Deep eutectic solvents composed of bio-phenol-derived superbase ionic liquids and ethylene glycol for CO2 capture

Deep eutectic solvents (DESs) formed by bio-phenol-derived superbase ionic liquids (ILs) and ethylene glycol (EG) exhibit a high CO2 capacity, up to 1.0 mol CO2/mol DESs, which is much better than those of the parent ILs. Surprisingly, mechanism results indicate that CO2 reacts with EG, but doesn’t react with phenolic anions in the solvent, which is different from other DESs formed by superbase ILs and EG. The reaction pathway between CO2 and DESs used in this work may include two steps. The first step is the acid–base reaction between the phenolic anion and EG, which forms HO–CH2–CH2–O−, and then CO2 is attached to the anion HO–CH2–CH2–O− to form a carbonate species.