Composite polymeric membranes for gas separation and their preparation and use.

摘要

The invention relates to composite membranes for the separation of gas mixtures and a method for their preparation. The membranes have a high selectivity in the separation of He/N2 and O2/N2 mixtures, suitable mechanical properties and a high permeability. They consist of a microporous polymeric base of an aromatic polyimide of the general formula II <CHEM> where n1 = 150 to 240, and/or a polyamidoimide of the general formula IV, <CHEM> where n2 = 140 to 220, and a polymeric thin selective layer formed from a poly(2,6-dimethyl-1,4-phenyleneoxide) or a derivative thereof, of the general formula I, <CHEM> where n3 = 500 to 1000 and R = Br, NO2 or SO3Me, with Me = H, Na, K, Cr or Co. The method for the preparation of the composite polymeric membranes consists in forming a thin polymeric layer of the polyphenyleneoxide of formula I on the microporous polymeric base of formula II and/or of formula IV.