Author(s):
Ferreira, Tiago J. ; Carvalho, Thiago O. ; Pais, Joana ; Esteves, Laura M. ; Silva, Ludmila P. C. ; Reis, Patrícia M. ; Esperança, José M. S. S. ; Esteves, Isabel A. A. C.
Date: 2024
Persistent ID: http://hdl.handle.net/10362/174296
Origin: Repositório Institucional da UNL
Subject(s): CO Post-combustion; CO/N separation by selective sorption; IL@MOF composites; Ionic Liquids (IL); Metal-organic frameworks (MOF); Chemical Engineering (miscellaneous); Environmental Science (miscellaneous); Energy (miscellaneous); SDG 13 - Climate Action
Description
Funding 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: © 2024
Post-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.
