Engineering Metal-Organic-Framework (MOF)-Based Membranes for Gas and Liquid Separation

Abstract

Separation is one of the most energy-intensive processes in the chemical industry, and membrane-based separation technology contributes significantly to energy conservation and emission reduction. Additionally, metal-organic framework (MOF) materials have been widely investigated and have been found to have enormous potential in membrane separation due to their uniform pore size and high designability. Notably, pure MOF films and MOF mixed matrix membranes (MMMs) are the core of the “next generation” MOF materials. However, there are some tough issues with MOF-based membranes that affect separation performance. For pure MOF membranes, problems such as framework flexibility, defects, and grain orientation need to be addressed. Meanwhile, there still exist bottlenecks for MMMs such as MOF aggregation, plasticization and aging of the polymer matrix, poor interface compatibility, etc. Herein, corresponding methods are introduced to solve these problems, including inhibiting framework flexibility, regulating synthesis conditions, and enhancing the interaction between MOF and substrate. A series of high-quality MOF-based membranes have been obtained based on these techniques. Overall, these membranes revealed desired separation performance in both gas separation (e.g., CO2, H2, and olefin/paraffin) and liquid separation (e.g., water purification, organic solvent nanofiltration, and chiral separation).

12 Connecting Sites Linked Three‐dimensional Covalent Organic Frameworks with Intrinsic Non‐interpenetrated shp Topology for Photocatalytic H2O2 Synthesis

“…Similar to their reticular analogues including supramolecular frameworks (SMFs) [6] and metal–organic frameworks (MOFs), [7] COFs could be designed and fabricated in a bottom‐up manner from organic building blocks with required geometry depending on reticular chemistry principles [8] . However, the intrinsic rarity of dynamic covalent bonds available for constructing COFs and the difficulty in determining the structure of COFs in particular for the interpenetrated 3D COFs at this stage lead to the limited known topologies of COFs including 9 topologies for 2D COFs and 30 topologies for 3D COFs, in good contrast to more than 70000 MOFs with 7000 topologies reported thus far [9] . As a result, developing new organic building blocks with different configuration and symmetry forms one of the most preferred strategies towards developing new topologies of COFs particularly for 3D COFs, which is certainly also critical for the rational design and synthesis of COFs with desired functionalities and in turn extending the application potentials of COFs.…”

CO2/CH4 Separation in Amino Acid Ionic Liquids, Polymerized Ionic Liquids, and Mixed Matrix Membranes

“…MOFs have also been extensively studied for CO 2 capture, CH 4 recovery, and olefin/paraffin separation. MOF membranes demonstrate superior molecular sieving capabilities based on differences in chemical affinity and pore size [ 6 ]. Polymers, on the other hand, remain the primary choice for commercial membranes due to their ease of processing and low costs.…”

Challenges and recent advances in MOF-based gas separation membranes

“…8 Therefore, it has a wide range of applications in the fields of oil–water separation, ion separation, and gas separation. 9,10…”