Amine-functionalized ionic liquids for CO₂ capture

In petroleum industry, the release of more and more carbon dioxide (CO₂) brings greenhouse effect and even results in climate change, leading CO₂ capture to become an urgent issue. To design ideal and effective absorbent, interaction mechanism for CO₂ 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 NH₂ (bound on cation or/and anion), and water solvent were disclosed on CO₂ 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 CO₂ capture. Graphical abstract In present work, no/halogen/amino/hydroxy-functionalized imidazolium tetrafluoroborate ILs were studied for CO₂ absorption at the CAM-B3LYP/6-311++G** level of theory by SMD-GIL solvation model. NH₂ is more potent group in absorbing CO₂ than halogen and OH, and its number is proportional to the adsorption capacity of IL. A potentially high-capacity CO₂ absorbent with four NH₂ 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.