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 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