Synthesis and performance evaluation of copper and magnesium-based metal organic framework supported ionic liquid membrane for CO2/N2 separation

• Published in: Chemosphere (Oxford) Vol. 311; p. 136913
• Main Authors: Ali, Syed Awais, Shah, Syed Nasir, Shah, Mansoor Ul Hassan, Younas, Mohammad
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2023
• Subjects: Ionic liquid; Metal-organic framework; Post-combustion CO2 capture; Supported ionic liquid membrane; CO2; Mg (NO3)2.6H2O; XRD; GPU; Ionic liquid; [P66614][Cl]; CH3OH; FTIR; EDX; DMF; C2H5OH; IL; N2; MOF; PTFE; [Bmim][Tf2N]; TMA; BTC; SILM; NMR; Cu (NO3)2.3H2O; ZIF; FWHM; Metal-organic framework; Mg; SEM; Post-combustion CO2 capture; Supported ionic liquid membrane
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.136913

The CO2 emission is enhancing drastically because of the continuous emission from industries and transport sector. Although the CO2 emission had decreased in the first half of 2020 by 8.8% due to COVID-19 restrictions however, it is again on the rise and it might exceed the estimated level in 2030. The current methods used for CO2 separation have serious operational and environmental constraints. To overcome these problems we have devised a supported ionic liquid membrane (SILM) incorporated with the blend of bimetallic metal-organic framework (MOF) of copper and magnesium ions (CuxMgx) and Trihexyltetradecylphosphonium chloride [P66614] [Cl] ionic liquid (IL). CuxMgx MOF were synthesized and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and energy dispersive X-ray analysis (EDX). CuxMgx MOF with [P66614] [Cl] IL were immobilized on a flat sheet of polytetrafluoroethylene (PTFE) membrane. Single gas permeation tests of membranes loaded with 0.2/0.8 wt/wt% MOF/IL solution showed the highest CO2 permeability of 2937 Barrer and CO2/N2 selectivity of 33.26. The performance of SILM was also investigated with different water loadings of (30 wt % and 50 wt %) in addition to MOF/IL solution and at different feed pressure varying from 0.5 to 2 bars. Membranes showed enhancement in CO2 permeability to 3738 and 4628 Barrer whereas CO2/N2 selectivity decreased to 23.53 and 21.8 with membranes loaded with 30 and 50 wt % water, respectively, at a feed pressure of 2 bar. The gas permeation results show that the incorporation of CuxMgx MOF with IL in polymeric membrane enhances the CO2/N2 separation under humid conditions but slightly decreases CO2/N2 selectivity with an increase in feed pressure. The SILM synthesized in this research is highly viable for industrial flue gases because of the incorporation of phosphonium-based ILs that have high thermal stability.
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•(Cux.Mgx) MOF was synthesized and characterized with SEM, XRD, FTIR and EDX.•MOF@IL/PTFE supported ionic liquid membrane showed good affinity towards CO2 capturing.•High permeabilities of gas pairs were achieved under mild feed conditions.•Immobilization enhances the long-term separation stability under humid condition.