Preparation And Gas Permeability Of Zif-7 Membranes Prepared Via Two-Step Crystallization Technique

Continuous and dense ZIF-7 membranes were successfully synthesized on alpha-Al2O3 porous substrate via two-step crystallization technique. ZIF-7 seeding layer was first deposited on porous alpha-Al2O3 substrate by in-situ low temperature crystallization, and then ZIF-7 membrane layer can be grown through the secondary high-temperature crystallization. Two synthesis solutions with different concentration were used to prepare ZIF-7 seeding layer and membrane layer on porous alpha-Al2O3 substrate, respectively. As a result, a continuous and defect-free ZIF-7 membrane layer can be prepared on porous alpha-Al2O3 substrate, as confirmed by scanning electron microscope. XRD characterization shows that the resulting membrane layer is composed of pure ZIF-7 phase without any impurity. A single gas permeation test of H-2, O-2, CH4 or CO2 was conducted based on our prepared ZIF-7 membrane. The ZIF-7 membrane exhibited excellent H-2 molecular sieving properties due to its suitable pore aperture and defect-free membrane layer.