Improvement of the CO2 Absorption Performance Using Ionic Liquid [NH(2)emim][BF4] and [emim][BF4]/[bmim][BF4] Mixtures

Functional ionic liquids (ILs) have potential advantages in reducing CO2 emissions when applied for CO2 absorption. However, the higher viscosity of functional ILs greatly affects the CO2 absorption separation process. To improve the absorption performance, a functional IL [NH(2)e-mim][BF4] was synthesized and mixed with low-viscosity conventional ILs [emim][BF4]/[bmim][BF4] based on their respective advantages in terms of CO2 reduction, and the CO, absorption effect and regeneration performance of the binary ILs were investigated. {[NH(2)e-mim][BF4] + [emim][BF4]/[bmim][BF4]} showed better performance when the mole fraction of [NH(2)e-mim][BF4] (X[NH2e-mim][BF4]) was 0.4, and the CO2 absorption performance reduced with the increase in the temperature. Density and viscosity of the binary rose with the increase of X[NH2e-mim][BF4] and decrease in temperature. The optimal regeneration temperature was approximately 353.15 K when X[NH2e-mim][BF4] was 0.4 in 0.1 MPa. During five cycles of absorption and regeneration, CO2 absorption capacity of {[NH(2)e-mim][BF4] + [emim][BF4]/[bmim][BF4]} was maintained at 75-85% of the first absorption capacity. Moreover, the quality and density changed slightly, and viscosity showed a 5-10% increase in each loop. Thus, the mixed system had an effective regeneration performance.