Carbon Molecular Sieve Membranes from Compatibilized Polyimide-Polybenzimidazole Immiscible Polymer Blends for Gas Separations

Separation of gases from mixtures is an important industrial process. High gas selectivity of one polymer and high gas permeability of another could be combined by the use of polymer blend membranes to improve gas pair separation. Compatibilization of immiscible polymers must be done in order to further improve the properties of these membranes. Although, better selectivities for gas pairs could be obtained from polymer precursor membranes, the permeability values remain low. Carbonization of the precursor membranes at high temperatures under inert environment is employed to improve the separation properties of these membranes. Especially, high H₂ permeability values are obtained together with high gas pair selectivities, which are two basic requirements for the industrial applications.