Enhanced CO2 Capture and Hydrogen Purification by Hydroxy Metal–Organic Framework/Polyimide Mixed Matrix Membranes

• Published in: ChemSusChem Vol. 12; no. 19; pp. 4405 - 4411
• Main Authors: Ma, Canghai, Urban, Jeffrey J.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 08.10.2019; ChemPubSoc Europe
• Subjects: Bonding strength; carbon capture; Carbon dioxide; Carbon sequestration; Chemical industry; Compatibility; Hydrogen bonds; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Membrane separation; Membranes; Metal-organic frameworks; Methane; Organic chemistry; Purification; Selectivity; Separation; separations; Upper bounds
• ISSN: 1864-5631; 1864-564X; 1864-564X
• DOI: 10.1002/cssc.201902248

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. Out of bounds: Mixed‐matrix membranes incorporating the hydroxy‐functionalized metal‐organic framework UiO‐66‐(OH)2 exhibit gas separation performance beyond the 2008 Robeson CO2/CH4, H2/CH4, and H2/N2 upper bounds, owing to intimate hydrogen‐bonding interactions between hydroxy groups and carboxylic acid groups in the UiO‐66‐(OH)2 and polymer phase, respectively.