EP3358043A1 - Électrode permettant la production de chlore et son procédé de fabrication - Google Patents

Électrode permettant la production de chlore et son procédé de fabrication Download PDF

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Publication number
EP3358043A1
EP3358043A1 EP16851508.8A EP16851508A EP3358043A1 EP 3358043 A1 EP3358043 A1 EP 3358043A1 EP 16851508 A EP16851508 A EP 16851508A EP 3358043 A1 EP3358043 A1 EP 3358043A1
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Prior art keywords
catalyst layer
palladium
conductive substrate
generating electrode
oxide
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German (de)
English (en)
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EP3358043A4 (fr
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Satoshi Hatano
Hiroki Higobashi
Satoshi KAKUI
Kouichi SODA
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Osaka Soda Co Ltd
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Osaka Soda Co Ltd
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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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/04—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
    • C23C18/1208—Oxides, e.g. ceramics
    • C23C18/1216—Metal oxides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/1225—Deposition of multilayers of inorganic material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/125—Process of deposition of the inorganic material
    • C23C18/1262—Process of deposition of the inorganic material involving particles, e.g. carbon nanotubes [CNT], flakes
    • C23C18/1266—Particles formed in situ
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/125—Process of deposition of the inorganic material
    • C23C18/1295—Process of deposition of the inorganic material with after-treatment of the deposited inorganic material
    • 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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/24—Halogens or compounds thereof
    • C25B1/26—Chlorine; Compounds thereof
    • 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
    • C25B11/052—Electrodes comprising one or more electrocatalytic coatings on a substrate
    • C25B11/053—Electrodes comprising one or more electrocatalytic coatings on a substrate characterised by multilayer electrocatalytic coatings

Definitions

  • the present invention relates to a chlorine generating electrode, and particularly to an electrode to be used for on-site generation of sodium hypochlorite using dilute saltwater as in seawater electrolysis, and a method for producing the chlorine generating electrode.
  • a method for generating a hypochlorite by electrolysis of saltwater has been heretofore known, and use of a coating film of a mixed metal oxide as an electrode is widely known in the art.
  • Patent Document 1 discloses an anode obtained by covering titanium or a titanium alloy with a mixture including a platinum group metal ternary mixture of platinum-palladium oxide-ruthenium dioxide having a composition of 3 to 42% by weight of platinum, 3 to 34% by weight of palladium oxide and 42 to 94% by weight of ruthenium dioxide; and 20 to 40% by weight of titanium dioxide based on the amount of the mixture.
  • a platinum group metal ternary mixture of platinum-palladium oxide-ruthenium dioxide having a composition of 3 to 42% by weight of platinum, 3 to 34% by weight of palladium oxide and 42 to 94% by weight of ruthenium dioxide; and 20 to 40% by weight of titanium dioxide based on the amount of the mixture.
  • an electrode for producing chlorine and a hypochlorite is a film of a mixed oxide of a platinum group metal oxide and a valve metal oxide
  • the mixed oxide includes platinum group metal oxides of ruthenium, palladium and iridium, and an oxide of titanium
  • the molar ratio of the platinum group metal oxides to the valve metal oxide is 90 : 10 to 40 : 60
  • the molar ratio of ruthenium to iridium is 90 : 10 to 50 : 50
  • the molar ratio of palladium oxide to ruthenium oxide and iridium oxide is 5 : 95 to 40 : 60.
  • Patent Document 3 proposes a hypochlorite producing anode which includes a film containing 10 to 45% by weight of palladium oxide, 15 to 45% by weight of ruthenium oxide, 10 to 40% by weight of titanium dioxide, 10 to 20% by weight of platinum, and 2 to 10% by weight of an oxide of at least one metal selected from cobalt, lanthanum, cerium and yttrium.
  • An electrode having a platinum group oxide as described in Patent Documents 1 to 3 has high oxidation efficiency of chloride ions, and is capable of generating high-concentration hypochlorite ions with a high chlorine generation efficiency of more than 90%, so that a high-concentration hypochlorite can be obtained with a lower electric power consumption rate as compared to a conventional anode.
  • saltwater a sodium chloride aqueous solution
  • a concentration of 2.5 to 32% is used as an electrolytic solution
  • more dilute saltwater e.g. saltwater with a concentration of 1% or less, which can be used for ballast water etc.
  • chlorine generation efficiency is markedly reduced.
  • a main object of the present invention is to provide a chlorine generating electrode which has high chlorine generation efficiency, and is excellent in long-term durability even when used for electrolysis of low-concentration saltwater. Further, an object of the present invention is to provide a method for producing the chlorine generating electrode, a method for producing a hypochlorite using the chlorine generating electrode, and an electrolytic cell including the electrode.
  • the present inventors have extensively conducted studies for achieving the above-mentioned object.
  • the present inventors have devised a chlorine generating electrode including a conductive substrate, and a catalyst layer provided on the conductive substrate, the catalyst layer containing at least palladium oxide, ruthenium oxide and titanium oxide, the palladium oxide being in the form of particles having an average particle size of 5 ⁇ m or less, and found that the chlorine generating electrode has high chlorine generation efficiency, and is excellent in long-term durability even when used for electrolysis of low-concentration saltwater.
  • the present invention has been completed by further conducting studies based on the above-mentioned findings.
  • Item 2 The chlorine generating electrode according to item 1, wherein the catalyst layer has an X-ray diffraction peak intensity of 500 cps or more at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray.
  • Item 3 The chlorine generating electrode according to item 1 or 2, wherein the catalyst layer has an X-ray diffraction peak half-value width of 1.5 deg or less at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray.
  • Item 4 The chlorine generating electrode according to any one of items 1 to 3, wherein the ratio of palladium metal contained in the catalyst layer is 1 mol% or more where the content of metal elements in the catalyst layer is 100 mol%.
  • Item 5 The chlorine generating electrode according to any one of items 1 to 4, which is used for electrolysis of saltwater with a concentration of 1% or less.
  • Item 8 The method for producing a chlorine generating electrode according to item 6 or 7, wherein the catalyst layer formed by the firing step has an X-ray diffraction peak intensity of 500 cps or more at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray.
  • Item 9 The method for producing a chlorine generating electrode according to any one of items 6 to 8, wherein the catalyst layer formed by the firing step has an X-ray diffraction peak half-value width of 1.5 deg or less at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray.
  • Item 11 A method for producing a hypochlorite, the method including the step of electrolyzing a metal chloride aqueous solution using the chlorine generating electrode according to any one of items 1 to 5.
  • a chlorine generating electrode which has high chlorine generation efficiency, and is excellent in long-term durability even when used for electrolysis of low-concentration saltwater. Further, according to the present invention, there can be provided a method for producing the chlorine generating electrode, a method for producing a hypochlorite using the chlorine generating electrode, and an electrolytic cell including the electrode.
  • a chlorine generating electrode of the present invention includes a conductive substrate, and a catalyst layer provided on the conductive substrate.
  • the catalyst layer contains at least palladium oxide, ruthenium oxide and titanium oxide, and the palladium oxide is in the form of particles having an average particle size of 5 ⁇ m or less.
  • the chlorine generating electrode of the present invention includes such a specific catalyst layer, and is therefore capable of exhibiting high chlorine generation efficiency and excellent long-term durability even when used for electrolysis of low-concentration saltwater (e.g. saltwater with a concentration of 1% or less) (e.g. the electrolytic solution is low-concentration saltwater).
  • low-concentration saltwater e.g. saltwater with a concentration of 1% or less
  • the electrolytic solution is low-concentration saltwater
  • the chlorine generating electrode of the present invention includes a conductive substrate and a catalyst layer.
  • the material of the conductive substrate is not particularly limited, and examples thereof include materials that are used for known chlorine generating electrodes.
  • Specific examples of the material of the conductive substrate include valve metals such as titanium, tantalum, zirconium and niobium, and alloys of two or more valve metals.
  • the shape of the conductive substrate is not particularly limited, and examples thereof include a plate shape, a disk shape, a rod shape, a cylindrical shape, an expanded metal shape and a punching metal shape.
  • a surface of the conductive substrate may be subjected to a sandblasting treatment (surface roughening treatment) or the like as necessary for the purpose of, for example, exhibiting an anchor effect on the catalyst layer.
  • the sandblasting treatment is a surface treatment method in which a high-pressure gas containing sand-like particles is sprayed to a surface of a material.
  • the sandblasting treatment can be performed by a known method.
  • the surface roughness of the conductive substrate can be controlled by adjusting the type of a polishing agent to be used, the treatment time and the like.
  • the material of the sand-like particles include alumina, glass and iron.
  • a degreasing treatment or the like may be performed as necessary.
  • the surface roughness Ra (arithmetic mean roughness) of the conductive substrate surface subjected to the roughening treatment is, for example, in a range of about 0.5 to 10 ⁇ m.
  • the surface roughness Ra can be set outside the above-mentioned range.
  • the surface of the conductive substrate may be subjected to a surface treatment with an acid or the like.
  • the acid is not particularly limited, and examples thereof include sulfuric acid, nitric acid, hydrochloric acid, oxalic acid and hydrofluoric acid.
  • the thickness of the conductive substrate is not particularly limited, and can be appropriately set according to, for example, a size of an electrolytic cell to be provided with the chlorine generating electrode.
  • the thickness of the conductive substrate is, for example, about 0.5 to 10 mm.
  • a catalyst layer is provided on the conductive substrate.
  • the catalyst layer contains at least palladium oxide, ruthenium oxide and titanium oxide. More specifically, a surface of the conductive substrate is provided with a film including the catalyst layer.
  • the average particle size of palladium oxide particles contained in the catalyst layer is 5 ⁇ m or less.
  • a conventional chlorine generating electrode has the problem that, for example, when low-concentration saltwater is used as an electrolytic solution, chlorine generation efficiency is considerably reduced, and when low-concentration saltwater is used as an electrolytic solution, a high voltage is required for electrolysis of saltwater, and therefore a large burden is imposed on the electrode, so that the electrode has a reduced life.
  • the catalyst layer contains palladium oxide, ruthenium oxide and titanium oxide, and the average particle size of palladium oxide is set to 5 ⁇ m or less, and thus the chlorine generating electrode is capable of exhibiting high chlorine generation efficiency and excellent long-term durability even when used for electrolysis of low-concentration saltwater.
  • the reason for this can be considered, for example, as follows. That is, in comparison of the surface areas of palladium oxide dispersed on the catalyst layer at the same molar ratio, the smaller the average particle size of palladium oxide, the larger the surface area thereof, and thus the larger the number of active points. Thus, it is considered that since the average particle size of palladium oxide contained in the catalyst layer is 5 ⁇ m or less, a function as a catalyst is improved.
  • the chlorine generating electrode of the present invention is capable of exhibiting high chlorine generation efficiency particularly when used for electrolysis of a metal chloride aqueous solution (particularly saltwater) with a low concentration of about 0.1 to 1%.
  • the average particle size of palladium oxide may be 5 ⁇ m or less, but from the viewpoint of further improving the chlorine generation efficiency of the chlorine generating electrode of the present invention, and also further improving the long-term durability of the electrode, the average particle size of palladium oxide is preferably about 0.01 to 5 ⁇ m, more preferably about 0.01 to 2.5 ⁇ m, still more preferably about 0.1 to 1.8 ⁇ m.
  • the average particle size thereof is a value measured under the following conditions.
  • Laser scattering particle distribution measuring apparatus LA-950 manufactured by HORIBA, Ltd.
  • Measurement method Suction is started for increasing the sample dispersion force. Thereafter, compressed air is supplied at 0.4 to 0.8 MPa to perform forced dispersion. A state with no sample is measured as a blank. The intensity of a feeder is adjusted, and measurement is started when the transmittance reaches 70 to 90%.
  • the transmittance is 70 to 90%, the number of repetitions is 30, and the particle size is on a volume basis.
  • each of the average particle sizes of the particles of these oxides is an average of the major axes of 20 particles present in a field of view of a SEM image of the catalyst layer.
  • the ratio of palladium oxide contained in the catalyst layer is not particularly limited, but from the viewpoint of further improving the chlorine generation efficiency of the chlorine generating electrode of the present invention, and also further improving the long-term durability of the electrode, the ratio of palladium metal contained in the catalyst layer is preferably 1 mol% or more, more preferably 1 to 90 mol%, further more preferably 3 to 75 mol%, especially preferably 5 to 75 mol% based on 100 mol% of metal elements contained in the catalyst layer.
  • the ratio of ruthenium metal contained in the catalyst layer is preferably 1 mol% or more, more preferably 1 to 90 mol%, further more preferably 3 to 70 mol%, especially preferably 3 to 50 mol%.
  • the ratio of titanium metal contained in the catalyst layer is preferably 1 mol% or more, more preferably 5 to 90 mol%, further more preferably 10 to 70 mol%, especially preferably 15 to 60 mol%.
  • the catalyst layer in addition to palladium oxide, ruthenium oxide and titanium oxide, other components may be contained in the catalyst layer in the present invention.
  • the other components include platinum group metals or platinum group metal oxides, and specific examples thereof include platinum, iridium oxide and rhodium oxide.
  • the catalyst layer may contain transition metal oxides such as manganese oxide, cobalt oxide and chromium oxide, valve metal oxides such as tantalum oxide, zirconium oxide and niobium oxide.
  • the ratio of the other components is preferably 60 mol% or less, more preferably 5 to 50 mol%, further more preferably 5 to 40 mol% in terms of a ratio of metals contained in the catalyst layer.
  • the X-ray diffraction peak intensity at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray is preferably 500 cps or more, more preferably 500 to 4000 cps, further more preferably 1000 to 4000 cps, especially preferably 1300 to 4000 cps in the present invention.
  • the peak intensity is 500 cps or more, stable chlorine generation efficiency can be suitably maintained.
  • the crystallinity of palladium oxide becomes higher, so that a function as a catalyst can be suitably exhibited.
  • the X-ray diffraction peak half-value width at a palladium oxide diffraction peak 2 ⁇ of 33° to 35° as measured by an X-ray diffraction method using a CuK ⁇ ray is preferably 1.5 deg or less, more preferably 0.1 to 1.0 deg, further more preferably 0.1 to 0.9 deg, especially preferably 0.1 to 0.8 deg.
  • the peak width is 1.5 deg or less, stable chlorine generation efficiency can be suitably maintained.
  • the crystallinity of palladium oxide becomes higher, so that a function as a catalyst can be suitably exhibited.
  • X-ray diffraction measurement of the catalyst layer is performed under the following conditions.
  • Measurement method A measurement sample is placed in such a manner that the sample can be irradiated with an X-ray from the measurement equipment main body. A current and a voltage are applied to age the sample, and then the sample is irradiated with an X-ray to perform measurement.
  • the thickness of the catalyst layer is not particularly limited, and can be appropriately set according to, for example, a size of an electrolytic cell to be provided with the chlorine generating electrode.
  • the thickness of the catalyst layer is, for example, about 0.1 to 10 ⁇ m.
  • the catalyst layer can be formed, for example, as follows. First, a coating step of coating a conductive substrate with a solution containing at least a palladium compound, a ruthenium compound and a titanium compound is carried out. Here, the ratio of the palladium compound, the ruthenium compound and the titanium compound is adjusted so as to coincide with the foregoing ratio of palladium metal, ruthenium metal and the titanium metal in the catalyst layer. The above-mentioned other components may be added to the solution.
  • the palladium compound is not particularly limited as long as it forms palladium oxide in the catalyst layer after the later-described firing step, and examples of the palladium compound include palladium oxide, palladium chloride and palladium nitrate. Among them, palladium oxide and palladium chloride are preferable.
  • the ruthenium compound is not particularly limited as long as it forms ruthenium oxide in the catalyst layer after the later-described firing step, and examples of the ruthenium compound include ruthenium oxide, ruthenium chloride and ruthenium nitrate. Among them, ruthenium oxide is preferable.
  • the titanium compound is not particularly limited as long as it forms titanium oxide in the catalyst layer after the later-described firing step, and examples of the titanium compound include butyl titanate, titanium alcoholate and titanium trichloride. Among them, butyl titanate and titanium alcoholate are preferable.
  • the liquid to be used for the solution is not particularly limited, and examples thereof include organic solvents such as n-butanol, propanol, and hexanol.
  • the solution may contain palladium oxide, but even when palladium chloride, palladium nitrate or the like is used, palladium chloride, palladium nitrate or the like may be converted into palladium oxide in the later-described firing step.
  • the coating step at least one of palladium chloride and palladium nitrate is used as a palladium compound, and in the later-described firing step, the palladium compound is heated at a temperature of 400 to 600°C to generate palladium oxide particles having an average particle size of 5 ⁇ m from the palladium chloride, palladium nitrate or the like.
  • a firing step of firing the conductive substrate coated with the solution is carried out. Accordingly, a catalyst layer is formed on a surface of the conductive substrate. Preferably, the solution on the conductive substrate is evaporated before the conductive substrate is fired.
  • the coating step and the firing step may be repeated a plurality of times. By repeating these steps a plurality of times, the thickness of the catalyst layer can be increased.
  • the heating temperature in the firing step is not particularly limited, but is preferably about 400 to 650°C, more preferably about 450 to 650°C, further more preferably about 450 to 600°C.
  • the firing time is preferably about 5 to 60 minutes, more preferably about 5 to 40 minutes, further more preferably about 5 to 30 minutes.
  • the chlorine generating electrode of the present invention can be suitably produced which includes a conductive substrate, and a catalyst layer provided on the conductive substrate.
  • the chlorine generating electrode of the present invention can be placed in an electrolytic cell. That is, the electrolytic cell in the present invention includes the above-mentioned chlorine generating electrode.
  • the chlorine generating electrode serves as an anode, and further a cathode is provided.
  • the material that forms the cathode is not particularly limited, and examples thereof include stainless steel and titanium.
  • a hypochlorite can be suitably produced by electrolyzing a metal chloride aqueous solution using the chlorine generating electrode of the present invention.
  • a metal chloride aqueous solution e.g. saltwater (e.g. ballast water, seawater, or the like), a potassium chloride aqueous solution or the like is preferable.
  • the hypochlorite include sodium hypochlorite and potassium hypochlorite.
  • the chlorine generating electrode of the present invention can be suitably used for electrolysis of, for example, saltwater with a low concentration of 1% or less. That is, in the method for producing a hypochlorite using the chlorine generating electrode of the present invention, the concentration of a metal chloride in a metal chloride aqueous solution is preferably 1% or less.
  • the temperature during electrolysis is not particularly limited, but is preferably about 2 to 35°C, more preferably about 5 to 30°C from the viewpoint of ensuring that the chlorine generating electrode has high chlorine generation efficiency, and improved long-term durability even when used for electrolysis of low-concentration saltwater.
  • the current density during electrolysis is not particularly limited, but is preferably about 1 to 20 A/dm 2 , more preferably about 1 to 15 A/dm 2 from the viewpoint of ensuring that the chlorine generating electrode has high chlorine generation efficiency, and improved long-term durability even when used for electrolysis of low-concentration saltwater.
  • the average particle size of palladium oxide used as a raw material was measured under the following conditions.
  • Measuring equipment Laser scattering particle distribution measuring apparatus LA-950 (manufactured by HORIBA, Ltd.) Measurement method: Suction is started for increasing the sample dispersion force. Thereafter, compressed air is supplied at 0.4 to 0.8 MPa to perform forced dispersion. A state with no sample is measured as a blank. The intensity of a feeder is adjusted, and measurement is started when the transmittance reaches 70 to 90%. Measurement conditions: The transmittance is 70 to 90%, the number of repetitions is 30, and the particle size is on a volume basis.
  • a surface of the catalyst layer is observed with SEM, major axes of 20 particles observed in the field of view are measured, and the average thereof is determined.
  • Palladium oxide is considerably different from ruthenium oxide and titanium oxide in particle size of particles used as a raw material, and therefore it is possible to distinguish palladium oxide particles from the other particles in a SEM image.
  • X-ray diffraction measurement of the catalyst layer was performed under the following conditions.
  • Measurement method A measurement sample is placed in such a manner that the sample can be irradiated with an X-ray from the measurement equipment main body. A current and a voltage are applied to age the sample, and then the sample is irradiated with an X-ray to perform measurement.
  • X-ray source CuK ⁇ ray Output setting: 40 kV, 40 mA
  • Preparation of sample the electrode is cut to 35 mm ⁇ 50 mm ⁇ 1 mm.
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution of palladium oxide, ruthenium chloride and butyl titanate each having a predetermined average particle size as a raw material of a catalyst layer (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 500°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • the average particle size of palladium oxide used as a raw material was 0.52 ⁇ m.
  • X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°. The results are shown in Table 1.
  • Fig. 1 shows a SEM image of the surface of the catalyst layer of the anode obtained in Example 1 (magnification: 5,000).
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution of palladium oxide, ruthenium chloride and butyl titanate each having a predetermined average particle size as a raw material of a catalyst layer (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 450°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • the average particle size of palladium oxide used as a raw material was 0.17 ⁇ m.
  • X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°.
  • Table 1 shows a SEM image of the surface of the catalyst layer of the anode obtained in Example 2 (magnification: 5,000).
  • Fig. 9 shows a graph showing a relationship between a diffraction peak 2 ⁇ (°) and a peak intensity (cps) as measured by X-ray diffraction for the catalyst layer of the anode obtained in Example 2.
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution of palladium oxide, ruthenium chloride and butyl titanate each having a predetermined average particle size as a raw material of a catalyst layer (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 550°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • the average particle size of palladium oxide used as a raw material was 1.53 ⁇ m.
  • X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°.
  • Table 1 shows a SEM image of the surface of the catalyst layer of the anode obtained in Example 3 (magnification: 5,000).
  • Fig. 10 shows a graph showing a relationship between a diffraction peak 2 ⁇ (°) and a peak intensity (cps) as measured by X-ray diffraction for the catalyst layer of the anode obtained in Example 3.
  • Example 1 Except that as a raw material of a catalyst layer, cobalt nitrate was added so as to attain a composition as shown in Table 1, the same procedure as in Example 1 was carried out to prepare an anode.
  • X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°.
  • Table 1 shows a SEM image of the surface of the catalyst layer of the anode obtained in Example 4 (magnification: 10,000).
  • Fig. 11 shows a graph showing a relationship between a diffraction peak 2 ⁇ (°) and a peak intensity (cps) as measured by X-ray diffraction for the catalyst layer of the anode obtained in Example 4.
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution containing a predetermined amount of each of palladium chloride, ruthenium chloride and butyl titanate as a catalyst raw material (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 500°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • Observation of the surface of the catalyst layer of the resulting anode with SEM revealed that palladium oxide particles of about 0.4 to 0.5 ⁇ m were present.
  • the major axes of randomly selected 20 particles were measured by the above-mentioned method, and an average particle size was calculated. The average particle size was 0.15 ⁇ m.
  • X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°. The results are shown in Table 1.
  • Fig. 5 shows a SEM image of the surface of the catalyst layer of the anode obtained in Example 5 (magnification: 10,000).
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution containing a predetermined amount of each of palladium chloride, ruthenium chloride and butyl titanate as a catalyst raw material (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 400°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • Fig. 6 shows a SEM image of the surface of the catalyst layer of the anode obtained in Comparative Example 1 (magnification: 5,000).
  • a surface of a conductive substrate (thickness: 1 mm) composed of a titanium flat plate was subjected to a sandblasting treatment with #36 alumina.
  • the thus-roughened surface of the conductive substrate was coated with a n-butanol solution containing a predetermined amount of each of ruthenium chloride and butyl titanate as a catalyst raw material (the composition of the catalyst layer has values (mol%) as shown in Table 1), dried at 120°C for 10 minutes, and then fired at 500°C for 10 minutes.
  • the coating-drying-firing process was repeated to prepare an anode with a catalyst layer provided on a surface of a conductive substrate.
  • Fig. 7 shows a SEM image of the surface of the catalyst layer of the anode obtained in Comparative Example 2 (magnification: 5,000).
  • Example 2 Except that the average particle size of palladium oxide used as a raw material was 5.14 ⁇ m, the same procedure as in Example 1 was carried out to prepare an anode. In addition, for the catalyst layer of the anode, X-ray diffraction measurement using a CuK ⁇ ray was performed to determine the X-ray diffraction peak intensity and half width at a diffraction peak 2 ⁇ of about 34°. The results are shown in Table 1.
  • Fig. 8 shows a SEM image of the surface of the catalyst layer of the anode obtained in Comparative Example 3 (magnification: 5,000).
  • Example 1 Composition of catalyst layer (mol%) Average particle size of palladium oxide X-ray diffraction peak intensity X-ray diffraction peak half-value width Chlorine generation efficiency Ru Pd Co Ti ( ⁇ m) (cps) (deg) (%)
  • Example 1 20 30 - 50 0.52 1,600 0.80 65
  • Example 2 20 40 - 40 0.17 2,800 0.35
  • Example 3 10 70 - 20 1.53 3,100 0.24 66
  • Example 4 20 30 10 40 0.52 1,400 0.45 66
  • Example 5 40 10 - 50 0.15* 1,700 0.75 65 Comparative Example 1 30 20 - 50 - 400 2.00 42 Comparative Example 2 50 - - 50 - - - 38 Comparative Example 3 20 30 - 50 5.14 1,500 1.50 58 *
  • the average particle size of palladium oxide in Example 5 is a value measured by observing a surface of the catalyst layer with SEM.
  • Saltwater with each saltwater concentration (0.1%, 0.15% or 0.5%) was electrolyzed using the anode obtained in Example 4, and stainless steel as a cathode, and chlorine generation efficiency was obtained from an effective chlorine concentration.
  • chlorine generation efficiency (after elapse of 1,100 hours) at a current density of 4.2 A/dm 2 was determined at each saltwater concentration.
  • Figs. 12 to 14 show graphs showing a relationship between the temperature and the chlorine generation efficiency. As is evident from the graph shown in Fig. 12 , the chlorine generation efficiency was 50% or more even at an electrolysis temperature of 10°C when the saltwater concentration was 0.1%.
  • the graph shown in Fig. 12 shows that the chlorine generation efficiency was 50% or more even at an electrolysis temperature of 10°C when the saltwater concentration was 0.1%.
  • the chlorine generation efficiency was 50% or more even at an electrolysis temperature of 5°C when the saltwater concentration was 0.15%.
  • the chlorine generation efficiency was 70% or more even at an electrolysis temperature of 2°C when the saltwater concentration was 0.5%.
  • chlorine generation efficiency was not significantly reduced even with an electrolysis time of more than 4,500 hours (chlorine generation efficiency was 46% with an electrolysis time of 0 hour, while chlorine generation efficiency was 42% with an electrolysis time of 4,573 hours) when the anode of Example 4 was used.
  • initial chlorine generation efficiency was high (chlorine generation efficiency was 46% with an electrolysis time of 0 hour), but chlorine generation efficiency was considerably reduced with an electrolysis time of more than 1,000 hours (chlorine generation efficiency was 39% with an electrolysis time of 1,176 hours).

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JP7706693B2 (ja) * 2021-08-31 2025-07-14 株式会社大阪ソーダ 塩素発生用電極およびその製造方法
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JP2023095833A (ja) * 2021-12-24 2023-07-06 石福金属興業株式会社 塩素発生用電極
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