Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Phase behavior of {carbon dioxide + [bmim][Ac]} mixtures

Shiflett, M. B.[Mark B.], Kasprzak, D. J.[Daniel J.], Junk, C. P.[Christopher P.], Yokozeki, A.[Akimichi]
J. Chem. Thermodyn. 2008, 40, 1, 25-31
ABSTRACT
Carbon dioxide solubility {(vapor + liquid) equilibria: VLE} in ionic liquid, 1-butyl-3-methylimidazolium acetate ([bmim][Ac]), has been measured with a gravimetric microbalance at four isotherms about (283, 298, 323, and 348) K up to about 2 MPa. (Vapor + liquid + liquid) equilibria (VLLE: or liquid liquid separations) have also been investigated with a volumetric method used in our previous works, since the present analysis of the VLE data using our equation-of-state model has predicted the VLLE at CO2-rich side solutions. The prediction for the VLLE has been confirmed experimentally. CO2 solubilities at the ionic liquid-rich side show extremely unusual behaviors; CO2 dissolves in the ionic liquid to a great degree, but there is hardly any vapor pressure above these mixtures up to about 20 mol% of CO2. It indicates that CO2 may have formed a non-volatile or very low vapor pressure molecular complex with the ionic liquid. The thermodynamic excess properties (enthalpy, entropy, and Gibbs free energy) of the present system do support such a complex formation. We have conducted several other experiments to investigate the complex formation (or chemical reactions), and conclude that a minor chemical reaction occurs but the complex formation is reversible without much degradation of the ionic liquid.
Compounds
# Formula Name
1 CO2 carbon dioxide
2 C10H18N2O2 1-butyl-3-methylimidazolium acetate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 2
  • Mass density, kg/m3 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Pycnometric method
  • 1
  • POMD
  • 1
  • 2
  • Molar volume, m3/mol ; Liquid mixture 1
  • Temperature, K; Liquid mixture 1
  • Liquid mixture 1
  • Liquid mixture 2
  • Gas
  • Pycnometric method
  • 3
  • POMD
  • 1
  • 2
  • Molar volume, m3/mol ; Liquid mixture 2
  • Temperature, K; Liquid mixture 2
  • Liquid mixture 2
  • Liquid mixture 1
  • Gas
  • Pycnometric method
  • 3
  • POMD
  • 1
  • 2
  • Mole fraction - 1 ; Liquid mixture 1
  • Temperature, K; Liquid mixture 1
  • Liquid mixture 1
  • Liquid mixture 2
  • Gas
  • volumetric method
  • 3
  • POMD
  • 1
  • 2
  • Mole fraction - 1 ; Liquid mixture 2
  • Temperature, K; Liquid mixture 2
  • Liquid mixture 2
  • Liquid mixture 1
  • Gas
  • volumetric method
  • 3
  • POMD
  • 1
  • 2
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Gas
  • gravimetric microbalance
  • 32