Oxidative absorption of H2S by functional ionic liquids mixtures

Hydrogen sulfide (H 2 S) is a highly toxic and corrosive pollutant threatening human health and the environment. Ionic liquids (ILs) are widely used for H 2 S capture, but existing research focuses on conventional or alkaline functional ILs with low capacity or high energy consumption. This work synthesizes a novel oxidative functional IL, tetraethylammonium metavanadate ([N 2222 ][VO 3 ]), for dilute H 2 S absorption. With [Bmim][BF 4 ] as solvent, the mixture absorbs 1.13 mol H 2 S/mol IL at 50 °C and 0.005 MPa partial pressure. The IL mixture converts H 2 S to sulfur and water in situ and regenerates completely with oxygen at 80 °C for five cycles without capacity loss. Characterization and DFT calculations confirm vanadium’s key role in oxidative absorption, changing from V 5+ to V 3+ . The mechanism is verified at the molecular level. The mild regeneration temperature and sulfur recovery offer a scalable solution for low-energy desulfurization processes.