Polyoxometalate/Ionic Liquid Desulfurization System for Hydrogen Sulfide Removal from High-Temperature Gas Stream

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Industrial gases at high temperatures often contain harmful hydrogen sulfide (H₂S).
• Effective H₂S removal from such gases is challenging due to extreme conditions.
• Existing desulfurization methods have limitations for high-temperature applications.

Purpose of the Study:

• To develop and evaluate novel polyoxometalate-ionic liquid systems for high-temperature H₂S removal.
• To identify the optimal combination of polyoxometalate and ionic liquid for efficient and regenerable desulfurization.
• To elucidate the mechanism of H₂S oxidation and regeneration.

Main Methods:

• Synthesis of three polyoxometalates: (n-Bu₄N)₃VMo₁₂O₄₀, (n-Bu₄N)₃PMo₁₂O₄₀, and (n-Bu₄N)₄[α-SiMo₁₂O₄₀].
• Dissolution of polyoxometalates in four ionic liquids: [Bmim]Cl, [Bmim]HCO₃, [Bmim]Mes, and [Bmim]OAc.
• Testing desulfurization performance at high temperatures (90-180 °C) and analyzing regeneration via air blowing.
• Characterization using FT-IR and XPS to understand the chemical transformations during H₂S removal and regeneration.

Main Results:

• The system (n-Bu₄N)₃VMo₁₂O₄₀/[Bmim]OAc demonstrated superior performance, achieving >98.6% H₂S removal efficiency within 10 hours.
• The desulfurization solution was effectively regenerated by blowing air, restoring the active species.
• FT-IR and XPS analysis confirmed the involvement of central atom V and coordination atom Mo in H₂S oxidation, with redox recovery during regeneration.

Conclusions:

• The (n-Bu₄N)₃VMo₁₂O₄₀/[Bmim]OAc system is a highly efficient and regenerable solution for high-temperature H₂S removal.
• This approach offers a promising alternative for treating industrial off-gases.
• The study provides insights into the catalytic mechanism of polyoxometalates in H₂S oxidation.