Lawrence Berkeley National Laboratory

Membrane separation technology provides substantial savings in energy and cost for molecular separations in chemical industry, ideally complementing conventional thermally driven separation approaches. However, current membranes are subject to limitations, primarily lying in the Robeson permeability-selectivity upper bound limits. In this study, hydroxy metal-organic framework (MOF)/polyimide mixed-matrix membranes are found to enable high separation performance for applications including CO₂ capture and hydrogen purification while offering enhanced compatibility with state-of-the-art membrane-manufacturing processes. The mixed-matrix membranes exceed the present Robeson upper bounds with H₂ and CO₂ permeabilities of 907 and 650 Barrers, respectively and H₂ /CH₄ and CO₂ /CH₄ selectivities of 45 and 32, respectively. The unparalleled performance results from intimate interactions at the boundary of the hydroxy MOFs and carboxylic polymers through strong hydrogen bonds. The principle of design opens the door to highly permeable membranes with synergistic compatibility with established membrane manufacturing platforms for energy-efficient molecular separations.