Multicomponent membranes are known as are processes for the separation of gases therewith. Such membranes employ a polymer membrane porous to gases which carries a polymer coating occluding the pores of the first. U.S. Pat. No. 4,230,463 describes in detail these multicomponent membranes and discloses a plurality of organic polymers for use as the porous separation membrane including polysulfone, copolymers of styrene and acrylonitrile, polycarbonate and cellulose acetate. Coating materials also include a variety of polymers such as polysiloxane, polyisoprene, alpha-methylstyrene and polysiloxane copolymers and polystyrene. The multicomponent membrane can be employed to separate selectively at least one gas such as hydrogen from a mixture comprising carbon monoxide, carbon dioxide, helium, nitrogen, oxygen, argon, hydrogen sulfide, nitrous oxide, ammonia and C.sub.1 to C.sub.5 hydrocarbons.
An earlier U.S. Pat. No. 3,350,844 provides a process for the separation of helium, hydrogen or oxygen from a mixture of gases containing nitrogen or a hydrocarbon such as methane and one of the foregoing. The process employs a polyarylene oxide membrane. The polymer film is not crosslinked and therefore has poor solvent resistance necessitating that the gas mixtures be relatively pure. Crosslinking of polymeric materials for use as semipermeable membranes is known from U.S. Pat. No. 4,353,802, however, the membranes are employed for desalination of water by reverse osmosis rather than for gas separation.
Thus, the art of which I am aware has not provided a semipermeable membrane, highly selective for certain gases in a mixture, particularly mixtures of carbon dioxide and methane. Nor, have existing membranes possessed improved strength, flexibility and solvent resistance.