Nanosized Core–Shell Zeolitic Imidazolate Frameworks‐Based Membranes for Gas Separation

Abstract

The field of mixed matrix membranes (MMMs) for separation technology has advanced by using metal–organic frameworks (MOFs) with significant gas adsorption. Herein, the nanosized zeolitic imidazolate frameworks (ZIFs) core–shell crystals, i.e., ZIF‐67@ZIF‐8 (ZIF‐67 acting as core and ZIF‐8 as shell) are synthesized using the seed‐mediated growth method. ZIF‐67@ZIF‐8 nanocrystals present higher surface area, gas uptake, and thermal stability in comparison with the ZIF‐8 and ZIF‐67 nanoparticles. Nanosized ZIF‐67@ZIF‐8 fillers are loaded into the synthesized polyimide and Pebax 1657 matrices and the gas separation properties are compared with the pure ZIF‐67 and ZIF‐8 MMMs. The highest H2 permeability of 1150 barrer and H2/CH4 selectivity of 21.5 is observed for 20 wt% of ZIF‐67@ZIF‐8 MMM, which demonstrates 100% improvement compared to the permeability of the pristine polyimide membrane. H2 permeability of ZIF‐67@ZIF‐8 MMMs increases by up to 86% and 50% in comparison to the ZIF‐67 and ZIF‐8 MMMs, respectively. This indicates that the interaction and dispersibility of the particles with the polymer matrices can be tuned through the careful engineering of the double‐layered fillers. At the same time, the internal core would impart higher gas uptake and permeability to the overall system.

Acoustotemplating: rapid synthesis of freestanding quasi-2D MOF/graphene oxide heterostructures for supercapacitor applications

“…Metal–organic frameworks (MOFs)—crystalline coordination network lattices of metal cation nodes linked with organic ligands—are highly-tunable porous architectures, 1,2 whose versatile chemistry has led to their exploitation in a number of fields. These include catalysis, 3–7 gas adsorption and separation, 8–10 molecular sieving, 11 and water treatment, 12,13 amongst others. 14,15 Despite such versatility and exceptional porosity (up to 90% of its free volume), MOFs inherently suffer from low electrical conductivity.…”

Heterostructured hybrids of metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs)

“…4d), which were embedded in polyimide and Pebax 1657 substrates. 56 Krishna et al studied the differences in the structures and mechanisms for the synthesis of the mixed-linker ZIF by manufacturing a series of ZIF-8-90 hybrids (Fig. 4e).…”

“…100–102 A series of mixed matrix membranes of the core–shell ZIF-67@ZIF-8 (ref. 56) and ZIF-L@ZIF-67 (ref. 103) has also been obtained using a similar method.…”

“…Many reports focused on the core–shell ZIF-8@ZIF-67 hybrids, 100–102,104 ZIF-67@ZIF-8 (ref. 56 and 105) and other types of core–shell MOF@MOF 18,106 were obtained via the seed-mediated growth methodology (Fig. 12a).…”

Influence of microstructural variations on morphology and separation properties of polybutadiene-based polyurethanes

“…10 Moreover, tuning the morphology of block copolymer membranes for a better gas separation performance was accomplished by the incorporation of nanoparticles in the polymer matrix. [27][28][29][30][31] Interaction of llers with the functional groups of either so or hard blocks reduces phase-intermixing in the PU matrix.…”