Amine-functionalized ionic liquids for CO capture.

In petroleum industry, the release of more and more carbon dioxide (CO) brings greenhouse effect and even results in climate change, leading CO capture to become an urgent issue. To design ideal and effective absorbent, interaction mechanism for CO capture was systematically investigated in a series of imidazolium-based ionic liquids (ILs). The potential effects of alkyl side chain, electron-philic halogen (F, Cl, Br) atom(s), electron-denoting groups OH and NH (bound on cation or/and anion), and water solvent were disclosed on CO capture using CAM-B3LYP functional with SMD-GIL solvation model, and the most potential green effective absorbent was predicted. This work provides an explicit idea and theoretical basis about the design of desired IL for CO capture. Graphical abstract In present work, no/halogen/amino/hydroxy-functionalized imidazolium tetrafluoroborate ILs were studied for CO absorption at the CAM-B3LYP/6-311++G** level of theory by SMD-GIL solvation model. NH is more potent group in absorbing CO than halogen and OH, and its number is proportional to the adsorption capacity of IL. A potentially high-capacity CO absorbent with four NH groups was predicted. In addition, the mixture of water could further enhance such chemical absorption by lowering the activation energy barriers and viscosity of IL.