Combined Superbase Ionic Liquid Approach to Separate CO2from Flue Gas

Adam J. Greer, S. F.Rebecca Taylor, Helen Daly, Johan Jacquemin, Christopher Hardacre

Research output: Contribution to journalArticlepeer-review

Abstract

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 CO2and SO2, respectively, under realistic gas concentrations. The results show that [P66614][Tetz] is capable of efficiently capturing SO2in preference to CO2and 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 CO2uptake 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 SO2were irreversibly absorbed to the [Benzim]-anion responsible for the decrease in CO2capacity. While optimization of this dual-IL system is required, this feasibility study demonstrates that [P66614][Tetz] is a suitable sorbent for reversibly capturing SO2and significantly extending the lifetime of [P66614][Benzim] for CO2uptake.

Original languageEnglish
Pages (from-to)9453-9459
Number of pages7
JournalACS Sustainable Chemistry and Engineering
Volume10
Issue number29
DOIs
Publication statusPublished - 25 Jul 2022

Keywords

  • COcapture
  • flue gas
  • ionic liquids
  • scrubber
  • SOcapture

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