Abstract: The palladium-modified polyimide-silica (Pd-PI-SiO2) hybrid membrane supported on the kieselguhr-mullite ceramic membrane substrate with a TiO2 transition layer was prepared by the sol-gel method. Infrared spectroscopy, scanning electron microscopy, low temperature N2 adsorption, and gas permeability measurement techniques were used to characterize its structure, micro-surface, pore distribution, and permeability for CH4, H2O, H2, CO2, CO, and N2. The results indicate that a bond is formed between PI and SiO2, and palladium exists in the hybrid membrane as a metallic state with good distribution, which can modify the micro-pore structure of the PI-SiO2 membrane. The pore diameter of the Pd-PI-SiO2 membrane is about 4 nm. The gas permeability measurements show that the N2 permeance flux of this hybrid membrane is 0.2×10-7 mol/(m2•Pa•s), and the separation coefficient of H2/N2 is 542. Palladium has an adsorption effect for hydrogen, which can promote the separation of hydrogen from the gaseous mixture.

Key words: sol-gel method, supported hybrid membrane, palladium modification, polyimide, silica, hydrogen separation