Oriented Titanium-MOF Membrane for Hydrogen Purification

Precise hydrogen sorting from purge gas (H₂/N₂) and coke gas (H₂/CH₄), commonly carried out by cryogenic distillation, still suffers from low separation efficiency, high energy consumption, and considerable capital cost. Though still in its infancy, membrane technology offers a potential to achieve more efficient hydrogen purification. In this study, an optimum separation of hydrogen towards both methane and nitrogen via a kinetically-driven mechanism is realized through preferred orientation control of a MOF membrane. Relying on the 0.3 nm-sized window aligned vertical to the substrate, b-oriented Ti-MOF membrane exhibits ultra-high hydrogen selectivity, surpassing the upper bound limit of separating H₂/N₂ and H₂/CH₄ gas pairs attained so far by inorganic membranes. This spectacular selectivity is combined with a high H₂ permeability owing to the synergistic effect of the 1 nm-sized MOF channel.