Thermodynamic analysis of highly efficient H 2 S absorption in diamine‐ethylene glycol blends

Abstract 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.