Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

Viscosity of Imidazolium-Based Ionic Liquids at Elevated Pressures: Cation and Anion Effects

Ahosseini, A.[Azita], Scurto, A. M.[Aaron M.]
Int. J. Thermophys. 2008, 29, 4, 1222-1243
ABSTRACT
The viscosity of imidazolium-based ionic liquids with four different cations and three different anions was measured to pressures of 126 MPa and at three temperatures (298.15 K, 323.15 K, and 343.15 K). The high-pressure viscosity of 1-ethyl-3-methylimidazolium ([EMIm]), 1-n-hexyl-3-methylimidazolium ([HMIm]), and 1-n-decyl-3-methylimidazolium ([DMIm]) cations with a common anion, bis(trifluoromethylsulfonyl)imide ([Tf2N]) was measured to determine the alkyl-chain length effect of the cation. An increase in the alkyl-chain length increased the viscosity at elevated pressures. [DMIm] exhibited a larger nonlinear increase with pressure over the shorter alkyl substituents. Anion effects were investigated with [HMIm] as a common cation and anions of [Tf2N], hexafluorophosphate ([PF6]), and tetrafluoroborate ([BF4]). [HMIm][PF6], with the highest viscosity, demonstrated a very nonlinear pressure dependence even at relatively moderate pressures (to 30 MPa), similar to the results for [BMIm][PF6]. A combined Litovitz and Tait equation was utilized to describe the viscosity of the ionic liquids with pressure and temperature and demonstrated good correlation with the experimental data.
Compounds
# Formula Name
1 C8H11F6N3O4S2 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide
2 C12H19F6N3O4S2 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide
3 C16H27F6N3O4S2 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide
4 C10H19BF4N2 1-hexyl-3-methylimidazolium tetrafluoroborate
5 C10H19F6N2P 1-hexyl-3-methylimidazolium hexafluorophosphate
6 C8H15F6N2P 1-butyl-3-methylimidazolium hexafluorophosphate
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
  • 1
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Cone and plate viscometry
  • 1
  • POMD
  • 1
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 3
  • POMD
  • 1
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 33
  • POMD
  • 2
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Cone and plate viscometry
  • 1
  • POMD
  • 2
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 3
  • POMD
  • 2
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 33
  • POMD
  • 3
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Cone and plate viscometry
  • 1
  • POMD
  • 3
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 3
  • POMD
  • 3
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 33
  • POMD
  • 4
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Cone and plate viscometry
  • 1
  • POMD
  • 4
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 3
  • POMD
  • 4
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 33
  • POMD
  • 5
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Cone and plate viscometry
  • 1
  • POMD
  • 5
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 3
  • POMD
  • 5
  • Viscosity, Pa*s ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Moving piston method
  • 31
  • POMD
  • 6
  • Viscosity, Pa*s ; Liquid
  • Pressure, kPa; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Moving piston method
  • 9