US3882002A - Anode for electrolytic processes - Google Patents

Anode for electrolytic processes Download PDF

Info

Publication number
US3882002A
US3882002A US494110A US49411074A US3882002A US 3882002 A US3882002 A US 3882002A US 494110 A US494110 A US 494110A US 49411074 A US49411074 A US 49411074A US 3882002 A US3882002 A US 3882002A
Authority
US
United States
Prior art keywords
oxide
anode
tin oxide
coating
noble metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US494110A
Inventor
Jr Edward H Cook
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ELECTRODE Corp A DE CORP
Oxytech Systems Inc
Original Assignee
Hooker Chemicals and Plastics Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hooker Chemicals and Plastics Corp filed Critical Hooker Chemicals and Plastics Corp
Priority to US494110A priority Critical patent/US3882002A/en
Priority to AR259713A priority patent/AR205045A1/en
Priority to US05/553,860 priority patent/US3986942A/en
Priority to US05/564,529 priority patent/US3951766A/en
Priority to US05/574,478 priority patent/US3943042A/en
Priority to US05/574,805 priority patent/US3940323A/en
Priority to US05/574,806 priority patent/US3956083A/en
Publication of US3882002A publication Critical patent/US3882002A/en
Application granted granted Critical
Priority to CA230,660A priority patent/CA1058563A/en
Priority to GB29900/75A priority patent/GB1485884A/en
Priority to DE19752532553 priority patent/DE2532553A1/en
Priority to NL7508764A priority patent/NL7508764A/en
Priority to BR7504830*A priority patent/BR7504830A/en
Priority to SE7508697A priority patent/SE7508697L/en
Priority to FR7523984A priority patent/FR2280718A1/en
Priority to IT25973/75A priority patent/IT1040223B/en
Priority to BE158853A priority patent/BE832010A/en
Priority to JP50094673A priority patent/JPS592753B2/en
Assigned to OCCIDENTAL CHEMICAL CORPORATION reassignment OCCIDENTAL CHEMICAL CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE APRIL 1, 1982. Assignors: HOOKER CHEMICALS & PLASTICS CORP.
Assigned to DIAMOND SHAMROCK TECHNOLOGIES, S.A. reassignment DIAMOND SHAMROCK TECHNOLOGIES, S.A. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: OCCIDENTAL CHEMICAL CORPORATION
Assigned to OXYTECH SYSTEMS, INC. reassignment OXYTECH SYSTEMS, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: OCCIDENTAL CHEMICAL CORPORATION, A NY CORP
Assigned to ELECTRODE CORPORATION, A DE CORP. reassignment ELECTRODE CORPORATION, A DE CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DIAMOND SHAMROCK TECHNOLOGIES, S.A.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
    • C25B11/093—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one noble metal or noble metal oxide and at least one non-noble metal oxide

Definitions

  • the present invention relates to improved electrodes particularly adapted for use as anodes in electrochemical process involving the electrolysis of brines.
  • the electrical conductivity of the noble metals is substantially higher and the chlorine overvoltage substantially lower than that of graphite.
  • the dimensional stability of the noble metals and noble metal oxides represents a substantial improvement over graphite.
  • the use of noble metals as a major material of construction in anodes results in an economic disadvantage due to the excessively high cost of such materials.
  • This invention provides a novel electrode. especially suited for use as an anode in chlor-alkali cells; the novel electrode comprising a valve metal substrate having a protective coating of conductive tin oxide on the surface thereof and an outer. thin layer of a noble metal or noble metal oxide. Electrodes of this type exhibit a high degree of durability in addition to the relatively low overvoltage characteristics of a noble metal or noble metal oxide. making them wellsuited for use as anodes in the electrolytic production of chorine.
  • the preferred substrate materials of the anodes of the invention are the valve metals. such as titanium. tantalum. niobium or zirconium. especially titanium. However. where suitably thick intermediate layers of tin oxide are employed. other more conductive metals may be considered for use as substrates.
  • the tin oxide coating which may range in coating weight from about 0.l grams per square meter to lOO grams per square meter or more. depending on the degree of protection desired. prevents contact of the substrate and the electrolyte, thus preventing or minimizing corrosion or surface oxidation and the attendant deterioration or passivation of the substrate. At the same time.
  • the outer layer provides the advantageous catalytic properties of the noble metals or noble metal oxides.
  • the protective layer of conductive tin oxide permits the use ofa relatively thin layer of the noble metal or noble metal oxide and a consequent savings resulting from a minimal use of the precious metal.
  • the layer of noble metal or noble metal oxide will have a coating weight in the range of about 0.] grams per square meter to about 20 grams per square meter or higher and preferably about 3 to [0 grams per square meter in thickness.
  • the disadvantage of pores or pinholes in the noble metal layer common in extremely thin layers is obviated by the presence of the intermediate layer of conductive tin oxide. Pores or pinholes in the noble metal layer.
  • the intermediate layer of tin oxide will continue to provide a catalytically active surface in those exposed areas.
  • the catalytic character istics of tin oxide although not as high as the noble metals or noble metal oxides. is quite substantially higher than the valve metal oxide. Thus. the overall deterioration of the catalytic properties of the anode is more gradual and maintenance problems are accordingly lessened.
  • the intermediate layer of tin oxide provides an increase in surface area of the anode with a consequent improvement in overvoltage. It has further been found that the adhesion of the noble metal or noble metal oxide to the substrate is increased by the presence of the intermediate layer of tin oxide and the problem of spalling of the surface layer is thereby reduced.
  • valve metal substrate which forms the inner or base component of the electrode is an electroconductive metal having sufficient mechanical strength to serve as a support for the coating and having a high degree of chemical resistivity, especially to the anodic environment of electrolytic cells.
  • Typical valve metals include. for example. Ti. Ta. Nb. Zr. and alloys thereof.
  • the valve metals are well known for their tendency to form an inert oxide film upon exposure to an anodic environment.
  • the preferred valve metal. based on cost and availability as well as electrical and chemical properties is titanium.
  • the conductivity ofthe substrate may be improved. if desired. by providing a central core of a highly conductive metal such as copper. in such an arrangement. the core must be electrically connected to and completely protected by the valve metal substrate.
  • Tin oxide can be readily formed as an adherent coat ing on a valve metal substrate, in a manner described hereinafter. to provide a protective. electrically conductive layer which is especially resistant to chemical attack in anodic environments. Pure tin oxide however has a relatively high electrical resistivity in comparison to metals and exhibits undesireble change in electrical resistivity as a function of temperature. It is well known that the electrical stability oftin oxide coatings may be substantially improved and the electrical resistivity lowered through the introduction of a minor proportion of a suitable inorganic material (commonly referred to as a dopant). A variety of materials. especially various metal oxides and other metal compounds and mixtures thereof.
  • fluorine compounds especially the metal salts of fluorine. such as sodium fluoride. potassium fluoride. lithium fluoride. berylium fluoride. aluminum fluoride. lead fluoride. chromium fluoride. calcium fluoride. and other metal fluorides. hydrazine. phenylhydrazine; phosphorus compounds such as phosphorus chloride.
  • the conductive tin oxide coatings of this invention comprise tin oxide. preferably containing a minor amount of a suitable dopant.
  • the preferred dopant is an antimony compound which may be added to the tin oxide coating composition either as an oxide or as a compound such as SbCl which may form the oxide when heated in an oxidizing atmosphere. Although the exact form of the antimony in the final coating is not certain.
  • compositions of this invention comprise mixtures of tin oxide and a minor amount of antimony oxide. the later being present preferably in an amount of between about 0.1 and 20 weight percent (calculated on the basis of total weight of SnO and Sb- O
  • Conductive tin oxide coatings may be adherently formed on the surface of the valve metal substrate by various methods known in the art. Typically such coatings may be formed by first chemically cleaning the substrate. for example. by degreasing and etching the surface in a suitable acid, e.g.. oxalic acid. then applying a solution of appropriate thermally decomposable salts.
  • the salts that may be employed include. in general. any thermally decomposable inorganic or organic salt or ester of tin and dopant. e.g.. antimony. including for example their chlorides. alkoxides, alkoxy halides. resinates. amines and the like.
  • Typical salts include for example. stannic chloride. dibutyltin dichloride. tin tetraethoxide. antimony trichloride. antimony pentachloride and the like.
  • Suitable solvents include for example. ethyl alcohol. propyl alcohol. butyl alcohol. pentyl alcohol. amyl alcohol. toluene. benzene and other organic solvents as well as water.
  • the solution of thermally decomposable salts containing for example. a salt of tin and a salt of antimony. or other dopant. in the desired proportions. may be applied to the cleaned surface of the valve metal substrate by painting. brushing. dipping. rolling. spraying or other method.
  • the coating is then dried by heating for example at about to 200 C for several minutes to evaporate the solvent. and then heating at a higher temperature. e.g.. 250 to 800 C in oxidizing atmosphere to convert the tin and antimony compounds'to their respective oxides.
  • the procedure may be repeated as many times as necessary to achieve a desired coating weight or thickness.
  • the final coating weight of this conductive tin oxide coating may vary considerably. but is preferably in the range of about 3 to about 30 grams per square meter.
  • a small amount. such as up to 3 percent by weight of a chlorine discharge catalyst such as at least one of the difluorides of manganese. iron. cobalt or nickel may by included in the tin oxide coating to lower the overpotential required for chlorine gas liberation in a chlor-alkali cell.
  • the chorine discharge catalyst may be added to the tin oxide coating by suspending a fine particulate preformed sinter of tin dioxide and the catalyst in the solution of thermally decomposable salts.
  • Such chlorine discharge catalysts in the tin oxide coating is not essential to the anodes of this invention but may be employed if desired in a known manner such as disclosed in US. Pat. No. 3.627.699.
  • the outer coating of the anode comprises a noble metal or noble metal oxide such as platinum. iridium. rhodium. palladium ruthenium or somium or mixtures or alloys of these metals or the oxides or mixtures of the oxides of these metals.
  • a noble metal or noble metal oxide such as platinum. iridium. rhodium. palladium ruthenium or somium or mixtures or alloys of these metals or the oxides or mixtures of the oxides of these metals.
  • An outer coating of a noble metal may be applied by known methods such as electroplating. chemical deposition from a platinum coating solution. spraying. or other methods.
  • the outer coating of the anode comprises a noble metal oxide.
  • Noble metal oxide coating may be applied by first depositing the noble metal in the metallic state and then oxidizing the noble metal coating. for example. by galvanic oxidation or chemical oxidation by means of an oxidant such as an oxidizing salt melt. or by heating to an elevated temperature. e.g.. 300 to 600 C or higher in an oxidizing atmosphere such as air oxygen. at atmospheric or superatmospheric pressures to convert the noble metal coating to a coating of the corresponding noble metal oxide.
  • Other suitable methods include. for example. electrophoretic deposition of the noble metal oxide; or application of a dispersion of the noble metal oxide in a carrier. such as alcohol. by spraying. brushing. rolling. dipping.
  • a preferred method for the formation of the noble metal oxide coating involves coating the conductive tin oxide surface with a solution of a noble metal compound. evaporating the solvent and converting the coating of noble metal compound to the oxide by chemical or electrochemical reaction.
  • the conductive tin oxide surface may be coated with a solution of a thermally decomposable salt of a noble metal. such as a solution of a noble metal halide in an alcohol. evaporation of the solvent.
  • EXAMPLE I lA Preparation of conductive tin oxide coating A strip of titanium plate was prepared by immersion in hot oxalic acid for several hours to etch the surface. then washed and dried. The titanium was then coated with a composition of tin oxide doped with antimony oxide. following the procedure of Example 4 of US. Pat. No. 3.627.699. in the following manner:
  • Tin dioxide was prepared by dissolving metallic tin (84 parts) in concentrated nitric acid and heating until tin dioxide was precipitated.
  • Antimony trioxide (l8 parts) was boiled in concentrated nitric acid until evolution of nitrogen oxides ceased. then thoroughly mixed with the precipitated tin oxide.
  • the mixture was further treated with hot nitric acid. then washed free of acid and air dried at about 200C.
  • About 3 percent by weight of manganese difluoride was added and mixed with the dried mixed oxides.
  • the mixture was then compressed into pellets. heated in air at about 800 C for 24 hours. then crushed and reduced to a particle size of less than 60 microns.
  • the crushed mixed oxide composition was again pelletized and heated as before and then crushed and ball-milled to a particle size of less than 5 mcirons.
  • An antimony trichloride-alkoxy-tin solution was prepared by boiling at reflux conditions for 24 hours a mixture of l5 parts of stannic chloride and 55 parts of namyl alcohol then dissolving therein 2. l 3 parts of antimony trichloride.
  • a suspension of 0.17 parts of the mixed oxide composition in 3.6 parts ofthe antimony trichloride-alkoxytin solution was prepared and painted on to the cleaned titanium surface and the coating was oven-dried at 150 C.
  • Two additional coats of the same composition were similarly applied and dried after which the coated strip was heated in air at 450 C for about 15 minutes to convert the coating substantially to oxides of tin and antimony with manganese fluoride.
  • the coating operation. including the final heating at 450 C was repeated three times to increase the thickness of the coating.
  • the theoretical composition of the conductive coating thus prepared. was 85.6 percent SnO 13.7 percent antimony oxides (calculated as Sb O and 0.7 percent MnF
  • the coating weight of the finished coating was 2L2 grams per square meter. lB. Preparation of RuO. Coating The conductive tin oxide coated titanium was further coated in the following manner:
  • Example 2 a minor proportion of a chlorine discharge agent.
  • manganese difluoride was incorporated in the conductive tin oxide coating.
  • An anode may also be prepared in accordance with this invention. following the procedure of Example I except that no chlorine discharge agent is added.
  • EXAMPLE ll Chlorine Cell Test The anode. prepared as described in Example [8. was installed and tested as an anode in a chlorine cell having a steel cathode separated from the anode by a cationic membrane. The anode compartment was supplied with preheated brine having a composition of about 310 g/l NaCl and pH of about 4.5. The anolyte was maintained at about C. The test was conducted at a constant current density of 310 malcm (2.0 ASl). The anode exhibited a potential of 1. l9 volts (v. a saturated calomel electrode) which potential remained stable during an extended test period.
  • anode composed of a titanium substrate leaving a coating of ruthenium oxide directly on the surface thereof was installed and tested under identical conditions.
  • the anode exhibited a potential of [.26 volts (v. a saturated calomel electrode).
  • anodes such as the anode of Example IB. where the outer coating of noble metal oxide is deposited on the surface of a layer of conductive tin oxide rather than directly on the surface of the valve metal substrate.
  • EXAMPLE 111 An anode prepared in accordance with Example 18. that is. an anode consisting of a titanium substrate. an outer coating of ruthenium oxide. and an intermediate layer of conductive tin oxide, was tested in comparison with an anode prepared in accordance with Example IA. that is. an anode consisting of a titanium substrate and a coating of conductive tin oxide.
  • the anodes were installed and tested under identical conditions in a chlorine cell having a steel cathode. separated from the anode by a cationic membrane.
  • the anode compartment was supplied with preheated brine having a concentration of about 310 grams of NaCl per liter and a pH of about 4.5.
  • the anolyte was maintained at about 95 C and the test was conducted at a constant current density of 310 ma/cm (2.0 A81).
  • the anode of Example 1B exhibited an initial potential of about 1.20 volts (v. a saturated calomel electrode), the potential remaining essentially constant over a 127 hour test period.
  • the anode of Example 1A exhibited an initial potential of about 1.52 volts (v. a saturated calomel electrode), the potential rising to 1.76 volts over the 128 hour test period.
  • EXAMPLE IV A sample of titanium mesh was coated with a layer of conductive tin oxide following the procedure of Example IA.
  • Example II A sample of titanium mesh coated with conductive tin oxide as described in Example IVA was further coated with an outer layer of ruthenium dioxide following the procedure of Example 18.
  • the mesh anodes prepared as described in A and B above. were installed and tested as anodes in chlorine cells wherein the electrode gap between the anode and a steel cathode was 1/8 inch. and the anode and cathode were separated by a cationic membrane.
  • the cells were operated with anolyte concentrations ranging from 250 to 310 grams NaCl/liter at a pH of 4.5. and temperatures ranging from 80 to 90 C.
  • the tests were conducted at a constant current density of 310 ma/cm (2.0 A5]
  • Anode plates (5 inches X 6 inches) prepared in accordance with the procedures of Examples 1A and 18.
  • the electrolyte composition ranged from 400 to 550 grams of NaClQ and to grams NaCl and 1.0 to 1.5 grams sodium dichromate per liter and a pH of about 6.7.
  • Example 1A having an outer coating of conductive tin oxide, exhibited an initial potential of 4.0 volts. The potential rose gradually to 5.4 volts during the first 40 hours of operation and the anode failed completely in less than two days of operation. Under identical conditions the anode of Example 15 exhibited a lower initial potential (3.50 volts) and excellent stability. rising to about 4.05 volts over an operating time of 91 days.
  • An electrolytic anode comprising a valve metal substrate. a coating thereon of conductive tin oxide. and an outer coating of at least one of a noble metal or noble metal oxide.
  • an electrolytic anode comprising a mixture of tin oxide and between about 0.1 and about 20 percent by weight of antimony oxide. based on the total weight of said mixture when calculated as Sn0 and Sb- O 7.
  • a method of electrolyzing aqueous alkali metal chloride solutions wherein chlorine is liberated at the anode the improvement which comprises using as said anode, a composite structure comprising a valve metal substrate. a coating of conductive tin oxide on the surface thereof. and an outer coating. on the surface of the conductive tin oxide. of at least one of a noble metal or noble metal oxide.
  • anode comprises a titanium substrate, a coating thereon of conductive tin oxide. and an outer coating of ruthenium oxide.
  • the conductive tin oxide comprises a mixture of tin oxide and between about 0.1 and 20 percent by weight of antimony oxide. based on the total weight of the mixture when calculated as SnO and Sb O

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Chemically Coating (AREA)

Abstract

An electrode, for use in electrolytic processes, comprises a valve metal substrate, such as titanium, a coating thereon of conductive tin oxide, and an outer coating of a noble metal or noble metal oxide.

Description

United States Patent 11 1 Cook, Jr. 1 May 6, 1975 [54] ANODE FOR ELECTROLYTIC PROCESSES 3.711.385 lll973 Beer 204/290 F 3.775.284 ll/l973 Bennett et al, 204/290 F [75] lnvemor Edward 3.770334 12 1973 OLeary 204/290 F 3.810.770 5/1974 Bianchi et =11. 204/290 F [73] Assignee: Hooker Chemicals & Plastics C p ga a Falls. NY. Primary Examiner-R. L. Andrews [22] Filed: Aug. 2 1974 Attorney, Agent. or Firm-Peter F. Casella; Donald C.
Studley [2]] Appl. No.: 494,110
52 us. 01. 204/98; 204/128; 104/190 F [57] ABSTRACT [111- Cold U Colb Bolk An electrode. for use in electrolytic processes, com- Fldd 0f Search 204/290 93 prises a valve metal substrate, such as titanium. a coating thereon of conductive tin oxide, and an outer coatl l References Cited ing of a noble metal or noble metal oxide.
UNITED STATES PATENTS 3,627,669 12/1971 Entwisle et al .1 204/290 F 9 Claims Drawmgs ANODE FOR ELECTROLYTIC PROCESSES BACKGROUND OF THE INVENTION The present invention relates to improved electrodes particularly adapted for use as anodes in electrochemical process involving the electrolysis of brines.
A variety of materials have been tested and used as chlorine anodes in electrolytic cells. In the past. the material most commonly used for this purpose has been graphite. However. the problems associated with the use of graphite anodes are several. The chlorine overvoltage of graphite is relatively high. in comparison for example with the noble metals. Furthermore. in the corrosive media of an electrochemical cell graphite wears readily. resulting in substantial loss of graphite and the ultimate expense of replacement as well as continued maintenance problems resulting from the need for frequent adjustment of spacing between the anode and cathode as the graphite wears away. The use of noble metals and noble metal oxides as anode materials provides substantial advantages over the use of graphite. The electrical conductivity of the noble metals is substantially higher and the chlorine overvoltage substantially lower than that of graphite. In addition. the dimensional stability of the noble metals and noble metal oxides represents a substantial improvement over graphite. However. the use of noble metals as a major material of construction in anodes results in an economic disadvantage due to the excessively high cost of such materials.
ln attempts to avoid the use of the expensive noble metals various other anode materials have been proposed for use as coatings over valve metal substrates. In US. Pat. No. 3.627.669. it is disclosed that mixtures of tin dioxide and oxides of antimony can be formed as adherent coatings on a valve metal substrate to form an anode useful in electrochemical processes. In the electrolytic production of chlorine. anodes of this type provide the advantage of economy in the elimination of the use of expensive noble metals or noble metal oxides. in addition the tin oxide coating provides an effective protection for the substrate. However. the tin oxide compositions. although useful as an anode material. exhibit a chlorine overvoltage that is substantially higher than that of the noble metals or noble metal oxides. Thus. despite the elimination of expensive noble metals. the cost of chlorine production. in processes using such anodes. is relatively high.
Considerable effort has been expended in recent years in attempts to develop improved anode materials and structures utilizing the advantages of noble metals or noble metal oxides. A great amount of effort has been directed to the development of anodes having a high operative surface area of noble metal or noble metal oxide in comparison with the total quantity of the material employed. This may be done. for example. by employing the noble metal as a thin film or coating over an electrically conductive substrate. However, when it is attempted to minimize the aforementioned economic disadvantage of the noble metals by applying them in the form of very thin films over a metal substrate, it has been found that such very thin films are often porous. The result is an exposure of the substrate to the anode environment. through the pores in the outer layer. In addition. in normal use in an electrolytic cell. a small amount of wear. spalling or flaking off of portions of the noble metal or noble metal oxide is likely to occur.
resulting in further exposure of the substrate. Many materials. otherwise suitable for use as a substrate are susceptible to chemical attack and rapid deterioration upon exposure to the anode environment. In an attempt to assure minimum deterioration of the substrate under such circumstances. anode manufacturers commonly utilize a valve metal such as titanium as the substrate material. Upon exposure to the anodic environment. titanium. as well as other valve metals. will form a surface layer of oxide which serves to protect the substrate from further chemical attack. The oxide thus formed. however. is not catalytically active and as a result the operative surface area of the anode is decreased.
Accordingly. it is an object of the present invention to provide improved electrodes for use as anodes in electrolytic processes. It is a further object to provide such anodes having an operative surface of noble metal or noble metal oxide and having improved efficiency and maintenance characteristics.
STATEMENT OF INVENTION This invention provides a novel electrode. especially suited for use as an anode in chlor-alkali cells; the novel electrode comprising a valve metal substrate having a protective coating of conductive tin oxide on the surface thereof and an outer. thin layer of a noble metal or noble metal oxide. Electrodes of this type exhibit a high degree of durability in addition to the relatively low overvoltage characteristics of a noble metal or noble metal oxide. making them wellsuited for use as anodes in the electrolytic production of chorine.
Among the advantages of such construction is the protection afforded the metal substrate by the coating of conductive tin oxide. The preferred substrate materials of the anodes of the invention are the valve metals. such as titanium. tantalum. niobium or zirconium. especially titanium. However. where suitably thick intermediate layers of tin oxide are employed. other more conductive metals may be considered for use as substrates. The tin oxide coating. which may range in coating weight from about 0.l grams per square meter to lOO grams per square meter or more. depending on the degree of protection desired. prevents contact of the substrate and the electrolyte, thus preventing or minimizing corrosion or surface oxidation and the attendant deterioration or passivation of the substrate. At the same time. the outer layer provides the advantageous catalytic properties of the noble metals or noble metal oxides. In addition. the protective layer of conductive tin oxide permits the use ofa relatively thin layer of the noble metal or noble metal oxide and a consequent savings resulting from a minimal use of the precious metal. Typically. the layer of noble metal or noble metal oxide will have a coating weight in the range of about 0.] grams per square meter to about 20 grams per square meter or higher and preferably about 3 to [0 grams per square meter in thickness. The disadvantage of pores or pinholes in the noble metal layer common in extremely thin layers is obviated by the presence of the intermediate layer of conductive tin oxide. Pores or pinholes in the noble metal layer. or wearing away of that outer layer over long periods of use result in the gradual exposure of the tin oxide layer. The intermediate layer of tin oxide will continue to provide a catalytically active surface in those exposed areas. The catalytic character istics of tin oxide. although not as high as the noble metals or noble metal oxides. is quite substantially higher than the valve metal oxide. Thus. the overall deterioration of the catalytic properties of the anode is more gradual and maintenance problems are accordingly lessened.
in addition. it has been found that the intermediate layer of tin oxide provides an increase in surface area of the anode with a consequent improvement in overvoltage. it has further been found that the adhesion of the noble metal or noble metal oxide to the substrate is increased by the presence of the intermediate layer of tin oxide and the problem of spalling of the surface layer is thereby reduced.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The valve metal substrate which forms the inner or base component of the electrode is an electroconductive metal having sufficient mechanical strength to serve as a support for the coating and having a high degree of chemical resistivity, especially to the anodic environment of electrolytic cells. Typical valve metals include. for example. Ti. Ta. Nb. Zr. and alloys thereof. The valve metals are well known for their tendency to form an inert oxide film upon exposure to an anodic environment. The preferred valve metal. based on cost and availability as well as electrical and chemical properties is titanium. The conductivity ofthe substrate may be improved. if desired. by providing a central core of a highly conductive metal such as copper. in such an arrangement. the core must be electrically connected to and completely protected by the valve metal substrate.
Tin oxide can be readily formed as an adherent coat ing on a valve metal substrate, in a manner described hereinafter. to provide a protective. electrically conductive layer which is especially resistant to chemical attack in anodic environments. Pure tin oxide however has a relatively high electrical resistivity in comparison to metals and exhibits undesireble change in electrical resistivity as a function of temperature. It is well known that the electrical stability oftin oxide coatings may be substantially improved and the electrical resistivity lowered through the introduction of a minor proportion of a suitable inorganic material (commonly referred to as a dopant). A variety of materials. especially various metal oxides and other metal compounds and mixtures thereof. have been disclosed in the prior art as suitable dopants for stabilizing and lowering the electrical resistivity of tin oxide compositions. Among the materials shown in the prior art to be useful as dopants in conductive tin oxide compositions and which may be employed in the tin oxide coating compositions of the anodes of this invention are included. for example. fluorine compounds. especially the metal salts of fluorine. such as sodium fluoride. potassium fluoride. lithium fluoride. berylium fluoride. aluminum fluoride. lead fluoride. chromium fluoride. calcium fluoride. and other metal fluorides. hydrazine. phenylhydrazine; phosphorus compounds such as phosphorus chloride. phosphorus oxychloride, ammonium phosphate. organic phosphorus esters such as tricresyl phosphate; as well as compounds of tellurium. tungsten. antimony. molybdenum. arsenic. and others and mixtures thereof. The conductive tin oxide coatings of this invention comprise tin oxide. preferably containing a minor amount of a suitable dopant. The preferred dopant is an antimony compound which may be added to the tin oxide coating composition either as an oxide or as a compound such as SbCl which may form the oxide when heated in an oxidizing atmosphere. Although the exact form of the antimony in the final coating is not certain. it is assumed to be present as Sb- O and data and proportions in this specification and the appended claims are based on that assumption. The preferred compositions of this invention comprise mixtures of tin oxide and a minor amount of antimony oxide. the later being present preferably in an amount of between about 0.1 and 20 weight percent (calculated on the basis of total weight of SnO and Sb- O Conductive tin oxide coatings may be adherently formed on the surface of the valve metal substrate by various methods known in the art. Typically such coatings may be formed by first chemically cleaning the substrate. for example. by degreasing and etching the surface in a suitable acid, e.g.. oxalic acid. then applying a solution of appropriate thermally decomposable salts. drying and heating in an oxidizing atmosphere. The salts that may be employed include. in general. any thermally decomposable inorganic or organic salt or ester of tin and dopant. e.g.. antimony. including for example their chlorides. alkoxides, alkoxy halides. resinates. amines and the like. Typical salts include for example. stannic chloride. dibutyltin dichloride. tin tetraethoxide. antimony trichloride. antimony pentachloride and the like. Suitable solvents include for example. ethyl alcohol. propyl alcohol. butyl alcohol. pentyl alcohol. amyl alcohol. toluene. benzene and other organic solvents as well as water.
The solution of thermally decomposable salts. containing for example. a salt of tin and a salt of antimony. or other dopant. in the desired proportions. may be applied to the cleaned surface of the valve metal substrate by painting. brushing. dipping. rolling. spraying or other method. The coating is then dried by heating for example at about to 200 C for several minutes to evaporate the solvent. and then heating at a higher temperature. e.g.. 250 to 800 C in oxidizing atmosphere to convert the tin and antimony compounds'to their respective oxides. The procedure may be repeated as many times as necessary to achieve a desired coating weight or thickness. The final coating weight of this conductive tin oxide coating may vary considerably. but is preferably in the range of about 3 to about 30 grams per square meter.
Optionally. a small amount. such as up to 3 percent by weight of a chlorine discharge catalyst such as at least one of the difluorides of manganese. iron. cobalt or nickel may by included in the tin oxide coating to lower the overpotential required for chlorine gas liberation in a chlor-alkali cell. The chorine discharge catalyst may be added to the tin oxide coating by suspending a fine particulate preformed sinter of tin dioxide and the catalyst in the solution of thermally decomposable salts. Such chlorine discharge catalysts in the tin oxide coating is not essential to the anodes of this invention but may be employed if desired in a known manner such as disclosed in US. Pat. No. 3.627.699.
The outer coating of the anode comprises a noble metal or noble metal oxide such as platinum. iridium. rhodium. palladium ruthenium or somium or mixtures or alloys of these metals or the oxides or mixtures of the oxides of these metals. An outer coating of a noble metal may be applied by known methods such as electroplating. chemical deposition from a platinum coating solution. spraying. or other methods.
Preferably. the outer coating of the anode comprises a noble metal oxide. Noble metal oxide coating may be applied by first depositing the noble metal in the metallic state and then oxidizing the noble metal coating. for example. by galvanic oxidation or chemical oxidation by means of an oxidant such as an oxidizing salt melt. or by heating to an elevated temperature. e.g.. 300 to 600 C or higher in an oxidizing atmosphere such as air oxygen. at atmospheric or superatmospheric pressures to convert the noble metal coating to a coating of the corresponding noble metal oxide. Other suitable methods include. for example. electrophoretic deposition of the noble metal oxide; or application of a dispersion of the noble metal oxide in a carrier. such as alcohol. by spraying. brushing. rolling. dipping. painting. or other method on to the tin oxide surface followed by heating at an elevated temperature to evaporate the carrier and sinter the oxide coating. A preferred method for the formation of the noble metal oxide coating involves coating the conductive tin oxide surface with a solution of a noble metal compound. evaporating the solvent and converting the coating of noble metal compound to the oxide by chemical or electrochemical reaction. For example. the conductive tin oxide surface may be coated with a solution of a thermally decomposable salt of a noble metal. such as a solution of a noble metal halide in an alcohol. evaporation of the solvent. followed by heating at an elevated temperature such as between about 300 and 800 C in an oxidizing atmosphere such as air or oxygen for a period of time sufficient to convert the noble metal halide to a noble metal oxide. The procedure for formation of a noble metal or noble metal oxide coating may be repeated as often as necessary to achieve the desired thickness. The foregoing and other methods for the preparation of coatings of noble metals and noble metal oxides are well known in the art and may be found for example in US. Pat. No. 3.711.385.
The following specific examples will serve to further illustrate this invention. In the examples and elsewhere in this specification and claims. all temperatures are in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.
EXAMPLE I lA. Preparation of conductive tin oxide coating A strip of titanium plate was prepared by immersion in hot oxalic acid for several hours to etch the surface. then washed and dried. The titanium was then coated with a composition of tin oxide doped with antimony oxide. following the procedure of Example 4 of US. Pat. No. 3.627.699. in the following manner:
Tin dioxide was prepared by dissolving metallic tin (84 parts) in concentrated nitric acid and heating until tin dioxide was precipitated. Antimony trioxide (l8 parts) was boiled in concentrated nitric acid until evolution of nitrogen oxides ceased. then thoroughly mixed with the precipitated tin oxide. The mixture was further treated with hot nitric acid. then washed free of acid and air dried at about 200C. About 3 percent by weight of manganese difluoride was added and mixed with the dried mixed oxides. The mixture was then compressed into pellets. heated in air at about 800 C for 24 hours. then crushed and reduced to a particle size of less than 60 microns. The crushed mixed oxide composition was again pelletized and heated as before and then crushed and ball-milled to a particle size of less than 5 mcirons.
An antimony trichloride-alkoxy-tin solution was prepared by boiling at reflux conditions for 24 hours a mixture of l5 parts of stannic chloride and 55 parts of namyl alcohol then dissolving therein 2. l 3 parts of antimony trichloride.
A suspension of 0.17 parts of the mixed oxide composition in 3.6 parts ofthe antimony trichloride-alkoxytin solution was prepared and painted on to the cleaned titanium surface and the coating was oven-dried at 150 C. Two additional coats of the same composition were similarly applied and dried after which the coated strip was heated in air at 450 C for about 15 minutes to convert the coating substantially to oxides of tin and antimony with manganese fluoride. The coating operation. including the final heating at 450 C was repeated three times to increase the thickness of the coating.
The theoretical composition of the conductive coating thus prepared. was 85.6 percent SnO 13.7 percent antimony oxides (calculated as Sb O and 0.7 percent MnF The coating weight of the finished coating was 2L2 grams per square meter. lB. Preparation of RuO. Coating The conductive tin oxide coated titanium was further coated in the following manner:
A solution of 1 gram of ruthenium trichloride in 0.4 cubic centimeters of 36 percent hydrochloric acid and 6.2 cubic centimeters of butyl alcohol was brushed several times on to the tin oxide surface and then allowed to dry in air at room temperature. After drying. the samples were heated in air at 560 C for 25 minutes to decompose the RuCl and form RuO An additional coating of RuCl was similarily applied. dried and thermally treated. to yield a final coating of RuO having a coating weight of about 6.0 grams of ruthenium per square meter.
In the foregoing Example. a minor proportion of a chlorine discharge agent. manganese difluoride was incorporated in the conductive tin oxide coating. An anode may also be prepared in accordance with this invention. following the procedure of Example I except that no chlorine discharge agent is added.
EXAMPLE ll Chlorine Cell Test The anode. prepared as described in Example [8. was installed and tested as an anode in a chlorine cell having a steel cathode separated from the anode by a cationic membrane. The anode compartment was supplied with preheated brine having a composition of about 310 g/l NaCl and pH of about 4.5. The anolyte was maintained at about C. The test was conducted at a constant current density of 310 malcm (2.0 ASl). The anode exhibited a potential of 1. l9 volts (v. a saturated calomel electrode) which potential remained stable during an extended test period.
For purposes of comparison. a commercially available anode composed of a titanium substrate leaving a coating of ruthenium oxide directly on the surface thereof was installed and tested under identical conditions. The anode exhibited a potential of [.26 volts (v. a saturated calomel electrode). Thus. it will be seen that an improvement in overvoltage is achieved in anodes. such as the anode of Example IB. where the outer coating of noble metal oxide is deposited on the surface of a layer of conductive tin oxide rather than directly on the surface of the valve metal substrate.
EXAMPLE 111 An anode prepared in accordance with Example 18. that is. an anode consisting of a titanium substrate. an outer coating of ruthenium oxide. and an intermediate layer of conductive tin oxide, was tested in comparison with an anode prepared in accordance with Example IA. that is. an anode consisting of a titanium substrate and a coating of conductive tin oxide. The anodes were installed and tested under identical conditions in a chlorine cell having a steel cathode. separated from the anode by a cationic membrane. The anode compartment was supplied with preheated brine having a concentration of about 310 grams of NaCl per liter and a pH of about 4.5. The anolyte was maintained at about 95 C and the test was conducted at a constant current density of 310 ma/cm (2.0 A81). The anode of Example 1B exhibited an initial potential of about 1.20 volts (v. a saturated calomel electrode), the potential remaining essentially constant over a 127 hour test period. Under identical test conditions, the anode of Example 1A exhibited an initial potential of about 1.52 volts (v. a saturated calomel electrode), the potential rising to 1.76 volts over the 128 hour test period.
EXAMPLE IV A. A sample of titanium mesh was coated with a layer of conductive tin oxide following the procedure of Example IA.
B. A sample of titanium mesh coated with conductive tin oxide as described in Example IVA was further coated with an outer layer of ruthenium dioxide following the procedure of Example 18.
The mesh anodes, prepared as described in A and B above. were installed and tested as anodes in chlorine cells wherein the electrode gap between the anode and a steel cathode was 1/8 inch. and the anode and cathode were separated by a cationic membrane. The cells were operated with anolyte concentrations ranging from 250 to 310 grams NaCl/liter at a pH of 4.5. and temperatures ranging from 80 to 90 C. The tests were conducted at a constant current density of 310 ma/cm (2.0 A5] The anode of Example IVB exhibited an initial potential of about 1.32 v and remained substan= EXAMPLE V Anode plates (5 inches X 6 inches) prepared in accordance with the procedures of Examples 1A and 18. were installed and tested in a chlorate cell which employs two anode plates surrounded by a mild steel cathode shell. The gap between the anode and cathode was 1/8 inch. The cell was operated at a current density of 4.0 ASl and maintained at about C. The electrolyte composition ranged from 400 to 550 grams of NaClQ and to grams NaCl and 1.0 to 1.5 grams sodium dichromate per liter and a pH of about 6.7.
The anode of Example 1A. having an outer coating of conductive tin oxide, exhibited an initial potential of 4.0 volts. The potential rose gradually to 5.4 volts during the first 40 hours of operation and the anode failed completely in less than two days of operation. Under identical conditions the anode of Example 15 exhibited a lower initial potential (3.50 volts) and excellent stability. rising to about 4.05 volts over an operating time of 91 days.
The foregoing specification is intended to illustrate the invention with certain preferred embodiments, but it is understood that the details disclosed herein can be modified without departing from the spirit and scope of the invention.
1 claim:
1. An electrolytic anode comprising a valve metal substrate. a coating thereon of conductive tin oxide. and an outer coating of at least one of a noble metal or noble metal oxide.
2. An electrolytic anode according to claim 1 wherein the substrate is titanium.
3. An electrolytic anode according to claim 2 wherein the conductive tin oxide comprises a mixture of tin dioxide and a minor amount of antimony oxide.
4. An electrolytic anode according to claim 2 wherein the outer coating is a noble metal oxide.
5. An electrolytic anode according to claim 4 wherein the outer coating is ruthenium oxide.
6. An electrolytic anode according to claim 5 wherein the conductive tin oxide comprises a mixture of tin oxide and between about 0.1 and about 20 percent by weight of antimony oxide. based on the total weight of said mixture when calculated as Sn0 and Sb- O 7. In a method of electrolyzing aqueous alkali metal chloride solutions wherein chlorine is liberated at the anode, the improvement which comprises using as said anode, a composite structure comprising a valve metal substrate. a coating of conductive tin oxide on the surface thereof. and an outer coating. on the surface of the conductive tin oxide. of at least one of a noble metal or noble metal oxide.
8. A method according to claim 7 wherein the anode comprises a titanium substrate, a coating thereon of conductive tin oxide. and an outer coating of ruthenium oxide.
9. A method according to claim 8 wherein the conductive tin oxide comprises a mixture of tin oxide and between about 0.1 and 20 percent by weight of antimony oxide. based on the total weight of the mixture when calculated as SnO and Sb O

Claims (9)

1. AN ELECTROLYTIC ANODE COMPRISING A VALVE METAL SUBSTRATE, A COATING THEREON OF CONDUCTIVE TIN OXIDE, AND AN OUTER COATING OF AT LEAST ONE OF NOBLE METAL OR NOBLE METAL OXIDE.
2. An electrolytic anode according to claim 1 wherein the substrate is titanium.
3. An electrolytic anode according to claim 2 wherein the conductive tin oxide comprises a mixture of tin dioxide and a minor amount of antimony oxide.
4. An electrolytic anode according to claim 2 wherein the outer coating is a noble metal oxide.
5. An electrolytic anode according to claim 4 wherein the outer coating is ruthenium oxide.
6. An electrolytic anode according to claim 5 wherein the conductive tin oxide comprises a mixture of tin oxide and between about 0.1 and about 20 percent by weight of antimony oxide, based on the total weight of said mixture when calculated as SnO2 and Sb2O3.
7. In a method of electrolyzing aqueous alkali metal chloride solutions wherein chlorine is liberated at the anode, the improvement which comprises using as said anode, a composite structure comprising a valve metal substrate, a coating of conductive tin oxide on the surface thereof, and an outer coating, on the surface of the conductive tin oxide, of at least one of a noble metal or noble metal oxide.
8. A method according to claim 7 wherein the anode comprises a titanium substrate, a coating thereon of conductive tin oxide, and an outer coating of ruthenium oxide.
9. A method according to claim 8 wherein the conductive tin oxide comprises a mixture of tin oxide and between about 0.1 and 20 percent by weight of antimony oxide, based on the total weight of the mixture when calculated as SnO2 and Sb2O3.
US494110A 1974-08-02 1974-08-02 Anode for electrolytic processes Expired - Lifetime US3882002A (en)

Priority Applications (17)

Application Number Priority Date Filing Date Title
US494110A US3882002A (en) 1974-08-02 1974-08-02 Anode for electrolytic processes
AR259713A AR205045A1 (en) 1974-08-02 1975-01-01 ELECTROLYTIC ANODE
US05/553,860 US3986942A (en) 1974-08-02 1975-02-27 Electrolytic process and apparatus
US05/564,529 US3951766A (en) 1974-08-02 1975-04-02 Electrolytic cell and method of using same
US05/574,478 US3943042A (en) 1974-08-02 1975-05-05 Anode for electrolytic processes
US05/574,805 US3940323A (en) 1974-08-02 1975-05-05 Anode for electrolytic processes
US05/574,806 US3956083A (en) 1974-08-02 1975-05-05 Electrochemical anode and process using the anode
CA230,660A CA1058563A (en) 1974-08-02 1975-07-03 Anode for electrolytic processes
GB29900/75A GB1485884A (en) 1974-08-02 1975-07-16 Anode for electrolytic cells
DE19752532553 DE2532553A1 (en) 1974-08-02 1975-07-21 ANODE FOR ELECTROLYTIC PROCEDURES
NL7508764A NL7508764A (en) 1974-08-02 1975-07-23 ELECTROLYSIS ANODE AND METHOD FOR ELECTROLYZING Aqueous ALKALINE METAL CHLORIDE SOLUTIONS.
BR7504830*A BR7504830A (en) 1974-08-02 1975-07-28 ELECTROLYTIC ANODES AND PERFECTING IN THE ELECTROLYSIS PROCESS OF AQUEOUS METAL CHLORIDE SOLUTIONS
SE7508697A SE7508697L (en) 1974-08-02 1975-07-31 ELECTROLYSIS ANOD
FR7523984A FR2280718A1 (en) 1974-08-02 1975-07-31 ANODE FOR ELECTROLYTIC PROCESSES
IT25973/75A IT1040223B (en) 1974-08-02 1975-07-31 ANODE FOR ELECTROLYTIC PROCESSES
BE158853A BE832010A (en) 1974-08-02 1975-07-31 ANODE FOR ELECTROLYTIC PROCESSES
JP50094673A JPS592753B2 (en) 1974-08-02 1975-08-02 How to get the job done

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US494110A US3882002A (en) 1974-08-02 1974-08-02 Anode for electrolytic processes

Related Child Applications (5)

Application Number Title Priority Date Filing Date
US05/553,860 Continuation-In-Part US3986942A (en) 1974-08-02 1975-02-27 Electrolytic process and apparatus
US05/564,529 Continuation-In-Part US3951766A (en) 1974-08-02 1975-04-02 Electrolytic cell and method of using same
US05/574,805 Continuation-In-Part US3940323A (en) 1974-08-02 1975-05-05 Anode for electrolytic processes
US05/574,806 Continuation-In-Part US3956083A (en) 1974-08-02 1975-05-05 Electrochemical anode and process using the anode
US05/574,478 Continuation-In-Part US3943042A (en) 1974-08-02 1975-05-05 Anode for electrolytic processes

Publications (1)

Publication Number Publication Date
US3882002A true US3882002A (en) 1975-05-06

Family

ID=23963089

Family Applications (1)

Application Number Title Priority Date Filing Date
US494110A Expired - Lifetime US3882002A (en) 1974-08-02 1974-08-02 Anode for electrolytic processes

Country Status (12)

Country Link
US (1) US3882002A (en)
JP (1) JPS592753B2 (en)
AR (1) AR205045A1 (en)
BE (1) BE832010A (en)
BR (1) BR7504830A (en)
CA (1) CA1058563A (en)
DE (1) DE2532553A1 (en)
FR (1) FR2280718A1 (en)
GB (1) GB1485884A (en)
IT (1) IT1040223B (en)
NL (1) NL7508764A (en)
SE (1) SE7508697L (en)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3940323A (en) * 1974-08-02 1976-02-24 Hooker Chemicals & Plastics Corporation Anode for electrolytic processes
US3943042A (en) * 1974-08-02 1976-03-09 Hooker Chemicals & Plastics Corporation Anode for electrolytic processes
US3956083A (en) * 1974-08-02 1976-05-11 Hooker Chemicals & Plastics Corporation Electrochemical anode and process using the anode
US3986942A (en) * 1974-08-02 1976-10-19 Hooker Chemicals & Plastics Corporation Electrolytic process and apparatus
US4028215A (en) * 1975-12-29 1977-06-07 Diamond Shamrock Corporation Manganese dioxide electrode
JPS5544514A (en) * 1978-09-22 1980-03-28 Permelec Electrode Ltd Electrode for electrolysis and production thereof
US4223049A (en) * 1978-05-23 1980-09-16 Research Triangle Institute Superficially mixed metal oxide electrodes
US4233148A (en) * 1979-10-01 1980-11-11 Great Lakes Carbon Corporation Electrode composition
US4378406A (en) * 1979-03-28 1983-03-29 University Of Florida Thin platinum films on tin oxide substrates
US4584084A (en) * 1984-03-02 1986-04-22 Permelec Electrode Ltd. Durable electrode for electrolysis and process for production thereof
US4585540A (en) * 1984-09-13 1986-04-29 Eltech Systems Corporation Composite catalytic material particularly for electrolysis electrodes and method of manufacture
FR2599050A1 (en) * 1986-05-22 1987-11-27 Permelec Electrode Ltd SUSTAINABLE ELECTRODES FOR ELECTROLYSIS WITH ANODE OXYGEN RELEASE AND PROCESS THEREOF
US5232576A (en) * 1990-09-04 1993-08-03 Permelec Electrode Ltd. Anode for chromium plating and processes for producing and using the same
US5314601A (en) * 1989-06-30 1994-05-24 Eltech Systems Corporation Electrodes of improved service life
US5324407A (en) * 1989-06-30 1994-06-28 Eltech Systems Corporation Substrate of improved plasma sprayed surface morphology and its use as an electrode in an electrolytic cell
US6527939B1 (en) 1999-06-28 2003-03-04 Eltech Systems Corporation Method of producing copper foil with an anode having multiple coating layers
US20030085199A1 (en) * 2001-11-08 2003-05-08 Korea Atomic Energy Research Institute & Technology Winners Co., Ltd. Method for manufacturing catalytic oxide anode using high temperature sintering
US20070261968A1 (en) * 2005-01-27 2007-11-15 Carlson Richard C High efficiency hypochlorite anode coating
WO2007148085A3 (en) * 2006-06-19 2008-02-28 Clarizon Ltd Electrode, method of manufacture and use thereof
US20100044219A1 (en) * 2003-05-07 2010-02-25 Eltech Systems Corporation Smooth Surface Morphology Chlorate Anode Coating
EP2447395A2 (en) 2010-10-28 2012-05-02 Bayer MaterialScience AG Electrode for producing chlorine through electrolysis
US8580091B2 (en) 2010-10-08 2013-11-12 Water Star, Inc. Multi-layer mixed metal oxide electrode and method for making same
US11668017B2 (en) 2018-07-30 2023-06-06 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes
CN116573728A (en) * 2023-06-05 2023-08-11 江阴米尔克电解设备有限公司 Titanium anode plate for water treatment and preparation method thereof

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1094891A (en) * 1976-03-15 1981-02-03 Diamond Shamrock Corporation Electrode coating method
JPS53153736U (en) * 1977-05-11 1978-12-04
JPS5597486A (en) * 1979-01-21 1980-07-24 Tdk Corp Electrode for electrolysis and its manufacture
CA1175883A (en) * 1980-06-30 1984-10-09 Joseph W. Mitchell Electrolytic printing electrode
JPS60184691A (en) * 1984-03-02 1985-09-20 Permelec Electrode Ltd Durable electrode and its manufacture
JPS61196056A (en) * 1985-02-26 1986-08-30 篠田　和殷 Roof snow falling apparatus
JPS6233965A (en) * 1985-04-09 1987-02-13 高口　博行 Apparatus for conveying and removing snow
JPH0240690Y2 (en) * 1985-07-04 1990-10-30
JPH0312115Y2 (en) * 1986-01-17 1991-03-22
JPS6311778A (en) * 1986-07-01 1988-01-19 山口　肇 Snow removing apparatus
CN102464382B (en) * 2010-11-05 2013-10-23 同济大学 A preparation method of a high oxygen evolution potential electrode for treating fluorine-containing organic wastewater
CN102689948B (en) * 2011-03-24 2013-11-13 同济大学 A SnO2 Electrode for Treating Fluorinated Organic Pollutants
MX376797B (en) * 2014-07-17 2025-03-07 Industrie De Nora Spa Catalytic or electrocatalytic generation of chlorine dioxide

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627669A (en) * 1968-12-13 1971-12-14 Ici Ltd Electrodes for electrochemical cells
US3711385A (en) * 1970-09-25 1973-01-16 Chemnor Corp Electrode having platinum metal oxide coating thereon,and method of use thereof
US3775284A (en) * 1970-03-23 1973-11-27 J Bennett Non-passivating barrier layer electrodes
US3776834A (en) * 1972-05-30 1973-12-04 Leary K O Partial replacement of ruthenium with tin in electrode coatings
US3810770A (en) * 1967-12-14 1974-05-14 G Bianchi Titanium or tantalum base electrodes with applied titanium or tantalum oxide face activated with noble metals or noble metal oxides

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1244650A (en) * 1968-10-18 1971-09-02 Ici Ltd Electrodes for electrochemical processes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810770A (en) * 1967-12-14 1974-05-14 G Bianchi Titanium or tantalum base electrodes with applied titanium or tantalum oxide face activated with noble metals or noble metal oxides
US3627669A (en) * 1968-12-13 1971-12-14 Ici Ltd Electrodes for electrochemical cells
US3775284A (en) * 1970-03-23 1973-11-27 J Bennett Non-passivating barrier layer electrodes
US3711385A (en) * 1970-09-25 1973-01-16 Chemnor Corp Electrode having platinum metal oxide coating thereon,and method of use thereof
US3776834A (en) * 1972-05-30 1973-12-04 Leary K O Partial replacement of ruthenium with tin in electrode coatings

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3940323A (en) * 1974-08-02 1976-02-24 Hooker Chemicals & Plastics Corporation Anode for electrolytic processes
US3943042A (en) * 1974-08-02 1976-03-09 Hooker Chemicals & Plastics Corporation Anode for electrolytic processes
US3956083A (en) * 1974-08-02 1976-05-11 Hooker Chemicals & Plastics Corporation Electrochemical anode and process using the anode
US3986942A (en) * 1974-08-02 1976-10-19 Hooker Chemicals & Plastics Corporation Electrolytic process and apparatus
US4028215A (en) * 1975-12-29 1977-06-07 Diamond Shamrock Corporation Manganese dioxide electrode
US4223049A (en) * 1978-05-23 1980-09-16 Research Triangle Institute Superficially mixed metal oxide electrodes
JPS5544514A (en) * 1978-09-22 1980-03-28 Permelec Electrode Ltd Electrode for electrolysis and production thereof
US4378406A (en) * 1979-03-28 1983-03-29 University Of Florida Thin platinum films on tin oxide substrates
US4233148A (en) * 1979-10-01 1980-11-11 Great Lakes Carbon Corporation Electrode composition
WO1981000865A1 (en) * 1979-10-01 1981-04-02 Great Lakes Carbon Corp Electrode composition
US4584084A (en) * 1984-03-02 1986-04-22 Permelec Electrode Ltd. Durable electrode for electrolysis and process for production thereof
US4585540A (en) * 1984-09-13 1986-04-29 Eltech Systems Corporation Composite catalytic material particularly for electrolysis electrodes and method of manufacture
FR2599050A1 (en) * 1986-05-22 1987-11-27 Permelec Electrode Ltd SUSTAINABLE ELECTRODES FOR ELECTROLYSIS WITH ANODE OXYGEN RELEASE AND PROCESS THEREOF
US4941953A (en) * 1986-05-22 1990-07-17 Permelec Electrode Ltd. Durable electrodes having a plated tinor tin oxide intermediate layer for electrolysis and process for producing the same
US5578176A (en) * 1989-06-30 1996-11-26 Eltech Systems Corporation Method of preparing electrodes of improved service life
US5324407A (en) * 1989-06-30 1994-06-28 Eltech Systems Corporation Substrate of improved plasma sprayed surface morphology and its use as an electrode in an electrolytic cell
US5435896A (en) * 1989-06-30 1995-07-25 Eltech Systems Corporation Cell having electrodes of improved service life
US5672394A (en) * 1989-06-30 1997-09-30 Eltech Systems Corporation Electrodes of improved service life
US6071570A (en) * 1989-06-30 2000-06-06 Eltech Systems Corporation Electrodes of improved service life
US5314601A (en) * 1989-06-30 1994-05-24 Eltech Systems Corporation Electrodes of improved service life
US5232576A (en) * 1990-09-04 1993-08-03 Permelec Electrode Ltd. Anode for chromium plating and processes for producing and using the same
EP0576402B1 (en) * 1992-06-25 1997-03-05 Eltech Systems Corporation Electrodes of improved service life
US6527939B1 (en) 1999-06-28 2003-03-04 Eltech Systems Corporation Method of producing copper foil with an anode having multiple coating layers
US20030085199A1 (en) * 2001-11-08 2003-05-08 Korea Atomic Energy Research Institute & Technology Winners Co., Ltd. Method for manufacturing catalytic oxide anode using high temperature sintering
US8142898B2 (en) 2003-05-07 2012-03-27 De Nora Tech, Inc. Smooth surface morphology chlorate anode coating
US20100044219A1 (en) * 2003-05-07 2010-02-25 Eltech Systems Corporation Smooth Surface Morphology Chlorate Anode Coating
US20070261968A1 (en) * 2005-01-27 2007-11-15 Carlson Richard C High efficiency hypochlorite anode coating
WO2007148085A3 (en) * 2006-06-19 2008-02-28 Clarizon Ltd Electrode, method of manufacture and use thereof
US7985327B2 (en) * 2006-06-19 2011-07-26 Clarizon Limited Electrode, method of manufacture and use thereof
US20100065420A1 (en) * 2006-06-19 2010-03-18 Clarizon Limited Electrode, method of manufacture and use thereof
US8580091B2 (en) 2010-10-08 2013-11-12 Water Star, Inc. Multi-layer mixed metal oxide electrode and method for making same
EP2447395A2 (en) 2010-10-28 2012-05-02 Bayer MaterialScience AG Electrode for producing chlorine through electrolysis
DE102010043085A1 (en) 2010-10-28 2012-05-03 Bayer Materialscience Aktiengesellschaft Electrode for electrolytic chlorine production
US11668017B2 (en) 2018-07-30 2023-06-06 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes
US12305300B2 (en) 2018-07-30 2025-05-20 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes
CN116573728A (en) * 2023-06-05 2023-08-11 江阴米尔克电解设备有限公司 Titanium anode plate for water treatment and preparation method thereof
CN116573728B (en) * 2023-06-05 2024-04-16 江阴米尔克电解设备有限公司 Preparation method of titanium anode plate for water treatment

Also Published As

Publication number Publication date
GB1485884A (en) 1977-09-14
IT1040223B (en) 1979-12-20
CA1058563A (en) 1979-07-17
FR2280718B1 (en) 1978-10-13
BE832010A (en) 1976-02-02
AR205045A1 (en) 1976-03-31
FR2280718A1 (en) 1976-02-27
JPS5140381A (en) 1976-04-05
BR7504830A (en) 1976-08-03
JPS592753B2 (en) 1984-01-20
SE7508697L (en) 1976-02-03
NL7508764A (en) 1976-02-04
DE2532553A1 (en) 1976-02-19

Similar Documents

Publication Publication Date Title
US3882002A (en) Anode for electrolytic processes
US3701724A (en) Electrodes for electrochemical processes
US3773555A (en) Method of making an electrode
US4070504A (en) Method of producing a valve metal electrode with valve metal oxide semi-conductor face and methods of manufacture and use
US3948751A (en) Valve metal electrode with valve metal oxide semi-conductive face
US9677183B2 (en) Electrocatalyst, electrode coating and electrode for the preparation of chlorine
US3950240A (en) Anode for electrolytic processes
US3986942A (en) Electrolytic process and apparatus
US4003817A (en) Valve metal electrode with valve metal oxide semi-conductive coating having a chlorine discharge in said coating
US3869312A (en) Electrodes and electrochemical processes
US3654121A (en) Electrolytic anode
US3875043A (en) Electrodes with multicomponent coatings
US4839007A (en) Method for purifying industrial waste water by direct oxidation of the organic pollutants
US3776834A (en) Partial replacement of ruthenium with tin in electrode coatings
US6527924B1 (en) Cathode for electrolyzing aqueous solutions
US4005004A (en) Electrode coating consisting of a solid solution of a noble metal oxide, titanium oxide, and zirconium oxide
US3926751A (en) Method of electrowinning metals
FI56981B (en) ELECTROCHEMICAL PROCESSER AND FOUNDATION FOER DESS FRAMSTAELLNING
US3940323A (en) Anode for electrolytic processes
US4318795A (en) Valve metal electrode with valve metal oxide semi-conductor face and methods of carrying out electrolysis reactions
US4012296A (en) Electrode for electrolytic processes
US4132620A (en) Electrocatalytic electrodes
US4049532A (en) Electrodes for electrochemical processes
US4072585A (en) Valve metal electrode with valve metal oxide semi-conductive coating having a chlorine discharge catalyst in said coating
CA1088026A (en) Stable electrode for electrochemical applications

Legal Events

Date Code Title Description
AS Assignment

Owner name: OCCIDENTAL CHEMICAL CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICALS & PLASTICS CORP.;REEL/FRAME:004109/0487

Effective date: 19820330

STCF Information on status: patent grant

Free format text: PATENTED FILE - (OLD CASE ADDED FOR FILE TRACKING PURPOSES)

AS Assignment

Owner name: DIAMOND SHAMROCK TECHNOLOGIES, S.A., ARTHERSTRASSE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION;REEL/FRAME:004336/0318

Effective date: 19840920

Owner name: DIAMOND SHAMROCK TECHNOLOGIES, S.A.,SWITZERLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION;REEL/FRAME:004336/0318

Effective date: 19840920

AS Assignment

Owner name: OXYTECH SYSTEMS, INC., CHARDON, OH A CORP. OF DE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION, A NY CORP;REEL/FRAME:004747/0454

Effective date: 19870219

Owner name: OXYTECH SYSTEMS, INC., OHIO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION, A NY CORP;REEL/FRAME:004747/0454

Effective date: 19870219

AS Assignment

Owner name: ELECTRODE CORPORATION, A DE CORP., OHIO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DIAMOND SHAMROCK TECHNOLOGIES, S.A.;REEL/FRAME:005004/0145

Effective date: 19881026