Gas separation by adsorbent membranes
AssigneeAir Products and Chemicals, Inc.
InventorsMadhukar B. Rao, Shivaji Sircar, Timothy C. Golden
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Abstract
Composite semipermeable membranes comprising porous adsorptive material supported by a porous substrate are disclosed for use in a process for the separation of multicomponent gas mixtures. In the process, one or more primary components adsorb within the pores of the adsorptive material and diffuse by surface flow through the membrane to yield a permeate stream enriched in one or more of the primary components. Methods for making the composite membranes are described.
Claims19
A process for the separation of a multicomponent fluid mixture containing one or more primary components and one or more secondary components comprising:
- (a) bringing said fluid mixture into contact with a first surface of a composite semipermeable membrane comprising porous adsorptive material supported by porous substrate, said porous substrate having essentially no effect upon the separation of said fluid mixture and serving only to support said porous adsorptive material, wherein a significant portion of at least one of said primary components is selectively adsorbed within pores in said adsorptive material and permeates through said pores by surface flow in an adsorbed fluid phase to produce a first fluid product enriched in at least one of said primary components at a second surface of said membrane;
- and
- (b) withdrawing the remaining fluid mixture from contact with said first surface to yield a second fluid product enriched in said secondary components.
A composite porous semipermeable membrane for the separation of a multicomponent fluid mixture comprising a porous adsorptive material supported by a porous substrate, said porous substrate having essentially no effect upon the separation of said fluid mixture and serving only to support said porous adsorptive material, wherein at least 10% of the pores in said porous adsorptive material are larger than 4.3 Angstroms in diameter, and wherein a significant portion of at least one component in said fluid mixture can be selectively adsorbed within said pores such that said component selectively permeates through said membrane by surface flow in an adsorbed phase, whereby the fluid permeating through said membrane is enriched in said component.
A method for making a layered composite semipermeable membrane for the separation of a multicomponent fluid mixture containing one or more primary components and one or more secondary components comprising the steps of:
- (a) coating a surface of a porous substrate with a layer of a polymeric material selected from the group consisting of polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, styrene-divinylbenzene copolymer, and mixtures thereof;
- (b) heating the resulting coated porous substrate in an inert atmosphere to a temperature sufficient to carbonize said polymeric material to form a layer of porous adsorptive material;
- and
- (c) cooling the resulting composite membrane to ambient temperature;
- wherein said porous adsorptive material can selectively adsorb a significant portion of at least one of said primary components and has a pore size distribution such that at least 10% of the pores have diameters larger than the largest of the molecular diameters of said primary and secondary components.
A method for making a densified composite semipermeable membrane for the separation of a multicomponent fluid mixture containing one or more primary components and one or more secondary components comprising the steps of:
- (a) introducing a solution of a polymer in a suitable solvent into the pores of a porous substrate, wherein said polymer is selected from the group consisting of polyvinylidene chloride, polyacrylonitrile, polyvinyl chloride, styrene-divinylbenzene copolymer, and mixtures thereof;
- (b) heating said porous substrate containing said solution under conditions sufficient to evaporate said solvent, deposit said polymer within said pores, and carbonize said polymer to form porous adsorptive material within said pores;
- and
- (c) cooling the resulting composite membrane to ambient temperature;
- wherein said porous adsorptive material can selectively adsorb a significant portion of at least one of said primary components and has a pore size distribution such that at least 10% of the pores have diameters larger than the largest of the molecular diameters of said primary and secondary components.
Dependencies are inferred from the claim text.