Glycerol-Derived Water-Lean Amines for Post-Combustion CO₂ Capture: The Improvement in Capacity and Viscosity

Water-lean absorbents are regarded as a new generation of post-combustion CO₂ capture technology that could significantly relieve those drawbacks posed by traditional aqueous alkanolamines. However, the exponential increase in viscosity during CO₂ absorption remains an urgent issue that needs to be resolved before their practical deployment. In this work, novel water-lean amines based on biomass glycerol have been devised as single-component CO₂ absorbents with low viscosity (79~110 cP at 25  $$ , 29~39 cP at 40  $$ ) under high capacity (12~18 wt % at 25  $$ , 10~17 wt % at 40  $$ ). The captured CO₂ could be smoothly released by thermal desorption. Results from preliminary stability test and 10 absorption-desorption cycles showed that such non-aqueous absorbents had significant structural toughness as well as reusability. Spectroscopic measurements including ¹³C NMR and in situ FTIR were performed to gain mechanistic insights by monitoring the entire CO₂ absorption and desorption process, while DSC, VLE and DFT calculations provided rational interpretation for reaction kinetics and thermodynamics. The synergistic promotion of glycerol ether group on both CO₂ chemical and physical absorption was also verified under high pressure conditions.