Phase-change absorption has shown a promising application prospect for acid gas capture because only the gas-rich phase needs to be transported to the stripper for recovery, which could drastically reduce the energy consumption of the regeneration process. In this study, the liquid–liquid phase-change behavior of a new recyclable ternary system, composed of 1,5-diazabicyclo[4.3.0]­non-5-ene (DBN)/hexadecane/hexanol, was evaluated for capturing H2S. The absorption adduct was the [DBNH]+[SH]− salt, and the cause of the phase change was attributed to the polarity difference between the upper and lower phases. Furthermore, considering that only the lower phase needed to be heated for regeneration, the gravimetric absorption capacity was calculated to be 0.205 g H2S/g lower phase at 1 bar and 293.15 K. To the best of our knowledge, this is the largest gravimetric absorption capacity for H2S capture obtained to date. Additionally, when the absorption reached equilibrium, DBN, hexanol, and H2S were concentrated in the lower phase, while hexadecane mostly remained in the upper phase. The DBN/hexadecane/hexanol system showed that the benign desulfurization efficiency was nearly 100% under the condition that the molar ratio of H2S gas to DBN is not more than 0.6 mol/mol. The cyclic absorption experiments showed that the H2S gas could be easily released by bubbling N2 at 80 °C, which indicated the low energy requirement for the regeneration of the absorbent.

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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 (lnK) of DESs to H 2 S was found.

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 H2S 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 1H 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 H2S. It is found that H2S absorption capacities of the most of DESs with HBA/HBD mass ratio of 1:4 were close to 1mol /mol at 303.15K 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 (lnK) of DESs to H2S was found