Ligand-engineered Zr-MOF membranes with fast water transport channels for alcohol–water separation

Metal–organic framework (MOF) membranes with rich functionality and a tunable pore system are promising for molecular separation. However, an inadequate pore microenvironment and low water stability may hamper the extension of their use in gas separation to liquid separation (e.g., organic solvent dehydration). In this study, we report a high-valence Zr-MOF membrane with high stability and tunable pore microenvironment, prepared using a mixed-ligand strategy based on fumarate (fum) and 2-methylfumarate (mes) ligands for the pervaporation dehydration of alcohols. The introduction of a methyl group in the ligand side chain narrowed the aperture size while balancing the hydrophilicity, thus facilitating the fast and selective permeation of water over alcohol molecules. The resulting mes/fum-Zr-MOF membrane with a mes content of 30% displayed excellent butanol/water separation performance with total flux of 5226 g⁻¹·m⁻²·h⁻¹, separation factor of 1281, and water content of 99.3% in the permeate, transcending the upper-bound of state-of-the-art MOF and polymer membranes, thereby exhibiting immense potential for alcohols dehydration.