Ultrathin, Highly Permeable Graphene Oxide/Zeolitic Imidazole Framework Polymeric Mixed-Matrix Composite Membranes: Engineering the CO₂-Philic Pathway

Abstract

High-performance, thin-film mixed-matrix membranes (MMMs) on a porous support have been developed, using zeolitic imidazole framework (ZIF) decorated graphene oxide (GO) as a filler, dispersed in a poly(vinyl imidazole)-copoly(oxyethylene methacrylate) (PVI-POEM) copolymer matrix. The low gas permeance of the neat GO-filler-based MMM was significantly improved by routing a CO 2 -permeable pathway through the semi-interconnected GO-ZIF nanocages. The good rubbery adhesion properties of PVI-POEM, together with the chemical similarity between PVI and the ZIF imidazole linker, induced excellent polymer/filler interface engineering in the GO-ZIF MMMs. Moreover, the GO-ZIF nanofillers were fully blanketed by the PVI-POEM copolymer, to prevent interfacial defects, while in turn an ultrathin, highly permeable GO-ZIF selective layer was formed. As a result, the GO-ZIF 5% composite MMM achieved a state of the art CO 2 permeance of 995.1 GPU, retaining excellent CO 2 /N 2 and CO 2 /CH 4 selectivities of 45.9 and 17.5, respectively. The CO 2 -philic pathway of GO-ZIF filler and good interaction bewteen the PVI-POEM and GO-ZIF generate a synergistic effect of CO 2 separation, in comparison with a neat PVI-POEM composite membrane (CO 2 permeance 626.4 GPU, CO 2 /N 2 selectivity 36.2).

Constructing Dual-Transport Pathways by Incorporating Beaded Nanofillers in Mixed Matrix Membranes for Efficient CO2 Separation

“…36 Figure 2b marks the (002), ( 112), (022), (013), ( 222), ( 123), ( 114), ( 233), ( 224), (015), and (044) planes of ZIF-8, and they were consistent with the crystal structure reported for ZIF-8. 46,47 Meanwhile, it can be observed from Figure 2b and Figure S6 that ZIF-8@AC-1, ZIF-8@AC-2, and ZIF-8@AC-3 had the same diffraction peaks as ZIF-8. These results implied that the crystal structure of ZIF-8 was undestroyed after AC modification.…”

Graphene-Based Metal–Organic Framework Hybrids for Applications in Catalysis, Environmental, and Energy Technologies

“…(a) Mixed-matrix composite GO-ZIF thin-film membrane on a PSf substrate and gas permeation pathway through this membrane. Reproduced with permission from ref . Copyright 2021 American Chemical Society.…”

“…A simple casting method was also used by Lee et al to prepare mixed-matrix GO-ZIF-8/ZIF-67 composite membranes on a polysulfone (PSf) substrate. 220 The composite was prepared by mixing a methanolic solution of Hmim with a GO suspension in methanol/deionized water, sonicating the resulting reaction mixture for 30 min, and then stirring it for 2 h before adding a methanolic solution of Zn(NO 3 ) 2 •6H 2 O and Co(NO 3 ) 2 •6H 2 O and stirring overnight. For membrane fabrication, GO-ZIF-8/ ZIF-67 was thoroughly dispersed in aqueous ethanol.…”

Highly Efficient Pd@CN Catalysts with Quasi-Ordered Mesopores Synthesized from Recycled Mother Liquid of Zeolitic Imidazolate Frameworks

“…Zeolitic imidazolate frameworks (ZIFs) as a special subfamily of metal–organic frameworks (MOFs) consist of transition-metal ions (such as Zn 2+ and Co 2+ ) and imidazolate linkers that form topologies similar to those of zeolites and inorganic nano-oxide materials. − By adjusting the components and modifying the functional groups, more than 150 kinds of ZIFs have been produced with different topological features. The unique structures of ZIFs inherit not only the advantages of high porosity, high specific surface area, uniform porous structures, and easy functionalization from MOFs but also the tunability and high stability from traditional zeolites, making them potentially promising for many applications in gas adsorption and separation, − chemical sensing, , biomedicine, , catalysis, − etc. As reported by Yang et al, Pd nanocubes@ZIF-8 catalysts were prepared by encapsulating Pd nanocubes within ZIF-8 for olefin hydrogenation, and the catalysts exhibited efficient performance in selective hydrogenation.…”

“…In this study, a simple and effective approach was developed for the recycling of the mother liquid of ZIFs. ZIF-67 is one of the most studied ZIFs, which can be used for CO 2 separation and catalysis , and can be carbonized to produce CN materials and Pd@CN catalysts . However, during the synthesis of ZIF-67, the residual mother liquid is often wasted.…”