Separation of CO2 and H2S Using Room-Temperature Ionic Liquid [bmim][MeSO4]

We have developed a ternary equation of state (EOS) model for the CO2/H2S/1-butyl-3-methylimidazolium methylsulfate ([bmim][MeSO4]) system to understand separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a modified RK (Redlich−Kwong) EOS, with empirical interaction parameters for each binary system. The interaction parameters have been determined using our measured VLE (vapor−liquid equilibrium) data for H2S/[bmim][MeSO4] and literature data for CO2/[bmim][MeSO4] and CO2/H2S. Due to limited VLE data for H2S/[bmim][MeSO4], we have also used VLLE (vapor−liquid−liquid equilibrium) measurements to construct the EOS model. The VLLE for H2S/[bmim][MeSO4] is highly asymmetric with a narrow (mole fraction H2S between 0.97 and 0.99) LLE gap which is the first such case reported in the literature and exhibits Type V phase behavior, according to the classification of van Konynenburg and Scott. The validity of the ternary EOS model has been checked by conducting VLE ...