Superbase ionic liquids (ILs) with a trihexyltetradecylphosphonium cation and a benzimidazolide ([P66614][Benzim]) or tetrazolide ([P66614][Tetz]) anion were investigated in a dual-IL system allowing the selective capture and separation of CO2 and SO2, respectively, under realistic gas concentrations. The results show that [P66614][Tetz] is capable of efficiently capturing SO2 in preference to CO2 and thus, in a stepwise separation process, protects [P66614][Benzim] from the negative effects of the highly acidic contaminant. This results in [P66614][Benzim] maintaining >53% of its original CO2 uptake capacity after 30 absorption/desorption cycles in comparison to the 89% decrease observed after 11 cycles when [P66614][Tetz] was not present. Characterization of the ILs post exposure revealed that small amounts of SO2 were irreversibly absorbed to the [Benzim]− anion responsible for the decrease in CO2 capacity. While optimization of this dual-IL system is required, this feasibility study demonstrates that [P66614][Tetz] is a suitable sorbent for reversibly capturing SO2 and significantly extending the lifetime of [P66614][Benzim] for CO2 uptake.
|Pages (from-to)||9453 - 9459|
|Number of pages||7|
|Journal||ACS Sustainable Chemistry & Engineering|
|Early online date||13 Jul 2022|
|Publication status||Published (in print/issue) - 25 Jul 2022|
Bibliographical noteAuthor not at UU at time of submission, no acceptance date. Set acc date as 1st of month of first publication to enable compliance section and exception set as OA.
- ionic liquids
- CO2 capture
- SO2 capture
- flue gas