We present a novel concept for the fabrication of custom-designed dual-layer metal organic framework (MOF) membranes that show great promise in improving permeability and selectivity performance for CO2/N2 separation as compared with the individual constituent MOF materials. A highly selective thin MOF layer with narrow pore size (shell layer) was grown on the surface of a highly permeable MOF layer with large pore size (core layer). Most importantly, the interaction between the two layers was optimized through the chemical binding between the two MOF materials affording continuous, defect-free membranes. The two MOF@MOF membranes: SIFISIX-3-Ni@SIFISIX-1-Cu and SIFISIX-3-Ni@HKUST-1, represent the first examples of inorganic membranes constructed by dual-layer MOF composites. The CO2/N2 selectivities of the HKUST-1 and SIFSIX-1-Cu membranes were improved from 5.2 to 13 and 3.4 to 7.8, respectively, after the growth of a selective layer of SIFSIX-3-Ni. This work emphasizes the importance of the custom-design of the membrane material rather than the screening approach of dozens of materials.

Dual-layer MOF@MOF inorganic membranes with tunable gas transport properties for post-combustion CO2 separation

2019 Fall National Meeting

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