CO2 Capture Mechanism by Deep Eutectic Solvents Formed by Choline Prolinate and Ethylene Glycol.

The choline prolinate ([Ch][Pro]) as a hydrogen bond acceptor and ethylene glycol (EG) as a hydrogen bond donor are both used to synthesize the deep eutectic solvents (DESs) [Ch][Pro]-EG to capture CO2. The CO2 capacity of [Ch][Pro]-EG is determined, and the nuclear magnetic resonance (NMR) and infrared (IR) spectrum are used to investigate the CO2 capture mechanism. The results indicate that CO2 reacts with both the amino group of [Pro]- anion and the hydroxyl group of EG, and the mechanism found in this work is different from that reported in the literature for the [Ch][Pro]-EG DESs.