Investigation of furoate-based ionic liquid as efficient SO2 absorbent

Abstract

A series of furoate anion-functionized ionic liquids (ILs) were synthesized and applied as new absorbents for SO₂. Results showed that these ILs possessed satisfactory performance for SO₂ absorption. At 293.15 K, the maximum absorption capacity was 0.69 and 0.24 g SO₂ per g P₄₄₄₂[FA] under 1.0 and 0.1 bar, respectively. The SO₂ enriched ILs were easily regenerated by bubbling N₂ at 343.15 K and recycled five times without obvious loss of absorption performance. The influences of temperature, SO₂ partial pressure, and water content in ILs on SO₂ absorption performance were systematically explored. The absorption capacity of ILs is discussed from aspects of the structure of cations, anions, and the interaction of cation–anion. The absorption mechanism was analyzed using NMR and FTIR methods. The selectivities of SO₂/CO₂, SO₂/N₂ and SO₂/O₂ were studied and [P₄₄₄₂][FA] achieved relatively high selectivity for SO₂ compared to other gases. Present furoate ILs demonstrate potential application as a SO₂ absorbent owing to their good performance.