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

The temperature of industrial gas containing harmful H₂S can reach hundreds of degrees. However, few processes can be used directly for H₂S removal from industrial high-temperature gas. In this work, three polyoxometalates with different central atoms ((n-Bu₄N)₃VMo₁₂O₄₀, (n-Bu₄N)₃PMo₁₂O₄₀, and (n-Bu₄N)₄[α-SiMo₁₂O₄₀]) were synthesized and dissolved in four ionic liquids (Bmim]Cl, [Bmim]HCO₃, [Bmim]Mes, or [Bmim]OAc) for H₂S removal from high-temperature (90-180 °C) gases. The result showed that (n-Bu₄N)₃VMo₁₂O₄₀/[Bmim]OAc exhibited the optimal desulfurization performance, maintaining more than 98.6% desulfurization efficiency within 10 h. The reacted desulfurization solution can be regenerated by blowing air. FT-IR and XPS results show that both the central atom V and the coordination atom Mo of the polyoxometalate are involved in the oxidation of H₂S; after the regeneration by introducing air, V(+IV) and Mo(+IV) recovered to V(+V) and Mo(+VI), respectively. Our research shows that (n-Bu₄N)₃VMo₁₂O₄₀/[Bmim]OAc is an efficient, easy-to-regenerate, and suitable high-temperature gas desulfurization solution.