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 oC, 29~39 cP at 40 oC) under high capacity (12~18 wt% at 25 oC, 10~17 wt% at 40 oC). 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.