US4233122A
Expired / Lapsed
US
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Electrolytic process for potassium hydroxide
Assignee: Olin Corp
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Filing: 1979-06-01
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Granted: 1980-11-11
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Expires: 1999-06-01
Abstract
Abstract Improved current efficiency is obtained in an electrolytic membrane cell for the production of potassium hydroxide by employing in combination: (a) a membrane comprised of a carboxylic acid substituted polymer prepared by reacting a fluorinated olefin with a comonomer having a functional group selected from the group consisting of carboxylic acid and a functional group which can be converted to carboxylic acid; (b) a potassium chloride brine feed through the anolyte chamber of the cell having a concentration in the range from about 250 to about 300 grams of potassium chloride per liter; (c) a cell operating temperature in the range from about 90 DEG to about 100 DEG C.; (d) producing a depleted brine in the anolyte chamber after electrolysis in which the potassium chloride consumed by electrolysis ranges from about 5 to about 15 percent by weight of the potassium chloride originally present in the brine feed, and (e) maintaining a catholyte potassium hydroxide concentration in the range from about 500 to about 600 grams potassium hydroxide per liter.
Inventors
- 👤 Richard W. Lynch
- 👤 Garland E. Hilliard
- 👤 Ronald L. Dotson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:39
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
166 words
A process for the production of potassium hydroxide in an electrolytic membrane cell by employing in combination: (a) a membrane comprised of a carboxylic acid substituted polymer prepared by reacting a fluorinated olefin with a comonomer having a functional group selected from the group consisting of carboxylic acid and a functional group which can be converted to carboxylic acid; (b) a potassium chloride brine feed through the anolyte chamber of the cell having a concentration in the range from about 250 to about 300 grams of potassium chloride per liter; (c) a cell operating temperature in the range from about 90 to about 100° C.; (d) producing a depleted brine in the anolyte chamber after electrolysis in which the potassium chloride consumed by electrolysis ranges from about 5 to about 15 percent by weight of the potassium chloride originally present in the brine feed, and, (e) maintaining a catholyte potassium hydroxide concentration in the range from about 500 to about 600 grams potassium hydroxide per liter.
Claim 2
Dependent Claim
166 words
A process for the production of potassium hydroxide in an electrolytic membrane cell by employing in combination: (a) a membrane comprised of a carboxylic acid substituted polymer prepared by reacting a fluorinated olefin with a comonomer having a functional group selected from the group consisting of carboxylic acid and a functional group which can be converted to carboxylic acid; (b) a potassium chloride brine feed through the anolyte chamber of the cell having a concentration in the range from about 250 to about 300 grams of potassium chloride per liter; (c) a cell operating temperature in the range from about 90 to about 100° C.; (d) producing a depleted brine in the anolyte chamber after electrolysis in which the potassium chloride consumed by electrolysis ranges from about 5 to about 15 percent by weight of the potassium chloride originally present in the brine feed, and, (e) maintaining a catholyte potassium hydroxide concentration in the range from about 500 to about 600 grams potassium hydroxide per liter.
Claim 3
Dependent Claim
68 words
The process of claim 1, wherein said carboxylic acid substituted polymer is a copolymer of tetrafluoroethylene and ##STR4## prepared with a catalyst of azobisisobutyronitrile in trichlorotrifluorethane to obtain a fluorinated copolymer having an ion exchange capacity of about 1.17 meq/g polymer and a T g of 190° C. press molded to form a film about 200 microns thick thereafter hydrolyzed in an aqueous methanol solution of sodium hydroxide.
Claim 4
Dependent Claim
72 words
The process of claim 1, wherein said carboxylic acid substituted polymer is a copolymer of tetrafluoroethylene acid CF 2 ═CFO--(CF 2 ) 3 --COOCH 3 copolymerized with a catalyst of azobisisobutyronitrile to obtain a fluorinated copolymer having an ion exchange capacity of about 1.45 meq/g polymer and a T g of about 235° C., press molded to form a film of thickness about 200 microns, hydrolyzed in aqueous methanol of sodium hydroxide.
Claim 5
Dependent Claim
96 words
The process of claim 1, wherein said carboxylic acid substituted polymer is a copolymer of tetrafluoroethylene and CF 2 ═CFO--(CF 2 ) 3 COOCH 3 (A) and CF 2 ═CFOCF 2 CF(CF 3 )O(CF 2 ) 3 COOCH 3 (B) copolymerized with a catalyst of azobisisobutyronitrile (mole ratios A/B of about 4:1) to obtain a fluorinated copolymer having an ion exchange capacity of about 1.45 meq/g polymer and T g of about 220° C., press molded to obtain a film of about 200 microns thickness, and hydrolyzed in an Aqueous solution of methanol of sodium hydroxide.
Claim 6
Dependent Claim
113 words
The process of claim 4, wherein said carboxylic acid substituted acid polymer is a copolymer of tetrafluoroethylene and CF 2 ═CFO(CF 2 ) 3 ═COOCH 3 with a catalyst of ammonium persulfate in water to obtain a fluorinated copolymer having an ion-exchange capacity of 1.20 meq/g polymer and T g of 210° C. The copolymer extruded to obtain a film having a thickness of 240 microns and width of 15 cm, and plied to a cloth made of copolymer of tetrafluoroethylene and ethylene (50 mesh:thickness 150 microns) compress-molded to form a reinforced film and hydrolyzed in an aqueous methanol solution of sodium hydroxide to obtain a carboxylic acid type fluorinated cation exchange membrane.
Claim 7
Dependent Claim
27 words
The process of claims 2,3,4, or 5, wherein said electrolytic cell is operated at a temperature in the range from about 90° C. to about 95° C.
Claim 8
Dependent Claim
33 words
The process of claim 6, wherein said potassium chloride present in the potassium chloride brine fed to said cell is depleted in the range from about 5 to about 10 percent during electrolysis.
References Cited (Backward Citations)
US4065366A
Cited
US4065366B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-11-11 | 1984-05-12 | 1984-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-11 | 1988-05-12 | 1988-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-11 | 1992-05-12 | 1992-11-11 | $7700.00 | Window Closed / Lapsed |