Abstract: Novel functional carbon membranes for gas separation were designed and prepared by incorporating Fe₃O₄ nanoparticles into carbon membranes precursor polyimide. The assynthesized membranes were characterized by TEM, XRD and VSM. The effects of Fe₃O₄ addition and the final pyrolysis temperature on the gas permeability were investigated. The results show that Fe₃O₄ nanoparticles transformed into other phase morphologies are helpful to form the graphite-like layers during the pyrolysis process, which make the membrane with two types of carbon structure : amorphous carbon and graphite-like layers. All the functional carbon membranes exhibit magnetism. Single gas permeation test results show that the assynthesized membranes exhibit an outstanding molecular sieving capability together with high gas permeability. The gas permeability of H₂ is 61 times higher than the pure carbon membrane and the H₂/CO₂ selectivity is also improved. Fe₃O₄ addition and the final pyrolysis temperature siginificantly impair the gas permeability. When the Fe₃O₄ content is 20wt%, the permeabilities of pure gas H₂, CO₂, O₂, N₂, CH₄ in the functional carbon membrane are 15476, 4385, 1565, 193 and 114 Barrers (1Barrer=1×10^-10 cm³ (STP) ·cm/(cm²·s·cmHg)), respecticvely. The final pyrolysis temperature also has a remarkable effect on the gas separation performance.

Key words: magnetism, functional carbon membrane, gas separation, permeability