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Patent US4224121A successfully refreshed from Google Patents.
US4224121A
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US
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Production of halogens by electrolysis of alkali metal halides in an electrolysis cell having catalytic electrodes bonded to the surface of a solid polymer electrolyte membrane
Assignee: De Nora SpA
•
Filing: 1978-07-06
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Granted: 1980-09-23
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Expires: 1998-07-06
Abstract
Abstract A halogen, such as chlorine, is generated by electrolysis of an aqueous solution of an alkali metal halide such as sodium chloride, in a cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively cation permeable, ion exchange membrane. One or more catalytic electrodes including at least one thermally stabilized, reduced oxide of a platinum group metal are bonded to the surface of the membrane. An aqueous brine solution is brought into contact with the anode and water or an aqueous NaOH solution is brought into contact with the cathode. The brine is electrolyzed to produce chlorine at the anode and hydrogen and caustic at the cathode. The cell membrane preferably has an anion rejecting cathode side barrier layer which rejects hyroxyl ions to block back migration of caustic to the anode thereby enhancing the cathode current efficiency of the cell and of the process.
Inventors
- 👤 Russell M. Dempsey
- 👤 Thomas G. Coker
- 👤 Anthony B. LaConti
- 👤 Anthony R. Fragala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:58
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/24; C25B1/26; C25B1/34; C25B1/46; C25B11/00; C25B11/04; C25B11/051; C25B11/073; C25B11/091; C25B11/095; Y; Y10; Y10S; Y10S204/00; Y10S204/03
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
240 words
A process for the continuous production of chlorine by the electrolysis of alkali metal chloride which comprises: (a) continuously bringing an aqueous alkali metal chloride solution to the anode chamber of an electrolytic cell which is separated from the cathode chamber by a cation selective ion exchange membrane, (b) bringing the solution into contact with a porous, gas permeable, particulate anode electrode bonded to and embedded in the membrane on the side facing the anode chamber, whereby the catalytic sites in the electrode are in contact with the ion exchanging sites of the membrane so that electrolysis can take place directly at the membrane-electrode interface, said anode being opposite to a porous, gas permeable, particulate cathode bonded to the other side of the membrane. (c) continuously bringing an aqueous medium selected from the group consisting of water and dilute caustic into the cathode chamber and into contact with the catalytic cathode electrode to provide a source of hydroxyl ions at the cathode and for continuously sweeping the cathode electrodes to dilute caustic formed at the cathode, (d) supplying current to the electrodes through current collectors in physical contact with the electrodes bonded to the membrane to electrolyze the alkali metal chloride at the anode to produce chlorine and to electrolyze water at the cathode to produce alkali metal hydroxide and hydrogen, (e) continuously removing chlorine from the anode compartment and alkali metal hydroxide and hydrogen from from the cathode compartment.
Claim 2
Dependent Claim
240 words
A process for the continuous production of chlorine by the electrolysis of alkali metal chloride which comprises: (a) continuously bringing an aqueous alkali metal chloride solution to the anode chamber of an electrolytic cell which is separated from the cathode chamber by a cation selective ion exchange membrane, (b) bringing the solution into contact with a porous, gas permeable, particulate anode electrode bonded to and embedded in the membrane on the side facing the anode chamber, whereby the catalytic sites in the electrode are in contact with the ion exchanging sites of the membrane so that electrolysis can take place directly at the membrane-electrode interface, said anode being opposite to a porous, gas permeable, particulate cathode bonded to the other side of the membrane. (c) continuously bringing an aqueous medium selected from the group consisting of water and dilute caustic into the cathode chamber and into contact with the catalytic cathode electrode to provide a source of hydroxyl ions at the cathode and for continuously sweeping the cathode electrodes to dilute caustic formed at the cathode, (d) supplying current to the electrodes through current collectors in physical contact with the electrodes bonded to the membrane to electrolyze the alkali metal chloride at the anode to produce chlorine and to electrolyze water at the cathode to produce alkali metal hydroxide and hydrogen, (e) continuously removing chlorine from the anode compartment and alkali metal hydroxide and hydrogen from from the cathode compartment.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein the porous, gas permeable, particulate anode is reduced, platinum group metal oxides.
Claim 4
Dependent Claim
19 words
The process of claim 2 wherein the porous, gas permeable, particulate anode is temperature stabilized, reduced oxides of ruthenium.
Claim 5
Dependent Claim
45 words
The process of claim 3 wherein the porous gas permeable, particulate anode in which the reduced oxides of ruthenium are further stabilized by the inclusion of reduced metallic oxides chosen from the group consisting of the reduced oxides of iridium, tantalum, titanium, niobium and hafnium.
Claim 6
Dependent Claim
30 words
The process of claim 4 wherein an aqueous NaCl solution brought into contact with a porous, gas permeable, particulate anode is reduced oxides of ruthenium and reduced oxides of iridium.
Claim 7
Dependent Claim
37 words
The process of claim 5 wherein the aqueous NaCl solution brought into contact with a porous, gas permeable, particulate anode is reduced oxides of ruthenium and of 5% to 25% by weight of reduced oxides of iridium.
Claim 8
Dependent Claim
35 words
The process of claim 5 wherein the aqueous NaCl solution is brought into contact with a porous, gas permeable, particulate anode is reduced oxides of ruthenium and 25% by weight of reduced oxides of iridium.
Claim 9
Dependent Claim
30 words
The process of claim 4 wherein the aqueous solution is brought into contact with a porous, gas permeable, particulate anode is reduced oxides of ruthenium and reduced oxides of tantalum.
Claim 10
Dependent Claim
27 words
The process of claim 3 wherein the aqueous solution is brought into contact with a porous, gas permeable, particulate anode is reduced oxides of ruthenium and graphite.
Claim 11
Dependent Claim
76 words
In the process of generating halogen and alkali metal hydroxide by electrolysis of aqueous alkali metal halide containing at least 150 grams of halide per liter of solution by means of a pair of catalytic electrodes separated by an ion permeable membrane, the improvement which comprises conducting the electrolysis with an electrode comprising a plurality of thermally stabilized, reduced oxide particles of platinum group metals bonded to and embedded in the cathodic side of the membrane.
Claim 12
Dependent Claim
76 words
In the process of generating halogen and alkali metal hydroxide by electrolysis of aqueous alkali metal halide containing at least 150 grams of halide per liter of solution by means of a pair of catalytic electrodes separated by an ion permeable membrane, the improvement which comprises conducting the electrolysis with an electrode comprising a plurality of thermally stabilized, reduced oxide particles of platinum group metals bonded to and embedded in the cathodic side of the membrane.
Claim 13
Dependent Claim
40 words
The process according to claim 10 wherein a layer of particles of thermally stabilized, reduced oxides of a platinum group metal is bonded to opposite sides of the membrane to form gas and electrolyte permeable catalytic anode and cathode electrodes.
Claim 14
Dependent Claim
25 words
The process according to claim 11 wherein the thermally stabilized, reduced oxide particles of a platinum group metal are bonded together by a fluorocarbon polymer.
Claim 15
Dependent Claim
114 words
A process for generating chlorine by electrolyzing an aqueous alkali metal chloride with a minimum concentration of 150 grams of chloride per liter of solution between anode and cathode electrodes separated by an ion exchange membrane which restrains flow of aqueous electrolyte therethrough, which comprises conducting said electrolysis with a cathode comprising a thin layer of electrochemically active particles of a material of the group consisting essentially of a platinum group metal and/or conductive oxides thereof, said layer being bonded to one side of said membrane to form a unitary membrane-electrode and in contact with a current distributor exposed to the electrolyte and having a hydrogen overvoltage higher than said cathode layer of particles.
Claim 16
Dependent Claim
114 words
A process for generating chlorine by electrolyzing an aqueous alkali metal chloride with a minimum concentration of 150 grams of chloride per liter of solution between anode and cathode electrodes separated by an ion exchange membrane which restrains flow of aqueous electrolyte therethrough, which comprises conducting said electrolysis with a cathode comprising a thin layer of electrochemically active particles of a material of the group consisting essentially of a platinum group metal and/or conductive oxides thereof, said layer being bonded to one side of said membrane to form a unitary membrane-electrode and in contact with a current distributor exposed to the electrolyte and having a hydrogen overvoltage higher than said cathode layer of particles.
Claim 17
Dependent Claim
21 words
The process, according to claim 13, wherein the current distributor is in contact with an electrolyte comprising an alkali metal hydroxide.
Claim 18
Dependent Claim
118 words
A process of generating chlorine by electrolyzing an aqueous alkali metal chloride having a minimum concentration of 150 grams of chloride per liter of solution between an anode and a cathode separated by an ion exchange membrane which restrains flow of aqueous electrolyte therethrough, which comprises conducting the electrolysis with an anode comprising a thin layer of electrochemically active particles, consisting essentially of platinum group metals and/or conductive oxides thereof, said layer being in contact with and bonded to one side of the membrane to form a unitary membrane electrode and in contact with a current distributor exposed to said aqueous alkali metal chloride and having a surface of higher chlorine overvoltage than said anode layer of particles.
Claim 19
Dependent Claim
118 words
A process of generating chlorine by electrolyzing an aqueous alkali metal chloride having a minimum concentration of 150 grams of chloride per liter of solution between an anode and a cathode separated by an ion exchange membrane which restrains flow of aqueous electrolyte therethrough, which comprises conducting the electrolysis with an anode comprising a thin layer of electrochemically active particles, consisting essentially of platinum group metals and/or conductive oxides thereof, said layer being in contact with and bonded to one side of the membrane to form a unitary membrane electrode and in contact with a current distributor exposed to said aqueous alkali metal chloride and having a surface of higher chlorine overvoltage than said anode layer of particles.
Claim 20
Dependent Claim
16 words
The process, according to claim 15, wherein the particles are bonded together by a fluorocarbon polymer.
Claim 21
Dependent Claim
17 words
The process, according to claim 16, wherein the anode layer is bonded to a cation exchange membrane.
Claim 22
Dependent Claim
19 words
The process, according to claim 17, wherein the anode layer is bonded to a fluorocarbon sulfonic acid cation membrane.
Claim 23
Dependent Claim
97 words
In a process for generating halogens and alkali hydroxides which comprises electrolyzing an aqueous alkali metal halide between an anode and a cathode electrode separated by a polymeric cation exchange membrane, at least one of the electrodes comprising plurality of electroconductive catalytic particles bonded to and embedded in said membrane to provide a gas and electrolyte permeable electrode, wherein the cathode side of said membrane has a lower water content than the remaining portion to provide an anion barrier which rejects the hydroxyl ions and minimizes diffusion of the alkali across the membrane to the anode electrode.
Claim 24
Dependent Claim
97 words
In a process for generating halogens and alkali hydroxides which comprises electrolyzing an aqueous alkali metal halide between an anode and a cathode electrode separated by a polymeric cation exchange membrane, at least one of the electrodes comprising plurality of electroconductive catalytic particles bonded to and embedded in said membrane to provide a gas and electrolyte permeable electrode, wherein the cathode side of said membrane has a lower water content than the remaining portion to provide an anion barrier which rejects the hydroxyl ions and minimizes diffusion of the alkali across the membrane to the anode electrode.
Claim 25
Dependent Claim
37 words
The process according to claim 19, wherein the composite membrane is a laminate of two layeres in which the anion rejection characteristic of the cathode side barrier layer is greater than that of the anode side layer.
Claim 26
Dependent Claim
25 words
The process, according to claim 20, wherein the membrane is a polymeric fluorocarbon cation exchange membrane having an anion rejecting cathode side sulfonamide barrier layer.
Claim 27
Dependent Claim
27 words
The process, according to claim 21, wherein the cathode side sulfonamide layer of the membrane has a cathode consisting of a plurality of electroconductive particles bonded thereto.
Claim 28
Dependent Claim
25 words
The process, according to claim 22, wherein the anode side of the membrane has an anode consisting of a plurality of electroconductive particles bonded thereto.
Claim 29
Dependent Claim
101 words
A process of generating chlorine which comprises electrolyzing aqueous alkali metal chloride at least 2.5 molar in concentration between a pair of gas permeable electrodes comprising an anode and cathode separated by a cation exchange membrane, the electrochemically active area of at least one of said electrodes being electrochemically active particles directly bonded to the membrane whereby ionic current may flow directly between the electrodes and the membrane without passage through an intervening body of fluid electrolyte, maintaining the anode in contact with alkali metal chloride at least 2.5 molar in concentration and maintaining the cathode in contact with aqueous alkali.
Claim 30
Dependent Claim
101 words
A process of generating chlorine which comprises electrolyzing aqueous alkali metal chloride at least 2.5 molar in concentration between a pair of gas permeable electrodes comprising an anode and cathode separated by a cation exchange membrane, the electrochemically active area of at least one of said electrodes being electrochemically active particles directly bonded to the membrane whereby ionic current may flow directly between the electrodes and the membrane without passage through an intervening body of fluid electrolyte, maintaining the anode in contact with alkali metal chloride at least 2.5 molar in concentration and maintaining the cathode in contact with aqueous alkali.
Claim 31
Dependent Claim
29 words
The process according to claim 24 wherein both anode and cathode are gas permeable and the active areas thereof are directly bonded to the opposite sides of the membrane.
Claim 32
Dependent Claim
37 words
The process according to claim 24 wherein the anode is bonded to the membrane and comprises particles of a platinum group metal and or oxides thereof bonded to the membrane and to each other by a fluorocarbon.
Claim 33
Dependent Claim
92 words
A process of generating chlorine which comprises electrolyzing an aqueous chloride containing at least 150 grams of chloride per liter of solution between anode and cathode separated by an ion exchange membrane, the cathode being a layer of electrochemically active particles bonded to the membrane to form a unitary electrode membrane structure and supplying potential to the cathode by a current distributor which has an electronically conductive surface in contact with the cathode and is exposed to the catholyte, said cathode having a lower hydrogen overvoltage than the electroconductive current distributor surface.
Claim 34
Dependent Claim
92 words
A process of generating chlorine which comprises electrolyzing an aqueous chloride containing at least 150 grams of chloride per liter of solution between anode and cathode separated by an ion exchange membrane, the cathode being a layer of electrochemically active particles bonded to the membrane to form a unitary electrode membrane structure and supplying potential to the cathode by a current distributor which has an electronically conductive surface in contact with the cathode and is exposed to the catholyte, said cathode having a lower hydrogen overvoltage than the electroconductive current distributor surface.
Claim 35
Dependent Claim
30 words
The process according to claim 27 wherein the cathode comprises a layer of particles of a platinum group metal or oxides thereof bonded to the cathode side of the membrane.
Claim 36
Dependent Claim
81 words
A process of generating chlorine which comprises electrolyzing an aqueous chloride containing at least 150 grams of said chloride per liter of solution between a cathode separated from the anode by an ion exchange membrane, the anode being electrochemically active particles bonded to the membrane, supplying potential to the anode by a current distributor which has an electroconductive surface which contacts the anode and is exposed to the chloride electrolyte, said anode having a lower chlorine overvoltage than the current distributor.
Claim 37
Dependent Claim
81 words
A process of generating chlorine which comprises electrolyzing an aqueous chloride containing at least 150 grams of said chloride per liter of solution between a cathode separated from the anode by an ion exchange membrane, the anode being electrochemically active particles bonded to the membrane, supplying potential to the anode by a current distributor which has an electroconductive surface which contacts the anode and is exposed to the chloride electrolyte, said anode having a lower chlorine overvoltage than the current distributor.
Claim 38
Dependent Claim
18 words
The process according to claim 29 wherein the voltage between the anode and cathode is below 3.7 volts.
Claim 39
Dependent Claim
130 words
A process of generating chlorine which comprises feeding aqueous alkali metal chloride containing at least 150 grams of alkali metal chloride per liter of solution into the anode compartment of an electrolytic cell having anode and cathode compartments separated by a cation exchange membrane having gas permeable layers of electrolytically resistant, electrochemically active, electrode particles bonded together and to opposite sides of the membrane, the membrane and its layers being sandwiched between and in contact with a pair of electroconductive current distributors having surfaces resistant to ttack by electrolyte to which they are exposed, applying a potential of opposite polarity to said current distributors, maintaining aqueous alkali metal chloride of at least said chloride concentration in contact with the anode and maintaining an alkaline solution in contact with the cathode.
Claim 40
Dependent Claim
130 words
A process of generating chlorine which comprises feeding aqueous alkali metal chloride containing at least 150 grams of alkali metal chloride per liter of solution into the anode compartment of an electrolytic cell having anode and cathode compartments separated by a cation exchange membrane having gas permeable layers of electrolytically resistant, electrochemically active, electrode particles bonded together and to opposite sides of the membrane, the membrane and its layers being sandwiched between and in contact with a pair of electroconductive current distributors having surfaces resistant to ttack by electrolyte to which they are exposed, applying a potential of opposite polarity to said current distributors, maintaining aqueous alkali metal chloride of at least said chloride concentration in contact with the anode and maintaining an alkaline solution in contact with the cathode.
Claim 41
Dependent Claim
23 words
The process according to claim 31 wherein the voltage applied between the anode and cathode by the current distributors is below 3.7 volts.
Claim 42
Dependent Claim
18 words
The process accirding to claim 32 wherein the current density is at least 100 amperes per square foot.
Claim 43
Dependent Claim
70 words
A process for generating chlorine which comprises electrolyzing an aqueous alkali metal chloride containing at least 2.5 molar chloride concentration between a pair of opposed electrodes comprising anode and cathode separated by an ion exchange membrane at least one of said electrodes bonded directly to the membrane to form a unitary membrane electrode structure, said electrode comprising a particulate mixture of graphite and a platinum group metal and/or oxide thereof.
Claim 44
Dependent Claim
70 words
A process for generating chlorine which comprises electrolyzing an aqueous alkali metal chloride containing at least 2.5 molar chloride concentration between a pair of opposed electrodes comprising anode and cathode separated by an ion exchange membrane at least one of said electrodes bonded directly to the membrane to form a unitary membrane electrode structure, said electrode comprising a particulate mixture of graphite and a platinum group metal and/or oxide thereof.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-23 | 1984-03-24 | 1984-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-23 | 1988-03-24 | 1988-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-23 | 1992-03-24 | 1992-09-23 | $7700.00 | Window Closed / Lapsed |