H2S absorption with deep eutectic solvents: Low partial pressure capture and thermodynamic analysis

Abstract In the present work, a series of deep eutectic solvents (DESs) based on organic amine as hydrogen bond acceptors (HBAs), and ethylene glycol (EG) as hydrogen bond donor (HBD) were prepared for the H 2 S absorption. Thermal decomposition temperature, HBA mass ratios, alkalinity and structure effect on absorption behavior were systematically investigated. The reaction mechanism was demonstrated by FT‐IR and 1 H NMR spectroscopy. The reaction equilibrium constants, Henry constant, enthalpy and entropy change were calculated based on the thermodynamic model to reveal the interactions between DESs and H 2 S. It was found that H 2 S absorption capacities of the most of DESs with HBA/HBD mass ratio of 1:4 was close to 1 mol/mol at 303.15 K and 0.2 bar. The absorption capacity of DESs depends on the alkalinity and structure of HBAs; Additionally, a good linear correlation between the alkalinity of HBA and the absorption equilibrium constant (ln K ) of DESs to H 2 S was found.