Anisotropic Porosity and Interface Synergy Enhanced Gas Permselectivity in Heterolayer Metal-Organic Framework Membrane.

The pursuit of sustainable, carbon-free separation technology hinges on the efficient separation of gas mixtures with high separation factors and flow rates, i. e. high permselectivity. However, achieving this objective is arduous due to the meticulous engineering at the angstrom scale and intricate chemical manipulation required to design the pores within membranes. To address this challenge, a proof-of-concept for an anisotropic porous membrane has been devised. Employing a meticulous step-by-step methodology, two distinct porous metal-organic frameworks (MOFs) are integrated to form a monolithic anisotropic membrane. By harnessing pore anisotropy (3.4 to 6 Å) aligned with the gas permeation direction and a unique interface characterized by cross-linked pores derived from the two distinct MOFs, this membrane transcends the performance limitations inherent in the individual MOF membranes (~45 % enhanced selectivity). This approach not only sheds light on the heterolayer membrane design strategy but also elucidates the intricate CO/N permselectivity relationship inherent in the interface structure.