Systems Analysis of Physical Absorption of CO₂ in Ionic Liquids for Pre-Combustion Carbon Capture

This study develops an integrated technical and economic modeling framework to investigate the feasibility of ionic liquids (ILs) for precombustion carbon capture. The IL 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is modeled as a potential physical solvent for CO₂ capture at integrated gasification combined cycle (IGCC) power plants. The analysis reveals that the energy penalty of the IL-based capture system comes mainly from the process and product streams compression and solvent pumping, while the major capital cost components are the compressors and absorbers. On the basis of the plant-level analysis, the cost of CO₂ avoided by the IL-based capture and storage system is estimated to be $63 per tonne of CO₂. Technical and economic comparisons between IL- and Selexol-based capture systems at the plant level show that an IL-based system could be a feasible option for CO₂ capture. Improving the CO₂ solubility of ILs can simplify the capture process configuration and lower the process energy and cost penalties to further enhance the viability of this technology.