Novel Amino-Functionalized Ionic Liquid/Organic Solvent with Low Viscosity for CO Capture.

To achieve low regeneration energy consumption and viscosity, a novel amino-functionalized ionic liquid [TEPAH][2-MI] combined with organic solvents has been proposed for CO capture in this work. The results demonstrated that the absorption loading of [TEPAH][2-MI]/-propanol (NPA)/ethylene glycol (EG) was 1.72 mol·mol (28 wt %, 257 g·L), which was much higher than that of monoethanolamine/water, and the regeneration efficiency was maintained at 90.7% after the fifth regeneration cycle. The viscosities of the solution were only 3.66 and 7.65 mPa·s before and after absorption, respectively, which were significantly lower than those of traditional nonaqueous absorbents. The reaction mechanism investigated via C NMR and quantum calculations summarized that CO first reacted with the amino group of [TEPAH] to form the carbamates through the zwitterion formation and protonation process, while CO reacted with the N atom of [2-MI] to directly form the carbamate. Then, some of them further reacted with NPA and EG to form the carbonates. Moreover, N and N tautomers of [TEPAH][2-MI] could convert into each other continuously when CO was absorbed. During CO desorption, the carbamates and carbonates reacted with AFILH to decompose and released CO directly.