Determination of cost-effective operating condition for CO₂ capturing using 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid (IL) is considered for CO₂ capturing in a typical absorption/stripper process. The use of ionic liquids is considered to be cost-effective because it requires less energy for solvent recovery compared to other conventional processes. A mathematical model was developed for the process based on Peng-Robinson (PR) equation of state (EoS). The model was validated with experimental data for CO₂ solubility in [BMIM][BF4]. The model is utilized to study the sorbent effect and energy demand for selected operating pressure at specific CO₂ capturing rates. The energy demand is expressed by the vapor-liquid equilibrium temperature necessary to remove the captured CO₂ from the spent solvent in the regeneration step. It is found that low recovery temperature can be achieved at specific pressure combination for the absorber/stripper units. In fact, the temperature requirement is less than that required by the typical monoethanolamine (MEA) solvent. The effect of the CO₂ loading in the sorbent stream on the process performance is also examined