Aligned Metal–Organic Framework Nanoplates in Mixed‐Matrix Membranes for Highly Selective CO₂/CH₄ Separation

Abstract

2D metal–organic frameworks are attractive filler in mixed matrix membranes (MMMs) due to the high aspect ratio and contact opportunity at the filler–polymer interface. However, their alignment in polymer matrix remains a challenge to fully play their functions. Herein, to our best knowledge, for the first time, the facile synthesis of KAUST‐7‐NH2 (KAUST, King University of Science and Technology) nanoplate is reported with 1D channels with an aspect ratio greater than 30. The nanoplates are incorporated and aligned in the 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride‐2,4‐diaminomesitylene (6FDA‐DAM) polymer matrix under the shear force with a filler loading up to 50 wt%. The large difference in adsorption abilities between CO2 and CH4 from the (001)‐oriented KAUST‐7‐NH2 nanoplate‐based MMMs and the favorable interaction at the filler–polymer interface contribute to the excellent CO2/CH4 separation performance. The resultant membranes show CO2/CH4 selectivity with 66.2% enhancement (surpassed 2008 Robeson upper bound), antiplasticization up to 17 bar, and long‐term stability up to 240 h indicating its good potential for natural gas treatment.

A roadmap to enhance gas permselectivity in metal–organic framework-based mixed-matrix membranes

“…This is because of the better interactions between the exposed (001) surface of the crystal and polymer. Similar improvement of selectivity and permeation by pore alignment is also reported by Pan and coworkers, 136 using a 2D MOF (KAUST-7-NH 2 ) as filler.…”

Constructing Molecular Sieve Channels in Mixed Matrix Membranes for Efficient CO2 Separation

“…In addition, N-Y-abtc showed an increased external surface area (from 9.26 to 43.97 m 2 /g) that will permit better polymer−filler interactions due to the more exposed contact area between the filler and the polymer than that of M-Y-abtc (Table S1). 37 The CO 2 and N 2 adsorption isotherms of N-Y-abtc and M-Y-abtc were collected at 298 K and 1 bar, and they are compared in Figure 3b,c and Table S1. N-Y-abtc showed a much higher CO 2 uptake (64.7 cm 3 /g, Figure 3b) than M-Y-abtc (37.9 cm 3 /g), which may be due to the increased adsorption sites for CO 2 in the smaller particle size of N-Y-abtc than those of M-Y-abtc.…”

Steering diffusion selectivity of chemical isomers within aligned nanochannels of metal-organic framework thin film

“…While the computational screening approaches for MOF-membrane design have received a signi cant interest, 26,27 experimental manipulation of diffusivity has remained challenging. Recent experimental efforts, such as downsizing MOF crystallite size, morphology control, 28 controlling nanochannel orientation [29][30][31] and employing novel heterostructure design [32][33][34][35][36] improve molecular diffusivity, however do not predictively tune the diffusivity.…”