Ferreira, Tiago J.Carvalho, Thiago O.Pais, JoanaEsteves, Laura M.Silva, Ludmila P. C.Reis, Patrícia M.Esperança, José M. S. S.Esteves, Isabel A. A. C.2024-10-292024-10-292024-122772-6568PURE: 101209788PURE UUID: 75486cbc-3b25-4f86-85ea-48704f411221Scopus: 85202584698WOS: 001316629500001ORCID: /0000-0001-9615-8678/work/170594223ORCID: /0000-0002-2242-6016/work/170594243ORCID: /0000-0002-5458-0448/work/170594431http://hdl.handle.net/10362/174296Funding Information: The authors thank Funda\u00E7\u00E3o para a Ci\u00EAncia e Tecnologia , FCT / MCTES (Portugal), for financial support through PhD grants SFRH/BD/139627/2018 and COVID/BD/152969/2023 (T. J. F.), PhD grant 2021.07148.BD (T. O. C.), FCT Investigator contract ( 2021.00511.CEECIND \u2013 P. M. R ), project PTDC/CTM-CTM/30326/2017 and Material Characterization Laboratory (LAMATE/UFF) for obtaining the PXRD diffractograms. Additionally, the work was also partially supported by the Associate Laboratory for Green Chemistry, LAQV, which is funded by national funds from FCT / MCTES ( 10.54499/UIDB/50006/2020, 10.54499/UIDP/50006/2020 and 10.54499/LA/P/0008/2020 ). The NMR spectrometers are part of The National NMR Facility, supported by FCT / MCTES (Grant RECI/BBB-BQB/0230/2012 ). Publisher Copyright: © 2024Post-combustion carbon dioxide (CO2) capture/separation is considered one of the main ways to minimize the impact of global warming caused by this greenhouse gas. This work used eight mono- and dicarboxylate-based ionic liquids (ILs) to impregnate metal-organic framework (MOF) ZIF-8. This anionic effect was studied for these mostly unreported IL@MOF composites to determine its impact on gas sorption and selectivity performance. Characterization results confirmed IL impregnation into the structure of ZIF-8, along with the conservation of microporosity and crystallinity in composites. Sorption-desorption equilibrium measurements were performed, and CO2 and nitrogen (N2) isotherms were obtained at 303 K for ZIF-8 and IL@ZIF-8 composites. At 0.15 bar, the dicarboxylate-based composite [C2MIM]2[Glu]@ZIF-8 showed the highest CO2 gas sorption, showing 50 % more sorption capacity than the best monocarboxylate-base composites at this pressure. Dicarboxylate-based composites also showed remarkable N2 sorption in the low-pressure range. The ideal CO2/N2 selectivity for a typical post-combustion composition was calculated, and a trend regarding the anionic carbon chain size was observed. The composite [C2MIM][Cap]@ZIF-8 showed nearly five times more selectivity than the pristine ZIF-8 at 1 bar of total pressure. Dicarboxylate-based composites, given their low-pressure high N2 sorption capacity, were not as selective as their respective monocarboxylate-based IL@ZIF-8 materials with the same carbon chain size.111298979engCO Post-combustionCO/N separation by selective sorptionIL@MOF compositesIonic Liquids (IL)Metal-organic frameworks (MOF)Chemical Engineering (miscellaneous)Environmental Science (miscellaneous)Energy (miscellaneous)SDG 13 - Climate Actionjournal article10.1016/j.ccst.2024.100282https://www.scopus.com/pages/publications/85202584698