Thermodynamic analysis of highly efficient H2S absorption in diamine-ethylene glycol blends

The efficient removal of hydrogen sulfide (H 2 S) is crucial for clean energy and environmental protection, with amine-based absorption being the mainstream due to its cost-effectiveness and high efficiency. This work designed eight hybrid absorbents using organic diamines and ethylene glycol (EG). Absorption capacity measurements revealed that at 303.15 K and 1 bar, short-chain diamines exhibited ~1 mol/mol, while long-chain ones reached ~2 mol/mol. Notably, the 1,4-butanediamine-EG reached a remarkable capacity of 1.7 mol/mol at 0.2 bar, and the N , N , N ′, N ′-tetramethyl-1,6-hexanediamine-EG reached 2.06 mol/mol at 1 bar. Absorption capacity positively correlated with diamine chain length, and primary/secondary amines outperformed tertiary amines at low partial pressures. A reaction equilibrium thermodynamic model was established to verify the structure–capacity relationship via parameters like equilibrium constant K . The selectivity of H 2 S/CO 2 was studied. This provides theoretical guidance for H 2 S absorbent design and industrial applications.