Abstract: Gas permeabilities and permselectivities for gas pairs H₂/N₂ and O₂/N₂ through a series of aromatic polyimide membranes, which were prepared from four different dianhydrides (e. g. BPDA, BTDA, TDPA, and DSDA) and two kinds of diamines (e. g. ODA and MDA), have been investigated. Systematic variations in chemical structure were found to lead to significant changes in permeability and permselectivity. The polyimide membranes based on BPDA with low permeability have the highest H₂/N₂ and O₂/N₂ separation factors. The polyimide membranes based on DSDA have simultaneously higher permeability and higher permselectivity.

Key words: gas separation, membrane, polyimide