Highly efficient and reversible CO2 capture by imidazolate-based ether-functionalized ionic liquids with a capture transforming process

In this work, several kinds of imidazolate-based ether-functionalized ionic liquids (ILs) were synthesized and used for CO 2 capture. It is note-worthy that IL with [C 6 O 2 mim] + as cation has much smaller molecular weight but similar mole capacity compared with those with [P 66614 ] + , which is usually used as cation for anion-functionalized ILs in the carbon capture process. Among these task functionalized ILs, [C 6 O 2 mim][4-Br-Im] can be a potential candidate for carbon capture. Not only has [C 6 O 2 mim][4-Br-Im] an extremely high CO 2 capacity (more than 1.60   mol CO 2 per mol IL achieved), but also shows high uptake efficiency and recovery capability. In addition, [C 6 O 2 mim][4-Br-Im] has higher thermal stability, higher water stability and lower absorption enthalpy. The mechanism of this carbon capture process was investigated by FT-IR and NMR spectroscopy. Surprisingly, in this process, CO 2 first bound the cations to form zwitterions. When CO 2 was continuously bubbled into ILs, the zwitterions started to dissociate and the anions combined with CO 2 . It is verified that this process is a carbon capture transforming process with the Cationic-drive transforming to Anionic-drive. This work offers a deep understanding of the combination process between CO 2 and imidazolate-based with aprotic heterocyclic anions.