porto Alegre, RS (Brazil).
Sandra
S
Einloft
PETROBRAS/CENPES, 21941-915 Rio de Janeiro, R.J. (Brazil).
Sonia C
SC
Menezes
Institute of Chemistry, UFRGS, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil).|School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK).
Jairton
J
Dupont
REQUIMTE, UCIBIO, LAQV, Dep. Química, Fac. Ciências e Tecnologia, UNL, 2829-516 Caparica (Portugal). ejc@fct.unl.pt.
Eurico J
EJ
Cabrita
D000473:Alkanes / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry* / Q000302:isolation & purification; D004058:Diffusion; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D012995:Solubility; D012997:Solvents / Q000737:chemistry
D000473:Alkanes; D007093:Imidazoles; D052578:Ionic Liquids; D012997:Solvents; D002245:Carbon Dioxide
NMR spectroscopy; carbon dioxide fixation; ionic liquids; molecular dynamics; substituent effects