MOF Nanosheet-Based Mixed Matrix Membranes with Metal–Organic Coordination Interfacial Interaction for Gas Separation

Abstract

In the mixed matrix membrane (MMM), the interface between the filler and the polymer matrix will directly affect the gas separation performance of the membranes. Reasonable interfacial design in MMMs is thus important and necessary. In this work, metal−organic coordination interaction is used to construct the interface in metal−organic framework (MOF) nanosheetbased polyimide MMMs where ultrathin Co-benzenedicarboxylate MOF nanosheets (CBMNs) with a thickness less than 5 nm and a lateral size more than 5 μm are synthesized as fillers and a carboxyl-functionalized polyimide (6FDA-durene-DABA) is used as a polymer matrix. Because of the high aspect ratio (>1000) of CBMNs, abundant metal−organic coordination bonds are formed between Co 2+ in CBMNs and the −COOH group in 6FDA-durene-DABA. As a result, the 6FDA-durene-DABA/CBMN MMMs exhibit improved separation performance for the CO 2 /CH 4 and H 2 /CH 4 gas pairs with H 2 /CH 4 and CO 2 /CH 4 selectivities up to 42.0 ± 4.0 and 33.6 ± 3.0, respectively. The enhanced interfacial interaction leads to the comprehensive separation performance of CO 2 /CH 4 and H 2 /CH 4 gas pairs approaching or surpassing the 2008 Robeson upper bound. In addition, the CO 2 plasticization pressure of the MMMs is significantly enhanced up to ∼20 bar, which is 2 times that of the pure 6FDA-durene-DABA membrane. When separating a mixed gas of CO 2 /CH 4 , the selectivity of CO 2 /CH 4 remains stable at around 23 and the CO 2 permeability keeps around 400 barrer during the long-term test.

Thin Film Mixed Matrix Hollow Fiber Membrane Fabricated by Incorporation of Amine Functionalized Metal-Organic Framework for CO2/N2 Separation

“…At the high content of MOF particles (15, 20, and 50 wt%), the aggregation of UiO-66-NH 2 in the polymeric matrix was observed ( Figure 7 E–G and Figure S2 ). It is reported that the MOF aggregation in polymeric matrix could lead to the formation of non-selective defects during the fabrication process [ 36 ]. Similar phenomenon was observed by Sutrisna et al [ 33 ].…”

Recent Progress in Mixed-Matrix Membranes for Hydrogen Separation

“…Despite the high promise of using MOF nanosheets in MMMs for H2 separation, one of the key challenges lies in the production of high-quality MOF nanosheets to support the largescale membrane fabrication [114]. [113], Copyright 2020 American Chemical Society, and (b) a schematic showing the preparation of the oriented and penetrating ZIF-7@PI MMM. Reprinted with permission from ref.…”

“…MMM with 20% ZIF-L-Co showed the best H 2 permeability at 1986 barrer. Bi et al also incorporated ultrathin Co-benzenedicarboxylate MOF nanosheets (CBMNs) into a 6FDA-Durene-DABA matrix ( Figure 6 a), leading to improved H 2 separation with a H 2 /CH 4 selectivity of up to 42 [ 113 ]. Recently, Ma et al proposed a new concept of fabricating MMMs [ 85 ].…”

“…Reprinted with permission from Ref. [ 113 ], Copyright 2020 American Chemical Society, and ( b ) a schematic showing the preparation of the oriented and penetrating ZIF-7@PI MMM. Reprinted with permission from ref.…”

“…Illustration of (a) the 6FDA-Durene-DABA/CBMN MMM. Reprinted with permission from Ref [113],. Copyright 2020 American Chemical Society, and (b) a schematic showing the preparation of the oriented and penetrating ZIF-7@PI MMM.…”