Metal Organic Framework - Based Mixed Matrix Membranes for Carbon Dioxide Separation: Recent Advances and Future Directions

Abstract

Gas separation and purification using polymeric membranes is a promising technology that constitutes an energy-efficient and eco-friendly process for large scale integration. However, pristine polymeric membranes typically suffer from the trade-off between permeability and selectivity represented by the Robeson's upper bound. Mixed matrix membranes (MMMs) synthesized by the addition of porous nano-fillers into polymer matrices, can enable a simultaneous increase in selectivity and permeability. Among the various porous fillers, metal-organic frameworks (MOFs) are recognized in recent days as a promising filler material for the fabrication of MMMs. In this article, we review representative examples of MMMs prepared by dispersion of MOFs into polymer matrices or by deposition on the surface of polymeric membranes. Addition of MOFs into other continuous phases, such as ionic liquids, are also included. CO₂ separation from hydrocarbons, H₂, N₂, and the like is emphasized. Hybrid fillers based on composites of MOFs with other nanomaterials, e.g., of MOF/GO, MOF/CNTs, and functionalized MOFs, are also presented and discussed. Synergetic effects and the result of interactions between filler/matrix and filler/filler are reviewed, and the impact of filler and matrix types and compositions, filler loading, surface area, porosity, pore sizes, and surface functionalities on tuning permeability are discoursed. Finally, selectivity, thermal, chemical, and mechanical stability of the resulting MMMs are analyzed. The review concludes with a perspective of up-scaling of such systems for CO₂ separation, including an overview of the most promising MMM systems.

Keywords: CO2; MOF; membranes; mixture; permeability; polymers; selectivity; separation.

Figure 1

(A) CO₂ separation efficiency of 6FDA-Durene based MMMs with various KAUST-7 loadings at 35°C and 2 bar (% is CO₂ concentrations in the feed gas). (B) SEM cross-section images of pristine 6FDA membrane and 6FDA based MMMs with wt. % contents of KAUST-7 nanocrystals (~80 nm). Reproduced from Chen K. et al. (2018) with permission from Elsevier.

Figure 2

(A) Relationships between pore diameter of fillers and kinetic diameter of gas molecules for different separation processes. Reproduced from Vinoba et al. (2017) with permission from Elsevier. (B) Types of MOFs with respective critical pore sizes.

Figure 3

Schematic representation of a UiO-66 MMM and of different chemical functionalization schemes for UiO-66, and effect of different coating layers on the membranes: (a) PTMSP, (b) PTMSP and pure Pebax, (c) PTMSP and 50 wt. % UiO-66 in Pebax, (d) PTMSP and 50 wt. % UiO-66-NH₂ in Pebax, (e) PTMSP and 50 wt. % UiO-66-(COOH)₂ in Pebax and (f) PTMSP and 80 wt. % UiO-66 in Pebax. Membranes (b–f) have an extra top protective layer. Reproduced from Sutrisna et al. (2018) with permission from RSC.

Figure 4

Characteristic examples of MOF filler effects: (A) Effect of ZIF-8 loading and size on CO₂ permeability and CO₂/N₂ selectivity of Pebax-ZIF-8 MMMs. Reproduced from Zheng et al. (2019) with permission from Elsevier. (B) Separation performance of various NH₂-MIL-53(Al) MMMs with different MOF loadings at 308 K for a mixture CO₂:CH₄ = 1:1. P_perm = 1 bar, Pret = 4 bar. CH₄ (black bars) and CO₂ (white bars) permeability (left y-axis) and CO₂/CH₄ separation factor (right y-axis). 1 Barrer = 3.348 × 10⁻¹⁹ kmol m/(m² s Pa). Reproduced from Zornoza et al. (2011a) with permission from RSC. (C) Effect of different Pebax fillers, namely, MMMs with ZIF-8@GO, ZIF-8 and GO, and (D) filler content in Pebax/ZIF-8@GO MMMs. Reproduced from Dong et al. (2016a) with permission from Elsevier. (E) Gas permeability and selectivity of MMMs with different CuBTC/GO loadings. Reproduced from Feijani et al. (2018) with permission from RSC.

Figure 5

Schematic representations of characteristic examples of MOF MMM formation mechanisms and filler/matrix interactions: (A) NH₂-MIL-101(Al)-decorated CNTs filled in 6FDA-durene membranes. Reproduced from Lin et al. (2015) with permission from ACS. (B) Synthesis of the PGMA-co-POEM copolymer and possible epoxide–amine reaction between UiO-66-NH₂ and PGMA-co-POEM with illustration of ultrathin membranes. Reproduced from Kim et al. (2019) with permission from RSC. (C) Possible interaction between Cd-6F and 6FDA-ODA in MMMs upon in situ polymerization. Reproduced from Lin et al. (2014) with permission from ACS. (D) Possible interactions between the Matrimid® polymer and -PA modified MOFs. Reproduced from Venna et al. (2015) with permission from RSC. (E) Fabrication of TSIL@NH₂-MIL-101 (Cr)/PIM-1 MMMs and the respective gas separation mechanism. Reproduced from Ma et al. (2016) with permission from RSC. (F) Formation of corona-MOFs and the respective corona-MOF loaded PDMS MMM. Reproduced from Katayama et al. (2019) with permission from ACS. (G) Formation of PDA@ZIF-8 and the possible CO₂ transport mechanism in Pebax/PDA@ZIF-8 MMMs. Reproduced from Dong et al. (2016b) with permission from RSC.

Figure 6

The performance of MOF-based MMMs [HKUST-1 (Car et al., ; Hu et al., ; Ge et al., ; Lin et al., ; Feijani et al., ; Chi et al., 2019); ZIF-7 (Li et al., ; Azizi and Hojjati, 2018); ZIF-8 (Ordoñez et al., ; Ban et al., ; Shahid et al., ; Dong et al., ,; Jusoh et al., ; Lin et al., ; Anastasiou et al., ; Castro-Muñoz and Fíla, ; Yang et al., ; Zheng et al., 2019); UiO-66 (Nik et al., ; Dong et al., ; Shen et al., ; Satheeshkumar et al., ; Sutrisna et al., ; Tien-Binh et al., ; Zamidi Ahmad et al., ; Jia et al., ; Jiang et al., ; Katayama et al., ; Kim et al., 2019); MOF-5 (Perez et al., 2009); MIL-53 (Zornoza et al., ; Chen et al., ; Hsieh et al., ; Ahmadi Feijani et al., ; Feijani et al., ; Tien-Binh et al., ; Mubashir et al., ; Jiang et al., 2019); ZIF-90 (Bae et al., 2010); ZIF-11 (Safak Boroglu and Yumru, 2017); KAUST-7 (Chen K. et al., 2018); CuBDC (Cheng et al., 2017); Mg-MOF-74 (Bae and Long, ; Tien-Binh et al., ; Smith et al., 2018); Ni-MOF-74 (Bachman and Long, ; Yang et al., 2019); ZIF-94 (Etxeberria-Benavides et al., 2018); MIL-101 (Xin et al., ; Ma et al., 2016); Bio-MOF-1 (Ishaq et al., 2019); Fe(BTC) (Nabais et al., 2018)] included in this review work for (A) CO₂/CH₄, and (B) CO₂/N₂ separation data in conjunction to redefined Robeson upper bounds (2019).