Ethanolammonium chloride-glycerol deep eutectic solvents for efficient and reversible absorption of NH3 through multiple hydrogen-bond interaction

Abstract

Efficiently separating NH3 from the exit gas of NH3 synthesis tower has significant economic and environmental benefits, such as improving the NH3 conversion rate and reducing pollution emission. In this study, a series of EtOHACl + Gly deep eutectic solvents (DESs) with numerous hydrogen-bond sites were synthesized. The findings suggest that the use of EtOHACl + Gly DESs can result in both exceptional NH3 absorption capacities and superior selectivities. EtOHACl + Gly (1:2) has the NH3 capacities of up to 12.39 mol/kg at 298.2 K and 105.5 kPa, while its N2 and H2 capacities are negligible. Additionally, the absorbed NH3 can be easily released by heating and reducing pressure, and the NH3 capacities remain stable after undergoing six cycles. The study also examined the interaction mechanism of EtOHACl + Gly DESs for the NH3 separation, utilizing spectral characterizations, quantum chemistry calculations and molecular dynamics simulations.