Mixed matrix membranes prepared from non-dried MOFs for CO₂/CH₄ separations

Abstract

Mixed matrix membranes (MMMs) aim at combining the processibility of polymers with the molecular sieving of fillers to improve gas separation performance. Metal-organic frameworks (MOFs) are a new family of materials with promising potential as fillers. The first part of this work reports on exploiting the versatility of MOF synthesis routes by forming ZIF-8 particles in polymer solutions to subsequently cast membranes directly from the solution. Although MOFs can be synthesised in a polymer medium, the decline in the synthesis yield does not allow for high loading in the MMMs. The second part describes a method for preparing MMMs with the commercial polyimide (PI) Matrimid® and ZIF-8, ZIF-7 and NH 2 -MIL-53(Al) as non-dried filler with 30 wt% and 50 wt% loading. A comparison of this method with the conventional approach of drying MOFs prior to incorporation exhibits the flexibility MOFs provide in membrane synthesis, in contrast to e.g. zeolites which intrinsically have to be calcined to become useful. The membranes with non-dried MOFs show some improvement in performance as compared to the unfilled polymer-only membranes, while those with dried MOFs even lose the inherent selectivity of the polymer.

Tuning of Nano-Based Materials for Embedding Into Low-Permeability Polyimides for a Featured Gas Separation

“…Finally, the last filler dispersion in NMP is maintained under stirring until use of MMM dope solution, in which the small amount of polymer is added for the priming step. Additionally, it is important to mention that the MMMs prepared by this protocol have shown enhancements in GS performance accompanied with the excellent filler dispersion over the membranes (Kertik et al, 2016;Castro-Muñoz et al, 2019a).…”

“…To face such an issue, the postsynthesis solvent exchange of the nanofiller could also be an alternative. For example, the removal of the solvent after the MOF [such as ZIF-8, ZIF-7, and NH 2 -MIL-53(Al)] synthesis has been reported (Kertik et al, 2016;Castro-Muñoz et al, 2019a). Such a procedure was named the "non-dried MOF method, " which basically avoids the drying step in the MOF production.…”

Fe3O4/MIL‐101(Fe) nanocomposite as an efficient and recyclable catalyst for Strecker reaction

“…New porous metal‐organic frameworks (MOFs) offer innovative opportunities in scientific and technological fields by combining the profits of both inorganic and organic moieties, in which provide unique properties of high surface areas and well defined cavities or channels that can lead to potential applications in gas storage, separation, optical devices, sensors, drug delivery, and heterogeneous catalysis…”

Facile synthesis of Fe3O4/MIL-101 nanocomposite as an efficient heterogeneous catalyst for degradation of pollutants in Fenton-like system

“…[6][7][8][9] These unique properties endow MOFs with wide applications in the areas of catalysis, 10 molecular separations, 11 sensing, 12,13 and gas adsorption, 14 etc. Moreover, MOF materials also exhibit tremendous potential in the degradation of pollutants in the wastewater.…”