Scalable metal-organic framework membranes through nonclassical crystallization for molecular separation.

Structurally ordered metal-organic framework (MOF) membranes hold great promise for selective molecular separations in chemical and pharmaceutical industries due to their precise pore size control and strong stability in organic solvents. However, the high surface energy of MOF nanodispersions complicates their assembly, leading to nonselective grain boundaries and poor processability, which hinder practical application. Here, we present a metastable phase crystallization (MPC) strategy that leverages nonclassical crystallization pathways to fabricate MOF membranes with high precision and structural uniformity. This approach combines sol-gel coating with vapor-phase reactions and ligand insertion, enabling the preparation of membranes with finely tunable pore sizes. Al-MOF membranes prepared by MPC exhibit excellent solvent permeance and solute retention, together with enhanced stability under elevated pressures and long-term operation. By tailoring pore sizes through ligand incorporation, molecular separation performance is further improved. A 10-tube tubular MOF membrane module with an effective area of 230 square centimeters highlights the potential scalability of this approach for industrial separations.