Composite porous carbonaceous membranes

Claim 1

A composite semipermeable membrane for the separation of a multicomponent fluid mixture containing one or more primary components and one or more secondary components prepared by the method comprising the steps of: (a) coating a surface of an inert porous substrate with a layer of an organic precursor material; (b) heating the resulting coated porous substrate in an inert atmosphere to a first temperature and holding the membrane at this temperature for a time sufficient to convert said precursor material into a layer of microporous carbonaceous adsorptive material; (c) cooling the resulting composite membrane to a temperature below said first temperature; (d) heating the membrane to a second temperature; (e) oxidizing the heated membrane at said second temperature in an oxidizing atmosphere containing one or more gases selected from the group consisting of air, oxygen, carbon oxides, nitrogen oxides, steam, and mixtures thereof; and (f) cooling the resulting oxidized membrane to a temperature below said second temperature; wherein at least 90% of the pores in said microporous carbonaceous adsorptive material are less than 12.9 Angstroms in diameter, and wherein said microporous carbonaceous adsorptive material can selectively adsorb portions of the primary components which diffuse through the membrane by selective surface flow.