Efficient CO₂ capture by tertiary amine-functionalized ionic liquids through Li,₊-stabilized zwitterionic adduct formation

Highly efficient CO₂ absorption was realized through formation of zwitterionic adducts, combining synthetic strategies to ionic liquids (ILs) and coordination. The essence of our strategy is to make use of multidentate cation coordination between Li,₊ and an organic base. Also PEG-functionalized organic bases were employed to enhance the CO ₂-philicity. The ILs were reacted with CO₂ to form the zwitterionic adduct. Coordination effects between various lithium salts and neutral ligands, as well as the CO₂ capacity of the chelated ILs obtained were investigated. For example, the CO₂ capacity of PEG150MeBu2N increased steadily from 0.10 to 0.66 (mol CO₂ absorbed per mol of base) through the formation of zwitterionic adducts being stabilized by Li,₊.