Mixing Effect of Ligand on Carbon Dioxide Capture Behavior of Zeolitic Imidazolate Framework/Poly(amide-b-ethylene oxide) Mixed Matrix Membranes

Mixed matrix membranes (MMMs) were synthesized from poly(amide-b-ethylene oxide) (Pebax) and mixed-ligand zeolitic imidazolate framework (ZIF-8-90(x)). The separation performance and microstructure of the membranes with different organic linker fractions and ZIF-8-90(x) loadings were characterized. Energy-dispersive X-ray microanalysis and field-emission scanning electron microscopy showed excellent adhesion between Pebax and ZIF-8-90(x), and no voids or clusters were observed. Single gas permeation measurements on MMMs revealed that the CO2/N-2 selectivity of the membranes with ZIF-8-90(x) was better than that of the membrane with ZIF-8. Permeation analysis showed that the membranes with mixed ZIF-8 and ZIF-90 offers a tight microstructure. Overall, this study demonstrated that the gas separation behavior of the Pebax membrane was significantly changed by ZIF-8-90(x) loading. The ZIF-8-90(x)/Pebax membranes can be a good candidate for CO2 capture applications.