Preparation of a 6FDA-DAM/ODA Mixed Matrix Membrane Doped with MOFs and Its Application in Gas Separation

Mixed matrix membranes (MMMs) can significantly improve gas separation performance, but the type and state of the filler in the membrane matrix are key indicators for the development of MMMs. Therefore, in this work, 6FDA-DAM/ODA (1:1), metal-organic frameworks (MOFs) with different particle sizes (UiO-66 and UiO-66-NH₂) were synthesized, and then MOFs were doped into 6FDA-DAM/ODA to prepare MMMs. The effects of the dopant materials and their particle sizes on the gas separation performance of the membranes were investigated by testing the permeability of the MMMs to H₂, CO₂, CH₄, and N₂. When the dopant material was UIO-66, the permeability and selectivity of MMMs for each gas were significantly improved compared with that of the original membrane; when the dopant material was 300 nm UIO-66-NH₂ with a loading of 10 wt %, the permeability performance and the CO₂/CH₄ selectivity increased from 44.1 to 57.2 compared with that of the original membrane. The permeation performance for CO₂, N₂, and H₂ and the selectivity for CO₂/N₂, H₂/N₂, and H₂/CH₄ were also significantly improved. In terms of comprehensive separation performance, doping 300 nm UiO-66-NH₂ was better than doping 70 and 400 nm UiO-66-NH₂ and also showed excellent performance in 50:50 (vol/vol) CO₂/CH₄ binary mixed gas separation. This work provides an idea for the fabrication of MMMs for high-performance gas separation.