A review of metal-organic frameworks and polymers in mixed matrix membranes for CO2 capture

Abstract

Polymeric membranes offer an appealing solution for sustainable CO₂ capture, with potential for large-scale deployment. However, balancing high permeability and selectivity is an inherent challenge for pristine membranes. To address this challenge, the development of mixed matrix membranes (MMMs) is a promising strategy. MMMs are obtained by carefully integrating porous nano-fillers into polymeric matrices, enabling the simultaneous enhancement of selectivity and permeability. In particular, metal-organic frameworks (MOFs) have gained recognition as MMM fillers for CO₂ capture. Here, a review of the current state, recent advancements, and challenges in the fabrication and engineering of MMMs with MOFs for selective CO₂ capture is proposed. Key considerations and promising research directions to fully exploit the gas separation potential of MOF-based MMMs in CO₂ capture applications are highlighted.

Keywords: CO2 capture; gas separation; inorganic filler; metal-organic framework (MOF); mixed matrix membrane (MMM).

Figure 1

Overview of subtopics covered in this review for the key research areas related to MOF-based MMMs for CO₂ capture. Colored circles indicate the maturity levels from established (green) to developing (yellow) and emerging (red) research areas. “Polymer and MOF choice” is discussed in sections 3.2 and 3.4 through 4.1, “Membrane fabrication” in section 3.3, “Material optimization” in sections 3.4 through 4.2, “Gas separation mechanism” in section 2, “Permeability and selectivity” in sections 2, 4.2, and 6.2, “Computational prediction” in section 5, and “Large-scale integration” in section 6.

Figure 2

(a) CO₂ uptake by size exclusion in rigid PCN-29. Adapted with permission from [50], Copyright 2011 American Chemical Society. This content is not subject to CC BY 4.0. (b) CO₂ uptake by flexible Co(BDP). Adapted with permission from [51], Copyright 2018 American Chemical Society. This content is not subject to CC BY 4.0. (c) CO₂ coordination to Mg²⁺ in Mg-MOF-74. Adapted with permission from [52], Copyright 2012 American Chemical Society. This content is not subject to CC BY 4.0. (d) CO₂ chemisorption to Lewis basic sites of IRMOF-74-III-(CH₂NH₂)₂, with possible pore environments before and after exposure to CO₂ under 95% relative humidity and dry conditions. Adapted with permission from [53], Copyright 2017 American Chemical Society. This content is not subject to CC BY 4.0.

Figure 3

The number of articles related to MOF-derived MMMs in the scientific literature published each year from 2007 to 2023. The bars represent the number of articles returned using the keywords ‘MOF’ or ‘metal organic framework’ and ‘MMM’ or ‘mixed matrix membrane’ in the article title, abstract, or keywords. Dark green bars indicate the number of articles that also contain ‘CO₂’ in the article title, abstract, or keywords. The Scopus database and search engine were used. Data last updated on October 13, 2024.

Figure 4

Illustration of different flat sheet MOF-based MMM preparation methods. (a) Different ways of preparing the MOF-based MMM precursor slurry. (b) Solvent casting process for symmetric MOF-based MMMs. (c) Solvent casting process of asymmetric MOF-based MMMs. (d) Phase inversion method for creating asymmetric MOF-based MMMs. Specifically, phase inversion is induced by a conditional change such as temperature.

Figure 5

(a) Schematic diagram of a composite hollow fiber mixed matrix membrane. (c, e) Cross-sectional scanning electron microscopy images of composite membranes with (c) PTMSP and (e) PTMSP and pure Pebax^® coating layers. (b, d, f) Gas separation performance of UiO-66/Pebax^® 1657-based composite membranes at different particle loadings, showing both pure gas (solid lines) and mixed gas (dashed lines) data: (b) CO₂ permeance, (d) CO₂/N₂ gas selectivity, and (f) CO₂/CH₄ gas selectivity [98]. Used with permission of The Royal Society of Chemistry, from [98] (“Surface functionalized UiO-66/Pebax-based ultrathin composite hollow fiber gas separation membranes” by P. D. Sutrisna et al., J. Mater. Chem. A, vol. 6, issue 3, © 2018); permission conveyed through Copyright Clearance Center, Inc. This content is not subject to CC BY 4.0.

Figure 6

Illustration of different MOF–polymer matrix interfaces. (a) An ideal MOF–polymer matrix interface. (b) Poor adhesion between the MOF and the polymer leads to polymer voids around the MOF. (c) Rigid polymer immobilizing the MOF due to poor compatibility. (d) Instigating particles block the pores of the MOF, decreasing the permeability and changing the selectivity of the MMM. (e) Stochastically aggregated MOF particles within the polymer matrix. (f) Plasticization of the polymer matrix due to swelling from the infiltration of instigating particles. (g) Plasticization of the polymer matrix due to polymer chain equilibration.

Figure 7

Illustration of different solutions to enhance MOF–polymer interfacial compatibility. (a) Polymer-grafted MOFs. (b) Percolation pathways through controlled MOF aggregation. (c) Amine-functionalized MOFs. (d) Hydroxy end group-functionalized polymer. (e) Ionic liquid-coated MOFs.

Figure 8

Cross-sectional SEM images of (a) HKUST-1 MMM and (d) HKUST-IL MMM and surface-rendered view of segmented FIB-SEM tomograms of (b, e) fillers and voids and (c, f) voids for (b, c; box size 35.7 µm × 26.5 µm × 23.3 µm) HKUST-1 MMM and (e, f; box size 40.7 µm × 24.0 µm × 23.0 µm) HKUST-IL MMM. Blue arrows point out MOF–polymer interfaces. Filler appears in cyan blue, and voids in red [132]. Adapted with permission from [132], Copyright 2016 American Chemical Society. This content is not subject to CC BY 4.0.

Figure 9

(a) HKUST-1 structure with cavities of 14 Å (green sphere), 11 Å (blue sphere), and 5 Å (purple sphere) pore diameter. Used with permission of The Royal Society of Chemistry, from [163] (“Methane storage in metal-organic frameworks”, by Y. He et al., Chem. Soc. Rev., vol. 43, issue 16, © 2014); permission conveyed through Copyright Clearance Center, Inc. This content is not subject to CC BY 4.0. (b) CO₂ adsorption at the open Cu(II) sites [63]. The color scheme of framework atoms: Cu, blue; C, gray; O, red; and H, white. The color scheme of the CO₂ atoms: C, gray; O, purple. Adapted with permission from [63], Copyright 2010 American Chemical Society. This content is not subject to CC BY 4.0.

Figure 10

Selectivity–permeability plots of MOF-based MMMs for CO₂ capture reported in the literature. Detailed data are available in Supporting Information File 1. Lines indicate the 1991 (dotted) and 2008 (dashed) Robeson upper bound, as well as the 2019 upper bound proposed by Comesaña-Gándara and coworkers [–14].

Figure 11

Schematic diagram of the UiO-66-PIM preparation method and cross-interface linking between UiO-66-NH₂ and PIM-1 obtained during the in situ polymerization [165]. Reprinted from [165], Journal of Membrane Science, vol. 548, by N. Tien-Binh; D. Rodrigue; S. Kaliaguine, “In-situ cross interface linking of PIM-1 polymer and UiO-66-NH2 for outstanding gas separation and physical aging control”, pages 429-438, Copyright (2017), with permission from Elsevier. This content is not subject to CC BY 4.0.

Figure 12

Selectivity/permeability characteristics of MOF-based MMMs for separation of ternary CO₂/H₂S/CH₄ mixtures reported in the literature [,–250]. Lines indicate the 1991 (dotted) and 2008 (dashed) Robeson upper bound, as well as the 2019 upper bound proposed by Comesaña-Gándara and coworkers [–14].

Figure 13

Schematic illustration and cross-section SEM images of (a) (001)-oriented membrane and (b) random fashion nanoparticle embedded in a polymer matrix. (c) Effects of temperature on CO₂ permeability and CO₂/CH₄ selectivity. (d) Long-term stability and reversibility of CO₂ permeability and CO₂/CH₄ selectivity under thermal stress in (001)-AlFFIVE(59.6)/6FDA-DAM-DAT membrane. From [20]. Reprinted with permission from AAAS. This content is not subject to CC BY 4.0.