A review of CO₂ capture by absorption in ionic liquid-based solvents

Concern has increased about climate change caused by carbon dioxide (CO₂) emissions through human activities in recent years. The Intergovernmental Panel on Climate Change predicts a 1.9°C rise in temperature by the year 2100, and this means a reduction in CO₂ is vital for human beings and all other life on earth. Therefore, there is an urgent need for the development of CO₂ separation processes to mitigate this potential problem. Post-combustion power plants can employ various types of separation technology. Among them, chemical absorption using aqueous amine is more developed and more reliable. The conventional solvents used in the chemical absorption process together with the use of absorbents, ionic liquid, alkanolamines and their blended aqueous solutions are reviewed in this work. Different ionic liquid-based solvents for CO₂ absorption and the most effective parameters on mass transfer phenomena between CO₂ and solvent are reviewed. The major concerns for this technology, including the physiochemical properties of ionic liquid-based solvents, Henry's constant and mass transfer coefficient and their correlations, and various factors for effective CO₂ absorption, are addressed.