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
• • 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
  • C25B11/042—Electrodes formed of a single material
  • C25B11/043—Carbon, e.g. diamond or graphene
• • 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
  • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
  • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
• • 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

• An electrode especially useful as an anode in the electrolysis of alkali metal chlorides, includes a graphite body, a first surface covering of a hard ceramic such as titanium carbide or titanium nitride and at least one metal and/or metal oxide of the platinum group and a second oxide coating which is electrically porous and resistant to the electrolysis conditions.
• This invention relates to an electrode having a graphite body and to a process of manufacturing same. More particularly, this invention relates to an electrode and especially an anode useful for the electrolysis of alkali metal chlorides.
• a two-layer electrodes consisting mainly of titanium.
• Such layers consist of a noble metal and a protective porous coating of the base metal (French Pat. 1,502,587), of noble metal and titanium dioxide (Dutch Pat. 99,396), or of noble metal and silicon dioxide (opened Dutch application 6612095), or of layers which are applied from the electrolyte, to which water-glass, zirconium oxychloride, aluminum chloride, gallium chloride, and boric acid may be added for this purpose (opened Dutch application 6612096; printed German application 1,567,925), or of platinum or iron, which is subsequently oxidized (U.S. Pat. 3,103,484).
• the printed German application 1,421,047 discloses an anode 'which is made from a titanium alloy and which has been coated with a thin layer of titanium nitride by being heated in a nitrogen or ammonia atmosphere so that the anode will resist aggressive fluids and its conductivity is improved.
• the electrode of the invention comprises a graphite body having a first surface covering comprising a hard ceramic and of at least one metal and/ or metal oxide of the platinum metals and a second oxide coating which is electrically porous and resists the chemical conditions of the electrolysis.
• the first surface covering on the graphite body may consist of a mixture of a hard ceramic and at least one metal and/or metal oxide of the platinum metals, or the first covering may consist of two layers, namely, a lower layer of a hard ceramic and an upper layer of a metal and/or metal oxide of the platinum metals.
• the hard ceramic is preferably titanium carbide and more particularly titanium nitride.
• a metal from the platinum group and/or any of the oxides thereof can be used in the first covering with the ceramic material.
• the platinum metals include Ru, Rh, Pd, Os, Ir and Pt.
• An oxide of a platinum metal is a particularly suitable constituent of the first covering.
• An oxide coating of silicon dioxide, titanium dioxide, zirconium dioxide, columbium pentoxide or tantalum pentoxide is preferably used to protect the first surface covering.
• the graphite body can have any shape suitable for use as an electrode. Thus, it can be a rod, bar, sheet, block, etc.
• the graphite body can also be referred to as a skeleton, or frame, or an inner core, etc.
• body of graphite is provided with a first surface covering comprising a hard ceramic and at least one metal and/or metal oxide of the platinum metals, and the covering is subsequently protected with an oxide coating, which is electrically porous and resists the chemical conditions of the electrolysis.
• the covering on the graphite body may be formed in any of three ways:
• a hard ceramic and at least one metal and/or metal oxide of the platinum group are jointly applied in a mixture by plasma spraying.
• the hard ceramic is first applied by plasma spraying and at least one metal and/or metal oxide of the platinum group is produced from a suspension or solution by impregnation and subsequent annealing at an elevated temperature, which is suitably in the range of 300600 C.
• the hard ceramic is first applied by plasma spraying and at least one metal and/or metal oxide of the platinum group is deposited from the gaseous phase on the hard ceramic layer.
• the hard ceramic is preferably titanium carbide and particularly titanium nitride, and the metal and/r metal oxide of the platinum group is preferably an oxide of a platinum metal.
• the protective second coating is produced by a hydrolytic decomposition of the chlorides of silicon, titanium, zirconium, columbium or tantalum followed by volatilization of the solvent.
• the electrode has a high durability (wear resistance) and dimensional stability as well as desirable electrical properties. Because of the excellent conductivity of the hard ceramics and the activation by a metal and/0r metal oxide of the platinum metals, the overvoltage of the chlorine is reduced to a value which is economically desirable.
• the electrode is highly short circuit-proof. An erosion of the layer of platinum metal or platinum metal oxide is prevented by the oxide with which the electrode is coated on the outside.
• the invention enables the use of graphite, which is economically desirable, as a base or core material in making the electrode.
• EXAMPLE 1 A graphite block having dimensions of 40 x 40 x millimeters is covered on one side by plasma spraying with titanium nitride so that a layer is formed which has a thickness between 0.1 and 0.3 millimeter.
• the titanium nitride layer is washed with alcohol and subsequently dried and is then covered with a solution of 1 gram RuCl in 5 milliliters butanol and 2 grams linseed oil in such a manner that about 15 grams ruthenium per square meter are applied.
• This covering is baked for 15 minutes at 400 C. in an atmosphere of hydrogen or town gas so that a mixture of ruthenium metal and ruthenium oxide is formed.
• This layer is coated with a solution of 5 grams TiCl, in 20 milliliters butanol and the resulting coating is also baked for 15 minutes in the stated atmosphere at 400 C.
• EXAMPLE 2 A graphite block is coated with titanium nitride as described in Example 1. Thereafter, the titanium nitride layer is covered with a homogeneous layer of ruthenium metal deposited from the gaseous phase. For this purpose, the graphite block is heated under a vacuum or in a protective gas atmosphere to temperatures above 300 C. by induction heating. As a volatile ruthenium compound, the diaromatic metal complex of ruthenium (II) or (O) 'with benzene or hexamethylbenzene is used. The complex is thermally decomposed on the heated surface of the titanium nitride so that metallic ruthenium is deposited. This layer is protected by an electrically porous SiO layer, which is formed by the application of a mixture of 5 grams SiCl, in 20 milliliters butanol and subsequent baking at 400 C.
• an electrically porous SiO layer which is formed by the application of a mixture of 5 grams SiCl, in 20 milliliters
• EXAMPLE 3 A graphite block is covered with titanium nitride as in Example 1 and is covered with a palladium-iridium resinate solution and baked at 400 C. The resulting covering of 15 grams per square meter is then protected by a porous tantalum pentoxide layer, which has been formed by brushing an alcoholic tantalum pentachloride solution onto the nitride layer, followed by annealing at 400 C. within 15 minutes.
• EXAMPLE 4 A graphite block is covered with a mixture of titanium nitride and ruthenium oxide (3%) by plasma spraying. In this step, the resulting ruthenium metal-oxide mixture is concentrated at the surface of the titanium nitride layer and is subsequently protected by a porous zirconium oxide layer, which is formed by the application of an alcoholic ZrCl, solution and subsequent annealing at 400 C.
• Electrode comprising a graphite body having a first surface covering comprising a hard ceramic selected from the group of titanium carbide and titanium nitride and of at least one metal and/or metal oxide of the platinum group and a second protective oxide coating from the group of the oxides of silicon, titanium, zirconium, columbium and tantalum over said first covering which is electrically porous and resistant to electrolysis conditions.
• Electrode of claim 1 wherein said first surface covering comprises a mixture of said hard ceramic and at least one metal and/or metal oxide of the platinum metals.
• Electrode of claim 1 wherein said first surface covering comprises said hard ceramic base layer and a layer of at least one metal and/or metal oxide of the platinum group over said ceramic layer.
• Electrode of claim 1 wherein said first covering contains an oxide of a platinum metal.

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• 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)
• Electrolytic Production Of Metals (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5795378

Family Applications (1)

Country Status (17)

Cited By (14)

Families Citing this family (6)

• 1971
  • 1971-01-08 DE DE19712100652 patent/DE2100652A1/de active Pending
  • 1971-11-16 AT AT990771A patent/AT313313B/de not_active IP Right Cessation
  • 1971-12-08 CS CS718555A patent/CS171244B2/cs unknown
  • 1971-12-17 FR FR7145390A patent/FR2120796A5/fr not_active Expired
  • 1971-12-23 AU AU37272/71A patent/AU453074B2/en not_active Expired
  • 1971-12-28 ES ES398386A patent/ES398386A1/es not_active Expired
  • 1971-12-29 US US00213847A patent/US3788968A/en not_active Expired - Lifetime
  • 1971-12-30 SE SE7116962A patent/SE377141B/xx unknown
  • 1971-12-30 IT IT33128/71A patent/IT944571B/it active
• 1972
  • 1972-01-04 BE BE777682A patent/BE777682A/xx unknown
  • 1972-01-04 GB GB32272A patent/GB1355622A/en not_active Expired
  • 1972-01-06 NL NL7200171A patent/NL7200171A/xx unknown
  • 1972-01-06 CH CH18472A patent/CH564099A5/xx not_active IP Right Cessation
  • 1972-01-06 RO RO69311A patent/RO61492A/ro unknown
  • 1972-01-07 BR BR90/72A patent/BR7200090D0/pt unknown
  • 1972-01-07 CA CA131,967A patent/CA974931A/en not_active Expired
  • 1972-01-07 ZA ZA720110A patent/ZA72110B/xx unknown
  • 1972-02-22 ES ES400039A patent/ES400039A1/es not_active Expired

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