•The hydrothermal stability of ZIF-8 strongly depends on the zinc salts variations.•Samples synthesized from zinc acetate exhibit the highest hydrothermal stability.•ZIF-8 membrane is suitable for the separation of humidified C3H6/C3H8 mixtures.Zeolitic-imidazolate framework-8 (ZIF-8), a representative member of the ZIF class, have attracted extensive application in gas adsorption, membrane separation and catalysis. Since the discovery of ZIF-8, they are always synthesized from zinc nitrate. In this work, we evaluate the hydrothermal stability of ZIF-8 nanocrystals and polycrystalline membranes synthesized from four kinds of common zinc salts. Several physical techniques (X-ray diffraction, scanning electron microscope, and nitrogen adsorption) indicate that ZIF-8 nanocrystals derived from zinc acetate, rather than zinc nitrate, exhibit the highest hydrothermal stability. After immersed in water (∼3 wt%) at 80 °C for 10 days, nanocrystals derived from zinc acetate still could sustain ∼45% relative crystallinity, whereas those from zinc nitrate were transformed to amorphous products. The polycrystalline membrane derived from zinc acetate also exhibits the highest dynamic hydrothermal stability. This work is benefit to the synthesis of ZIF-8 materials for application in water-sensitive systems.

•H2-permeable Pd membranes were deposited on porous stainless steel (PSS) tubes.•Aluminizing and oxidation treatments improved PSS surface and membrane integrity.•Effects of these treatments on membrane performance were investigated.•Intermetallic diffusion was not observed after treated at 500 °C in H2 for 200 h.Composite palladium membranes based on porous stainless steel (PSS) substrate are idea hydrogen separators and purifiers for hydrogen energy systems, and the surface modification of the PSS is of key importance. In this work, the macroporous PSS tubes were aluminized through pack cementation at 850 °C in argon, followed by an oxidation with air at 600 °C. Palladium membranes were prepared by electroless plating. Their permeation performances were tested, and the hydrogen permeation kinetics was discussed. The substrate materials and the palladium membranes were characterized by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD). An Al2O3-enriched surface layer with small pore size was created through aluminizing and oxidation treatments, which greatly improves the membrane integrity. The intermetallic diffusion between the palladium membranes and the PSS substrate material was not observed after a heat-treatment at 500 °C under hydrogen for 200 h. However, the aluminizing and oxidation treatments still need to be further optimized in order to improve the membrane permeability and selectivity, and particularly, the high diffusion resistance of the substrate materials greatly limited the hydrogen flux.