We have developed a ternary equation of state (EOS) model for the CO2/H2S/1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system in order to understand the separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical interaction parameters for each binary system. These interaction parameters have been determined using our previously measured VLE (vapor liquid equilibrium) data for CO2/[bmim][PF6] and literature data for H2S/[bmim][PF6] and CO2/H2S. VLLE (vapor liquid liquid equilibrium) measurements have been made and validate EOS model predictions which suggest that the CO2/[bmim][PF6] and H2S/[bmim][PF6] systems are Type V phase behavior, according to the classification of van Konynenburg and Scott. The validity of the ternary EOS model calculations has also been checked by conducting VLE experiments for the CO2/H2S/[bmim][PF6] system. With this EOS model, isothermal ternary phase diagrams and solubility (VLE) behavior have been calculated for various (T, P, and feed compositions) conditions. The CO2/H2S gas selectivity is nearly independent of the amount of ionic liquid addition and ranged from about 3.2 to 4.0. For large CO2/H2S mole ratios (9/1) at 298.15 K, the addition of the ionic liquid increases the CO2/H2S gas selectivity from about 1.2 to 3.7. For high temperature (333.15 K) and high CO2/H2S feed ratios, the addition of the ionic liquid provides the only means of separation because no VLE exists for the CO2/H2S binary system without the ionic liquid.
Compounds
#
Formula
Name
1
H2S
hydrogen sulfide
2
CO2
carbon dioxide
3
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.