CO2 capture by carboxylate ionic liquids: fine-tuning the performance by altering hydrogen bonding motifs

Identifier:  imarina:9462734

Handle: https://hdl.handle.net/20.500.11797/imarina9462734

Authors:  Yousefe, Mohammad; Glinska, Katarzyna; Sweeney, Michael; Moura, Leila; Swadzba-Kwasny, Malgorzata; Puga, Alberto

Abstract:
The use of ionic liquids (ILs) for CO2 capture has drawn significant attention due to their tuneable structural design and non-volatility. Among these, carboxylate ionic liquids, particularly in the presence of water as a hydrogen bond donor, show great promise due to their effective chemical sorption mechanism, leading to bicarbonate, and low regeneration energy requirements. The additional presence of hydroxyl groups in their structures is expected to affect both hydrogen bonding network and CO2 capture capacity. This study systematically investigates the role of hydroxyl moieties in tetraalkylammonium cations of carboxylate ionic liquid hydrates on their physicochemical properties and CO2 solubility. The ILs studied are based on the trimethylpropylammonium cation or choline as a hydroxyl-containing analogue, paired with either acetate or propionate. The solubilities of CO2 in each IL at different H2O/IL hydration ratios were determined by a headspace gas chromatography method. The effects of water, in addition to those of cationic hydroxyl, on CO2 capture performance were evaluated. To this end, nuclear magnetic resonance and infrared spectroscopy results are presented and analyzed to propose distinct chemical sorption mechanisms in either scenario.