Imidazolium-based ionic liquids with cyano groups for the selective absorption of ethane and ethylene

Leila Moura, Walid Darwich, Catherine C. Santini, Margarida F. Costa Gomes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

The density, viscosity and absorption of ethane and ethylene were determined experimentally, as a function of temperature and at atmospheric pressure, in different imidazolium-based ionic liquids: 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)imide, [C1C8Im][NTf2], 1-methyl-3-(propyn-3-yl)imidazolium bis(trifluoromethanesulfonyl)imide [C1(C2H2CH)Im][NTf2], 1-(3-cyanopropyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C1C3CNIm][NTf2], 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide [C1C3CNIm][DCA], 1-butyl-3-methylimidazolium dicyanamide, [C1C4Im][DCA] and 1-butyl-3-methylimidazolium methylphosphite [C1C4Im][C1HPO3]. The densities and viscosities of the ionic liquids studied are strongly dependent on the anion and, at 313K, follow the order: [C1(C2H2CH)Im][NTf2]>[C1C3CNIm][NTf2]>[C1C3CNIm][DCA]>[C1C4Im][C1HO3]>[C1C4Im][DCA] and [C1C3CNIm][NTf2]>[C1C3CNIm][DCA]>[C1C4Im][C1HPO3]>[C1(C2H2CH)Im][NTf2]>[C1C4Im][DCA], respectively. The differences in the molecular structures of the ionic liquids allowed the identification of the influence of increasing the alkyl side chain of the cation, of the presence of unsaturated CC and CN bonds on the alkyl side chain of the cation and finally of a phosphite based anion on the selective absorption of ethane and ethylene. The solubility of ethylene is higher than that of ethane in the ionic liquids studied and varies from 18.41×10-3 in [C1C8Im][NTf2] at 303.17K to 1.603×10-3 in [C1C4Im][DCA] at 343.61K. The introduction of the different functional groups leads to a decrease on the gas absorption compared with that of [C1C8Im][NTf2] but to an increase of the ideal separation selectivity of ethane and ethylene.

Original languageEnglish
Pages (from-to)755-762
Number of pages8
JournalChemical Engineering Journal
Volume280
Early online date17 Jun 2015
DOIs
Publication statusPublished - 04 Jul 2015

Keywords

  • Ethane
  • Ethylene
  • Gas separation
  • Ionic liquids

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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