Patent US4147600A successfully refreshed from Google Patents.
US4147600A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrolytic method of producing concentrated hydroxide solutions
Assignee: Occidental Chemical Corp
•
Filing: 1978-01-06
•
Granted: 1979-04-03
•
Expires: 1998-01-06
Abstract
Abstract A method for economically producing a concentrated alkali metal hydroxide solution by electrolytic means is described. The method involves the tandem operation of diaphragm and membrane electrolytic cells. More particularly, the cell liquor from the diaphragm cell or cells is utilized in place of all or part of the water usually utilized in the catholyte compartment of the membrane cell or cells.
Inventors
- 👤 John Rutherford
- 👤 Charles F. Eggers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 04:05
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
189 words
A method of electrolytically producing a concentrated aqueous alkali metal hydroxide solution utilizing a diaphragm electrolytic cell and a membrane electrolytic cell comprising the steps of: (a) feeding aqueous alkali metal halide into a diaphragm electrolytic cell, said cell having a permeable diaphragm separating an anolyte and a catholyte compartment, (b) electrolytically decomposing said alkali metal halide to produce halogen in the anolyte compartment and hydrogen and alkali metal hydroxide in the catholyte compartment, (c) removing an aqueous solution comprising alkali metal hydroxide and alkali metal halide from said catholyte compartment, (d) feeding said solution into the catholyte compartment of a membrane electrolytic cell, while feeding an aqueous alkali metal halide solution into the anolyte compartment of the membrane cell, said membrane electrolytic cell having a permselective membrane positioned between the catholyte and anolyte compartments, (e) electrolytically decomposing additional alkali metal halide in said membrane cell to produce halogen in the anolyte compartment and hydrogen and alkali metal hydroxide in the catholytic compartment, and, (f) removing from the catholyte compartment of said membrane cell a concentrated aqueous alkali metal hydroxide solution having a reduced concentration of alkali metal halide.
Claim 2
Independent Claim
189 words
A method of electrolytically producing a concentrated aqueous alkali metal hydroxide solution utilizing a diaphragm electrolytic cell and a membrane electrolytic cell comprising the steps of: (a) feeding aqueous alkali metal halide into a diaphragm electrolytic cell, said cell having a permeable diaphragm separating an anolyte and a catholyte compartment, (b) electrolytically decomposing said alkali metal halide to produce halogen in the anolyte compartment and hydrogen and alkali metal hydroxide in the catholyte compartment, (c) removing an aqueous solution comprising alkali metal hydroxide and alkali metal halide from said catholyte compartment, (d) feeding said solution into the catholyte compartment of a membrane electrolytic cell, while feeding an aqueous alkali metal halide solution into the anolyte compartment of the membrane cell, said membrane electrolytic cell having a permselective membrane positioned between the catholyte and anolyte compartments, (e) electrolytically decomposing additional alkali metal halide in said membrane cell to produce halogen in the anolyte compartment and hydrogen and alkali metal hydroxide in the catholytic compartment, and, (f) removing from the catholyte compartment of said membrane cell a concentrated aqueous alkali metal hydroxide solution having a reduced concentration of alkali metal halide.
Claim 3
Dependent Claim
37 words
The method of claim 1 wherein the permselective membrane is a hydrolyzed copolymer of tetrafluoroethylene and a fluorosulfonated perfluorovinyl ether, having the general formula: FSO 2 CF 2 CF 2 OCF(CF 3 )CF 2 OCF═CF 2 .
Claim 4
Dependent Claim
29 words
The method of claim 2 wherein the membrane electrolytic cell contains a buffer compartment separating said anolyte and said catholyte compartments, said buffer compartment formed between two permselective membranes.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein the alkali metal halide is sodium chloride.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein the permeable diaphragm consists of an asbestos diaphragm.
Claim 7
Dependent Claim
23 words
The method of claim 1 wherein the concentrated alkali metal hydroxide solution contains at least about 200 grams per liter alkali metal hydroxide.
Claim 8
Dependent Claim
29 words
The method of claim 1 wherein the concentrated alkali metal hydroxide solution is evaporated to produce a product containing at least about 50 percent by weight alkali metal hydroxide.
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) | 1982-04-02 | 1982-10-02 | 1983-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-02 | 1986-10-02 | 1987-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-02 | 1990-10-02 | 1991-04-03 | $7700.00 | Window Closed / Lapsed |