Capture of CO2 by Ionic Liquids

Since CO2 is one of the most important greenhouse gases, the research and development in the carbon capture have long been the focus of many academic and industrial studies. Ionic liquids have a number of unique properties, such as no-volatility, non-flammation, recyclability, high thermal stability, strong solubility capacity, and the tunability of molecular structures and physicochemical properties. Thus they have promising application in absorption and separation of CO2. In this paper, the recent progress in the CO2 capture by using regular ionic liquids, task-specific ionic liquids, supported ionic-liquids membranes, polymerized ionic liquids and the mixtures of ionic liquids with some molecular solvents have been reviewed. The effects of cationic structure, anionic property, alkyl chain length, functionalization of both the cations and the anions, characteristics of the supported membranes, the polymerized degree of ionic liquids, temperature and pressure of the systems on the selective capture of CO2 are discussed in detail. The possible mechanisms for the capture and selective separation of CO2 are also demonstrated. Furthermore, the advantages and disadvantages have been analyzed for the above mentioned ionic liquids systems in the capture of CO2. The future development in this area is prospected, and several important issues are suggested for the further work.