A pragmatic thermal treatment strategy for improved gas separation in 2D Zeolite-based mixed matrix membranes

Mixed matrix membranes (MMMs) combine the desirable properties of polymers and inorganic fillers, yet interfacial incompatibility frequently results in non-selective voids that compromise selectivity. Here, we report a straightforward heat treatment (200–400 °C) to enhance interfacial compatibility in MMMs composed of 6FDA-DAM-AB-TFMB polyimide (PI) and two-dimensional zeolite (MFI) fillers. Incorporating porous zeolite fillers increases gas permeability, particularly for polar molecules such as CO 2 , while heat treatment induces crosslinking and polymer chain rearrangement, effectively eliminating non-selective voids and boosting selectivity. Moreover, partial carbonization during the thermal process generates a microporous structure that substantially increases overall gas permeability. Consequently, the MFI/PI-30 % membrane treated at 400 °C achieves exceptional CO 2 and H 2 permeabilities of 2220.8 Barrer (12.7 × higher) and 1767.2 Barrer (10.3 × higher), respectively, while retaining CO 2 /CH 4 and H 2 /CH 4 selectivity—surpassing the 2008 Robeson upper bound. The key innovation of this study is leveraging a moderate-temperature heat treatment that simultaneously mitigates interfacial incompatibility and creates micropores, thereby significantly enhancing both permeability and selectivity. This simple, scalable strategy holds great promise for the development of high-performance MMMs in advanced gas separation applications.