Mixed matrix membranes (MMMs) with amine-functionalized ZIF-L for enhanced CO2 separation performance

Abstract

Amine-functionalized Metal-Organic Frameworks (MOFs) stand out as highly promising materials in membrane separation technology. Nevertheless, the incorporation of amine-functionalized additives may lead to uncontrollable alterations in MOF morphology. Two intact blade-like MOFs (PEI (Polyethylenimine)-ZIF-L and PAMAM (Polyamidoamine)-ZIF-L) were successfully synthesized by controlling the conditions and then introduced into Pebax 2533 to fabricate Mixed Matrix Membranes (MMMs). Hydrogen bonding and other interactions with Pebax can be formed by PEI-ZIF-L and PAMAM-ZIF-L to enhance interfacial compatibility. Simultaneously, a reversible reaction with CO₂ molecules can be undergone by the amine groups, resulting in facilitated transport in MMMs. The CO₂ separation performance of the MMMs is enhanced by this process, with the facilitation being more pronounced under humid conditions. Under humid conditions, the CO₂ permeabilities of Pebax-PEI-ZIF-L (2 wt%) and Pebax-PAMAM-ZIF-L (2 wt%) MMMs were 639.4 Barrer and 702.7 Barrer, respectively, while the CO₂/N₂ selectivities were 26.68 and 24.35, respectively. Both permeability and selectivity exhibited a significant increase of 200% and 130%, respectively, compared to pure Pebax. Furthermore, the MMMs demonstrated excellent long-term stability during 72 h of continuous operation in a humid environment, showcasing significant potential for industrial applications, particularly in humid flue gas carbon capture.