Mechanism study on H2S capture of ionic liquids based on triethylenetetramine blended with ethylene glycol

Amino-functionalized ILs are promising absorbents for H2S. In this work, three triethylenetetramine functionalized ionic liquids (TETAH-ILs) were synthesized and applied to construct mixture solutions with ethylene glycol (EG). Among [TETAH][HCOO]-EG, [TETAH][BF4]-EG and [TETAH]Br-EG absorbents, [TETAH][BF4]-EG showed the greatest H2S absorption capacity. In addition, a series of factors, such as IL molar fraction, absorption temperature and H2S flow rate, were also investigated to evaluate the effects on absorption performance of [TETAH][BF4]-EG absorbent. The results showed that the 10 % [TETAH] [BF4]-EG mixed solution has excellent absorption capacity (1.128 mol H2S/mol IL) at 303.15 K and 100 mL/min. In addition, the absorbent could remain 75.12 % absorption capacity after four regenerations, which displayed potential for reversibility. Furthermore, the mechanism of H2S absorption by TETAH-ILs was proposed by combining FT-IR and H-1 NMR characterization and electron density topology analysis. Furthermore, the mechanism of H2S absorption by TETAH-ILs was proposed by combining FT-IR and H-1 NMR characterization and theoretical calculation. The results revealed that the mechanism of H2S absorption by TETAH-ILs was the formation of IL-H2S complexes through a series of hydrogen bonds. (C) 2022 Published by Elsevier B.V.

Automated summary

Amino-functionalized ILs are promising absorbents for H2S, and in this study, three triethylenetetramine functionalized ionic liquids (TETAH-ILs) were synthesized and mixed with ethylene glycol (EG) to form solutions. Among the [TETAH][HCOO]-EG, [TETAH][BF4]-EG, and [TETAH]Br-EG absorbents, [TETAH][BF4]-EG exhibited the highest H2S absorption capacity. Various factors, including IL molar fraction, absorption temperature, and H2S flow rate, were investigated to evaluate their effects on the absorption performance of [TETAH][BF4]-EG. The results showed that the 10% [TETAH][BF4]-EG mixed solution had excellent absorption capacity at 303.15 K and 100 mL/min. Additionally, the absorbent retained 75.12% absorption capacity after four regenerations, indicating its potential for reversibility. The mechanism of H2S absorption by TETAH-ILs was proposed based on FT-IR and H-1 NMR characterization and theoretical calculation, revealing the formation of IL-H2S complexes through a series of hydrogen bonds.