# US 5,707,423 A · Substituted polyacetylene separation membrane > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,423 A - Document ID: US5707423A - Status: Granted - Kind: A - Application number: 08/663,906 - Filed: 1996-06-14 - Granted: 1998-01-13 - Earliest claimed: 1996-06-14 - Assignees: Membrane Technology and Research, Inc. - Inventors: Ingo Pinnau; Atsushi Morisato - Web page: https://patentgrep.com/patent/US5707423A ## CPC - B01D 71/44: Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of groups B01D71/26-B01D71/42 - B01D 53/228: {characterised by specific membranes} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract A separation membrane useful for gas separation, particularly separation of C.sub.2+ hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula: ##STR1## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) ›PMP!. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations. ## Claims ### Claim 1 A process for separating a component of a first fluid mixture comprising the steps of: (a) bringing said first fluid mixture into contact with a feed side of a separation membrane, said separation membrane comprising a polymer having repeating units of the formula: ##STR9## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl, said polymer being characterized by an oxygen permeability at room temperature of at least about 500 Barrer; (b) providing a driving force for transmembrane permeation; (c) withdrawing from a permeate side of said separation membrane a second fluid mixture wherein said component is enriched, compared with said first fluid mixture. ### Claim 2 (depends on 1) The process of claim 1, wherein said first fluid mixture is gaseous. ### Claim 3 (depends on 1) The process of claim 1, wherein said first fluid mixture is liquid. ### Claim 4 (depends on 1) The process of claim 1, wherein said first fluid mixture is liquid and said second fluid mixture is gas. ### Claim 5 (depends on 1) The process of claim 1, wherein said component comprises a condensable component. ### Claim 6 (depends on 1) The process of claim 1, wherein said component comprises an organic compound. ### Claim 7 (depends on 1) The process of claim 1, wherein said component comprises a hydrocarbon. ### Claim 8 (depends on 1) The process of claim 1, wherein said component comprises a C.sub.2+ hydrocarbon. ### Claim 9 (depends on 1) The process of claim 1, wherein said first fluid mixture comprises natural gas. ### Claim 10 A gas separation process comprising the steps of: (a) bringing a gas mixture containing a component to be separated into contact with a feed side of a separation membrane, said separation membrane comprising a polymer having repeating units of the formula: ##STR10## said polymer being characterized by an oxygen permeability at room temperature of at least about 500 Barrer: (b) providing a driving force for transmembrane permeation; (c) withdrawing from a permeate side of said separation membrane a gas that is enriched in said component compared with said gas mixture. ### Claim 11 (depends on 10) The process of claim 10, wherein said gas mixture comprises methane and said component comprises a C.sub.2+ hydrocarbon. ### Claim 12 A process for recovering natural gas liquid, comprising the steps of: (a) providing a membrane having a feed side and a permeate side; said membrane comprising a polymer having repeating units of the formula: ##STR11## said polymer being characterized by an oxygen permeability at room temperature of at least about 500 Barrer; (b) passing a gas containing a C.sub.2+ hydrocarbon across said feed side; (c) withdrawing from said permeate side a permeate vapor stream enriched in said C.sub.2+ hydrocarbon compared with said gas; (d) condensing at least a portion of said permeate vapor stream to form said natural gas liquid. ### Claim 13 A separation membrane comprising a polymer having repeating units of the formula: ##STR12## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl, said polymer being characterized by an oxygen permeability at room temperature of at least about 500 Barrer. ### Claim 14 (depends on 13) The polymer of claim 13, wherein R.sub.1 is methyl. ### Claim 15 (depends on 13) The polymer of claim 13, wherein R.sub.2 is hydrogen. ### Claim 16 (depends on 13) The membrane of claim 13, wherein said polymer is 4-methyl-2-pentyne. ### Claim 17 (depends on 13) The membrane of claim 13, wherein said polymer is a copolymer. ### Claim 18 (depends on 13) The membrane of claim 13, wherein said membrane comprises a film of said polymer. ### Claim 19 (depends on 13) The membrane of claim 13, wherein said membrane comprises a support layer and a selective layer coating said support layer. ### Claim 20 (depends on 19) The membrane of claim 19, wherein said support layer comprises said polymer. ### Claim 21 (depends on 19) The membrane of claim 19, wherein said selective layer comprises said polymer. ### Claim 22 (depends on 19) The membrane of claim 19, wherein said membrane comprises a support layer and a selective layer coating said support layer, and wherein said support layer is microporous. ### Claim 23 (depends on 13) The membrane of claim 13, wherein said membrane comprises an integral asymmetric membrane. ### Claim 24 (depends on 13) The membrane of claim 13, wherein said membrane comprises a laminate having at least two layers, at least one of said layers comprising said polymer. ### Claim 25 (depends on 13) The membrane of claim 13, wherein said membrane comprises a laminate having at least three layers, at least one of said layers comprising said polymer. ### Claim 26 (depends on 13) The membrane of claim 13, wherein said membrane comprises a sealing layer, said sealing layer comprising said polymer. ### Claim 27 (depends on 13) The membrane of claim 13, wherein said membrane comprises a gutter layer, said gutter layer comprising said polymer. ### Claim 28 (depends on 13) The membrane of claim 13, wherein said polymer has a molecular weight of at least about 10.sup.5. ### Claim 29 (depends on 13) The membrane of claim 13, wherein said polymer has a molecular weight of at least about 10.sup.6. ### Claim 30 (depends on 13) The membrane of claim 13, wherein said polymer has a fractional free volume of at least about 0.2. ### Claim 31 (depends on 13) The membrane of claim 13, wherein said polymer has a fractional free volume of at least about 0.25. ### Claim 32 (depends on 13) The membrane of claim 13, wherein said polymer is characterized by a methane permeability at room temperature of at least about 500 Barrer. ### Claim 33 (depends on 13) The membrane of claim 13, wherein said polymer is characterized by an n-butane permeability at room temperature of at least about 2,500 Barrer. ### Claim 34 (depends on 13) The membrane of claim 13, wherein said membrane exhibits a mixed gas selectivity for n-butane over methane of at least about 5. ### Claim 35 (depends on 13) The membrane of claim 13, wherein said membrane is prepared from a solution of said polymer in a solvent chosen from the group consisting of cyclohexane, methylcyclohexane and carbon tetrachloride.