Free-Standing Metal–Organic Framework Membranes Made by Solvent-Free Space-Confined Conversion for Efficient H₂/CO₂ Separation

Abstract

Metal−organic frameworks (MOFs) are promising candidates for the advanced membrane materials based on their diverse structures, modifiable pore environment, precise pore sizes, etc. Nevertheless, the use of supports and large amounts of solvents in traditional solvothermal synthesis of MOF membranes is considered inefficient, costly, and environmentally problematic, coupled with challenges in their scalable manufacturing. In this work, we report a solvent-free space-confined conversion (SFSC) approach for the fabrication of a series of free-standing MOF (ZIF-8, Zn(EtIm) 2 , and Zn 2 (BIm) 4 ) membranes. This approach excludes the employment of solvents and supports that require tedious pretreatment and, thus, makes the process more environment-friendly and highly efficient. The free-standing membranes feature a robust and unique architecture, which comprise dense surface layers and highly porous interlayer with large amounts of irregular-shaped micron-scale pore cavities, inducing satisfactory H 2 /CO 2 selectivities and exceptional H 2 permeances. The ZIF-8 membrane affords a considerable H 2 permeance of 2653.7 GPU with a competitive H 2 /CO 2 selectivity of 17.1, and the Zn(EtIm) 2 membrane exhibits a high H 2 /CO 2 selectivity of 22.1 with an excellent H 2 permeance (6268.7 GPU). The SFSC approach potentially provides a new pathway for preparing free-standing MOF membranes under solvent-free conditions, rendering it feasible for scale-up production of membrane materials for gas separation.

Vertical Graphene-Supported High-Hydrogen Permeance ZIF-8 Membranes

“…Comparison of H 2 /CH 4 separation performance for ZIF-8 membranes in this work and the other MOF membranes (HKUST-1, , KAUST-7, ZIF-22, ZIF-90, ZIF-9, ZIF-67, , ZIF-7-8, ZIF-7, , MIL-120, and ZIF-8 ,,,,,− ).…”

Hydrogen-bonded organic frameworks for membrane separation

“…A diverse array of MOF/COF membranes, encompassing polycrystalline and MMMs, have exhibited compelling properties in gas separation. 127,128 Conversely, while HOF materials are more prevalent in gas adsorption separation, research on HOF-based gas separation membranes remains limited. Given the myriad advantages of HOFs, particularly their facile preparation and processing/regeneration, it is foreseeable that they are better suited for membrane manufacturing and practical utilization.…”

Metal–Organic Framework‐Integrated Composites for Bone Tissue Regeneration

“…[68] Additionally, MOF synthesis can be intricate and costly, potentially limiting their widespread adoption in BTE in comparison to more readily available and cost-effective materials. [69] In contrast to traditional materials, MOF composites shine in terms of biocompatibility, tunable properties, and drug delivery capabilities. [70] Still, they may not possess the mechanical fortitude exhibited by metals and ceramics, which have a longer history of use in implant applications.…”