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EP0131978A1 - Process for manufacturing an electrode for electrochemical processes, and cathode for the electrolytic production of hydrogen - Google Patents

Process for manufacturing an electrode for electrochemical processes, and cathode for the electrolytic production of hydrogen Download PDF

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Publication number
EP0131978A1
EP0131978A1 EP84200825A EP84200825A EP0131978A1 EP 0131978 A1 EP0131978 A1 EP 0131978A1 EP 84200825 A EP84200825 A EP 84200825A EP 84200825 A EP84200825 A EP 84200825A EP 0131978 A1 EP0131978 A1 EP 0131978A1
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EP
European Patent Office
Prior art keywords
electrode
metal
active metal
colloidal silica
cathode
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.)
Granted
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EP84200825A
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German (de)
French (fr)
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EP0131978B1 (en
Inventor
Edgard Nicolas
Louis Merckaert
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Solvay SA
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Solvay SA
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Priority to AT84200825T priority Critical patent/ATE32530T1/en
Publication of EP0131978A1 publication Critical patent/EP0131978A1/en
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Publication of EP0131978B1 publication Critical patent/EP0131978B1/en
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    • 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

Definitions

  • the present invention relates to a method of manufacturing an electrode for electrochemical processes.
  • electrolysis processes it is generally sought to reduce the potentials of electrochemical reactions at the electrodes to as low a value as possible. This is particularly the case in the electrolysis processes in which hydrogen gas is produced on the active surface of a cathode, such as the processes for the electrolysis of water, aqueous solutions of hydrochloric acid and aqueous solutions of sodium chloride.
  • the cathodes most commonly used hitherto for the electrolysis of water or aqueous solutions of sodium or potassium chloride have generally consisted of plates or lattices of mild steel. These known cathodes have the advantage of easy implementation and low cost. The overvoltage on the evolution of hydrogen on these known steel cathodes is however relatively high, which increases the cost of the electrolysis processes. Steel cathodes have the additional disadvantage of being the site of progressive corrosion on contact with concentrated aqueous solutions of sodium hydroxide, as they are generally obtained in electrolysis cells with selective permeability membranes. ''
  • cathodes have been proposed obtained by applying, on a steel or nickel support, a coating formed of a nickel powder mixed with a polysilicate and then subjecting the nickel powder sintering in a reducing atmosphere, at a temperature above 760 ° C (Journal of the Electrochemical Society, vol.128, N ° 4, April 1981 - DEHALL: "Electrodes for alkaline water electrolysis", pages 740 to 746).
  • these known cathodes Compared to the electrodes formed from steel or nickel plates as such, these known cathodes generally allow an improvement in the energy efficiency of the processes for the electrolysis of water or aqueous solutions of sodium chloride.
  • the invention aims to provide a method of manufacturing electrodes which, when used as cathodes in electrolysis processes where hydrogen is generated, make it possible to further improve the energy efficiency of the electrolysis process .
  • the invention relates to a method of manufacturing an electrode for electrochemical processes, according to which an electrically conductive substrate is coated with a material containing a powder of at least one active metal for the electrochemical reduction of protons and said material is heated on the substrate, successively in an oxidizing atmosphere then in a reducing atmosphere; according to the invention, a material is used in which the aforementioned active metal is in the form of an unsintered powder, associated with colloidal silica.
  • the active metal selected must be a metal which can be oxidized by heating in an oxidizing atmosphere, and whose oxide can be reduced to the solid metallic state by heating in a reducing atmosphere.
  • the selection of the active metal also depends on the destination of the electrode. In the case where it is intended to serve as a cathode for the electrolytic production of hydrogen in an electrolysis process, it is advantageously selected from cobalt, iron, manganese and nickel.
  • the substrate can be made of any electrically conductive material compatible with the active metal and the oxidation and reduction treatments used.
  • the active metal is selected from cobalt, iron, manganese and nickel, it is advantageous to choose the material of the substrate from these metals and their alloys.
  • the substrate can have any suitable shape with the destination of the electrode. It can be, for example, a solid or perforated plate, a wire, a trellis or a stack of beads. It may have a smooth surface state, a rough surface state being however preferred. It may possibly be linked to an underlying support made of a different material, for example a material that is better conductive of electricity such as copper or aluminum.
  • Heating in an oxidizing atmosphere has the function of oxidizing the active metal.
  • the choice of temperature, atmosphere and heating time depends on the active metal selected and must therefore be determined in each particular case by routine laboratory work. After heating in an oxidizing atmosphere, the active metal is in the state of metal oxide.
  • Heating in a reducing atmosphere has the function of reducing this metal oxide to the state of metal.
  • the choice of heating conditions also depends on the active metal selected.
  • the material of the electrode which is subjected to heating in an oxidizing atmosphere contains the active metal powder in the unsintered state, associated with colloidal silica.
  • an active metal powder is desirable to use as fine as possible.
  • a powder is used in which the average particle diameter does not exceed 50 microns and preferably 30 microns. Powders which are generally well suited are those in which the average particle diameter is between 1 and 25 microns, more especially those with an average diameter of less than 20 microns.
  • the active metal powder is associated with colloidal silica.
  • the optimum amount of colloidal silica to be used depends on various factors, in particular the nature of the active metal and its particle size. In general, a relative amount by weight of colloidal silica in the material is used, comprised between 0.5 and 10% of the weight of active metal, the amounts comprised between 0.8 and 4% of this weight being preferred.
  • the colloidal silica can be used in the form of a gel which is mixed as it is with the active metal powder to form the aforementioned material.
  • the active metal powder is dispersed in a colloidal silica solution, preferably aqueous, to form the aforementioned material which is then applied as it is, to the state of a liquid suspension, on the substrate by any suitable means, for example by soaking the substrate in the suspension, by coating with a brush or roller or by spraying.
  • a colloidal silica solution preferably aqueous
  • the maximum admissible concentration of silica in the suspension is imposed by the need to produce a stable colloidal silica solution. It depends on various factors, in particular on the concentration of the active metal suspension and on the possible presence of additives such as stabilizers of the colloidal solution or thickeners.
  • the silica content of the colloidal solution should not exceed 30% by weight, values between 3 and 28% and more especially between 10 and 25% being desired.
  • the active metal powder can be dispersed in the colloidal silica solution as it is and the resulting suspension applied to the substrate.
  • the optimum amount of dilution water is variable depending on the particle size of the active metal powder, the relative amount of active metal added to the colloidal silica solution and the desired viscosity. In practice, good results are obtained by using an amount of dilution water such that the weight content of active metal in the resulting aqueous suspension is between 10 and 80 X, preferably 15 and 60 X, the contents included. between 20 and 50% being especially advantageous.
  • the drying is advantageous to subject the aforementioned material to drying on the substrate, before heating it in an oxidizing atmosphere, the drying having the function of removing at least most of the water from the solution colloidal.
  • the drying is advantageously regulated so that, at the end of the latter, the water content of the material does not exceed 10%, preferably 5% of the weight of the material. During drying, sintering of the active metal powder should be avoided.
  • a colloidal silica solution which additionally contains lithium ions as stabilizing agent.
  • the lithium ions can be introduced by any suitable means into the colloidal silica solution, preferably in the form of lithium hydroxide.
  • the content of lithium ions in the colloidal solution is preferably adjusted so as to achieve therein a molar ratio Si0 2 : Li0 2 of between 3 and 25, preferably 4 and 10.
  • Solutions of colloidal silica especially suitable in the context of the invention are those described in patent US-A-2,668,149 (DU PONT).
  • the heating in an oxidizing atmosphere and the heating in a reducing atmosphere are preferably carried out at temperatures for which no melting or sintering of the metal powder is caused.
  • heating in an oxidizing atmosphere can be carried out in air, preferably at a temperature not exceeding not 850 ° C and heating in a reducing atmosphere may be carried out in hydrogen at a temperature not exceeding 600 ° C.
  • Suitable working temperatures are those between 600 and 800 ° C, and more particularly between 700 and 760 ° C, for heating in an oxidizing atmosphere and those between 300 and 500 ° C, and more particularly between 350 and 450 ° C, for heating in a reducing atmosphere.
  • the electrode obtained after heating in a reducing atmosphere can generally, after cooling, be used as it is, in the electrochemical process for which it is intended.
  • oxidation treatment after heating in a reducing atmosphere.
  • This oxidation treatment can be carried out in ambient air and it is preferably carried out at a temperature above ambient temperature but not exceeding the maximum temperature of heating in a reducing atmosphere.
  • a practical way to achieve this is to cool the electrode in the presence of air after heating in a reducing atmosphere.
  • a coating containing a metal selected from chromium, molybdenum, cobalt, nickel is applied to the electrode, after heating in a reducing atmosphere, ruthenium, rhodium, palladium, osmium, iridium, platinum, lanthanum and rare earth elements.
  • this embodiment of the invention allows an additional gain in electrical voltage in electrochemical processes, and especially in electrolysis processes.
  • the metal of the coating can be applied to the electrode by any suitable means, for example by a technique of projection in a plasma jet.
  • the coating metal is selected from chromium, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, it is useful to carry out a deposition by process electrolytic. To this end, it has been found to be especially advantageous to carry out the electrolytic deposition of the selected metal, in an electrolyte containing ions of said metal, where the electrode is the site of an electrolytic reduction of protons.
  • a layer of a heat-decomposable compound of said metal is first deposited there, then said compound is subjected to a treatment thermal decomposition to release an oxide from said metal, and the oxide is then heated in a reducing atmosphere.
  • the thermally decomposable compound can be any compound which, by heating in a controlled atmosphere, releases an oxide of the metal selected for the coating.
  • It can be, for example, a nitrate, a sulfate, a phosphate, a chloride, a salt of carboxylic acid such as a formate, an acetate, a propionate or an oxalate. It can be used in the solid state, for example in the form of a powder, or in the liquid state, for example in the form of a molten salt, of a suspension or of a solution.
  • the heating temperature and the controlled atmosphere must be chosen according to the metal selected and the thermally decomposable compound used.
  • the heating can be carried out in an inert atmosphere (for example in a nitrogen or argon atmosphere).
  • an oxidizing atmosphere generally in air, at a temperature below 1000 ° C, preferably not exceeding 850 ° C; temperatures between 100 and 800 ° C and more especially those not exceeding 750 ° C are preferred.
  • Heating in a reducing atmosphere can generally be carried out in a hydrogen atmosphere, at a temperature not exceeding 600 ° C, usually between 200 and 500 ° C, depending on the metal selected for coating the electrode.
  • the electrodes obtained by the process according to the invention find applications in various electrochemical processes, such as, for example, cathodic protection, electrolysis and fuel cells.
  • the invention therefore also relates to the use of an electrode obtained by the process according to the invention, as a cathode for the electrolytic production of hydrogen by electrochemical reduction of protons in an aqueous alkaline medium.
  • Such use is especially advantageous in electrolysis cells for the production of aqueous solutions of alkali metal hypochlorite, as well as in cells with a permeable diaphragm and a membrane with selective permeability for the electrolysis of aqueous solutions of chloride.
  • sodium such as those described in patents FR-A-2 164 623, 2 223 083, 2 230 411, 2 248 335 and 2 387 897 (SOLVAY & Cie).
  • an aqueous brine containing 255 g of sodium chloride per kg was electrolysed in a laboratory cell with vertical electrodes, separated by a membrane with selective cation permeability NAFION (DU BRIDGE OF NEMOURS).
  • the cylindrical cell included an anode formed of a circular titanium plate, pierced with vertical slits and coated with an active material of mixed crystals, consisting of 50% by weight of ruthenium dioxide and 50% by weight of titanium dioxide.
  • the cathode consisted of a non-perforated disc whose constitution is defined in each example.
  • each electrode of the cell was 102 cm 2 , and the distance between the anode and the cathode was fixed at 6 mm, the membrane being placed at equal distance from the anode and the cathode.
  • the anode chamber was continuously supplied with the above-mentioned aqueous brine and the cathode chamber with a dilute aqueous solution of sodium hydroxide, the concentration of which was adjusted to maintain, in the catholyte, a concentration of about 32% by weight of sodium hydroxide.
  • the temperature was continuously maintained at 90 ° C in the cell.
  • the density of the electrolysis current was maintained at the fixed value of 3 kA per m 2 of area of the cathode. This produced chlorine at the anode and hydrogen at the cathode.
  • a coating composition was prepared, by mixing the following constituents:
  • the nickel powder used in this coating composition had a particle size such that its specific surface was approximately equal to 0.6 m 2 / g.
  • colloidal silica solution a colloidal solution containing approximately 20% by weight of silica and 2.1 x by weight of lithium oxide was used.
  • a polysaccharide As a thickener, a polysaccharide was used.
  • a nickel plate serving as a substrate On a nickel plate serving as a substrate, six consecutive layers of this coating composition were applied, the plate being subjected to drying for half an hour in an oven at 70 ° C. after the application of each layer.
  • the substrate and its coating were then heated in an oven at 750 ° C for 5 hours, in the presence of air, so as to oxidize practically all of the nickel in the coating. After being cooled, they were treated at 450 ° C for one hour in an oven swept by a stream of hydrogen, then cooled to room temperature, while maintaining the atmosphere of hydrogen in the oven.
  • Electrolysis results The electrode obtained at the end of the process which has just been described has been mounted as such as a cathode in the electrolysis cell. During electrolysis, the voltage across the cell was established at 3.29 V.
  • Electrolysis results The voltage at the terminals of the electrolysis cell using the electrode thus obtained as a cathode has stabilized at 3.16 V.
  • the potential of the cathode has also been measured by means of the Luggin capillary measurement method, connected to a KCl saturated calomel reference electrode (ECS) (Modern Electrochemistry, Bockris and Reddy, Plenum Press, 1970, vol.2, pages 890 and 891).
  • ECS KCl saturated calomel reference electrode
  • the cell cathode consisted of a plate of sandblasted nickel as it was. During electrolysis, the voltage across the cell stabilized at 3.36 V.
  • composition of the cathode The coating composition described in Example 1 was used, which was applied in five successive layers on a nickel plate, the plate being subjected to drying by half - hour in an oven at 70 ° C after the application of each layer.
  • the thickness of the coating material thus formed on the nickel plate was about 100 microns and it weighed about 400 g per m 2 of area.
  • the plate and its coating were then heated for 30 minutes in an oven at 750 ° C swept by a stream of hydrogen, so as to cause sintering of the nickel powder.
  • a comparison of Examples 2 and 8 further shows that the absence of sintering before heating in an oxidizing atmosphere does not harm the cathodic potential.

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Abstract

An electrically conductive substrate is coated with a material containing an unsintered powder of a metal active for electrochemical proton reduction and colloidal silica and the said material is heated on the substrate successively in an oxidizing atmosphere and then in a reducing atmosphere. The electrode may be employed as a cathode for electrolytic production of hydrogen in an alkaline medium.

Description

La présente invention a pour objet un procédé de fabrication d'une électrode pour procédés électrochimiques.The present invention relates to a method of manufacturing an electrode for electrochemical processes.

Dans les procédés d'électrolyse, on cherche généralement à réduire jusqu'à une valeur aussi faible que possible les potentiels des réactions électrochimiques aux électrodes. C'est particulièrement le cas dans les procédés d'électrolyse dans lesquels on produit de l'hydrogène gazeux à la surface active d'une cathode, tels que les procédés d'électrolyse de l'eau, de solutions aqueuses d'acide chlorhydrique et de solutions aqueuses de chlorure de sodium.In electrolysis processes, it is generally sought to reduce the potentials of electrochemical reactions at the electrodes to as low a value as possible. This is particularly the case in the electrolysis processes in which hydrogen gas is produced on the active surface of a cathode, such as the processes for the electrolysis of water, aqueous solutions of hydrochloric acid and aqueous solutions of sodium chloride.

Les cathodes les plus couramment utilisées jusqu'à présent pour l'électrolyse de l'eau ou des solutions aqueuses de chlorure de sodium ou de potassium ont généralement consisté en des plaques ou des treillis d'acier doux. Ces cathodes connues présentent en effet l'avantage d'une mise en oeuvre aisée et d'un faible coût. La surtension au dégagement d'hydrogène sur ces cathodes connues en acier est toutefois relativement élevée, ce qui grève le coût des procédés d'électrolyse. Les cathodes en acier présentent le désavantage supplémentaire d'être le siège d'une corrosion progressive au contact des solutions aqueuses concentrées d'hydroxyde de sodium, telles qu'elles sont généralement obtenues dans les cellules d'électrolyse à membrane à perméabilité sélective. 'The cathodes most commonly used hitherto for the electrolysis of water or aqueous solutions of sodium or potassium chloride have generally consisted of plates or lattices of mild steel. These known cathodes have the advantage of easy implementation and low cost. The overvoltage on the evolution of hydrogen on these known steel cathodes is however relatively high, which increases the cost of the electrolysis processes. Steel cathodes have the additional disadvantage of being the site of progressive corrosion on contact with concentrated aqueous solutions of sodium hydroxide, as they are generally obtained in electrolysis cells with selective permeability membranes. ''

Pour améliorer le rendement énergétique des procédés d'électrolyse, on a proposé des cathodes obtenues en appliquant, sur un support en acier ou en nickel, un enduit formé d'une poudre de nickel mélangée à un polysilicate et en soumettant ensuite la poudre de nickel à un frittage en atmosphère réductrice, à une température supérieure à 760°C (Journal of the Electrochemical Society, vol.128, N°4, avril 1981 - D.E.HALL : "Electrodes for alkaline water electrolysis", pages 740 à 746).To improve the energy efficiency of electrolysis processes, cathodes have been proposed obtained by applying, on a steel or nickel support, a coating formed of a nickel powder mixed with a polysilicate and then subjecting the nickel powder sintering in a reducing atmosphere, at a temperature above 760 ° C (Journal of the Electrochemical Society, vol.128, N ° 4, April 1981 - DEHALL: "Electrodes for alkaline water electrolysis", pages 740 to 746).

Dans le brevet US-A-4 362 647 (AGENCY 0F INDUSTRIAL SCIENCE & TECHNOLOGY), on a proposé des cathodes obtenues en soumettant une plaque de nickel ou une poudre de nickel frittée sur un support conducteur, à deux traitements thermiques consécutifs, respectivement une oxydation à une température supérieure à 800°C et une réduction à une température comprise entre 300 et 600°C. Dans ce procédé connu, l'oxydation est habituellement réalisée à une température comprise entre 900 et 1000°C.In US-A-4 362 647 (AGENCY 0F INDUSTRIAL SCIENCE & TECHNOLOGY), cathodes obtained by subjecting a nickel plate or a nickel powder sintered on a conductive support have been proposed to two consecutive heat treatments, respectively a oxidation at a temperature above 800 ° C and reduction at a temperature between 300 and 600 ° C. In this known process, the oxidation is usually carried out at a temperature between 900 and 1000 ° C.

Comparées aux électrodes formées de plaques en acier ou en nickel telles quelles, ces cathodes connues permettent en général une amélioration du rendement énergétique des procédés d'électrolyse de l'eau ou des solutions aqueuses de chlorure de sodium.Compared to the electrodes formed from steel or nickel plates as such, these known cathodes generally allow an improvement in the energy efficiency of the processes for the electrolysis of water or aqueous solutions of sodium chloride.

L'invention vise à fournir un procédé de fabrication d'électrodes qui, lorsqu'elles sont utilisées comme cathodes dans des procédés d'électrolyse où on génère de l'hydrogène, permettent d'améliorer davantage encore le rendement énergétique du procédé d'électrolyse.The invention aims to provide a method of manufacturing electrodes which, when used as cathodes in electrolysis processes where hydrogen is generated, make it possible to further improve the energy efficiency of the electrolysis process .

En conséquence, l'invention concerne un procédé de fabrication d'une électrode pour procédés électrochimiques, selon lequel on enduit un substrat conducteur de l'électricité avec un matériau contenant une poudre d'au moins un métal actif pour la réduction électrochimique des protons et on chauffe ledit matériau sur le substrat, successivement en atmosphère oxydante puis en atmosphère réductrice; selon l'invention, on met en oeuvre un matériau dans lequel le métal actif précité est à l'état d'une poudre non frittée, associée à de la silice colloïdale.Consequently, the invention relates to a method of manufacturing an electrode for electrochemical processes, according to which an electrically conductive substrate is coated with a material containing a powder of at least one active metal for the electrochemical reduction of protons and said material is heated on the substrate, successively in an oxidizing atmosphere then in a reducing atmosphere; according to the invention, a material is used in which the aforementioned active metal is in the form of an unsintered powder, associated with colloidal silica.

Dans le procédé selon l'invention, le métal actif sélectionné doit être un métal qui puisse être oxydé par chauffage en atmosphère oxydante, et dont l'oxyde puisse être réduit à l'état métallique solide par chauffage en atmosphère réductrice. La sélection du métal actif dépend par ailleurs de la destination de l'électrode. Dans le cas où celle-ci est destinée à servir de cathode pour la production électrolytique d'hydrogène dans un procédé d'électrolyse, on le sélectionne avantageusement parmi le cobalt, le fer, le manganèse et le nickel.In the process according to the invention, the active metal selected must be a metal which can be oxidized by heating in an oxidizing atmosphere, and whose oxide can be reduced to the solid metallic state by heating in a reducing atmosphere. The selection of the active metal also depends on the destination of the electrode. In the case where it is intended to serve as a cathode for the electrolytic production of hydrogen in an electrolysis process, it is advantageously selected from cobalt, iron, manganese and nickel.

Le substrat peut être réalisé en tout matériau conducteur de l'électricité compatible avec le métal actif et les traitements d'oxydation et de réduction mis en oeuvre. Par exemple, dans le cas où le métal actif est sélectionné parmi le cobalt, le fer, le manganèse et le nickel, on peut avantageusement choisir le matériau du substrat parmi ces métaux et leurs alliages.The substrate can be made of any electrically conductive material compatible with the active metal and the oxidation and reduction treatments used. For example, in the case where the active metal is selected from cobalt, iron, manganese and nickel, it is advantageous to choose the material of the substrate from these metals and their alloys.

Le substrat peut avoir n'importe quelle forme appropriée avec la destination de l'électrode. Il peut être, par exemple, une plaque pleine ou ajourée, un fil, un treillis ou un empilage de billes. Il peut présenter un état de surface lisse, un état de surface rugueux étant toutefois préféré. Il peut éventuellement être lié à un support sous-jacent en un matériau différent, par exemple un matériau meilleur conducteur de l'électricité tel que du cuivre ou de l'aluminium.The substrate can have any suitable shape with the destination of the electrode. It can be, for example, a solid or perforated plate, a wire, a trellis or a stack of beads. It may have a smooth surface state, a rough surface state being however preferred. It may possibly be linked to an underlying support made of a different material, for example a material that is better conductive of electricity such as copper or aluminum.

Le chauffage en atmosphère oxydante a pour fonction d'oxyder le métal actif. Le choix de la température, de l'atmosphère et du temps de chauffage dépend du métal actif sélectionné et doit dès lors être déterminé dans chaque cas particulier par un travail de routine au laboratoire. A l'issue du chauffage en atmosphère oxydante, le métal actif est à l'état d'oxyde métallique.Heating in an oxidizing atmosphere has the function of oxidizing the active metal. The choice of temperature, atmosphere and heating time depends on the active metal selected and must therefore be determined in each particular case by routine laboratory work. After heating in an oxidizing atmosphere, the active metal is in the state of metal oxide.

Le chauffage en atmosphère réductrice a pour fonction de réduire cet oxyde métallique jusqu'à l'état de métal. Le choix des conditions du chauffage dépend également du métal actif sélectionné.Heating in a reducing atmosphere has the function of reducing this metal oxide to the state of metal. The choice of heating conditions also depends on the active metal selected.

Selon l'invention, le matériau de l'électrode que l'on soumet au chauffage en atmosphère oxydante contient la poudre de métal actif à l'état non fritté, associée à de la silice colloïdale. Ainsi, selon une première caractéristique du procédé selon l'invention, on évite expréssement de fritter la poudre de métal actif avant de chauffer le matériau en atmosphère oxydante. Il est souhaitable d'utiliser une poudre de métal actif aussi fine que possible. En règle générale, on utilise une poudre dans laquelle le diamètre moyen des particules n'excède pas 50 microns et de préférence 30 microns. Des poudres qui conviennent généralement bien sont celles dans lesquelles le diamètre moyen des particules est compris entre 1 et 25 microns, plus spécialement celles de diamètre moyen inférieur à 20 microns.According to the invention, the material of the electrode which is subjected to heating in an oxidizing atmosphere contains the active metal powder in the unsintered state, associated with colloidal silica. Thus, according to a first characteristic of the method according to the invention, it is expressly avoided to sinter the active metal powder before heating the material in an oxidizing atmosphere. It is desirable to use an active metal powder as fine as possible. As a general rule, a powder is used in which the average particle diameter does not exceed 50 microns and preferably 30 microns. Powders which are generally well suited are those in which the average particle diameter is between 1 and 25 microns, more especially those with an average diameter of less than 20 microns.

Selon la seconde caractéristique du procédé selon l'invention, la poudre de métal actif est associée à de la silice colloïdale. La quantité optimum de silice colloïdale à mettre en oeuvre dépend de divers facteurs, notamment de la nature du métal actif et de sa granulométrie. En général, on utilise une quantité pondérale relative de silice colloïdale dans le matériau, comprise entre 0,5 et 10 % du poids de métal actif, les quantités comprises entre 0,8 et 4 % de ce poids étant préférées.According to the second characteristic of the method according to the invention, the active metal powder is associated with colloidal silica. The optimum amount of colloidal silica to be used depends on various factors, in particular the nature of the active metal and its particle size. In general, a relative amount by weight of colloidal silica in the material is used, comprised between 0.5 and 10% of the weight of active metal, the amounts comprised between 0.8 and 4% of this weight being preferred.

Dans le procédé selon l'invention, la silice colloïdale peut être mise en oeuvre à l'état d'un gel que l'on mélange tel quel à la poudre de métal actif pour former le matériau précité.In the process according to the invention, the colloidal silica can be used in the form of a gel which is mixed as it is with the active metal powder to form the aforementioned material.

Selon une forme d'exécution spécialement avantageuse du procédé selon l'invention, on disperse la poudre de métal actif dans une solution de silice colloidale, de préférence aqueuse, pour former le matériau précité que l'on applique alors tel quel, à l'état d'une suspension liquide, sur le substrat par tout moyen approprié, par exemple par trempage du substrat dans la suspension, par enduction à la brosse ou au rouleau ou par pulvérisation. Dans cette forme de réalisation de l'invention, la concentration maximum admissible en silice de la suspension est imposée par la nécessité de réaliser une solution de silice colloidale stable. Elle dépend de divers facteurs, en particulier de la concentration de la suspension en métal actif et de la présence éventuelle d'additifs tels que des stabilisants de la solution colloidale ou des épaississants. En règle générale, dans le cas de solutions aqueuses, il convient que la teneur en silice de la solution colloïdale n'excède pas 30 % en poids, des valeurs comprises entre 3 et 28 % et plus spécialement entre 10 et 25 % étant souhaitées.According to a particularly advantageous embodiment of the method according to the invention, the active metal powder is dispersed in a colloidal silica solution, preferably aqueous, to form the aforementioned material which is then applied as it is, to the state of a liquid suspension, on the substrate by any suitable means, for example by soaking the substrate in the suspension, by coating with a brush or roller or by spraying. In this embodiment of the invention, the maximum admissible concentration of silica in the suspension is imposed by the need to produce a stable colloidal silica solution. It depends on various factors, in particular on the concentration of the active metal suspension and on the possible presence of additives such as stabilizers of the colloidal solution or thickeners. As a general rule, in the case of aqueous solutions, the silica content of the colloidal solution should not exceed 30% by weight, values between 3 and 28% and more especially between 10 and 25% being desired.

La poudre de métal actif peut être dispersée dans la solution de silice colloidale telle quelle et la suspension résultante appliquée sur le substrat. En général, il est souhaitable de diluer la solution de silice colloidale avec de l'eau avant d'y disperser la poudre de métal actif, de manière à faciliter cette dispersion et à conférer à la suspension une viscosité compatible avec une bonne enduction du substrat. La quantité optimum d'eau de dilution est variable selon la granulométrie de la poudre de métal actif, la quantité relative de métal actif additionnée à la solution de silice colloïdale et la viscosité recherchée. En pratique, on obtient de bons résultats en mettant en oeuvre une quantité d'eau de dilution telle que la teneur pondérale en métal actif de la suspension aqueuse résultante soit comprise entre 10 et 80 X, de préférence 15 et 60 X, les teneurs comprises entre 20 et 50 % étant spécialement avantageuses.The active metal powder can be dispersed in the colloidal silica solution as it is and the resulting suspension applied to the substrate. In general, it is desirable to dilute the colloidal silica solution with water before dispersing the active metal powder therein, so as to facilitate this. dispersion and to give the suspension a viscosity compatible with good coating of the substrate. The optimum amount of dilution water is variable depending on the particle size of the active metal powder, the relative amount of active metal added to the colloidal silica solution and the desired viscosity. In practice, good results are obtained by using an amount of dilution water such that the weight content of active metal in the resulting aqueous suspension is between 10 and 80 X, preferably 15 and 60 X, the contents included. between 20 and 50% being especially advantageous.

Suivant une variante de la forme de réalisation de l'invention. qui vient d'être décrite, il est avantageux de soumettre le matériau précité à un séchage sur le substrat, avant de le chauffer en atmosphère oxydante, le séchage ayant pour fonction d'évacuer au moins la majeure partie de l'eau de la solution colloidale. Dans cette variante de l'invention, on règle avantageusement le séchage pour qu'à l'issue de celui-ci la teneur en eau du matériau n'excède pas 10 %, de préférence 5 % du poids du matériau. Pendant le séchage, il convient d'éviter un frittage de la poudre de métal actif.According to a variant of the embodiment of the invention. which has just been described, it is advantageous to subject the aforementioned material to drying on the substrate, before heating it in an oxidizing atmosphere, the drying having the function of removing at least most of the water from the solution colloidal. In this variant of the invention, the drying is advantageously regulated so that, at the end of the latter, the water content of the material does not exceed 10%, preferably 5% of the weight of the material. During drying, sintering of the active metal powder should be avoided.

Dans une autre variante de la forme de réalisation de l'invention, qui vient d'être décrite, on met en oeuvre une solution de silice colloïdale qui contient en outre des ions du lithium à titre d'agent stabilisant. Dans cette variante de l'invention, les ions du lithium peuvent être introduits par tout moyen approprié dans la solution de silice colloïdale, de préférence à l'état d'hydroxyde de lithium. La teneur en ions du lithium dans la solution colloïdale est de préférence réglée de manière à y réaliser un rapport molaire Si02:Li02 compris entre 3 et 25, de préférence 4 et 10. Des solutions de silice colloïdale convenant spécialement bien dans le cadre de l'invention sont celles décrites dans le brevet US-A-2 668 149 (DU PONT).In another variant of the embodiment of the invention, which has just been described, a colloidal silica solution is used which additionally contains lithium ions as stabilizing agent. In this variant of the invention, the lithium ions can be introduced by any suitable means into the colloidal silica solution, preferably in the form of lithium hydroxide. The content of lithium ions in the colloidal solution is preferably adjusted so as to achieve therein a molar ratio Si0 2 : Li0 2 of between 3 and 25, preferably 4 and 10. Solutions of colloidal silica especially suitable in the context of the invention are those described in patent US-A-2,668,149 (DU PONT).

Dans le procédé selon l'invention, le chauffage en atmosphère oxydante et le chauffage en atmosphère réductrice sont de préférence opérés à des températures pour lesquelles on ne provoque pas une fusion ni un frittage de la poudre métallique.In the process according to the invention, the heating in an oxidizing atmosphere and the heating in a reducing atmosphere are preferably carried out at temperatures for which no melting or sintering of the metal powder is caused.

A titre d'exemple, dans le cas où le métal actif est sélectionné parmi le cobalt, le fer, le manganèse et le nickel, le chauffage en atmosphère oxydante peut être opéré dans de l'air, de préférence à une température n'excédant pas 850°C et le chauffage en atmosphère réductrice peut être opéré dans de l'hydrogène à une température n'excédant pas 600°C. Des températures de travail qui conviennent bien sont celles comprises entre 600 et 800°C, et plus spécialement entre 700 et 760°C, pour le chauffage en atmosphère oxydante et celles comprises entre 300 et 500°C, et plus spécialement entre 350 et 450°C, pour le chauffage en atmosphère réductrice.For example, in the case where the active metal is selected from cobalt, iron, manganese and nickel, heating in an oxidizing atmosphere can be carried out in air, preferably at a temperature not exceeding not 850 ° C and heating in a reducing atmosphere may be carried out in hydrogen at a temperature not exceeding 600 ° C. Suitable working temperatures are those between 600 and 800 ° C, and more particularly between 700 and 760 ° C, for heating in an oxidizing atmosphere and those between 300 and 500 ° C, and more particularly between 350 and 450 ° C, for heating in a reducing atmosphere.

L'électrode obtenue à l'issue du chauffage en atmosphère réductrice peut généralement, après refroidissement, être utilisée telle quelle, dans le procédé électrochimique auquel elle est destinée.The electrode obtained after heating in a reducing atmosphere can generally, after cooling, be used as it is, in the electrochemical process for which it is intended.

On préfère toutefois, selon une forme d'exécution particulière de l'invention, soumettre l'électrode à un traitement d'oxydation à l'issue du chauffage en atmosphère réductrice. Ce traitement d'oxydation peut être opéré à l'air ambiant et il est de préférence exécuté à une température supérieure à la température ambiante mais n'excédant pas la température maximum du chauffage en atmosphère réductrice. Un moyen pratique de la réaliser consiste à refroidir l'électrode en présence d'air à l'issue du chauffage en atmosphère réductrice.However, it is preferred, according to a particular embodiment of the invention, to subject the electrode to an oxidation treatment after heating in a reducing atmosphere. This oxidation treatment can be carried out in ambient air and it is preferably carried out at a temperature above ambient temperature but not exceeding the maximum temperature of heating in a reducing atmosphere. A practical way to achieve this is to cool the electrode in the presence of air after heating in a reducing atmosphere.

Dans une autre forme d'exécution du procédé selon l'invention, on applique sur l'électrode, à l'issue du chauffage en atmosphère réductrice, un revêtement contenant un métal sélectionné parmi le chrome, le molybdène, le cobalt, le nickel, le ruthénium, le rhodium, le palladium, l'osmium, l'iridium, le platine, le lanthane et les éléments des terres rares.In another embodiment of the method according to the invention, a coating containing a metal selected from chromium, molybdenum, cobalt, nickel, is applied to the electrode, after heating in a reducing atmosphere, ruthenium, rhodium, palladium, osmium, iridium, platinum, lanthanum and rare earth elements.

Toutes autres choses restant égales, cette forme d'exécution de l'invention permet un gain supplémentaire de tension électrique dans les procédés électrochimiques, et spécialement dans les procédés d'électrolyse.All other things remaining equal, this embodiment of the invention allows an additional gain in electrical voltage in electrochemical processes, and especially in electrolysis processes.

Dans la mise en oeuvre de cette forme d'exécution de l'invention, le métal du revêtement peut être appliqué sur l'électrode par tout moyen approprié, par exemple par une technique de projection dans un jet de plasma. Dans le cas où le métal du revêtement est sélectionné parmi le chrome, le cobalt, le nickel, le ruthénium, le rhodium, le palladium, l'osmium, l'iridium et le platine, on peut utilement mettre en oeuvre un dépôt par procédé électrolytique. A cet effet, il s'est avéré spécialement avantageux de réaliser le dépôt électrolytique du métal sélectionné, dans un électrolyte contenant des ions dudit métal, où l'électrode est le siège d'une réduction électrolytique de protons.In the implementation of this embodiment of the invention, the metal of the coating can be applied to the electrode by any suitable means, for example by a technique of projection in a plasma jet. In the case where the coating metal is selected from chromium, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, it is useful to carry out a deposition by process electrolytic. To this end, it has been found to be especially advantageous to carry out the electrolytic deposition of the selected metal, in an electrolyte containing ions of said metal, where the electrode is the site of an electrolytic reduction of protons.

Selon une variante intéressante de cette forme d'exécution de l'invention, pour appliquer le métal du revêtement sur l'électrode, on y dépose d'abord une couche d'un composé thermodécomposable dudit métal, puis on soumet ledit composé à un traitement thermique de décomposition en sorte de libérer un oxyde dudit métal, et on chauffe ensuite l'oxyde en atmosphère réductrice. Cette variante de cette forme d'exécution du procédé selon l'invention trouve une application spécialement intéressante dans le cas où le métal du revêtement est sélectionné parmi le lanthane et les éléments des terres rares. Dans cette variante, le composé thermodécomposable peut être tout composé qui, par chauffage en atmosphère contrôlée, libère un oxyde du métal sélectionné pour le revêtement. Il peut être, par exemple, un nitrate, un sulfate, un phosphate, un chlorure, un sel d'acide carboxylique tel qu'un formiate, un acétate, un propionate ou un oxalate. Il peut être utilisé à l'état solide, par exemple à l'état d'une poudre, ou à l'état liquide, par exemple sous la forme d'un sel fondu, d'une suspension ou d'une solution. La température du chauffage et l'atmosphère contrôlée doivent être choisies en fonction du métal sélectionné et du composé thermodécomposable mis en oeuvre. Dans certaines conditions partiëulières (notamment lorsque le composé thermodécomposable est un nitrate ou un oxalate), on peut exécuter le chauffage en atmosphère inerte (par exemple en atmosphère d'azote ou d'argon). En pratique, on préfère toutefois exécuter le chauffage en atmosphère oxydante; généralement à l'air, à une température inférieure à 1000°C, de preférence n'excédant pas 850°C; des températures comprises entre 100 et 800°C et plus spécialement celles n'excédant pas 750°C ont la préférence. Le chauffage en atmosphère réductrice peut généralement être exécuté en atmosphère d'hydrogène, à une température n'excédant pas 600°C, habituellement comprise entre 200 et 500°C, selon le métal sélectionné pour le revêtement de l'électrode.According to an advantageous variant of this embodiment of the invention, to apply the metal of the coating to the electrode, a layer of a heat-decomposable compound of said metal is first deposited there, then said compound is subjected to a treatment thermal decomposition to release an oxide from said metal, and the oxide is then heated in a reducing atmosphere. This variant of this embodiment of the method according to the invention finds a particularly advantageous application in the case where the coating metal is selected from lanthanum and rare earth elements. In this variant, the thermally decomposable compound can be any compound which, by heating in a controlled atmosphere, releases an oxide of the metal selected for the coating. It can be, for example, a nitrate, a sulfate, a phosphate, a chloride, a salt of carboxylic acid such as a formate, an acetate, a propionate or an oxalate. It can be used in the solid state, for example in the form of a powder, or in the liquid state, for example in the form of a molten salt, of a suspension or of a solution. The heating temperature and the controlled atmosphere must be chosen according to the metal selected and the thermally decomposable compound used. Under certain particular conditions (in particular when the heat-decomposable compound is a nitrate or an oxalate), the heating can be carried out in an inert atmosphere (for example in a nitrogen or argon atmosphere). In practice, however, it is preferred to carry out the heating in an oxidizing atmosphere; generally in air, at a temperature below 1000 ° C, preferably not exceeding 850 ° C; temperatures between 100 and 800 ° C and more especially those not exceeding 750 ° C are preferred. Heating in a reducing atmosphere can generally be carried out in a hydrogen atmosphere, at a temperature not exceeding 600 ° C, usually between 200 and 500 ° C, depending on the metal selected for coating the electrode.

Les électrodes obtenues par le procédé selon l'invention trouvent des applications dans divers procédés électrochimiques, tels que, par exemple, la protection cathodique, l'électrolyse et les piles à combustibles.The electrodes obtained by the process according to the invention find applications in various electrochemical processes, such as, for example, cathodic protection, electrolysis and fuel cells.

L'invention concerne dès lors aussi l'utilisation d'une électrode obtenue par le procédé selon l'invention, comme cathode pour la production électrolytique d'hydrogène par réduction électrochimique de protons en milieu alcalin aqueux. Une telle utilisation s'avère spécialement avantageuse dans les cellules d'électrolyse pour la production de solutions aqueuses d'hypochlorite de métal alcalin, ainsi que dans les cellules à diaphragme perméable et à membrane à perméabilité sélective pour l'électrolyse de solutions aqueuses de chlorure de sodium, telles que celles décrites dans les brevets FR-A-2 164 623, 2 223 083, 2 230 411, 2 248 335 et 2 387 897 (SOLVAY & Cie).The invention therefore also relates to the use of an electrode obtained by the process according to the invention, as a cathode for the electrolytic production of hydrogen by electrochemical reduction of protons in an aqueous alkaline medium. Such use is especially advantageous in electrolysis cells for the production of aqueous solutions of alkali metal hypochlorite, as well as in cells with a permeable diaphragm and a membrane with selective permeability for the electrolysis of aqueous solutions of chloride. sodium, such as those described in patents FR-A-2 164 623, 2 223 083, 2 230 411, 2 248 335 and 2 387 897 (SOLVAY & Cie).

L'intérêt de l'invention va ressortir de la description des exemples d'application suivants.The advantage of the invention will become apparent from the description of the following application examples.

Dans chacun des exemples qui vont suivre, on a procédé à l'électrolyse d'une saumure aqueuse contenant 255 g de chlorure de sodium par kg, dans une cellule de laboratoire à électrodes verticales, séparées par une membrane à perméabilité sélective cationique NAFION (DU PONT DE NEMOURS).In each of the following examples, an aqueous brine containing 255 g of sodium chloride per kg was electrolysed in a laboratory cell with vertical electrodes, separated by a membrane with selective cation permeability NAFION (DU BRIDGE OF NEMOURS).

La cellule, de forme cylindrique, comprenait une anode formée d'une plaque circulaire en titane, percée de fentes verticales et revêtue d'un matériau actif de cristaux mixtes, constitués de 50 % en poids de bioxyde de ruthénium et 50 % en poids de bioxyde de titane.The cylindrical cell included an anode formed of a circular titanium plate, pierced with vertical slits and coated with an active material of mixed crystals, consisting of 50% by weight of ruthenium dioxide and 50% by weight of titanium dioxide.

La cathode a consisté en un disque non ajouré dont la constitution est définie dans chaque exemple.The cathode consisted of a non-perforated disc whose constitution is defined in each example.

La surface globale de chaque électrode de la cellule était égale à 102 cm2, et la distance entre l'anode et la cathode a été fixée à 6 mm, la membrane étant disposée à égale distance de l'anode et de la cathode.The overall surface of each electrode of the cell was 102 cm 2 , and the distance between the anode and the cathode was fixed at 6 mm, the membrane being placed at equal distance from the anode and the cathode.

Pendant l'électrolyse, on a alimenté en permanence la chambre anodique avec la saumure aqueuse précitée et la chambre cathodique avec une solution aqueuse diluée d'hydroxyde de sodium, dont la concentration a été réglée pour maintenir, dans le catholyte, une concentration d'environ 32 % en poids d'hydroxyde de sodium. La température a été maintenue en permanence à 90°C dans la cellule. Dans tous les essais, la densité du courant d'électrolyse a été maintenue à la valeur fixe de 3 kA par m2 d'aire de la cathode. On a ainsi produit du chlore à l'anode et de l'hydrogène à la cathode.During the electrolysis, the anode chamber was continuously supplied with the above-mentioned aqueous brine and the cathode chamber with a dilute aqueous solution of sodium hydroxide, the concentration of which was adjusted to maintain, in the catholyte, a concentration of about 32% by weight of sodium hydroxide. The temperature was continuously maintained at 90 ° C in the cell. In all the tests, the density of the electrolysis current was maintained at the fixed value of 3 kA per m 2 of area of the cathode. This produced chlorine at the anode and hydrogen at the cathode.

Première série d'essais (conformes à l'invention)First series of tests (in accordance with the invention) Exemple 1Example 1

(a) Constitution de la cathode : On a utilisé, pour la cathode, une électrode obtenue de la manière décrite ci-après, conforme à l'invention.(a) Composition of the cathode: An electrode obtained in the manner described below, in accordance with the invention, was used for the cathode.

On a préparé une composition d'enduit, en mélangeant les constituants suivants :

Figure imgb0001
A coating composition was prepared, by mixing the following constituents:
Figure imgb0001

La poudre de nickel mise en oeuvre dans cette composition d'enduit présentait une granulométrie telle que sa surface spécifique était environ égale à 0,6 m2/g.The nickel powder used in this coating composition had a particle size such that its specific surface was approximately equal to 0.6 m 2 / g.

Pour la solution de silice colloidale, on a utilisé une solution colloïdale contenant approximativement 20 % en poids de silice et 2,1 x en poids d'oxyde de lithium.For the colloidal silica solution, a colloidal solution containing approximately 20% by weight of silica and 2.1 x by weight of lithium oxide was used.

A titre d'épaississant, on a utilisé un polysaccharide.As a thickener, a polysaccharide was used.

Sur une plaque en nickel servant de substrat, on a appliqué six couches consécutives de cette composition d'enduit, la plaque étant soumise à un séchage d'une demi-heure en étuve à 70°C après l'application de chaque couche. L'épaisseur du matériau d'enduit ainsi formé sur le substrat, à l'issue de l'application des six couches, était d'environ 100 microns et il pesait environ 400 g par m 2 d'aire.On a nickel plate serving as a substrate, six consecutive layers of this coating composition were applied, the plate being subjected to drying for half an hour in an oven at 70 ° C. after the application of each layer. The thickness of the coating material thus formed on the substrate, after the application of the six layers, was approximately 100 microns and it weighed approximately 400 g per m 2 of area.

Le substrat et son enduit ont ensuite été chauffés dans un four à 750°C, pendant 5 heures, en présence d'air, de manière à oxyder pratiquement la totalité du nickel de l'enduit. Après avoir été refroidis, ils ont été traités à 450°C pendant une heure, dans un four balayé par un courant d'hydrogène, puis refroidis jusqu'à la température ambiante, tout en maintenant l'atmosphère d'hydrogène dans le four.The substrate and its coating were then heated in an oven at 750 ° C for 5 hours, in the presence of air, so as to oxidize practically all of the nickel in the coating. After being cooled, they were treated at 450 ° C for one hour in an oven swept by a stream of hydrogen, then cooled to room temperature, while maintaining the atmosphere of hydrogen in the oven.

(b) Résultats d'électrolyse : L'électrode obtenue à l'issue du procédé qui vient d'être décrit a été montée telle quelle comme cathode dans la cellule d'électrolyse. Au cours de l'électrolyse, la tension aux bornes de la cellule s'est établie à 3,29 V.(b) Electrolysis results: The electrode obtained at the end of the process which has just been described has been mounted as such as a cathode in the electrolysis cell. During electrolysis, the voltage across the cell was established at 3.29 V.

Exemple 2Example 2

(a) Constitution de la cathode : On a fabriqué une électrode en procédant de la manière décrite à l'exemple 1, sauf pour ce qui concerne le refroidissement final : celui-ci, qui a fait suite au traitement à 450°C en atmosphère d'hydrogène, a été effectué à l'air, de manière à provoquer une réoxydation partielle du nickel.(a) Composition of the cathode: An electrode was produced by proceeding in the manner described in Example 1, except for the final cooling: this, which followed the treatment at 450 ° C. in an atmosphere of hydrogen, was carried out in air, so as to cause a partial reoxidation of the nickel.

(b) Résultats d'électrolyse : La tension aux bornes de la cellule d'électrolyse utilisant l'électrode ainsi obtenue comme cathode, s'est stabilisée à 3,16 V. On a par ailleurs mesuré le potentiel de la cathode au moyen de la méthode de mesure au capillaire de Luggin, relié à une électrode de référence au calomel saturé en KCl (ECS) (Modern Electrochemistry, Bockris and Reddy, Plenum Press, 1970, vol.2, pages 890 et 891). Le potentiel cathodique s'est rapidement stabilisé à environ -1,18 V.(b) Electrolysis results: The voltage at the terminals of the electrolysis cell using the electrode thus obtained as a cathode has stabilized at 3.16 V. The potential of the cathode has also been measured by means of the Luggin capillary measurement method, connected to a KCl saturated calomel reference electrode (ECS) (Modern Electrochemistry, Bockris and Reddy, Plenum Press, 1970, vol.2, pages 890 and 891). The cathodic potential quickly stabilized at around -1.18 V.

Exemple 3Example 3

(a) Constitution de la cathode : Pour fabriquer la cathode, on a d'abord procédé de la manière décrite à l'exemple 1. L'électrode ainsi obtenue a subi cinq enductions consecutives avec une solution aqueuse d'un composé hydrosoluble du lanthane, de manidère qu'il y corresponde un poids total d'environ 50 g de lanthane par m2 d'aire de l'électrode. A l'issue de chacune des clinq enductions, l'électrode a été soumise à un séchage d'une demi-heure en étuve à 70°C, puis à un chauffage oxydant dans un four à 750°C pendant 5 minutes en présence d'air et ensuite à un traitement de réduction pendant une heure dans un four à 450°C balayé par un courant d'hydrogène.(a) Constitution of the Cathode: In order to manufacture the cathode, the procedure was first carried out as described in Example 1. The electrode thus obtained was subjected to five consecutive coatings with an aqueous solution of a water-soluble lanthanum compound , so that there corresponds a total weight of approximately 50 g of lanthanum per m 2 of area of the electrode. At the end of each of the clinq coatings, the elect trode was subjected to drying for half an hour in an oven at 70 ° C, then to oxidative heating in an oven at 750 ° C for 5 minutes in the presence of air and then to a reduction treatment for one hour in an oven at 450 ° C swept by a stream of hydrogen.

(b) Résultats d'électrolyse : La tension aux bornes de la cellule utilisant cette cathode s'est établie à 3,19 V.(b) Electrolysis results: The voltage across the cell using this cathode was 3.19 V.

Exemple 4Example 4

(a) Constitution de la cathode : On a répété les opérations du procédé décrit à l'exemple 3, en y apportant les modifications suivantes :

  • - la solution du composé hydrosoluble de lanthane a été remplacée par une solution aqueuse d'un composé hydrosoluble du molybdène;
  • - la quantité de solution mise en oeuvre dans les cinq enductions a été réglée pour qu'il y corresponde un apport, sur l'électrode, d'environ 150 g de molybdène par m2 d'aire de l'électrode;
  • - le chauffage oxydant a été effectué à 400°C, pendant 1 heure.
(a) Constitution of the cathode: The operations of the process described in Example 3 were repeated, with the following modifications:
  • - The solution of the water-soluble lanthanum compound has been replaced by an aqueous solution of a water-soluble molybdenum compound;
  • - The quantity of solution used in the five coatings has been adjusted so that there corresponds a supply, on the electrode, of approximately 150 g of molybdenum per m 2 of area of the electrode;
  • - the oxidative heating was carried out at 400 ° C, for 1 hour.

(b) Résultats d'électrolyse : La tension aux bornes de la cellule d'électrolyse s'est fixée à 3,13 V.(b) Electrolysis results: The voltage across the electrolysis cell was fixed at 3.13 V.

Exemple 5Example 5

(a) Constitution de la cathode : On a commencé par fabriquer une électrode de la manière décrite à l'exemple 1. L'électrode ainsi obtenue a été placée comme cathode provisoire dans la cellule d'électrolyse décrite plus haut, et on a démarré l'électrolyse comme décrit. Dès que la tension aux bornes de la cellule s'est stabilisée, on a introduit dans le catholyte une solution d'acide hexachloroplatinique, en quantité réglée pour qu'il y corresponde un dépôt électrolytique d'environ 2 g de platine par m2 d'aire de la cathode provisoire.(a) Composition of the cathode: We started by manufacturing an electrode as described in Example 1. The electrode thus obtained was placed as a temporary cathode in the electrolysis cell described above, and we started electrolysis as described. As soon as the voltage at the terminals of the cell has stabilized, a solution of hexachloroplatinic acid is introduced into the catholyte, in a quantity adjusted so that there corresponds an electrolytic deposit of approximately 2 g of platinum per m 2 d area of the temporary cathode.

(b) Résultats d'électrolyse : Après avoir ajouté la solution d'acide hexachloroplatinique comme décrit ci-dessus, la tension aux bornes de la cellule a décru et s'est stabilisée à environ 3,13 V.(b) Electrolysis results: After adding the hexachloroplatinic acid solution as described above, the voltage across the cell decreased and stabilized at around 3.13 V.

Seconde série d'essais (essais de référence)Second series of tests (reference tests) Exemple 6Example 6

Dans cet essai, la cathode de la cellule a consisté en une plaque de nickel sablé telle quelle. Au cours de l'électrolyse, la tension aux bornes de la cellule s'est stabilisée à 3,36 V.In this test, the cell cathode consisted of a plate of sandblasted nickel as it was. During electrolysis, the voltage across the cell stabilized at 3.36 V.

Exemple 7Example 7

(a) Constitution de la cathode : On a utilisé la composition d'enduit décrite à l'exemple 1, que l'on a appliquée en cinq couches successives sur une plaque en nickel, la plaque étant soumise à un séchage d'une demi-heure en étuve à 70°C après l'application de chaque couche. L'épaisseur du matériau d'enduit ainsi formé sur la plaque de nickel était d'environ 100 microns et il pesait environ 400 g par m2 d'aire.(a) Composition of the cathode: The coating composition described in Example 1 was used, which was applied in five successive layers on a nickel plate, the plate being subjected to drying by half - hour in an oven at 70 ° C after the application of each layer. The thickness of the coating material thus formed on the nickel plate was about 100 microns and it weighed about 400 g per m 2 of area.

La plaque et son enduit ont ensuite été chauffés pendant 30 minutes dans un four à 750°C balayé par un courant d'hydrogène, de manière à provoquer un frittage de la poudre de nickel.The plate and its coating were then heated for 30 minutes in an oven at 750 ° C swept by a stream of hydrogen, so as to cause sintering of the nickel powder.

(b) Résultats d'électrolyse : La tension aux bornes de la cellule, au cours de l'électrolyse, s'est établie à 3,33 V.(b) Electrolysis results: The voltage across the cell during electrolysis was 3.33 V.

Exemple 8Example 8

(a) Constitution de la cathode : On a opéré comme pour l'électrode de l'exemple 2, mais en procédant en plus à un frittage de la poudre de nickel avant le chauffage en atmosphère oxydante. Pour exécuter le frittage, le substrat et son enduit ont été chauffés dans un four sous atmosphère d'hydrogène, à 750°C pendant 30 minutes.(a) Constitution of the cathode: The operation was carried out as for the electrode of example 2, but in addition carrying out a sintering of the nickel powder before heating in an oxidizing atmosphere. To carry out the sintering, the substrate and its coating were heated in an oven under a hydrogen atmosphere, at 750 ° C. for 30 minutes.

(b) Résultats d'électrolyse : Le potentiel de la cathode, mesuré comme à l'exemple 2, s'est stabilisé à -1,20 V.(b) Electrolysis results: The potential of the cathode, measured as in Example 2, stabilized at -1.20 V.

Une comparaison des résultats d'électrolyse obtenus aux essais des exemples 1 à 5 avec ceux des exemples 6 et 8 montre que les cathodes obtenues par le procédé selon l'invention permettent généralement un gain de tension substantiel.A comparison of the electrolysis results obtained in the tests of Examples 1 to 5 with those of Examples 6 and 8 shows that the cathodes obtained by the method according to the invention generally allow a substantial voltage gain.

Une comparaison des exemples 2 et 8 montre en outre que l'absence de frittage avant le chauffage en atmosphère oxydante ne nuit pas au potentiel cathodique.A comparison of Examples 2 and 8 further shows that the absence of sintering before heating in an oxidizing atmosphere does not harm the cathodic potential.

Claims (10)

1 - Procédé de fabrication d'une électrode pour procédés électrochimiques, selon lequel on enduit.un substrat conducteur de l'électricité avec un matériau contenant une poudre d'au moins un métal actif pour la réduction électrochimique des protons et on :hauffe ledit matériau sur le substrat, successivement en atmosphère oxydante puis en atmosphère réductrice, caractérisé en ce qu'on met en oeuvre un matériau dans lequel le métal actif précité est à L'état d'une poudre non frittée, associée à de la silice colloïdale.1 - Method for manufacturing an electrode for electrochemical processes, according to which an electrically conductive substrate is coated with a material containing a powder of at least one active metal for the electrochemical reduction of protons and said material is heated on the substrate, successively in an oxidizing atmosphere then in a reducing atmosphere, characterized in that a material is used in which the abovementioned active metal is in the state of an unsintered powder, associated with colloidal silica. 2 - Procédé selon la revendication 1, caractérisé en ce qu'on net en oeuvre un matériau dans lequel la quantité de silice colloïdale est comprise entre 0,8 et 4 % du poids de métal actif.2 - Process according to claim 1, characterized in that a material is used in which the amount of colloidal silica is between 0.8 and 4% of the weight of active metal. 3 - Procédé selon la revendication 1 ou 2, caractérisé en ce qu'on met en oeuvre, pour le matériau, une suspension de la poudre de métal actif dans une solution de silice colloïdale.3 - Method according to claim 1 or 2, characterized in that one implements, for the material, a suspension of the active metal powder in a colloidal silica solution. 4 - Procédé selon la revendication 3, caractérisé en ce qu'on met en oeuvre une suspension contenant de 20 à 50 % en poids de métal actif dans une solution aqueuse de silice colloïdale contenant un poids de silice compris entre 0,8 et 4 % du poids de métal actif.4 - Method according to claim 3, characterized in that a suspension containing 20 to 50% by weight of active metal is used in an aqueous solution of colloidal silica containing a weight of silica of between 0.8 and 4% the weight of active metal. 5 - Procédé selon la revendication 3 ou 4, caractérisé en ce qu'on met en oeuvre une solution de silice colloidale qui contient des ions du lithium en quantité réglée pour obtenir un rapport molaire SiO2;LiO2 compris entre 4 et 10.5 - Process according to claim 3 or 4, characterized in that a colloidal silica solution is used which contains lithium ions in a quantity adjusted to obtain a molar ratio SiO 2 ; LiO 2 of between 4 and 10. 6 - Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce qu'on met en oeuvre un substrat en un matériau sélectionné parmi le cobalt, le fer, le manganèse, le nickel et les alliages de ces métaux et un métal actif sélectionné parmi le cobalt, le fer, le manganèse et le nickel.6 - Method according to any one of claims 1 to 5, characterized in that a substrate is used in a material selected from cobalt, iron, manganese, nickel and the alloys of these metals and a metal active selected from cobalt, iron, manganese and nickel. 7 - Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce qu'on chauffe le matériau à une température comprise entre 600 et 800°C en atmosphère oxydante et à une température comprise entre 300 et 500°C en atmosphère réductrice.7 - Method according to any one of claims 1 to 6, characterized in that the material is heated to a temperature between 600 and 800 ° C in an oxidizing atmosphere and to a temperature between 300 and 500 ° C in a reducing atmosphere . 8 - Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce qu'à l'issue du chauffage en atmosphère réductrice, on applique sur l'électrode un revêtement contenant un métal sélectionné parmi le chrome, le molybdène, le cobalt, le nickel, le ruthénium, le rhodium, le palladium, l'osmium, l'iridium, le platine, le lanthane et les éléments des terres rares.8 - Method according to any one of claims 1 to 7, characterized in that at the end of the heating in a reducing atmosphere, a coating is applied to the electrode containing a metal selected from chromium, molybdenum, cobalt , nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, lanthanum and rare earth elements. 9 - Procédé selon la revendication 8, caractérisé en ce que, pour appliquer le métal du revêtement sur l'électrode, on y dépose d'abord une couche d'un composé thermodécomposable dudit métal, puis on soumet ledit composé à un traitement thermique de décomposition en sorte de libérer un oxyde dudit métal et on chauffe ensuite l'oxyde en atmosphère réductrice.9 - Process according to claim 8, characterized in that, to apply the metal of the coating on the electrode, a layer of a thermo-decomposable compound of said metal is first deposited there, then said compound is subjected to a heat treatment of decomposes so as to release an oxide from said metal and the oxide is then heated in a reducing atmosphere. 10 - Cathode pour la production électrolytique d'hydrogène par réduction électrochimique de protons en milieu alcalin aqueux, caractérisée en ce qu'elle est une électrode obtenue par le procédé selon l'une quelconque des revendications 1 à 9.10 - Cathode for the electrolytic production of hydrogen by electrochemical reduction of protons in an aqueous alkaline medium, characterized in that it is an electrode obtained by the process according to any one of claims 1 to 9.
EP84200825A 1983-06-20 1984-06-12 Process for manufacturing an electrode for electrochemical processes, and cathode for the electrolytic production of hydrogen Expired EP0131978B1 (en)

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AT84200825T ATE32530T1 (en) 1983-06-20 1984-06-12 MANUFACTURING PROCESS OF AN ELECTRODE FOR ELECTROCHEMICAL PROCESSES AND CATHODE FOR ELECTROLYTIC HYDROGEN GENERATION.

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FR8310285 1983-06-20
FR8310285A FR2547598A1 (en) 1983-06-20 1983-06-20 METHOD FOR MANUFACTURING ELECTRODE FOR ELECTROCHEMICAL METHODS AND CATHODE FOR THE ELECTROLYTIC PRODUCTION OF HYDROGEN

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US6001236A (en) * 1992-04-01 1999-12-14 Moltech Invent S.A. Application of refractory borides to protect carbon-containing components of aluminium production cells
US5651874A (en) * 1993-05-28 1997-07-29 Moltech Invent S.A. Method for production of aluminum utilizing protected carbon-containing components
US5413689A (en) * 1992-06-12 1995-05-09 Moltech Invent S.A. Carbon containing body or mass useful as cell component
SK128095A3 (en) * 1993-04-19 1996-03-06 Moltech Invent Sa Treated carbon or carbon-based cathodic components for cells for production of aluminium
US5679224A (en) * 1993-11-23 1997-10-21 Moltech Invent S.A. Treated carbon or carbon-based cathodic components of aluminum production cells
US5753163A (en) * 1995-08-28 1998-05-19 Moltech. Invent S.A. Production of bodies of refractory borides
US5968325A (en) * 1997-01-07 1999-10-19 A.T.S. Electro-Lube Holdings Ltd. Auto-electrolytic hydrogen generator
CA2243219A1 (en) * 1998-07-14 2000-01-14 A.T.S. Electro-Lube Holdings Ltd. Electrolytic generation of nitrogen
CN101142462B (en) * 2004-06-30 2011-07-06 乔治敦铁轨设备公司 System and method for inspecting railroad track
FR2994198B1 (en) 2012-08-03 2015-02-20 Centre Nat Rech Scient COMPOSITE ELECTRODES FOR ELECTROLYSIS OF WATER.
JP6326397B2 (en) * 2015-11-20 2018-05-16 株式会社健明 Hydrogen generator and hot water supply system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1433017A (en) * 1920-11-05 1922-10-24 Ralph H Mckee Electrode
EP0009406A2 (en) * 1978-09-21 1980-04-02 The British Petroleum Company p.l.c. Metal electrodes for use in electrochemical cells and method of preparation thereof
US4362647A (en) * 1980-06-05 1982-12-07 Agency Of Industrial Science & Technology Electrode and the method for producing the same

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2019108A1 (en) * 1968-09-28 1970-06-26 Ucb Union Chimique
US3926770A (en) * 1972-06-08 1975-12-16 Ppg Industries Inc Electrolytic cell having silicon bipolar electrodes
US4243503A (en) * 1978-08-29 1981-01-06 Diamond Shamrock Corporation Method and electrode with admixed fillers
US4329219A (en) * 1979-10-29 1982-05-11 Druzhinin Ernest A Electrode for electrochemical processes
US4464421A (en) * 1982-02-04 1984-08-07 Corning Glass Works Glass frits containing WO3 or MoO3 in RuO2 -based resistors

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1433017A (en) * 1920-11-05 1922-10-24 Ralph H Mckee Electrode
EP0009406A2 (en) * 1978-09-21 1980-04-02 The British Petroleum Company p.l.c. Metal electrodes for use in electrochemical cells and method of preparation thereof
US4362647A (en) * 1980-06-05 1982-12-07 Agency Of Industrial Science & Technology Electrode and the method for producing the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF THE ELECTROCHEMICAL SOCIETY: ELECTROCHEMICAL SCIENCE AND TECHNOLOGY, vol. 128, no. 4, avril 1981, pages 741-746; D.E. HALL: "Electrodes for alkaline water electrolysis" *

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BR8403008A (en) 1985-05-28
ES533526A0 (en) 1985-04-16
PT78754A (en) 1984-07-01
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NO162524C (en) 1990-01-10
DE3469374D1 (en) 1988-03-24
FR2547598A1 (en) 1984-12-21
EP0131978B1 (en) 1988-02-17
CA1229573A (en) 1987-11-24
NO162524B (en) 1989-10-02
JPS6024388A (en) 1985-02-07
FI74742C (en) 1988-03-10
PT78754B (en) 1986-07-14
FI842495A0 (en) 1984-06-20
US4534837A (en) 1985-08-13
FI842495A (en) 1984-12-21
ATE32530T1 (en) 1988-03-15
JPH0676670B2 (en) 1994-09-28
ES8504968A1 (en) 1985-04-16

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