Integrally-layered polymeric membranes and method of use

A process for selectively separating a desired component from a hydrocarbon feedstream comprising:

• a) contacting one side of a polymeric membrane assembly with the hydrocarbon feedstream, wherein the polymeric membrane assembly is comprised of at least one polymeric membrane element which is comprised of at least two adjacent polymer membrane layers, wherein the two adjacent polymer membrane layer compositions are chemically cross-linked between the contacting faces of the two adjacent polymer membrane layers thereby forming a integrally-layered, multi-layer membrane, and wherein each of the two adjacent polymer membrane layer compositions is comprised of a dianhydride, a diamine, a cross-linking agent and a difunctional dihydroxy polymer selected from:
• i) dihydroxy end-functionalized ethylene propylene copolymers with an ethylene content from about 25 wt % to about 80 wt %;
• ii) dihydroxy end-functionalized ethylene propylene diene terpolymers with an ethylene content from about 25 wt % to about 80 wt %;
• iii) dihydroxy end-functionalized polyisoprenes;
• dihydroxy end-functionalized polybutadienes;
• dihydroxy end-functionalized polyisobutylenes;
• iv) dihydroxy end-functionalized acrylate homopolymers, copolymers and terpolymers;
• dihydroxy end-functionalized methacrylate homopolymers, copolymers and terpolymers;
• and mixtures thereof, wherein the mixtures of acrylate and methacrylate monomers range from C1 to C18;
• v) dihydroxy end-functionalized condensation homopolymers, copolymers, terpolymers and higher order compositions of structurally different monomers, including alcohol-terminated end-functionalized esters and dihydroxy end-functionalized multimonomer polyesters;
• and mixtures thereof, wherein the polyalkyladipate structures range from C1 to C18;
• vi) dihydroxy end-functionalized perfluoroelastomers;
• vii) dihydroxy end-functionalized urethane homopolymers, copolymers, terpolymers, and higher order compositions of structurally different monomers;
• viii) dihydroxy end-functionalized carbonate homopolymers, copolymers, terpolymers, and higher order compositions of structurally different monomers;
• ix) dihydroxy end-functionalized ethylene alpha-olefin copolymers;
• dihydroxy end-functionalized propylene alpha-olefin copolymers;
• and dihydroxy end-functionalized ethylene propylene alpha-olefin terpolymers, wherein the alpha-olefins are linear or branched and range from C3 to C18;
• x) dihydroxy end-functionalized styrene homopolymers, copolymers, terpolymers, and higher order compositions of structurally different monomers;
• xi) dihydroxy end-functionalized silicone homopolymers, copolymers, terpolymers, and higher order compositions of structurally different monomers;
• xii) dihydroxy end-functionalized styrene butadiene copolymers;
• dihydroxy end-functionalized styrene isoprene copolymers;
• and
• xiii) dihydroxy end-functionalized styrene butadiene block copolymers;
• and dihydroxy end-functionalized styrene isoprene block copolymers;
• b) selectively diffusing the desired component from one side of the membrane assembly to the opposite side of the polymeric membrane assembly;
• and
• c) retrieving a permeate from the opposite side of the polymeric membrane assembly;
• wherein the concentration by wt % of the desired component in the permeate stream is higher than the concentration by wt % of the desired component in the hydrocarbon feedstream.