# US 2013/0239805 A1 · Methods of preparing a crossliked fiber membrane > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0239805 A1 - Document ID: US20130239805A1 - Status: Published application - Kind: A1 - Application number: 13/872,523 - Filed: 2013-04-29 - Published: 2013-09-19 - Earliest claimed: 2010-08-25 - Assignees: Chevron U.S.A. Inc. - Inventors: Shabbir Husain - Web page: https://patentgrep.com/patent/US20130239805A1 ## CPC - B01D 69/087: {Details relating to the spinning process} - B01D 53/228: {characterised by specific membranes} - B01D 67/00931: {by introduction of specific groups after membrane formation, e.g. by grafting} - B01D 71/64: Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors - D01D 5/06: Wet spinning methods {(D01D5/0046 takes precedence)} - D01D 5/24: with a hollow structure; Spinnerette packs therefor (D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08) - D01F 6/74: from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles - B01D 2323/30: Cross-linking - 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) - D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS - D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS ## Abstract Disclosed herein is a method for preparing a crosslinked hollow fiber membrane. The method involves spinning a one phase solution comprising a monoesterified polyimide polymer, acetone as a volatile solvent, a spinning solvent, a spinning non-solvent, and optionally an organic and/or inorganic additive, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 50 wt. %, based on the total weight of the solution. ## Claims ### Claim 1 A method for preparing a crosslinked hollow fiber membrane, the method comprising spinning into a monoesterifed fiber a one phase solution comprising a monoesterified polyimide polymer, acetone as a volatile solvent, a spinning solvent, and a spinning non-solvent, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 50 wt. %, based on the total weight of the solution; and subjecting the monoesterified fiber to one of esterfication and transesterification conditions to prepare a crosslinked hollow fiber membrane. ### Claim 2 (depends on 1) The method of claim 1, wherein the monoesterifed fiber is subjected to esterification conditions. ### Claim 3 (depends on 1) The method of claim 1, wherein the monoesterified polyimide polymer is present in the spinning solution in an amount between about 20 and about 50 weight percent. ### Claim 4 (depends on 1) The method of claim 1, wherein the monoesterified, polyimide polymer has an average molecular weight between about 50,000 and about 300,000. ### Claim 5 (depends on 1) The method of claim 1, wherein the monoesterified, polyimide polymer has a polydispersity index between about 2 and about 5. ### Claim 6 (depends on 1) The method of claim 1, wherein the volatile solvent is present in an amount of greater than 25 wt. % to about 35 wt. %, based on the total weight of the solution. ### Claim 7 (depends on 1) The method of claim 1, wherein the volatile solvent is present in an amount of about 35 wt. % to about 50 wt. %, based on the total weight of the solution. ### Claim 8 (depends on 1) The method of claim 1, wherein the spinning solvent is an organic solvent selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and diglyme. ### Claim 9 (depends on 1) The method of claim 1, wherein the one phase solution further comprises one or more inorganic additives. ### Claim 10 (depends on 9) The method of claim 9, wherein the inorganic additive is an antilyotropic salt. ### Claim 11 (depends on 1) The method of claim 1, wherein the spinning non-solvent is selected from the group consisting of a C2 to C10 aliphatic alcohol, water, and mixtures thereof. ### Claim 12 (depends on 1) The method of claim 1, wherein the spinning non-solvent is ethanol. ### Claim 13 (depends on 1) The method of claim 1, further comprising subjecting the monoesterified fiber to transesterification conditions. ### Claim 14 (depends on 1) The method of claim 1, wherein the monoesterified hollow fiber is spun from the spinning dope by a dry-jet/wet-quench spinning process comprising: (a) extruding the monoesterified polyimide polymer through orifices of a spinneret to provide a monoesterified hollow fiber; (b) conveying the monoesterified hollow fiber through an air gap and through a coagulating bath of de-ionized water; and (c) winding the monoesterified hollow fiber around a take-up drum at a take-up rate between about 10 m/min and about 150 m/min, wherein the dry-jet/wet-quench spinning process has a draw ratio of less than 150. ### Claim 15 (depends on 14) The method of claim 14, wherein the temperature of the spinning solution is greater than about 40° C. ### Claim 16 (depends on 14) The method of claim 14, wherein the temperature of the coagulating bath is between about 10° C. and about 70° C. ### Claim 17 (depends on 14) The method of claim 14, wherein the dry-jet/wet-quench spinning process has an air gap height that is greater than 0.1 centimeter. ### Claim 18 (depends on 14) The method of claim 14, wherein the dry-jet/wet-quench spinning process has a face velocity of air surrounding the spinneret that is greater than 15 m per minute. ### Claim 19 (depends on 1) The method of claim 1, wherein the resulting crosslinked membrane comprises a porous substructure and a relatively defect free dense skin of uniform density. ### Claim 20 (depends on 1) A method of using a hollow fibers membrane made according to the method of claim 1, comprising: (a) providing a feed stream selected from the group consisting of air, a mixture of methane and nitrogen, a mixture of methane and hydrogen, a mixture of methane and hydrogen sulfide, a refinery stream, a mixture of carbon dioxide and methane, and syngas, the feed stream including a gaseous component selected from the group consisting of nitrogen, oxygen, hydrogen, hydrogen sulfide and carbon dioxide; (b) maintaining a pressure differential between an upstream side of the membrane and a downstream side of the membrane; (c) contacting the upstream side of the membrane with the feed stream at a pressure between about 20 psia and about 4000 psia; (d) isolating a permeate stream on the downstream side of the membrane having a larger mole fraction of the faster permeating component of the feed stream; and (e) isolating a retentate stream having a smaller mole fraction of the faster permeating component of the feed stream.