Reversible capture of SO2 through functionalized ionic liquids

Abstract

Emission of SO2 in flue gas from the combustion of fossil fuels leads to severe environmental problems. Exploration of green and efficient methods to capture SO2 is an interesting topic, especially at lower SO2 partial pressures. In this work, ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Et2NEMim][Tf2N]) and 1-(2-diethylaminoethyl)-3- methylimidazolium tetrazolate ([Et2NEMim][Tetz]) were synthesized. The performances of the two ILs to capture SO2 were studied under different conditions. It was demonstrated that the ILs were very efficient for SO2 absorption. The [Et2NEMim][Tetz] IL designed in this work could absorb 0.47 g SO 2 gIL-1 at 0.0101 MPa SO 2 partial pressure, which is the highest capacity reported to date under the same conditions. The main reason for the large capacity was that both the cation and the anion could capture SO2 chemically. In addition, the IL could easily be regenerated, and the very high absorption capacity and rapid absorption/desorption rates were not changed over five repeated cycles. Say it ain't SO2! The ionic liquid [Et2NEMim][Tetz] is synthesized and demonstrated to have an extremely high absorption capacity and rapid absorption/desorption rates for the capture of SO2. [Et 2NEMim][Tetz] can be regenerated and reused, making it a very attractive ionic liquid for practical SO2 capture applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.