A systematic review on CO2 capture with ionic liquids: Current status and future prospects

Global warming due to the emission of greenhouse gases, especially carbon dioxide (CO2), has a significant effect on the climate change and has become a widespread concern in the recent years. Carbon capture, utilization, and sequestration (CCUS) strategy appears to be effective in decreasing the carbon dioxide level in the atmosphere. Despite a great progress in this field, there are still major limitations in commercialized the CO2 capture methods that rely on absorption phenomena. High capital costs of for the CO2 capture, low absorption and desorption rates (which require large facilities), solvent losses due to evaporation, and the use of corrosive solvents are among main obstructions. Recently, CO2 capture with ionic liquids (ILs) has appreciably attracted researchers' attention. The distinct properties of ILs such as negligible vapor pressure and their affinity to capture the CO2 molecules make them a feasible alternative for currently available solvents including, different amines. This paper covers a brief review of previous engineering and research works on various CO2 capture techniques, the description of CO2 capture process using ILs, mechanisms of the CO2 capture with ILs at molecular level, CO2 and ILs properties, characterization of the CO2/IL systems, impacts of operating and fluids conditions on CO2 absorption capacity by ILs, and CO2 solubility and selectivity in ILs. Moreover, the technical and economic aspects of the CO2 capture with ILs, screening criteria for ILs/CO2 systems, and important results obtained from previous studies will form the last parts of this manuscript. This review offers a proper/systematic guideline that assists researchers and engineers to comprehensively understand and to effectively design the CO2/ILs processes, focusing on the thermodynamic and mass transfer aspects.