US4236980A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for alkali metal chloride electrolysis
Assignee: Hoechst AG
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Filing: 1979-10-18
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Granted: 1980-12-02
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Expires: 1999-10-18
Abstract
Abstract For the electrolysis of an aqueous alkali metal chloride solution in a membrane cell with a perfluorinated cation exchange membrane it is important that there is only a minimum amount of cations of polyvalent metals, such as calcium. Otherwise, deposits within the membrane will occur, among other effects. It has been found that the disturbances caused by the above-mentioned cations can be considerably reduced, if an aliphatic polybasic phosphonic acid or the alkali metal salt thereof is added to the alkali metal chloride solution.
Inventors
- 👤 Nikolaj Medic
- 👤 Theodor Auel
- 👤 Dieter Bergner
- 👤 Jurgen Russow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:50
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/46
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
56 words
Process for the electrolysis of an aqueous alkali metal chloride solution which is contaminated by cations of polyvalent metals, in an electrolysis cell whose anode and cathode compartments are separated by a perfluorinated cation exchange membrane, which comprises adding to the alkali metal chloride solution an aliphatic polybasic phosphonic acid or the alkali metal salt thereof.
Claim 2
Dependent Claim
56 words
Process for the electrolysis of an aqueous alkali metal chloride solution which is contaminated by cations of polyvalent metals, in an electrolysis cell whose anode and cathode compartments are separated by a perfluorinated cation exchange membrane, which comprises adding to the alkali metal chloride solution an aliphatic polybasic phosphonic acid or the alkali metal salt thereof.
Claim 3
Dependent Claim
15 words
A process as claimed in claim 1, wherein the phosphonic acid is free of nitrogen.
Claim 4
Dependent Claim
25 words
A process as claimed in claim 1, wherein the phosphonic acid contains at least 2 PO 3 H 2 or COOH groups in the molecule.
Claim 5
Dependent Claim
24 words
A process as claimed in claim 1, which comprises interrupting the electrolysis current for a short time once to 10 times per 24 hours.
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) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |