CO2 capture behavior switch triggered by MIL-140A membrane microstructure manipulation

High-valence metal-organic frameworks (HV MOFs) membranes for diverse separations exhibit exceptional potential in advancing carbon neutrality goals, owing to their outstanding structural stability. However, available HV MOFs membranes for high-performance gas separations such as multiscenario CO 2 capture remained very scarce, owing to high growth energy barrier and architectural manipulation complexity. In this work, we report the facile microstructural regulation of zirconium-based MIL-140A membranes with anisotropic ultramicropore windows for swithable CO 2 -selective/rejective separations. Experimental results indicated that the phase purity, crystallinity and structural compactness of MIL-140A membranes were highly sensitive to the N,N -dimethylformamide (DMF) solvent dosage and acetic acid (HAc) modulator content, which exerted significant influence on the ultimate multifunctional CO 2 separation capacities. Specifically, the preferred ( h0h )-oriented MIL-140A membranes with optimal CO 2 /CH 4 selectivity could be obtained at high temperature with suitable DMF content and no modulator. On the other hand, ensuring appropriate HAc and DMF contents during a mild-temperature secondary growth were crucial for obtaining highly ( 200 )-oriented MIL-140A membranes with excellent H 2 /CO 2 separation capability. These structure-performance relationships of MIL-140A membranes established in this work could help to advance the field of microstructural engineering and architectural design of robust HV MOF membranes for advanced separation applications.