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

Abstract

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.