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

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.