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Indexed by:期刊论文

Date of Publication:2019-03-04

Journal:CHEMICAL ENGINEERING COMMUNICATIONS

Included Journals:SCIE、EI

Volume:206

Issue:3

Page Number:301-317

ISSN No.:0098-6445

Key Words:gamma-Alumina nanopore; Confinement effect; Ionic liquids; Molecular dynamics; Support ionic liquid membranes

Abstract:CO2 permeation through imidazolium-based ionic liquids (ILs, [BMIM][Ac], [EMIM][Ac], [OMIM][Ac], [BMIM][BF4], and [BMIM][PF6]) confined in 1.0, 2.0, and 3.5 nm gamma-alumina pores was investigated using molecular dynamics simulation. It was found that the nanopore confinement effect influenced the structure of confined ILs greatly, resulting in a layered structure and anisotropic orientation of ILs. In the center of 2.0-nm pore, the long alkyl chain of [BMIM](+) tended to be parallel to the wall, providing a straight diffusion path benefiting the CO2 permeation. The CO2 diffusion coefficients in confined [EMIM][Ac], [BMIM][Ac], and [OMIM][Ac] were 2.3-4.1, 2.4-6.4, and 14.4-21.7 x 10(-10) m(2) s(-1), respectively. This order was opposite to that in the bulk ILs, because the longer alkyl chain led to a more ordered structure, facilitating CO2 diffusion. In addition, the CO2 solubilities were 445-722 mol m(-3) MPa-1 for the five ILs confined in 1.0 nm pore, which were larger than those in 2.0 and 3.5 nm pores (196-335 mol center dot m(-3) MPa-1), due to the larger free volume. Both parallel orientation of alkyl chain and large free volume could increase the CO2 permeability in confined ILs.