US4127457A
Expired / Lapsed
US
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Method of reducing chlorate formation in a chlor-alkali electrolytic cell
Assignee: BASF Corp
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Filing: 1978-03-01
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Granted: 1978-11-28
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Expires: 1998-03-01
Abstract
Abstract In a chlor-alkali electrolytic cell in which an aqueous alkali metal chloride solution is electrolyzed, said electrolytic cell having an anode compartment containing an anode and a cathode compartment containing a cathode separated by a substantially fluid impervious membrane barrier consisting of a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether, the formation of alkali metal chlorates in the anode compartment is reduced by operating the chlor-alkali cell at high salt conversions greater than 40% and preferably between about 60% and about 80% conversion.
Inventors
- 👤 Michael Krumpelt
- 👤 Stanley T. Hirozawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:58
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
126 words
In a process wherein an aqueous alkali metal chloride solution is electrolyzed in an electrolytic cell having an anode compartment containing an anode and anolyte and a cathode compartment containing a cathode and catholyte and a substantially fluid impervious selectively permeable barrier separating the anode and cathode compartments and wherein said alkali metal chloride solution is continuously circulated through said anode compartment, the improvement comprising reducing chlorate formation in said anolyte by introducing an alkali metal chloride solution into said anode compartment and operating said cell at an alkali metal chloride conversion factor of between 40% and 80% and removing alkali metal hydroxide from said cathode compartment so as to maintain an alkali metal hydroxide concentration of about 15 percent to about 20 percent by weight.
Claim 2
Dependent Claim
126 words
In a process wherein an aqueous alkali metal chloride solution is electrolyzed in an electrolytic cell having an anode compartment containing an anode and anolyte and a cathode compartment containing a cathode and catholyte and a substantially fluid impervious selectively permeable barrier separating the anode and cathode compartments and wherein said alkali metal chloride solution is continuously circulated through said anode compartment, the improvement comprising reducing chlorate formation in said anolyte by introducing an alkali metal chloride solution into said anode compartment and operating said cell at an alkali metal chloride conversion factor of between 40% and 80% and removing alkali metal hydroxide from said cathode compartment so as to maintain an alkali metal hydroxide concentration of about 15 percent to about 20 percent by weight.
Claim 3
Dependent Claim
42 words
The process of claim 1 wherein said selectively permeable barrier consists essentially of a hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether having an equivalent weight number of about 1000 to about 1500 and a thickness of 0.1 to 0.4 millimeter.
Claim 4
Dependent Claim
21 words
The process of claim 1 wherein said alkali metal chloride is sodium chloride and said alkali metal hydroxide is sodium hydroxide.
Claim 5
Dependent Claim
33 words
The process of claim 3 wherein said anode comprises a titanium substrate coated with an activating coating containing at least one material selected from the platinum group metals and the platinum group oxides.
Claim 6
Dependent Claim
20 words
The process of claim 4 wherein said cathode comprises a steel substrate coated with nickel by a plasma spraying process.
Claim 7
Dependent Claim
13 words
The process of claim 5 wherein said anode comprises a ruthenium activating coating.
Claim 8
Dependent Claim
20 words
The process of claim 4 wherein said cathode comprises a steel substrate coated with nickel by an electroless coating process.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-27 | 1982-05-29 | 1982-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-27 | 1986-05-29 | 1986-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-27 | 1990-05-29 | 1990-11-28 | $7700.00 | Window Closed / Lapsed |