DBU-Based Protic Ionic Liquids for CO₂ Capture

The applications of the novel anion-functionalized protic ionic liquid (ILs), prepared from superbase 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU) with imidazole, in the CO₂ absorption have been investigated. It has been detected that this ionic liquid can reversibly capture about 1 mol of CO₂ per mole ionic liquid. In addition, the influence of temperature, pressure, water, and substituent of anions has been uncovered. The capture of CO₂ was significantly affected by the substituents in imidazole-based anion, suggesting that electric-charge distribution in imidazole ring system can play an important role in determining the reaction of ILs with CO₂.