Modelling solubility of CO2 and hydrocarbon gas mixture in ionic liquid ([emim][FAP]) using ASPEN Plus

In the present study bubble point pressure, solubility and selectivity of CO2 and Hydrocarbon mixture with [emim][FAP] as an ionic liquid has been studied by ASPEN Plus simulations. Ternary systems considered were CO2, [emim][FAP] and one of the hydrocarbons (HC) viz., methane, ethane, propane, and butane. Peng Robinson equation of state with quadratic van der Waals (vdW) mixing rule model was chosen to perform the thermodynamic calculations in FLASH3 column. Wide range of temperatures, molar ratios of CO2/HC, and HC/[emim][FAP] were considered for this study. Results showed that, type of hydrocarbon (or carbon chain length) had a dominant effect on the selectivity of CO2 over hydrocarbon. Selectivity of CH4 compared with other hydrocarbons is higher by more than one order of magnitude. Concentration of hydrocarbon in the feed stream of the ternary system is the main deciding factor in addition to temperature in determining the solubility, bubble point pressure and phase transition from two phase liquid system to single liquid phase.