WO2013141211A1 - 電解セル及び電解槽 - Google Patents
電解セル及び電解槽 Download PDFInfo
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- WO2013141211A1 WO2013141211A1 PCT/JP2013/057681 JP2013057681W WO2013141211A1 WO 2013141211 A1 WO2013141211 A1 WO 2013141211A1 JP 2013057681 W JP2013057681 W JP 2013057681W WO 2013141211 A1 WO2013141211 A1 WO 2013141211A1
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- absorption layer
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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
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
- C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/18—After-treatment
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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
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
- C25B1/46—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells
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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
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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
- C25B11/042—Electrodes formed of a single material
- C25B11/046—Alloys
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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
- C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
- C25B11/085—Organic compound
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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
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
Definitions
- the present invention relates to an electrolytic cell and an electrolytic cell for alkaline salt electrolysis, water electrolysis, and fuel cell.
- electrolysis In the electrolysis (hereinafter referred to as “electrolysis”) of an aqueous alkali metal chloride solution such as saline, an ion exchange membrane method using an electrolytic cell equipped with an ion exchange membrane is mainly used.
- This electrolytic cell includes an electrolytic cell connected in series inside thereof. Electrolysis is performed with an ion exchange membrane interposed between the electrolysis cells.
- a cathode chamber having a cathode and an anode chamber having an anode are arranged back to back via a partition wall (back plate).
- an electrolytic cell described in Patent Document 1 is known.
- Patent Document 2 discloses an electrolysis cathode structure in which Raney nickel is formed on the surface of the current collector by dispersion plating.
- Raney nickel attached to the current collector by dispersion plating is weak in adhesion to the current collector, and may be peeled off during electrolysis.
- Raney nickel in a portion in contact with the elastic body may be physically peeled off.
- Raney nickel with a specific surface area that is too large after alkali development it may cause heat generation or ignition when Raney nickel in the open cathode structure is exposed to air after the electrolytic cell is stopped. Need attention.
- the technique described in Patent Document 2 cannot be applied to an electrolytic cell that originally has an electrode structure without a current collector.
- an object of the present invention is to provide a highly durable electrolytic cell and electrolytic cell that can suppress deterioration of the cathode due to a reverse current when electrolysis is stopped.
- the inventors of the present invention electrically connected a cathode and a reverse current absorption layer that is more easily oxidized than the cathode in an electrolytic cell. It has been found that the deterioration of the resin can be greatly suppressed, and the present invention has been achieved. That is, the present invention is as follows.
- the present invention is formed on an anode chamber, a cathode chamber, a partition wall separating the anode chamber and the cathode chamber, an anode installed in the anode chamber, a cathode installed in the cathode chamber, a substrate, and the substrate And a reverse current absorber disposed in the cathode chamber, the anode and the cathode are electrically connected, and the cathode and the reverse current absorption layer are electrically connected.
- An electrolytic cell is provided.
- this invention provides an electrolytic cell provided with the said electrolytic cell.
- the reverse current absorption layer preferably contains an element having a lower redox potential than the cathode (an element having a lower redox potential).
- the reverse current absorption layer includes C, Cr, Ni, Ti, Fe, Co, Cu, Al, Zr, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, Au, Bi, Cd, Hg,
- One or more elements selected from the group consisting of Mn, Mo, Sn, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu It is preferable to include.
- the pore volume of pores having a pore diameter of 10 nm or more in the pore diameter distribution curve measured by a nitrogen gas adsorption method is preferably 80% or more of the total pore volume.
- the reverse current absorption layer is preferably formed by spraying Ni or NiO on at least a part of the surface of the substrate.
- the reverse current absorption layer is formed by spraying NiO on at least a part of the surface of the substrate and then performing a reduction treatment on the NiO.
- the cathode preferably has a Ni base and a catalyst layer formed on the Ni base.
- the cathode chamber further includes a current collector, a support that supports the current collector, and a metal elastic body, and the metal elastic body is between the current collector and the cathode.
- the support is disposed between the current collector and the partition, and the partition, the support, the current collector, the metal elastic body, and the cathode are electrically connected.
- At least a part of the base material of the reverse current absorber may be a current collector, and a reverse current absorption layer may be formed on the surface of the current collector.
- At least a part of the base material of the reverse current absorber may be a metal elastic body, and a reverse current absorption layer may be formed on the surface of the metal elastic body.
- At least a part of the base material of the reverse current absorber may be a partition, and a reverse current absorption layer may be formed on the surface of the partition.
- At least a part of the base material of the reverse current absorber may be a support, and a reverse current absorption layer may be formed on the surface of the support.
- At least a part of the reverse current absorber may be disposed between the cathode and the metal elastic body.
- At least a part of the reverse current absorber may be disposed between the metal elastic body and the current collector.
- At least a part of the reverse current absorber may be disposed between the current collector and the partition.
- the cathode chamber further includes a support that supports the cathode, the support is disposed between the cathode and the partition, and the partition, the support, and the cathode are electrically connected. It is preferable.
- At least a part of the base material of the reverse current absorber may be a partition, and a reverse current absorption layer may be formed on the surface of the partition.
- At least part of the base material of the reverse current absorber may be a support, and a reverse current absorption layer may be formed on the surface of the support.
- the reverse current absorber may be disposed between the cathode and the partition.
- At least a part of the substrate of the reverse current absorber may be a cube, a rectangular parallelepiped, a plate, a rod, a net, or a sphere.
- the specific surface area of the reverse current absorption layer is preferably 0.01 to 100 m 2 / g.
- the total amount of electricity absorbed by all reverse current absorbers is preferably 1,000 to 2,000,000 C / m 2 .
- the total effective surface area of all reverse current absorbers is preferably 10 to 100,000 m 2 .
- an electrolysis cell and an electrolyzer capable of suppressing deterioration of the cathode due to a reverse current when electrolysis is stopped.
- FIG. 1 is a cross-sectional view of an electrolysis cell 1 according to the first embodiment of the present invention.
- the electrolysis cell 1 was installed in the anode chamber 10, the cathode chamber 20, the partition wall 30 installed between the anode chamber 10 and the cathode chamber 20, the anode 11 installed in the anode chamber 10, and the cathode chamber 20. It has a cathode 21, a base material 18a, and a reverse current absorption layer 18b formed on the base material 18a, and a reverse current absorber 18 installed in the cathode chamber.
- the anode 11 and the cathode 21 belonging to one electrolytic cell 1 are electrically connected to each other.
- the electrolytic cell 1 includes the following cathode structure.
- the cathode structure 40 includes a cathode chamber 20, a cathode 21 installed in the cathode chamber 20, and a reverse current absorber 18 installed in the cathode chamber 20.
- the reverse current absorber 18 is shown in FIG. As shown, it has a base material 18a and a reverse current absorption layer 18b formed on the base material 18a, and the cathode 21 and the reverse current absorption layer 18b are electrically connected.
- the cathode chamber 20 further includes a current collector 23, a support 24 that supports the current collector, and a metal elastic body 22.
- the metal elastic body 22 is installed between the current collector 23 and the cathode 21.
- the support 24 is installed between the current collector 23 and the partition wall 30.
- the current collector 23 is electrically connected to the cathode 21 via the metal elastic body 22.
- the partition wall 30 is electrically connected to the current collector 23 via the support 24. Therefore, the partition wall 30, the support 24, the current collector 23, the metal elastic body 22, and the cathode 21 are electrically connected.
- the cathode 21 and the reverse current absorption layer 18b are electrically connected.
- the cathode 21 and the reverse current absorption layer may be directly connected, or may be indirectly connected via a current collector, a support, a metal elastic body, a partition wall, or the like.
- the entire surface of the cathode 21 is preferably covered with a catalyst layer for the reduction reaction.
- the form of electrical connection is that the partition wall 30 and the support 24, the support 24 and the current collector 23, the current collector 23 and the metal elastic body 22 are directly attached, and the cathode 21 is laminated on the metal elastic body 22. It may be a form. As a method for directly attaching these constituent members to each other, welding or the like can be mentioned. Further, the reverse current absorber 18, the cathode 21, and the current collector 23 may be collectively referred to as a cathode structure 40.
- FIG. 2 is a sectional view of two adjacent electrolytic cells 1 in the electrolytic cell 4 of this embodiment.
- FIG. 3 shows the electrolytic cell 4.
- FIG. 4 shows a process of assembling the electrolytic cell 4.
- the electrolytic cell 1, the cation exchange membrane 2, and the electrolytic cell 1 are arranged in series in this order.
- An ion exchange membrane 2 is disposed between the anode chamber of one electrolytic cell 1 and the cathode chamber of the other electrolytic cell 1 of two adjacent electrolytic cells in the electrolytic cell. That is, the anode chamber 10 of the electrolysis cell 1 and the cathode chamber 20 of the electrolysis cell 1 adjacent thereto are separated by the cation exchange membrane 2.
- FIG. 2 shows a sectional view of two adjacent electrolytic cells 1 in the electrolytic cell 4 of this embodiment.
- FIG. 3 shows the electrolytic cell 4.
- FIG. 4 shows a process of assembling the electrolytic cell 4.
- the electrolytic cell 1, the cation exchange membrane 2, and the electrolytic cell 1 are arranged
- the electrolytic cell 4 is composed of a plurality of electrolytic cells 1 connected in series via an ion exchange membrane 2. That is, the electrolytic cell 4 is a bipolar electrolytic cell including a plurality of electrolytic cells 1 arranged in series and an ion exchange membrane 2 arranged between adjacent electrolytic cells 1. As shown in FIG. 4, the electrolytic cell 4 is assembled by arranging a plurality of electrolytic cells 1 in series via an ion exchange membrane 2 and connecting them by a press 5.
- the electrolytic cell 4 has an anode terminal 7 and a cathode terminal 6 connected to a power source.
- the anode 11 of the electrolytic cell 1 located at the end of the plurality of electrolytic cells 1 connected in series in the electrolytic cell 4 is electrically connected to the anode terminal 7.
- the cathode 21 of the electrolytic cell located at the end opposite to the anode terminal 7 is electrically connected to the cathode terminal 6. The current during electrolysis flows from the anode terminal 7 side toward the cathode terminal 6 via the anode and cathode of each electrolysis cell 1.
- the electrolysis cell anode terminal cell which has only an anode chamber
- the electrolysis cell cathode terminal cell which has only a cathode chamber in the both ends of the connected electrolysis cell 1.
- the anode terminal 7 is connected to the anode terminal cell arranged at one end
- the cathode terminal 6 is connected to the cathode terminal cell arranged at the other end.
- salt water is supplied to each anode chamber 10, and pure water or a low-concentration sodium hydroxide aqueous solution is supplied to the cathode chamber 20.
- Each liquid is supplied to each electrolytic cell 1 from an electrolytic solution supply pipe (not shown) via an electrolytic solution supply hose (not shown).
- the electrolytic solution and the product by electrolysis are collected from an electrolytic solution collection pipe (not shown in the drawing).
- sodium ions in brine move from the anode chamber 10 of one electrolytic cell 1 through the ion exchange membrane 2 to the cathode chamber 20 of the adjacent electrolytic cell 1. Therefore, the current during electrolysis flows along the direction in which the electrolysis cells 1 are connected in series.
- the reverse current is generated by a voltage (potential difference) between the electrolytic cell 1 and the grounded electrolyte supply pipe or electrolyte recovery pipe when the electrolysis is stopped.
- the reverse current flows to the electrolyte supply pipe or the electrolyte recovery pipe via the electrolyte supply hose.
- the reverse current flows in the direction opposite to the direction of current during electrolysis.
- This reverse current is generated due to a state in which a battery using chlorine as a reactive species is formed when electrolysis is stopped.
- chlorine generated on the anode chamber 10 side is dissolved in the electrolyte solution (such as saline) in the anode chamber 10. Since the chlorine dissolved in the anode chamber 10 is highly reactive, a reaction occurs in which chlorine is decomposed at the anode 11 when the electrolysis is stopped. Thereby, when the electrolysis is stopped, a voltage is generated between the electrolytic cell 1 and the grounded electrolyte supply pipe or electrolyte recovery pipe, and a reverse current flows.
- the cathode 21 is deteriorated (oxidation of the cathode 21, dissolution or oxidation of the catalyst layer) due to the reverse current.
- a catalyst material that dissolves due to a reverse current such as Ru or Sn
- the cathode catalyst layer dissolves due to the reverse current when electrolysis is stopped, and the amount of catalyst on the cathode 21 decreases. The life of the cathode 21 is extremely shortened.
- ⁇ Mechanism> The mechanism by which the deterioration of the cathode is suppressed by the reverse current being consumed by the reverse current absorber 18 will be described.
- the cathode potential is maintained at about ⁇ 1.2 V (vs. Ag
- the potential rises while the oxidation reaction proceeds on the cathode, and the potential of the cathode finally reaches the oxygen generation potential.
- the reverse current absorption layer having a lower redox potential than the components contained in the catalyst layer of the cathode is electrically connected to the cathode. Therefore, the reverse current generated when the electrolysis is stopped is consumed not by the cathode but by the reverse current absorption layer electrically connected to the cathode. That is, the reverse current absorption layer absorbs the reverse current, and the oxidation reaction of the reverse current absorption layer corresponding to the reverse current electricity quantity proceeds. As a result, the oxidation / deterioration of the catalyst layer of the cathode 21 due to the reverse current is suppressed.
- the reverse current absorber it is possible to prevent the performance and durability of the cathode catalyst layer from being deteriorated due to impurities (particularly Fe ions) contained in the catholyte. This is presumably because the reverse current absorption layer has a large specific surface area, and the electrolytic reduction reaction of Fe ions in the reverse current absorption layer is more likely to occur than in the cathode catalyst layer.
- an oxidation reaction (2) of Ni metal proceeds in the vicinity of ⁇ 0.9 V (vs. Ag
- the oxidation elution reaction (3) of Ru which is a component of the catalyst layer, proceeds in the vicinity of ⁇ 0.1 V (vs. Ag
- the oxidation reaction (4) of nickel hydroxide generated by the reaction (2) proceeds to generate trivalent to tetravalent Ni.
- the oxygen generation reaction (5) proceeds near +0.3 V (vs. Ag
- the cathodic potential is approximately -1.0 V vs. Ag
- the oxidation elution reaction (3) of Ru which is a component of the catalyst layer, does not start immediately when a reverse current flows, but is an oxidation reaction (1), (2) of a substance having a lower redox potential. Starts after the end. That is, by making the amount of electricity consumed in the oxidation reaction of hydrogen and nickel having a lower redox potential than Ru of the catalyst layer larger than the reverse current amount of electricity, the oxidation elution reaction of Ru of the catalyst layer (3 ) Can be suppressed.
- the Ni oxidation reaction (6) (reaction (2) in the reverse current absorption layer is performed. If the amount of electricity consumed in this reaction (6) is greater than the amount of reverse current, the potential of the cathode (catalyst layer) rises above the potential of the reverse current absorption layer. do not do. This is because since the cathode and the reverse current absorber are electrically connected, their potentials are always the same. As a result, the oxidation reaction (6) of Ni in the reverse current absorption layer proceeds in preference to the elution reaction (3) of Ru, so that the oxidation elution reaction (3) of Ru in the catalyst layer can be suppressed.
- the cathode catalyst layer is made of Ru
- elements other than Ru may be used for the catalyst layer.
- elements for the catalyst layer C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu are mentioned.
- the same effect as in the case of Ru can be obtained. Even when the above elements other than Ru are used in the catalyst layer, when the cathode potential is increased, the oxidation reaction proceeds and the performance is deteriorated. In addition, the reactions (1), (2), (4), and (5) proceed. Among these reactions, the trivalent to tetravalent nickel compounds produced in the reaction (4) have a needle-like, hexagonal or hexagonal columnar structure, and are produced at the interface between the catalyst layer and the cathode substrate. To do.
- a cathode 21 is provided in the frame of the cathode chamber 20.
- the cathode 21 preferably has a nickel base and a catalyst layer covering the nickel base.
- the components of the catalyst layer on the nickel substrate include C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Examples thereof include metals such as Ho, Er, Tm, Yb, and Lu, and oxides or hydroxides of the metals.
- Examples of the method for forming the catalyst layer include plating, alloy plating, dispersion / composite plating, CVD, PVD, thermal decomposition, and thermal spraying. These methods may be combined. Moreover, you may perform a reduction process to the cathode 21 as needed. In addition, as a base material of the cathode 21, you may use a nickel alloy other than a nickel base material.
- the reverse current absorption layer 18b preferably contains an element having a base redox potential (lower redox potential) than that of the cathode. That is, it is preferable that the oxidation-reduction potential of the oxidation reaction of the reverse current absorption layer 18b is lower than the oxidation-reduction potential of the oxidation reaction of the catalyst layer covering the surface of the cathode 21.
- Examples of the material of the reverse current absorption layer 18b include inorganic materials such as a metal material having a high specific surface area, an oxide material, and a carbon material having a high specific surface area.
- a material having a redox potential lower than that of the component contained in the catalyst layer (coating) of the cathode 21 is preferable.
- Such materials include C, Cr, Ni, Ti, Fe, Co, Cu, Al, Zr, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, Au, Bi, Cd, Hg. , Mn, Mo, Sn, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like.
- the material constituting the reverse current absorption layer 18b is Ni, Mn, Cr, Fe, Co, Re, La, Ce, which has a lower oxidation-reduction potential than Ru.
- Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and the like can be used. Due to the reaction in which a hydroxide or oxide is formed from the above elements contained in the reverse current absorption layer 18b, the amount of electricity of the reverse current is absorbed, and the oxidation of the cathode is suppressed.
- the reverse current absorption layer 18b Even when the mixture, alloy or composite oxide of the above elements is used as the reverse current absorption layer 18b, the effect of absorbing the reverse current can be obtained.
- the metal material constituting the reverse current absorption layer 18b is Ni, Mn, Cr, Fe, Co, Re, La, Ce, which has a lower redox potential than Pt.
- Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and the like can be used.
- Examples of the carbon material having a high specific surface area include activated carbon, activated carbon carbon fiber, carbon black, graphite, carbon fiber, carbon nanotube, and mesoporous carbon.
- a carbon material having a high specific surface area can function as a capacitor that accumulates an electric quantity of reverse current.
- Organic materials such as a conductive polymer may be used as the material for the reverse current absorption layer 18b.
- the conductive polymer include polyaniline, 1,5-diaminoanthraquinone, cyclic indole trimer, and poly (3-methylthiophene).
- the materials for the reverse current absorption layer 18b can be used in combination.
- a metal material and an oxide material having a high specific surface area are preferable, and nickel having a high specific surface area is more preferable.
- the reverse current absorption layer 18b is more preferably a porous layer containing Ni or NiO.
- the crystallinity of the reverse current absorption layer is increased, and the physical durability and the chemical durability are increased.
- High physical durability means that the reverse current absorption layer becomes strong due to the presence of nickel metal as a skeleton, and the reverse current absorption layer collects even when a physical force (for example, pressure by a metal elastic body) is applied. It means that it is difficult to peel off from the electric body.
- High chemical durability means that the nickel metal existing as a skeleton in the reverse current absorption layer is not oxidized or reduced. Since the reverse electrochemical reaction is a surface reaction, nickel metal can exist stably while maintaining the skeletal structure even in forward electrolysis and reverse electrolysis due to high chemical durability.
- the full width at half maximum is more preferably 0.5 ° or less, and particularly preferably 0.38 ° or less.
- the lower limit of the full width at half maximum is not particularly limited, for example, the full width at half maximum is 0.01 ° or more. Preferably, it is 0.1 ° or more, and more preferably 0.2 ° or more.
- Elements other than Ni such as C, Cr, Al, Zr, Ru, Rh, Ag, Re, Os, Ir, Pt, Au, Bi, Cd, Co, Cu, Fe, Hg, Mn, Mo, Pd, Sn, Ti, W, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are also reactions in which these elements become hydroxides or oxides.
- the reverse current absorption layer may contain, in addition to Ni or NiO, these elements, or a mixture, alloy, or composite oxide of these elements.
- the ratio of Ni in the total elements included in the reverse current absorption layer 18b is preferably 10 mol% or more and 100 mol% or less. More preferably, it is 30 mol% or more and 100 mol% or less. More preferably, it is 50 mol% or more and 100 mol% or less.
- the reverse current absorption layer 18b is preferably formed by spraying Ni or NiO on at least a part of the surface of the current collector. Further, when NiO is sprayed, it is preferably formed by performing reduction treatment on NiO after spraying NiO. Thereby, the reverse current absorption amount of the reverse current absorption layer can be increased from the beginning of electrolysis. Furthermore, the durability of the reverse current absorption layer 18b is further increased.
- the pore volume of pores having a pore diameter of 10 nm or more in the pore diameter distribution curve measured by a nitrogen gas adsorption method is preferably 80% or more of the total pore volume. 85% or more, more preferably 90% or more.
- the specific surface area, pore size distribution curve, and pore volume of the reverse current absorption layer can be obtained as follows.
- the measurement sample is put in a dedicated cell, and pretreatment is performed by heating and evacuating to remove the adsorbate on the pore surface in advance. Thereafter, the adsorption and desorption isotherm of nitrogen adsorption on the measurement sample is measured at -196 ° C.
- the specific surface area of the measurement sample can be obtained.
- the pore diameter distribution curve and pore volume of the measurement sample can be obtained by analyzing by the BJH method.
- the total effective surface area of all reverse current absorbers (reverse current absorption layers) provided in one electrolytic cell is preferably 10 to 100,000 m 2 .
- the effective surface area means the surface area including the pores of the reverse current absorption layer.
- the total of the effective surface areas of all reverse current absorbers (reverse current absorption layers) provided in one electrolytic cell is within the above range, so that the reverse current absorber (reverse current absorption layer) has sufficient reverse current. Can be absorbed into.
- the total effective surface area (total effective surface area) of all reverse current absorbers (reverse current absorption layers) included in one electrolytic cell is the specific surface area of the reverse current absorber (reverse current absorption layer) measured by the nitrogen adsorption method ( m 2 / g) and the amount (g) of all the reverse current absorbers (reverse current absorption layers) included in one electrolytic cell.
- the upper limits of the redox capacity and charge / discharge capacity of the reverse current absorber (reverse current absorption layer 18b) are not particularly limited.
- the oxidation / reduction ability and charge / discharge ability of the reverse current absorption layer are the total amount of electricity that can be absorbed by all reverse current absorbers (reverse current absorption layers) installed in one electrolytic cell by the electrolytic area of the electrolytic cell. It is expressed by the value divided.
- the electrolytic area of the electrolytic cell is equal to the sum of the areas of either the cathodes or the anodes in the electrolytic cell.
- the reverse current absorber (reverse current absorption layer) preferably has an oxidation-reduction ability of an electric quantity of 1,000 C to 2,000,000 C per 1 m 2 of electrolytic area. That is, it is preferable that the total amount of absorbed electricity of all reverse current absorbers (reverse current absorption layers) included in one electrolytic cell is 1,000 to 2,000,000 [Coulomb / m 2 ]. As described above, in order to allow the reverse current absorption layer to proceed with a reaction that consumes a sufficient amount of electricity to absorb the reverse current, the reverse current absorber is introduced in an amount corresponding to the reverse current. do it. If the amount of electricity that can be absorbed by all reverse current absorbers included in one electrolysis cell is within the above range, the reverse current absorber can sufficiently absorb the reverse current.
- the reverse current absorption layer preferably has a charge / discharge capacity of 2,000,000 C or less per 1 m 2 of electrolysis area, and more preferably has a charge / discharge capacity of 1,500,000 C or less. preferable.
- the reverse current absorption layer has a redox potential of the electrolyte area 1 m 2 per 1,000C or more electrical quantity, the reverse current absorption layer, when the quantity of electricity more than 1,000C per electrolysis area 1 m 2 is flowed, It means that an oxidation reaction or a reduction reaction can occur on the surface.
- the reverse current absorption layer has a charge-discharge capacity of the electrolysis area 1 m 2 per 1,000C or more electrical quantity, the reverse current absorption layer, when the electric quantity over the electrolyte area 1 m 2 per 1,000C flows, It means that the surface can be charged.
- the reverse current absorption layer 18b may be a thin film, a powder, a plate, or a net.
- the reverse current absorption layer 18b may be fixed to the substrate 18a, or may cover the substrate.
- the specific surface area of the reverse current absorption layer 18b is preferably 0.01 to 100 m 2 / g, preferably 0.01 to 30 m 2 / g, 0 It is very preferably 1 to 15 m 2 / g.
- the specific surface area can be measured by a nitrogen adsorption method (BET method). When the specific surface area is 0.01 m 2 / g or more, the effect of the present invention is easily obtained. When the specific surface area is 100 m 2 / g or less, after the electrolytic cell is stopped, the reverse current absorber does not generate heat or ignite when it comes into contact with air, and can be handled safely.
- the reverse current absorption layer In order to advance the oxidation reaction of the reverse current absorption layer that consumes a sufficient amount of electricity to absorb the amount of electricity of the reverse current, it is sufficient to introduce an amount of the reverse current absorption layer corresponding to the amount of reverse current electricity. . Since the electrochemical reaction is a surface reaction, the reverse current absorption layer needs to have a larger surface area in order to cause more electrochemical reaction to proceed in the reverse current absorption layer. For this reason, when comparing two reverse current absorption layers having the same mass, a reverse current absorber having a larger specific surface area causes more electrochemical reaction to proceed and absorbs more reverse current electricity. can do. Further, when two reverse current absorption layers having the same specific surface area are compared, the larger the mass, the larger the total surface area, so that a larger amount of electricity can be absorbed.
- the reverse current absorption layer 18b In order to make the reverse current absorption layer 18b into a desired porous layer, raw material powder such as metallic nickel powder and nickel oxide powder is granulated into particles of 10 to 100 ⁇ m, and then reverse current absorption is performed from the raw material powder by a thermal spraying method.
- the layer 18b may be formed. This is because the adhesion between the reverse current absorption layer 18b and the substrate 18a and the adhesion between the nickel particles in the reverse current absorption layer 18b are appropriately improved by forming the reverse current absorption layer by a thermal spraying method.
- the reverse current absorption layer 18b is formed on the current collector 23, the adhesion between the reverse current absorption layer 18b and the current collector 23 is also appropriately improved. Thereby, durability can also be improved.
- the reverse current absorption 18b layer is formed by spraying. It is good to form.
- raw material powders such as metallic nickel powder and nickel oxide powder that are in a semi-molten state in high-temperature plasma may be sprayed onto the substrate.
- the raw material powder is preferably granulated into particles of 10 to 100 ⁇ m. Thereby, the adhesiveness of a base material and a reverse current absorption layer becomes good.
- the sprayed raw material powder in a semi-molten state is cooled and hardened simultaneously with the adhesion to the base material, and becomes particles having moderately high crystallinity.
- a raw material powder such as metallic nickel powder or nickel oxide powder is used in an amount of 10 to 100 ⁇ m. Then, a reverse current absorption layer may be formed from the raw material powder by a thermal spraying method.
- the substrate 18a of the reverse current absorber 18 may be independent from the current collector, the metal elastic body, the partition wall, and the support.
- the independent reverse current absorber can be easily added later to the cathode chamber of the existing electrolytic cell. That is, according to the independent reverse current absorber, the reverse current absorption capability can be imparted to the cathode chamber of the existing electrolytic cell.
- the number of reverse current absorbers (its base material) may be one or plural.
- the shape of the base material of the reverse current absorber may be a cube, a rectangular parallelepiped, a plate, a rod, a net, or a sphere.
- the base material of at least a part of the reverse current absorber may be a metal elastic body, a partition wall, or a support body.
- the reverse current absorber may be disposed between the cathode and the metal elastic body.
- the reverse current absorber may be disposed between the metal elastic body and the current collector.
- the reverse current absorber may be installed between the current collector and the partition wall.
- the reverse current absorber When the substrate of the reverse current absorber is independent from the current collector, metal elastic body, partition wall and support, the reverse current absorber is between the cathode and the metal elastic body, in the metal elastic body, or in the metal elastic body. It is installed between the body and the current collector, between the current collector and the partition, or on the partition. When there is a reverse current absorber between the cathode and the metal elastic body, the reverse current absorber is directly electrically connected to the cathode. When there is a reverse current absorber between the metal elastic body and the current collector, the reverse current absorber is electrically connected to the cathode through the metal elastic body.
- the reverse current absorber When there is a reverse current absorber between the current collector and the partition wall, the reverse current absorber is electrically connected to the cathode through the current collector and the metal elastic body. Alternatively, the reverse current absorber is electrically connected to the cathode via a support, a current collector, and a metal elastic body.
- At least a part of the base material of the reverse current absorber may be a metal elastic body, and a reverse current absorption layer may be formed on the surface of the metal elastic body. Since the reverse current absorption layer is formed on the surface of the metal elastic body and the metal elastic body is electrically connected to the cathode, the reverse current absorption body can absorb the reverse current.
- the metal elastic body is a reverse current absorber
- the reverse current absorber can be easily installed only by placing the metal elastic body on the current collector. Further, since the metal elastic body, which is a reverse current absorber, is in direct contact with the cathode, the cathode protection effect is enhanced. In addition, when the metal elastic body is a reverse current absorber, the reverse current absorber can be easily replaced.
- At least part of the base material of the reverse current absorber may be a partition, and a reverse current absorption layer may be formed on the surface of the partition. Since the partition wall is electrically connected to the cathode through the support, the current collector, and the metal elastic body, the reverse current absorption layer formed on the partition wall can absorb the reverse current. Since the partition wall is a reverse current absorber, the production cost of the electrolytic cell can be reduced.
- At least part of the base material of the reverse current absorber may be a support, and a reverse current absorption layer may be formed on the surface of the support. Since the support is electrically connected to the cathode via the current collector and the metal elastic body, the reverse current absorption layer formed on the support can absorb the reverse current. Since the support is a reverse current absorber, the production cost of the electrolytic cell can be reduced.
- At least part of the base material of the reverse current absorber may be a current collector, and a reverse current absorption layer may be formed on the surface of the current collector. Since the current collector is electrically connected to the cathode via the metal elastic body, the reverse current absorption layer formed on the current collector can absorb the reverse current. Since the current collector is a reverse current absorber, the production cost of the electrolysis cell can be suppressed.
- the total amount of absorbed electricity of all reverse current absorbers included in one electrolysis cell can be measured, for example, by the following method.
- the potential of the reverse current absorber is the same as that during salt electrolysis (-1.2V).
- AgCl) the potential of the reverse current absorber is monitored while applying a reverse current at a constant current, and the time until reaching a certain potential is measured. For example, the time until the potential of the reverse current absorber reaches ⁇ 0.1 V (vs. Ag
- the product of the time and the current density of the reverse current calculates the reverse current electric quantity that can be absorbed by all the reverse current absorbers until Ru is oxidized and eluted.
- Examples of the method for producing a reverse current absorber include a CVD method, a PVD method, a thermal decomposition method, and a thermal spraying method.
- Thermal spraying methods are classified according to the heat source and the material to be sprayed, and specific examples thereof include flame spraying, high-speed flame spraying, arc spraying, plasma spraying, line explosion spraying, cold spraying and the like. These methods may be combined.
- a reverse current absorption layer is formed on a substrate to obtain a reverse current absorber.
- Examples of the reduction treatment method include a method in which a reducing agent such as hydrogen or hydrazine is brought into direct contact with the reverse current absorber, a method in which the reverse current absorber is electrochemically reduced, and the like.
- Specific examples of the method for producing the reverse current absorber include a method in which nickel oxide powder, metallic nickel powder or Raney nickel powder is sprayed onto the surface of the substrate. Hydrogen reduction and electrolytic reduction may be performed on the base material sprayed with this powder. Electrolytic reduction may be performed as electrolysis of an alkali metal compound when the reverse current absorber is used.
- electrolytic reduction when the reverse current absorber is used, for example, electrolysis of an aqueous caustic soda solution at a current density of 0.1 to 15 kA / m 2 is preferable. At this time, most of the hydrogen generation reaction proceeds at the cathode and does not proceed at the reverse current absorber. However, since the reverse current absorber is electrically connected to the cathode, the potential of the reverse current absorber is maintained at the hydrogen generation potential. The reverse current absorber is exposed to a reducing atmosphere. Electrolytic reduction may be performed by such a method. Alternatively, electrolytic reduction using a reverse current absorber may be performed as a cathode for hydrogen generation in electrolysis of an alkali metal compound. When electrolytic reduction using a reverse current absorber as a cathode for hydrogen generation is performed, for example, electrolysis of an aqueous caustic soda solution at a current density of 0.1 to 15 kA / m 2 is preferable.
- the partition wall 30 is disposed between the anode chamber 10 and the cathode chamber 20.
- the partition wall 30 is sometimes called a separator, and partitions the anode chamber 10 and the cathode chamber 20.
- known separators for electrolysis can be used, and examples include partition walls in which a plate made of nickel on the cathode side and titanium on the anode side is welded.
- the anode chamber 10 has an anode 11.
- the anode chamber 10 includes an anode-side electrolyte supply unit that supplies an electrolyte to the anode chamber 10 and a baffle plate that is disposed above the anode-side electrolyte supply unit and is substantially parallel to the partition wall 30. And an anode-side gas-liquid separation part that is disposed above the baffle plate and separates the gas from the electrolyte mixed with the gas.
- An anode 11 is provided in the frame of the anode chamber 10.
- a metal electrode such as a so-called DSA (registered trademark: Permerek electrode) can be used.
- DSA is a titanium substrate whose surface is coated with an oxide containing ruthenium, iridium, and titanium.
- the anode side electrolyte solution supply unit supplies the electrolyte solution to the anode chamber 10 and is connected to the electrolyte solution supply pipe.
- the anode-side electrolyte supply unit is preferably arranged below the anode chamber 10.
- a pipe dispensersion pipe
- More preferably, such a pipe is arranged along the surface of the anode 11 in parallel with the bottom 19 of the electrolysis cell.
- This pipe is connected to an electrolytic solution supply pipe (liquid supply nozzle) that supplies the electrolytic solution into the electrolytic cell 1.
- the electrolytic solution supplied from the liquid supply nozzle is conveyed into the electrolytic cell 1 by a pipe, and is supplied into the anode chamber 10 through an opening provided on the surface of the pipe. It is preferable to arrange the pipe along the surface of the anode 11 in parallel with the bottom portion 19 of the electrolytic cell, because the electrolyte can be uniformly supplied into the anode chamber 10.
- the anode side gas-liquid separator is disposed above the baffle plate.
- the anode-side gas-liquid separator has a function of separating the generated gas such as chlorine gas and the electrolytic solution.
- the upper direction means the upper direction in the electrolysis cell 1 of FIG. 1
- the lower direction means the lower direction in the electrolysis cell 1 of FIG.
- the electrolytic cell 1 of the present embodiment is provided with an anode-side gas-liquid separation unit for separating gas and liquid. It is preferable that a defoaming plate for eliminating bubbles is installed in the anode side gas-liquid separation unit. When the gas-liquid mixed phase flow passes through the defoaming plate, the bubbles are repelled, so that the electrolyte and gas can be separated. As a result, vibration during electrolysis can be prevented.
- the baffle plate is preferably disposed above the anode-side electrolyte supply unit and is disposed substantially parallel to the partition walls 30.
- the baffle plate is a partition plate that controls the flow of the electrolytic solution in the anode chamber 10.
- an electrolytic solution salt water or the like
- the baffle plate is preferably disposed so as to separate the space near the anode 11 and the space near the partition wall 30. From this point of view, the baffle plate is preferably provided so as to face each surface of the anode 11 and the partition wall 30.
- the electrolytic solution concentration (salt water concentration) decreases due to the progress of electrolysis, and product gas such as chlorine gas is generated.
- product gas such as chlorine gas
- the specific gravity difference of a gas-liquid arises in the space near the anode 11 partitioned by the baffle plate and the space near the partition 30.
- a current collector may be separately provided inside the anode chamber 10. Such a current collector may have the same material and configuration as the current collector of the cathode chamber described later. In the anode chamber 10, the anode 11 itself can also function as a current collector.
- the cathode chamber 20 includes a cathode 21 and a reverse current absorber, and the cathode 21 and the reverse current absorber are electrically connected.
- the cathode chamber 20 preferably includes a cathode side electrolyte supply unit and a cathode side gas-liquid separation unit. Note that the description of the same parts as those constituting the anode chamber 10 among the parts constituting the cathode chamber 20 is omitted.
- the cathode chamber 20 preferably includes a current collector 23. Thereby, the current collection effect increases.
- the current collector 23 has a plate shape and is preferably disposed substantially parallel to the surface of the cathode 21.
- the current collector 23 is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium.
- the current collector 23 may be a mixture, alloy or composite oxide of these metals.
- the shape of the current collector 23 may be any shape as long as it functions as a current collector, and may be a net shape.
- each cathode 21 of the plurality of electrolysis cells 1 connected in series is pressed against the ion exchange membrane 2, and each anode 11 and each cathode
- the distance to the cathode 21 is shortened, and the voltage applied to the entire plurality of electrolysis cells 1 connected in series can be reduced. By reducing the voltage, the power consumption can be reduced.
- the metal elastic body 22 a spiral member, a spring member such as a coil, a cushioning mat, or the like can be used.
- a suitable material can be adopted as appropriate in consideration of stress that presses the ion exchange membrane.
- the metal elastic body 22 may be provided on the surface of the current collector 23 on the cathode chamber 20 side, or may be provided on the surface of the partition wall on the anode chamber 10 side. Normally, both chambers are partitioned so that the cathode chamber 20 is smaller than the anode chamber 10, so that the metal elastic body 22 is placed between the current collector 23 and the cathode 21 in the cathode chamber 20 from the viewpoint of the strength of the frame. It is preferable to provide in.
- the metal elastic body 23 consists of metals which have electrical conductivity, such as nickel, iron, copper, silver, and titanium.
- the cathode chamber 20 preferably includes a support 24 that electrically connects the current collector 23 and the partition wall 30. Thereby, an electric current can be sent efficiently.
- the support 24 is preferably made of a metal having electrical conductivity such as nickel, iron, copper, silver, or titanium. Further, the shape of the support 24 may be any shape as long as it can support the current collector 23, and may be a rod shape, a plate shape, or a net shape. In the first embodiment, the support 24 is plate-shaped. The plurality of supports 24 are disposed between the partition wall 30 and the current collector 23. The plurality of supports 24 are arranged so that their surfaces are parallel to each other. The support 24 is disposed substantially perpendicular to the partition wall 30 and the current collector 23.
- the anode side gasket is preferably disposed on the surface of the frame constituting the anode chamber 10.
- the cathode side gasket is preferably arranged on the surface of the frame constituting the cathode chamber 20.
- the electrolytic cells are connected to each other so that the anode-side gasket of one electrolytic cell and the cathode-side gasket of the electrolytic cell adjacent thereto sandwich the ion exchange membrane 2 (see FIGS. 2 and 3). With these gaskets, when a plurality of electrolytic cells 1 are connected in series via the ion exchange membrane 2, airtightness can be imparted to the connection location.
- the gasket is a seal between the ion exchange membrane and the electrolysis cell.
- Specific examples of the gasket include a frame-shaped rubber sheet having an opening formed at the center.
- Gaskets are required to be resistant to corrosive electrolytes and generated gases and to be usable for a long period of time. Therefore, from the viewpoint of chemical resistance and hardness, vulcanized products of ethylene / propylene / diene rubber (EPDM rubber), ethylene / propylene rubber (EPM rubber), peroxide crosslinked products, and the like are usually used as gaskets.
- gasket in which the area in contact with the liquid (liquid contact portion) is covered with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). You can also.
- PTFE polytetrafluoroethylene
- PFA perfluoroalkyl vinyl ether copolymer
- These gaskets only have to have openings so as not to hinder the flow of the electrolyte solution, and the shape thereof is not particularly limited.
- a frame-shaped gasket is attached with an adhesive or the like along the peripheral edge of each opening of the anode chamber frame constituting the anode chamber 10 or the cathode chamber frame constituting the cathode chamber 20.
- each electrolytic cell 1 to which a gasket is attached via the ion exchange membrane 2 may be tightened. Thereby, it can suppress that the electrolyte solution, the alkali metal hydroxide produced
- FIG. 2 shows that the electrolyte solution, the alkali metal hydroxide produced
- the ion exchange membrane 2 is not particularly limited, and a known one can be used.
- a fluorine-containing ion exchange membrane is preferable from the viewpoint of excellent heat resistance and chemical resistance.
- the fluorine-containing ion exchange membrane include those containing a fluorine-containing polymer having a function of selectively permeating cations generated during electrolysis and having an ion exchange group.
- the fluorine-containing polymer having an ion exchange group as used herein refers to a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis.
- Examples of such a fluorine-containing polymer include a heavy chain that has a main chain of a fluorinated hydrocarbon, has a functional group that can be converted into an ion exchange group by hydrolysis or the like as a pendant side chain, and can be melt-processed. Examples include coalescence.
- the second embodiment is the same as the first embodiment except for the following differences. Below, only the difference between 1st Embodiment and 2nd Embodiment is demonstrated, and the description about the common matter of both embodiment is abbreviate
- FIG. 6 is a cross-sectional view of the electrolysis cell 1 according to the second embodiment.
- the electrolytic cell 1 according to the second embodiment is different from the electrolytic cell 1 according to the first embodiment in that it does not include a metal elastic body and a current collector.
- the cathode chamber 20 provided in the electrolysis cell 1 of the second embodiment includes a support 24 disposed between the cathode 21 and the partition wall 30.
- the support 24 supports the cathode 21.
- the partition wall 30 is electrically connected to the cathode 21 via the support 24.
- the base material 18a of the reverse current absorber 18 may be independent of the partition wall and the support.
- the reverse current absorber is installed, for example, between the cathode and the partition wall.
- the reverse current absorber may be directly electrically connected to the surface of the cathode or the partition wall.
- At least part of the base material of the reverse current absorber may be a support, and a reverse current absorption layer may be formed on the surface of the support. Since the support is electrically connected to the cathode via the current collector and the metal elastic body, the reverse current absorption layer formed on the support can absorb the reverse current. Since the support is a reverse current absorber, the production cost of the electrolytic cell can be reduced.
- At least part of the base material of the reverse current absorber may be a partition, and a reverse current absorption layer may be formed on the surface of the partition. Since the partition wall is electrically connected to the cathode through the support, the current collector, and the metal elastic body, the reverse current absorption layer formed on the partition wall can absorb the reverse current. Since the partition wall is a reverse current absorber, the production cost of the electrolytic cell can be reduced.
- Example 1 Nickel oxide powder was plasma sprayed onto the surface of the nickel expanded metal (base material), and the base material was coated with the nickel oxide powder (reverse current absorption layer). Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas. Using the substrate coated with the reverse current absorption layer as a cathode, salt electrolysis for generating hydrogen was performed. The reverse current absorber of Example 1 was obtained by reduction treatment by electrolysis. The various conditions during electrolysis were as follows. Current density: 4 kA / m 2 , electrolysis temperature: 90 ° C., sodium hydroxide concentration: 32% by weight.
- the reverse current absorber was cut into a size of 3 cm ⁇ 3 cm, and fixed to a nickel rod covered with PTFE with a nickel screw. A platinum plate was used for the counter electrode (anode).
- a reverse current absorber was placed in a 32% by weight sodium hydroxide aqueous solution, a current was passed between the platinum plate and the reverse current absorber for 1 hour, and the sodium hydroxide aqueous solution was electrolyzed to generate hydrogen.
- the current density during electrolysis was 4 kA / m 2 .
- the potential of the reverse current absorber was measured while a reverse current having a current density of 250 A / m 2 was passed between the platinum plate and the reverse current absorber.
- the potential of the reverse current absorber is the potential of the reverse current absorber with respect to the Ag
- the time T from when the reverse current began to flow until the reverse current absorber reached the potential ( ⁇ 0.1 V) of the Ru oxidation elution reaction was measured. Time T was 3846 seconds.
- the amount of electricity that flows between the platinum plate and the reverse current absorber (reverse current absorption amount of the reverse current absorber, unit: C / m 2 ) was calculated by the product of the time T and the current density of 250 A / m 2 .
- the reverse current absorption amount of the reverse current absorber was 961,500 C / m 2 .
- the specific surface area of the reverse current absorber measured by the nitrogen adsorption method was 3.3 m 2 / g. Further, the reverse current absorber of Example 1 did not generate heat or ignite immediately after production. Further, the reverse current absorber of Example 1 did not generate heat or ignite even when taken out into the air without applying a reverse current after electrolysis of an aqueous sodium hydroxide solution.
- electrolysis experiment The effect of reverse current on the cathode was evaluated by the following electrolysis experiment.
- the electrolysis cell was manufactured from transparent acrylic.
- An anode cell (anode terminal cell) having an anode chamber in which an anode was installed faced a cathode cell having a cathode chamber (cathode terminal cell) in which a cathode was installed.
- a pair of gaskets was placed between the cells, and an ion exchange membrane was sandwiched between the pair of gaskets.
- an anode cell, a gasket, an ion exchange membrane, a gasket, and a cathode were stuck, and an electrolysis cell was obtained.
- anode As the anode, a so-called DSA (registered trademark) in which an oxide containing ruthenium, iridium and titanium as a component was formed on a titanium base material was used.
- DSA registered trademark
- the cathode a nickel plain woven wire mesh coated with ruthenium oxide and cerium oxide was used. About 2 mm on each side of the cathode cut out to a size of 95 mm long ⁇ 110 mm wide was bent at a right angle.
- the current collector nickel expanded metal was used. The size of the current collector was 95 mm long ⁇ 110 mm wide.
- the metal elastic body As the metal elastic body, a mat knitted with a nickel fine wire was used. A mat, which is a metal elastic body, was placed on the current collector.
- the cathode was placed on the current collector with the bent portion of the cathode facing the current collector. Then, the four corners of the cathode were fixed to the current collector with a string made of Teflon (registered trademark).
- a rubber gasket made of EPDM (ethylene propylene diene) was used.
- an ion exchange membrane “Aciplex” (registered trademark) F6801 (manufactured by Asahi Kasei Chemicals Corporation) was used.
- the reverse current absorber was attached by welding to the center of the current collector installed in the cathode chamber of the electrolysis cell.
- the base material portion was welded to the current collector, and the reverse current absorption layer portion was exposed in the cathode chamber. That is, in the electrolysis cell of Example 1, the reverse current absorber was installed on the current collector and electrically connected to the cathode via the mat that is a metal elastic body.
- the salt was electrolyzed using the above electrolytic cell.
- the salt water concentration (sodium chloride concentration) in the anode chamber was adjusted to 205 g / L.
- the sodium hydroxide concentration in the cathode chamber was adjusted to 32 wt%.
- Each temperature of the anode chamber and the cathode chamber was adjusted so that the temperature in each electrolysis cell was 90 ° C.
- Example 2 Nickel oxide powder was plasma sprayed onto the surface of the nickel expanded metal (base material), and the base material was coated with the nickel oxide powder (reverse current absorption layer). Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas.
- the reverse current absorber of Example 2 was obtained by reducing the base material coated with the reverse current absorption layer in a hydrogen atmosphere. Various conditions for hydrogen reduction were as follows. Atmospheric hydrogen concentration: 100%, Atmospheric temperature: 200 ° C., Reduction time: 1 hour.
- Example 2 Evaluation of reverse current absorption
- AgCl) was 1655 seconds.
- the reverse current absorption amount of the reverse current absorber of Example 2 was 413,750 C / m 2 .
- the specific surface area of the reverse current absorber of Example 2 measured by the nitrogen adsorption method was 4.2 m 2 / g. Further, the reverse current absorber of Example 2 did not generate heat or ignite immediately after production. Further, the reverse current absorber of Example 2 did not generate heat or ignite even when taken out into the air without applying a reverse current after electrolysis of an aqueous sodium hydroxide solution.
- Example 2 The electrolysis experiment of Example 2 was conducted using the same electrolytic cell as in Example 1 except that the reverse current absorber of Example 2 was provided instead of the reverse current absorber of Example 1.
- Example 3 The reverse current absorber of Example 3 was obtained by plasma spraying nickel oxide powder on the surface of nickel expanded metal (base material) and coating the base material with nickel oxide powder (reverse current absorption layer). . Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas.
- the reverse current absorption amount of the reverse current absorber of Example 3 was evaluated in the same manner as in Example 1.
- AgCl) was 201 seconds.
- the reverse current absorption amount of the reverse current absorber of Example 3 was 50,250 C / m 2 .
- the specific surface area of the reverse current absorber of Example 3 measured by the nitrogen adsorption method was 0.5 m 2 / g.
- the reverse current absorber of Example 3 did not generate heat or ignite immediately after production.
- the reverse current absorber of Example 3 did not generate heat or ignite even when taken out into the air without applying a reverse current after electrolysis of an aqueous sodium hydroxide solution.
- Example 3 An electrolysis experiment of Example 3 was performed using the same electrolytic cell as in Example 1 except that the reverse current absorber of Example 3 was provided instead of the reverse current absorber of Example 1.
- Example 4 The reverse current absorber produced in Example 2 and a cathode sample in which a plain weave wire net made of nickel was coated with ruthenium oxide and cerium oxide were each cut into a size of 3 cm ⁇ 3 cm. After the four corners of the reverse current absorber and the cathode were put together and overlapped, the four corners were tied and fixed with a string made of Teflon (registered trademark), whereby the reverse current absorber and the cathode were electrically connected.
- the cathode of Example 4 was fixed to a nickel rod covered with PTFE with a nickel screw. A platinum plate was used for the counter electrode (anode).
- Fe was added to an aqueous solution of sodium hydroxide having a concentration of 32% by weight to adjust the Fe content in the aqueous solution to 10 ppm.
- the above cathode and anode were placed in this aqueous solution, and hydrogen generation electrolysis was performed.
- the current density during electrolysis was 4 kA / m 2 , and the temperature of the aqueous solution was adjusted to 90 ° C.
- the cathode potential was continuously measured while electrolysis was continued.
- the cathode potential is the cathode potential with respect to the Ag
- Cathode hydrogen overvoltage [mV] -(cathode potential) [mV]-(solution resistance) [mV] -1089 [mV] (I)
- the sodium hydroxide aqueous solution was replaced 4 hours after the start of electrolysis.
- the Fe concentration in the aqueous sodium hydroxide solution after replacement was also adjusted to 10 ppm.
- FIG. 7 shows the increase value of the cathode hydrogen overvoltage at each time point from the start of electrolysis of Example 4 to 9 hours. As shown in FIG. 7, almost no increase in the hydrogen overvoltage of the cathode of Example 4 was observed until 9 hours passed from the start of electrolysis. That is, the resistance of the cathode of Example 4 to Fe was confirmed.
- Example 5 (Electrolysis experiment) The electrolysis experiment of Example 5 was conducted in the same manner as in Example 1 except that the cathode chamber (cathode terminal cell) of the electrolytic cell to be used was made of Ni and the reverse current absorber of Example 3 was attached to the partition wall.
- the reverse current absorber is electrically connected to the cathode via a support, a current collector, and a mat knitted with a nickel fine wire.
- the size of the reverse current absorber attached to the partition wall was 5 cm ⁇ 10 cm.
- Comparative Example 1 (Electrolysis experiment) An electrolysis experiment of Comparative Example 1 was performed using the same electrolysis cell as in Example 1 except that the reverse current absorber was not provided.
- Example 1 In the electrolysis of Example 1 using a reverse current absorber, since the reverse current absorber consumed a reverse current, it took 1936 seconds for the potential of the cathode to reach the potential of the Ru oxidation oxidation reaction. Even in the electrolysis of Example 2 including the reverse current absorber, since the reverse current absorber consumed the reverse current, it took 1137 seconds for the potential of the cathode to reach the potential of the Ru oxidation oxidation reaction. Even in the electrolysis of Example 3 equipped with the reverse current absorber, the reverse current absorber consumes the reverse current, so it took 620 seconds for the potential of the cathode to reach the potential of the Ru oxidation oxidation reaction.
- the potential of the cathode of Comparative Example 1 reached the potential of Ru oxidation elution reaction earlier than Examples 1 to 3, 5 and exceeded the potential of Ru oxidation elution reaction, and Ru elution was observed. From the results, it was found that in the electrolytic cell of Comparative Example 1, Ru elution started earlier than Examples 1 to 3, and 5. Therefore, it was found that in the electrolytic cell of Comparative Example 1, when a reverse current was passed for the same time as in Example 1, a larger amount of Ru than in Examples 1 to 3, 5 was eluted.
- the durability of the reverse current absorption layer was measured by the following method.
- a sample of the current collector on which the reverse current absorption layer was formed was cut into a size of 3 cm ⁇ 3 cm, and fixed to a nickel rod covered with PTFE with a nickel screw.
- a platinum plate was used as the counter electrode.
- the above sample and a platinum plate were placed in a 48 wt% aqueous sodium hydroxide solution, subjected to forward electrolysis for 5 hours at a current density of 12 kA / m 2 and an electrolysis temperature of 120 ° C, and then subjected to reverse electrolysis at 50 A / m 2 for 1 hour. went. This cycle consisting of forward electrolysis and reverse electrolysis was repeated.
- the current collector on which the reverse current absorption layer was formed was taken out, and the reverse current absorption amount was evaluated and the presence or absence of peeling of the reverse current absorption layer was visually evaluated.
- the reverse current absorption layer maintained the reverse current absorption amount after electrolysis for a predetermined time and peeling of the reverse current absorption layer was not observed, the reverse current absorption layer was evaluated as having high durability.
- Example 11 By using nickel expanded metal as the current collector and plasma spraying nickel oxide powder onto the current collector surface, the current collector surface is coated with nickel oxide powder to form a reverse current absorption layer that is a porous layer did. Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas.
- the durability of the reverse current absorption layer was evaluated. After the above cycle (forward electrolysis and reverse electrolysis) was performed 250 times over 1500 hours, the reverse current absorption amount was evaluated. The reverse current absorption potential reached ⁇ 0.1 V until the reverse current absorption layer reached ⁇ 0.1 V. The amount of electricity flowing to the absorption layer was 519,500 C / m 2 . Further, no peeling of the reverse current absorption layer was observed after 1500 hours of electrolysis.
- Example 12 A nickel expanded metal was used as a current collector, and the surface of the current collector was plasma sprayed with metal nickel powder, and the current collector surface was coated with metal nickel to form a reverse current absorption layer that was a porous layer. Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas.
- AgCl) was It was 21,550 C / m 2 .
- the durability of the reverse current absorption layer was evaluated. After the above cycle (forward electrolysis and reverse electrolysis) was performed 250 times over 1500 hours, the reverse current absorption amount was evaluated. The reverse current absorption potential reached ⁇ 0.1 V until the reverse current absorption layer reached ⁇ 0.1 V. The amount of electricity flowing to the absorption layer was 44,250 C / m 2 . Further, no peeling of the reverse current absorption layer was observed after 1500 hours of electrolysis.
- Nickel expanded metal was used as a current collector, and the surface of the current collector was coated with nickel oxide by plasma spraying nickel oxide powder on the surface of the current collector. Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas. Furthermore, the reverse current absorption layer which is a porous layer was formed by reducing the nickel oxide by performing salt electrolysis for generating hydrogen.
- the conditions for the salt electrolysis when reducing nickel oxide were a current density of 4 kA / m 2 , a sodium hydroxide concentration of 32% by weight, and a temperature of 90 ° C.
- the amount of electricity (reverse current absorption amount) that flowed in the reverse current absorption layer until the potential of the reverse current absorption layer reached ⁇ 0.1 V was 885,500 C / m 2 .
- the durability of the reverse current absorption layer was evaluated. After the above cycle (forward electrolysis and reverse electrolysis) was performed 250 times over 1500 hours, the reverse current absorption amount was evaluated. The reverse current absorption potential reached ⁇ 0.1 V until the reverse current absorption layer reached ⁇ 0.1 V. The amount of electricity flowing to the absorption layer was 910,250 C / m 2 . Further, no peeling of the reverse current absorption layer was observed after 1500 hours of electrolysis.
- the reverse current absorption layer of this example maintains the reverse current absorption even after electrolysis for 1500 hours, and has high durability.
- Table 1 shows the evaluation results of reverse current absorption, durability, and reverse current absorption after 1500 hours of electrolysis (in Table 1, “reverse current absorption (after electrolysis)”).
- Nickel expanded metal was used as a current collector, and the surface of the current collector was coated with nickel oxide by plasma spraying nickel oxide powder on the surface of the current collector. Nitrogen was used as the primary gas for plasma spraying, and hydrogen was used as the secondary gas. Furthermore, the hydrogen reduction process with respect to nickel oxide was performed, and the reverse current absorption layer which is a porous layer was formed.
- the conditions for the hydrogen reduction treatment were a hydrogen concentration of 100%, a temperature of 200 ° C., and a treatment time of 1 hour.
- AgCl) was It was 412,000 C / m 2 .
- the durability of the reverse current absorption layer was evaluated. After the above cycle (forward electrolysis and reverse electrolysis) was performed 250 times over 1500 hours, the reverse current absorption amount was evaluated. The reverse current absorption potential reached ⁇ 0.1 V until the reverse current absorption layer reached ⁇ 0.1 V. The amount of electricity flowing to the absorption layer was 318,500 C / m 2 . Further, no peeling of the reverse current absorption layer was observed after 1500 hours of electrolysis.
- the reverse current absorption layer of this example maintains the reverse current absorption even after electrolysis for 1500 hours, and has high durability.
- Table 1 shows the evaluation results of reverse current absorption, durability, and reverse current absorption after 1500 hours of electrolysis (in Table 1, “reverse current absorption (after electrolysis)”).
- the reverse current absorption layers of Examples 11 to 14 did not generate heat or ignite immediately after preparation. Further, the reverse current absorption layers of Examples 11 to 14 did not generate heat or ignite even when taken out into the air without applying a reverse current after electrolysis of an aqueous sodium hydroxide solution.
- the amount of electricity (reverse current absorption amount) that flowed in the reverse current absorption layer until the potential of the reverse current absorption layer reached ⁇ 0.1 V was 137,250 C / m 2 .
- the durability of the reverse current absorption layer was evaluated.
- the reverse current absorption amount was evaluated.
- the reverse current absorption potential reached ⁇ 0.1V until the reverse current absorption layer reached ⁇ 0.1V.
- amount of electricity flowing to the absorber layer was 4,000C / m 2.
- peeling of the reverse current absorption layer was observed after 48 hours of electrolysis.
- Raney nickel generated heat and partially red-hot.
- Table 1 shows the evaluation results of the reverse current absorption amount, durability, and reverse current absorption amount after electrolysis for 48 hours (in Table 1, “reverse current absorption amount (after electrolysis)”).
- FIG. 8 is a powder X-ray diffraction pattern of each reverse current absorption layer of Examples and Comparative Examples.
- the powder X-ray diffraction pattern is obtained from the measurement on the reverse current absorption layer peeled off from the current collector and processed into a powder form.
- the Raney nickel used in Comparative Example 11 was immersed in a sodium hydroxide aqueous solution and activated and then taken out into the air, the Raney nickel generated heat and partially red-hot. Therefore, Raney nickel powder X-ray diffraction measurement was performed after the exotherm had subsided.
- FIG. 9 shows a powder X-ray diffraction pattern of Raney nickel before dipping in an aqueous sodium hydroxide solution.
- the specific surface area of Raney nickel is generally very large. For this reason, it is presumed that the specific surface area of Raney nickel of Comparative Example 11 greatly exceeded 30 m 2 / g before taking out into the air and generating heat.
- the ratio of the pore volume having a pore diameter of 10 nm or more to the total pore volume was 68.5% or less, which is a measured value after heat generation, before taking out into the air and generating heat. Presumed.
- the specific surface area of Raney nickel before being immersed in sodium hydroxide aqueous solution was 0.4 m ⁇ 2 > / g.
- Example 15 The effect of the reverse current on the cathode was evaluated by conducting the following electrolysis experiment using the current collector on which the reverse current absorption layer was formed in the same manner as in Example 13.
- the electrolysis cell was manufactured from transparent acrylic.
- An anode cell (anode terminal cell) having an anode chamber in which an anode was installed faced a cathode cell having a cathode chamber (cathode terminal cell) in which a cathode was installed.
- a pair of gaskets was placed between the cells, and an ion exchange membrane was sandwiched between the pair of gaskets.
- an anode cell, a gasket, an ion exchange membrane, a gasket, and a cathode were stuck, and an electrolysis cell was obtained.
- DSA registered trademark
- ruthenium oxide, iridium oxide and titanium oxide were formed on a titanium base material
- cathode a nickel plain woven wire mesh coated with ruthenium oxide and cerium oxide was used. About 2 mm on each side of the cathode cut out to a size of 95 mm long ⁇ 110 mm wide was bent at a right angle.
- the current collector one having a reverse current absorption layer formed as in Example 13 was used. The size of the current collector was 95 mm long ⁇ 110 mm wide.
- the metal elastic body a mat knitted with a nickel fine wire was used. A mat, which is a metal elastic body, was placed on the current collector.
- the cathode was placed on the current collector with the bent portion of the cathode facing the current collector. Then, the four corners of the cathode were fixed to the current collector with a string made of Teflon (registered trademark). Thereby, the cathode, the metal elastic body, and the current collector were electrically connected.
- a rubber gasket made of EPDM (ethylene propylene diene) was used as the gasket.
- an ion exchange membrane “Aciplex” (registered trademark) F6801 (manufactured by Asahi Kasei Chemicals Corporation) was used.
- the salt was electrolyzed using the above electrolytic cell.
- the salt water concentration (sodium chloride concentration) in the anode chamber was adjusted to 205 g / L.
- the sodium hydroxide concentration in the cathode chamber was adjusted to 32 wt%.
- Each temperature of the anode chamber and the cathode chamber was adjusted so that the temperature in each electrolysis cell was 90 ° C.
- Comparative Example 12 An electrolytic cell of Comparative Example 12 similar to Example 15 was produced except that the reverse current absorption layer was not provided. An electrolysis experiment using the electrolysis cell of Comparative Example 12 was performed in the same manner as in Example 15 except that the current density of the reverse current was set to 50 A / m 2 .
- the electrolytic cell and the electrolytic cell according to the present invention can suppress the deterioration of the cathode due to the reverse current without passing the anticorrosion current when the electrolysis is stopped, and the operation is simple in that the anticorrosion current is unnecessary. Further, in the present invention, the reverse current absorber can be prevented from firing. Therefore, it is suitable for electrolysis of salt water or alkali metal salt aqueous solution, water electrolysis, fuel cell and the like.
- SYMBOLS 1 Electrolytic cell, 2 ... Ion exchange membrane, 4 ... Electrolytic cell, 5 ... Press device, 6 ... Cathode terminal, 7 ... Anode terminal, 10 ... Anode chamber, DESCRIPTION OF SYMBOLS 11 ... Anode, 18 ... Reverse current absorber, 18a ... Base material, 18b ... Reverse current absorption layer, 19 ... Bottom part of anode chamber, 20 ... Cathode chamber, 21 ... -Cathode, 22 ... metal elastic body, 23 ... current collector, 24 ... support, 30 ... partition, 40 ... cathode structure for electrolysis.
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Abstract
Description
図1は、本発明の第1実施形態の電解セル1の断面図である。電解セル1は、陽極室10と、陰極室20と、陽極室10及び陰極室20の間に設置された隔壁30と、陽極室10に設置された陽極11と、陰極室20に設置された陰極21と、基材18aと当該基材18a上に形成された逆電流吸収層18bとを有し、陰極室内に設置された逆電流吸収体18と、を備える。1つの電解セル1に属する陽極11及び陰極21は互いに電気的に接続されている。換言すれば、電解セル1は次の陰極構造体を備える。陰極構造体40は、陰極室20と、陰極室20に設置された陰極21と、陰極室20内に設置された逆電流吸収体18と、を備え、逆電流吸収体18は、図5に示すように基材18aと当該基材18a上に形成された逆電流吸収層18bとを有し、陰極21と逆電流吸収層18bとが電気的に接続されている。陰極室20は、集電体23と、当該集電体を支持する支持体24と、金属弾性体22とを更に有する。金属弾性体22は、集電体23及び陰極21の間に設置されている。支持体24は、集電体23及び隔壁30の間に設置されている。集電体23は、金属弾性体22を介して、陰極21と電気的に接続されている。隔壁30は、支持体24を介して、集電体23と電気的に接続されている。したがって、隔壁30、支持体24、集電体23、金属弾性体22及び陰極21は電気的に接続されている。陰極21及び逆電流吸収層18bは電気的に接続されている。陰極21及び逆電流吸収層は、直接接続されていてもよく、集電体、支持体、金属弾性体又は隔壁等を介して間接的に接続されていてもよい。陰極21の表面全体は還元反応のための触媒層で被覆されていることが好ましい。また、電気的接続の形態は、隔壁30と支持体24、支持体24と集電体23、集電体23と金属弾性体22がそれぞれ直接取り付けられ、金属弾性体22上に陰極21が積層される形態であってもよい。これらの各構成部材を互いに直接取り付ける方法として、溶接等があげられる。また、逆電流吸収体18、陰極21、および集電体23を総称して陰極構造体40としてもよい。
逆電流が逆電流吸収体18で消費されることにより陰極の劣化が抑制されるメカニズムについて説明する。食塩電解において水素発生の反応が進行中は、陰極の電位は、およそ-1.2V(vs.Ag|AgCl参照電極)に維持されている。しかし、電解を停止し、陰極に逆電流が流れると、陰極上で酸化反応が進行しながら電位が上昇し、陰極の電位は最終的に酸素発生電位に到達する。
Ruを含む触媒層で表面を被覆されたNi基材を陰極に使用した場合、電解停止後、逆電流が流れると陰極上で酸化反応が進行しながら電位が上昇し、陰極の電位が最終的に酸素発生電位に到達する。電解停止してから陰極の電位が酸素発生電位まで到達するまでの間、酸素発生電位より卑な酸化還元電位を持つ物質の様々な酸化反応が、酸化還元電位が卑である順に優先的に陰極上で進行する。具体的には、まず-1.0V(vs.Ag|AgCl)付近で陰極に吸着している水素の酸化反応(1)が進行する。次に、-0.9V(vs.Ag|AgCl)付近でNi金属(Ni基材表面)の酸化反応(2)が進行する。次に、-0.1V(vs.Ag|AgCl)付近で触媒層の成分であるRuの酸化溶出反応(3)が進行する。次に、+0.2V(vs.Ag|AgCl)付近で、(2)の反応で生成した水酸化ニッケルの酸化反応(4)が進行して、3価~4価のNiが生成する。そして+0.3V(vs.Ag|AgCl)付近で酸素発生反応(5)が進行する。
反応(1) H+OH-→H2O+e-
反応(2) Ni+2OH-→Ni(OH)2+2e-
反応(3) RuOxHy+aOH-→RuO4 2-+bH2O+ce-
反応(4) Ni(OH)2+OH-→NiOOH+H2O+e-
反応(5) 4OH-→O2+2H2O+4e-
vs.Ag|AgCl)に保持される。反応(2)が終了すると陰極電位は再び上昇を始め、次の反応(3)の電位(-0.1V vs.Ag|AgCl)に到達する。反応(3)が終了すると陰極電位は再び上昇し、次の反応(4)の電位(+0.2V
vs.Ag|AgCl)に到達する。反応(4)が終了すると陰極電位は再び上昇し、反応(5)の電位(+0.3Vvs.Ag|AgCl)に到達する。
以上、陰極の触媒層がRuから構成される場合について説明したが、Ru以外の元素を触媒層に用いてもよい。触媒層用の元素としては、C、Si、P、S、Al、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Y、Zr、Nb、Mo、Rh、Pd、Ag、Cd、In、Sn、Ta、W、Re、Os、Ir、Pt、Au、Hg、Pb、Bi、La、Ce、Pr、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Luが挙げられる。これらの元素の酸化還元電位よりも卑な酸化還元電位を持つ材料を逆電流吸収層の材料として選択することにより、Ruの場合と同様の上記効果を得ることができる。Ru以外の上記元素を触媒層に用いた場合も、陰極電位が上昇すると酸化反応が進行し性能低下などが起こってしまう。また、上記反応(1)、(2)、(4)、(5)は進行する。これらの反応のうち特に反応(4)で生成する3価~4価のニッケル化合物は、針状、六角形状、六角柱状の構造を有しており、しかも触媒層と陰極基材の界面で生成する。この結果、触媒層の陰極からの剥離が起こり、触媒層の性能低下、耐久性低下につながる。ここで、Niから構成される逆電流吸収層を有する逆電流吸収体を用いることによって、上記と同様の原理により、陰極電位を、陰極の触媒層に含まれる元素の酸化還元電位あるいは反応(4)の電位よりも卑な電位に維持することができるため、触媒層の酸化、陰極における3価~4価のニッケル化合物の生成を抑制し、触媒層の性能及び耐久性を維持することができる。
陰極室20の枠内には、陰極21が設けられている。陰極21は、ニッケル基材とニッケル基材を被覆する触媒層とを有することが好ましい。ニッケル基材上の触媒層の成分としては、C、Si、P、S、Al、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Y、Zr、Nb、Mo、Rh、Pd、Ag、Cd、In、Sn、Ta、W、Re、Os、Ir、Pt、Au、Hg、Pb、Bi、La、Ce、Pr、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu等の金属及び当該金属の酸化物又は水酸化物が挙げられる。触媒層の形成方法としては、メッキ、合金めっき、分散・複合めっき、CVD、PVD、熱分解及び溶射が挙げられる。これらの方法を組み合わせてもよい。また、必要に応じて陰極21に還元処理を施してもよい。なお、陰極21の基材としては、ニッケル基材以外に、ニッケル合金を用いてもよい。
逆電流吸収層18bは、陰極に比べて卑な酸化還元電位(低い酸化還元電位)を有する元素を含有することが好ましい。つまり、逆電流吸収層18bの酸化反応の酸化還元電位は、陰極21の表面を被覆する触媒層の酸化反応の酸化還元電位に比べて卑であることが好ましい。
逆電流吸収層の比表面積、細孔径分布曲線、細孔容積は、次のようにして得ることができる。測定試料を専用セルに入れ、加熱真空排気を行うことにより前処理を行い、細孔表面への吸着物を予め取り除く。その後、-196℃で測定サンプルへの窒素吸着の吸脱着等温線を測定する。得られた吸脱着等温線をBET法で解析することにより、測定サンプルの比表面積を求めることができる。また、BJH法で解析することにより、測定サンプルの細孔径分布曲線及び細孔容積を求めることができる。
1つ電解セルが備える全ての逆電流吸収体(逆電流吸収層)の実効表面積の総和(総実効表面積)は、窒素吸着法で測定した逆電流吸収体(逆電流吸収層)の比表面積(m2/g)と、1つの電解セルが備える全ての逆電流吸収体(逆電流吸収層)の量(g)を乗じることで算出される。
逆電流吸収体(逆電流吸収層18b)の酸化還元能及び充放電能の上限は特に限定されない。逆電流吸収層の酸化還元能及び充放電能は、1つの電解槽に設置された全ての逆電流吸収体(逆電流吸収層)が吸収できる電気量の総和を、その電解槽の電解面積で除した値で表される。電解槽の電解面積は、電解槽内の全ての陰極又は陽極のいずれか一方の面積の合計に等しい。逆電流吸収体(逆電流吸収層)は、電解面積1m2当たり1,000C以上2,000,000C以下の電気量の酸化還元能を有することが好ましい。つまり1つ電解セルが備える全ての逆電流吸収体(逆電流吸収層)の吸収電気量の総和は、1,000~2,000,000[Coulomb/m2]であることが好ましい。前述の通り、逆電流の電気量を吸収するために充分な電気量を消費する反応を逆電流吸収層で進行させるためには、逆電流電気量に見合うだけの量の逆電流吸収体を導入すればよい。1つ電解セルが備える全ての逆電流吸収体が吸収できる電気量が上記範囲内であれば、逆電流吸収体が逆電流を十分に吸収することができる。これにより、陰極の劣化をより抑制することができる。または、逆電流吸収層は、電解面積1m2当たり2,000,000C以下の電気量の充放電能を有することが好ましく、1,500,000C以下の電気量の充放電能を有することがより好ましい。
逆電流吸収体18の基材18aは、集電体、金属弾性体、隔壁及び支持体とは別の独立したものであってもよい。独立した逆電流吸収体は、既設の電解槽の陰極室に後から容易に付け足することができる。つまり、独立した逆電流吸収体によれば、既設の電解槽の陰極室に逆電流吸収能力を付与することができる。逆電流吸収体(の基材)の数は、1つであってもよく、複数であってもよい。また、逆電流吸収体の基材の形状は、立方体、直方体、板状、棒状、網状又は球状であってもよい。少なくとも一部の逆電流吸収体の基材が、金属弾性体、隔壁又は支持体であってもよい。逆電流吸収体は、陰極と金属弾性体の間に配置されていてもよい。逆電流吸収体は、金属弾性体と集電体の間に配置されていてもよい。逆電流吸収体は、集電体と隔壁の間に設置されていてもよい。
vs.Ag|AgCl)に設定した後、定電流にて逆電流を印加しながら逆電流吸収体の電位をモニターし、ある電位に到達するまでの時間を測定する。例えば、逆電流吸収体の電位が、Ruの酸化溶出が始まる電位である-0.1V(vs.Ag|AgCl)に到達するまでの時間を測定する。この時間と逆電流の電流密度との積によって、Ruの酸化溶出までに全ての逆電流吸収体が吸収できる逆電流電気量が算出される。
隔壁30は、陽極室10と陰極室20の間に配置されている。隔壁30は、セパレータと呼ばれることもあり、陽極室10と陰極室20とを区画するものである。隔壁30としては、電解用のセパレータとして公知のものを使用することができ、例えば、陰極側にニッケル、陽極側にチタンからなる板を溶接した隔壁等が挙げられる。
陽極室10は、陽極11を有する。また、陽極室10は、陽極室10に電解液を供給する陽極側電解液供給部と、陽極側電解液供給部の上方に配置され、隔壁30と略平行になるように配置されたバッフル板と、バッフル板の上方に配置され、気体が混入した電解液から気体を分離する陽極側気液分離部とを有することが好ましい。
陽極室10の枠内には、陽極11が設けられている。陽極11としては、いわゆるDSA(登録商標:ペルメレック電極)等の金属電極を用いることができる。DSAとは、ルテニウム、イリジウム、チタンを成分とする酸化物によって表面を被覆されたチタン基材である。
陽極側電解液供給部は、陽極室10に電解液を供給するものであり、電解液供給管に接続される。陽極側電解液供給部は、陽極室10の下方に配置されることが好ましい。陽極側電解液供給部としては、例えば、表面に開口部が形成されたパイプ(分散パイプ)等を用いることができる。かかるパイプは、陽極11の表面に沿って、電解セルの底部19に対して平行に配置されていることがより好ましい。このパイプは、電解セル1内に電解液を供給する電解液供給管(液供給ノズル)に接続される。液供給ノズルから供給された電解液はパイプによって電解セル1内まで搬送され、パイプの表面に設けられた開口部から陽極室10の内部に供給される。パイプを、陽極11の表面に沿って、電解セルの底部19に平行に配置することで、陽極室10の内部に均一に電解液を供給することができるため好ましい。
陽極側気液分離部は、バッフル板の上方に配置されることが好ましい。電解中において、陽極側気液分離部は、塩素ガス等の生成ガスと電解液を分離する機能を有する。なお、特に断りがない限り上方とは、図1の電解セル1における上方向を意味し、下方とは、図1の電解セル1における下方向を意味する。
バッフル板は、陽極側電解液供給部の上方に配置され、かつ、隔壁30と略平行に配置されることが好ましい。バッフル板は、陽極室10の電解液の流れを制御する仕切り板である。バッフル板を設けることで、陽極室10において電解液(塩水等)を内部循環させ、その濃度を均一にすることができる。内部循環を起こすために、バッフル板は、陽極11近傍の空間と隔壁30近傍の空間とを隔てるように配置することが好ましい。かかる観点から、バッフル板は、陽極11及び隔壁30の各表面に対向するように設けられていることが好ましい。バッフル板により仕切られた陽極近傍の空間では、電解が進行することにより電解液濃度(塩水濃度)が下がり、また、塩素ガス等の生成ガスが発生する。これにより、バッフル板により仕切られた陽極11近傍の空間と、隔壁30近傍の空間とで気液の比重差が生まれる。これを利用して、陽極室10における電解液の内部循環を促進させ、陽極室10の電解液の濃度分布をより均一にすることができる。
陰極室20は、陰極21と逆電流吸収体を有し、陰極21と逆電流吸収体は電気的に接続されている。また、陰極室20も陽極室10と同様に、陰極側電解液供給部、陰極側気液分離部を有していることが好ましい。なお、陰極室20を構成する各部位のうち、陽極室10を構成する各部位と同様のものについては説明を省略する。
陰極室20は集電体23を備えることが好ましい。これにより、集電効果が高まる。第1実施形態では、集電体23は板状であり、陰極21の表面と略平行に配置されることが好ましい。
集電体23と陰極21との間に金属弾性体22が設置されることにより、直列に接続された複数の電解セル1の各陰極21がイオン交換膜2に押し付けられ、各陽極11と各陰極21との間の距離が短くなり、直列に接続された複数の電解セル1全体に掛かる電圧を下げることができる。電圧が下がることにより、消費電量を下げることができる。
陰極室20は、集電体23と隔壁30とを電気的に接続する支持体24を備えることが好ましい。これにより、効率よく電流を流すことができる。
陽極側ガスケットは、陽極室10を構成する枠体表面に配置されることが好ましい。陰極側ガスケットは、陰極室20を構成する枠体表面に配置されていることが好ましい。1つの電解セルが備える陽極側ガスケットと、これに隣接する電解セルの陰極側ガスケットとが、イオン交換膜2を挟持するように、電解セル同士が接続される(図2、3参照)。これらのガスケットにより、イオン交換膜2を介して複数の電解セル1を直列に接続する際に、接続箇所に気密性を付与することができる。
イオン交換膜2は、特に限定されず、公知のものを用いることができる。例えば、塩化アルカリ等の電気分解により塩素とアルカリを製造する場合、耐熱性及び耐薬品性等に優れるという観点から、含フッ素系イオン交換膜が好ましい。含フッ素系イオン交換膜としては、電解時に発生する陽イオンを選択的に透過する機能を有し、かつイオン交換基を有する含フッ素系重合体を含むもの等が挙げられる。ここでいうイオン交換基を有する含フッ素系重合体とは、イオン交換基、又は、加水分解によりイオン交換基となり得るイオン交換基前駆体、を有する含フッ素系重合体をいう。このような含フッ素系重合体としては例えば、フッ素化炭化水素の主鎖からなり、加水分解等によりイオン交換基に変換可能な官能基をペンダント側鎖として有し、かつ溶融加工が可能な重合体等が挙げられる。
第2実施形態は、下記の相違点を除いて、第1実施形態と同様である。以下では、第1実施形態と第2実施形態との相違点についてのみ説明し、両実施形態の共通事項についての説明は省略する。第2実施形態によれば、第1実施形態と同様に、陰極の酸化及び劣化を抑制することが可能となる。
ニッケル製エキスパンドメタル(基材)の表面に、酸化ニッケル粉をプラズマ溶射して、基材を酸化ニッケル粉(逆電流吸収層)で被覆した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。この逆電流吸収層で被覆された基材を陰極に用いて、水素を発生させる食塩電解を実施した。電解による還元処理によって、実施例1の逆電流吸収体を得た。なお、電解時の諸条件は以下のとおりであった。
電流密度:4kA/m2、電解温度:90℃、水酸化ナトリウム濃度:32重量%。
逆電流吸収体を3cm×3cmサイズに切り出し、PTFEで被覆したニッケル製の棒にニッケル製のネジで固定した。対極(陽極)には白金板を使用した。
下記電解実験によって、逆電流が陰極に及ぼす影響を評価した。電解セルの陰極室内を外部から観察するために、電解セルを透明なアクリルから製作した。陽極が設置された陽極室を有する陽極セル(陽極ターミナルセル)と、陰極が設置された陰極室(陰極ターミナルセル)を有する陰極セルとを向い合せた。セル間に一対のガスケットを配置し、一対のガスケット間にイオン交換膜を挟んだ。そして、陽極セル、ガスケット、イオン交換膜、ガスケット及び陰極を密着させて、電解セルを得た。
vs.Ag|AgCl)まで到達し、酸素発生が観察された。
ニッケル製エキスパンドメタル(基材)の表面に、酸化ニッケル粉をプラズマ溶射して、基材を酸化ニッケル粉(逆電流吸収層)で被覆した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。この逆電流吸収層で被覆された基材を水素雰囲気中で還元処理することによって、実施例2の逆電流吸収体を得た。水素還元の諸条件は以下の通りであった。
雰囲気の水素濃度:100%、雰囲気の温度:200℃、還元時間:1時間。
実施例1と同様の方法で、実施例2の逆電流吸収体の逆電流吸収量を評価した。実施例2の逆電流吸収体の電位が-0.1V(vs.Ag|AgCl)に到達するまでの時間Tは1655秒だった。実施例2の逆電流吸収体の逆電流吸収量は、413,750C/m2だった。また、窒素吸着法にて測定した実施例2の逆電流吸収体の比表面積は、4.2m2/gだった。また、実施例2の逆電流吸収体は、作成直後に発熱・発火することはなかった。また、実施例2の逆電流吸収体は、水酸化ナトリウム水溶液の電解後、逆電流をかけずに空気中に取り出したときでも、発熱・発火することはなかった。
実施例1の逆電流吸収体の代わりに実施例2の逆電流吸収体を具備すること以外は実施例1と同様の上記電解セルを用いて、実施例2の電解実験を行った。
ニッケル製エキスパンドメタル(基材)の表面に、酸化ニッケル粉をプラズマ溶射して、基材を酸化ニッケル粉(逆電流吸収層)で被覆することにより、実施例3の逆電流吸収体を得た。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。
実施例1と同様の方法で、実施例3の逆電流吸収体の逆電流吸収量を評価した。実施例3の逆電流吸収体の電位が-0.1V(vs.Ag|AgCl)に到達するまでの時間Tは201秒だった。実施例3の逆電流吸収体の逆電流吸収量は、50,250C/m2だった。また、窒素吸着法にて測定した実施例3の逆電流吸収体の比表面積は、0.5m2/gだった。また、実施例3の逆電流吸収体は、作成直後に発熱・発火することはなかった。また、実施例3の逆電流吸収体は、水酸化ナトリウム水溶液の電解後、逆電流をかけずに空気中に取り出したときでも、発熱・発火することはなかった。
実施例1の逆電流吸収体の代わりに実施例3の逆電流吸収体を具備すること以外は実施例1と同様の上記電解セルを用いて、実施例3の電解実験を行った。
実施例2で作製した逆電流吸収体と、ニッケル製の平織り金網に、酸化ルテニウム及び酸化セリウムがコーティングされた陰極サンプルとを、それぞれ3cm×3cmサイズに切り出した。逆電流吸収体及び陰極それぞれの四隅を合わせて重ねた後、テフロン(登録商標)で作成した紐で四隅を結び付けて固定することにより、逆電流吸収体及び陰極を電気的に接続した。この実施例4の陰極をPTFEで被覆したニッケル製の棒にニッケル製のネジで固定した。対極(陽極)には白金板を使用した。
陰極の水素過電圧[mV]=-(陰極電位)[mV]-(溶液抵抗)[mV]-1089[mV] (I)
(電解実験)
使用する電解セルの陰極室(陰極ターミナルセル)をNiで製作し、隔壁に実施例3の逆電流吸収体を取り付けたこと以外は実施例1と同様に実施例5の電解実験を行った。逆電流吸収体は、支持体、集電体、ニッケル細線で編んだマットを介して陰極と電気的に接続している。また、隔壁に取り付けた逆電流吸収体のサイズは、5cm×10cmのサイズだった。
(電解実験)
逆電流吸収体を具備しないこと以外は実施例1と同様の上記電解セルを用いて、比較例1の電解実験を行った。
実施例4の逆電流吸収体を具備しなかったこと以外は実施例4と同様の実験を行った。比較例2の陰極の水素過電圧は電解開始から30分後には25mV上昇し、電解4時間後には44mV上昇した。
逆電流吸収体を用いた実施例1の電解では、逆電流吸収体が逆電流を消費するため、陰極の電位がRuの酸化溶出反応の電位に至るまでに1936秒がかかった。逆電流吸収体を備えた実施例2の電解でも、逆電流吸収体が逆電流を消費するため、陰極の電位がRuの酸化溶出反応の電位に至るまでに1137秒がかかった。逆電流吸収体を備えた実施例3の電解でも、逆電流吸収体が逆電流を消費するため、陰極の電位がRuの酸化溶出反応の電位に至るまでに620秒がかかった。逆電流吸収体を備えた実施例5の電解でも、逆電流吸収体が逆電流を消費するため、陰極の電位がRuの酸化溶出反応の電位に至るまでに2576秒がかかった。一方、逆電流吸収体を用いなかった比較例1の電解では、逆電流を消費する逆電流吸収体が存在しないため、実施例1~3、5に比べて短い時間(475秒)で、陰極の電位がRuの酸化溶出反応の電位に到達してしまうことがわかった。
逆電流吸収体を用いた実施例4の電解では、陰極の水素過電圧が9時間後もほとんど上昇しなかった。一方比較例2の電解では、陰極の水素過電圧が電解時間の経過とともに上昇した。この結果から、逆電流吸収体を取り付けると、陰極のFeに対する耐性が向上することが確認された。
逆電流吸収層が形成された集電体のサンプルを3cm×3cmサイズに切り出し、PTFEで被覆したニッケル製の棒にニッケル製のネジで固定した。対極(陽極)には白金板を使用した。32重量%水酸化ナトリウム水溶液中に上記のサンプル及び白金板を設置し、サンプルと白金板の間に電流を1時間流し、水酸化ナトリウム水溶液を電解して水素を発生させた。この間、ルギン管を通してAg|AgCl参照電極に対してサンプルの逆電流吸収層の電位を測定し、逆電流吸収層の電位を-1.2V(vs.Ag|AgCl)に保持した。その後、電流密度250A/m2の逆電流をサンプルと白金板の間に流しながら逆電流吸収層の電位を測定した。逆電流を流し始めた時点から逆電流吸収層の電位がRuの酸化溶出反応の電位(-0.1V)に到達するまでの時間Tを測定した。時間Tと電流密度250A/m2との積によって、サンプルと白金板の間に流れた電気量(逆電流吸収層の逆電流吸収量,単位:C/m2)を算出した。
逆電流吸収層の耐久性は以下の方法で測定した。逆電流吸収層が形成された集電体のサンプルを3cm×3cmサイズに切り出し、PTFEで被覆したニッケル製の棒にニッケル製のネジで固定した。対極には白金板を使用した。48重量%水酸化ナトリウム水溶液中に上記のサンプル及び白金板を設置し、電流密度12kA/m2、電解温度120℃で正電解を5時間行った後、50A/m2で逆電解を1時間行った。この正電解と逆電解とからなるサイクルを繰り返し行った。所定時間経過後、逆電流吸収層が形成された集電体を取り出し、逆電流吸収量の評価及び目視による逆電流吸収層の剥がれの有無の評価を行った。所定時間電解後に、逆電流吸収層が逆電流吸収量を維持しており、逆電流吸収層の剥がれが認められない場合に、逆電流吸収層の耐久性が高いと評価した。
集電体としてニッケル製エキスパンドメタルを用い、集電体表面に酸化ニッケル粉をプラズマ溶射することにより、集電体表面を酸化ニッケル粉で被覆して、多孔質層である逆電流吸収層を形成した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。
集電体としてニッケル製エキスパンドメタルを用い、集電体表面に金属ニッケル粉をプラズマ溶射し、集電体表面を金属ニッケルで被覆して、多孔質層である逆電流吸収層を形成した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。
集電体としてニッケル製エキスパンドメタルを用い、集電体表面に酸化ニッケル粉をプラズマ溶射することにより、集電体表面を酸化ニッケルで被覆した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。さらに、水素を発生させる食塩電解を行って酸化ニッケルを還元することにより、多孔質層である逆電流吸収層を形成した。なお、酸化ニッケルを還元する際の食塩電解の条件は、電流密度4kA/m2、水酸化ナトリウム濃度32重量%、温度90℃であった。
集電体としてニッケル製エキスパンドメタルを用い、集電体表面に酸化ニッケル粉をプラズマ溶射することにより、集電体表面を酸化ニッケルで被覆した。プラズマ溶射の一次ガスとしては窒素を使用し、二次ガスとして水素を使用した。さらに、酸化ニッケルに対する水素還元処理を行って、多孔質層である逆電流吸収層を形成した。水素還元処理の条件は、水素濃度100%、温度200℃、処理時間1時間であった。
集電体としてニッケル製エキスパンドメタルを用い、分散メッキにより集電体表面をラネーニッケルで被覆し、32重量%、80℃の水酸化ナトリウム水溶液に10時間浸漬して、ラネーニッケル中のAlを溶かし出し、逆電流吸収層を形成した。
図8は、実施例及び比較例の各逆電流吸収層の粉末X線回折パターンである。粉末X線回折パターンは、集電体から剥がして粉末状に加工した逆電流吸収層に対する測定から得たものである。比較例11で使用したラネーニッケルを水酸化ナトリウム水溶液に浸漬し活性化した後で空気中へ取り出すと、ラネーニッケルが発熱し、部分的に赤熱した。そのため、発熱が収まった後にラネーニッケルの粉末X線回折測定を行った。
実施例の逆電流吸収層の比表面積、細孔径分布曲線、細孔容積を島津製「TriStarII3020(窒素ガス吸着量測定装置)」を用いて測定した。測定結果を表1及び表2に示す。これらの測定は、集電体から剥がして粉末状に加工した逆電流吸収層について行った。なお、比較例11で使用したラネーニッケルを、水酸化ナトリウム水溶液に浸漬し活性化した後、空気中へ取り出すと、ラネーニッケルが発熱し、部分的に赤熱した。そのため、発熱が収まった後に、ラネーニッケルの比表面積測定及び細孔特性測定を行った。
実施例13と同様に逆電流吸収層を形成した集電体を用いて下記電解実験を行うことにより、逆電流が陰極に及ぼす影響を評価した。電解セルの陰極室内を外部から観察するために、電解セルを透明なアクリルから製作した。陽極が設置された陽極室を有する陽極セル(陽極ターミナルセル)と、陰極が設置された陰極室(陰極ターミナルセル)を有する陰極セルとを向い合せた。セル間に一対のガスケットを配置し、一対のガスケット間にイオン交換膜を挟んだ。そして、陽極セル、ガスケット、イオン交換膜、ガスケット及び陰極を密着させて、電解セルを得た。
逆電流吸収層を具備しないこと以外は実施例15と同様の比較例12の電解セルを作製した。逆電流の電流密度を50A/m2に設定した点以外は実施例15と同様にして、比較例12の電解セルを用いた電解実験を行った。
Claims (25)
- 陽極室と、
陰極室と、
前記陽極室と前記陰極室とを隔てる隔壁と、
前記陽極室に設置された陽極と、
前記陰極室に設置された陰極と、
基材と当該基材上に形成された逆電流吸収層とを有し、前記陰極室内に設置された逆電流吸収体と、
を備え、
前記陽極と前記陰極とが電気的に接続され、
前記陰極と前記逆電流吸収層とが電気的に接続されている、
電解セル。 - 前記逆電流吸収層は、前記陰極よりも酸化還元電位が低い元素を含む、
請求項1に記載の電解セル。 - 前記逆電流吸収層は、C、Cr、Ni、Ti、Fe、Co、Cu、Al、Zr、Ru、Rh、Pd、Ag、W、Re、Os、Ir、Pt、Au、Bi、Cd、Hg、Mn、Mo、Sn、Zn、La、Ce、Pr、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuからなる群より選択される1種以上の元素を含む、
請求項1又は2に記載の電解セル。 - 前記逆電流吸収層は、Ni又はNiOを含む多孔質層であり、かつ、前記逆電流吸収層の粉末X線回折パターンにおいて回折角2θ=44.5°におけるNi金属の回折線ピークの半値全幅が、0.6°以下である、
請求項1~3のいずれか一項に記載の電解セル。 - 窒素ガス吸着法により測定される前記逆電流吸収層の細孔径分布曲線において、細孔径が10nm以上である細孔の細孔容積が、全細孔容積の80%以上である、
請求項1~4のいずれか一項に記載の電解セル。 - 前記逆電流吸収層は、前記基材の表面の少なくとも一部にNi又はNiOを溶射することにより形成されたものである、
請求項1~5のいずれか一項に記載の電解セル。 - 前記逆電流吸収層は、前記基材の表面の少なくとも一部にNiOを溶射した後、前記NiOに対して還元処理を行うことにより形成されたものである、
請求項6に記載の電解セル。 - 前記陰極は、Ni基材と、当該Ni基材上に形成された触媒層とを有する、
請求項1~7のいずれか一項に記載の電解セル。 - 前記陰極室は、集電体と、当該集電体を支持する支持体と、金属弾性体とを更に有し、
前記金属弾性体は、前記集電体及び前記陰極の間に配置され、
前記支持体は、前記集電体及び前記隔壁の間に配置され、
前記隔壁、前記支持体、前記集電体、前記金属弾性体及び前記陰極は電気的に接続されている、
請求項1~8のいずれか一項に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記集電体であり、
前記集電体の表面に前記逆電流吸収層が形成されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記金属弾性体であり、
前記金属弾性体の表面に前記逆電流吸収層が形成されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記隔壁であり、
前記隔壁の表面に前記逆電流吸収層が形成されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記支持体であり、
前記支持体の表面に前記逆電流吸収層が形成されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の少なくとも一部は、前記陰極と前記金属弾性体との間に配置されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の少なくとも一部は、前記金属弾性体と前記集電体との間に配置されている、
請求項9に記載の電解セル。 - 前記逆電流吸収体の少なくとも一部は、前記集電体と前記隔壁との間に配置されている、
請求項9に記載の電解セル。 - 前記陰極室は、前記陰極を支持する支持体を更に有し、
前記支持体は、前記陰極及び前記隔壁の間に配置され、
前記隔壁、前記支持体及び前記陰極は電気的に接続されている、
請求項1~8のいずれか一項に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記隔壁であり、
前記隔壁の表面に前記逆電流吸収層が形成されている、
請求項17に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、前記支持体であり、
前記支持体の表面に前記逆電流吸収層が形成されている、
請求項17又は18に記載の電解セル。 - 前記逆電流吸収体は、前記陰極及び前記隔壁の間に配置されている、
請求項17~19のいずれか一項に記載の電解セル。 - 前記逆電流吸収体の前記基材の少なくとも一部が、立方体、直方体、板状、棒状、網状又は球状である、
請求項1~20のいずれか一項に記載の電解セル。 - 前記逆電流吸収層の比表面積が0.01~100m2/gである、
請求項1~21のいずれか一項に記載の電解セル。 - 全ての前記逆電流吸収体の吸収電気量の総和は、1,000~2,000,000C/m2である、
請求項1~22のいずれか一項に記載の電解セル。 - 全ての逆電流吸収体の実効表面積の総和は、10~100,000m2である、
請求項1~23のいずれか一項に記載の電解セル。 - 請求項1~24のいずれか一項に記載の電解セルを備える、電解槽。
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JP2018165379A (ja) * | 2017-03-28 | 2018-10-25 | 高砂熱学工業株式会社 | 水電解方法、水電解装置、水電解システム、水電解・燃料電池運転方法、水電解・燃料電池装置及び水電解・燃料電池システム |
JP2021526588A (ja) * | 2018-06-14 | 2021-10-07 | ティッセンクルップ・ウーデ・クロリンエンジニアズ ゲー エム ベー ハー | 弾性支持要素を有する電解セル |
JP7167191B2 (ja) | 2018-06-14 | 2022-11-08 | ティッセンクルップ・ウーデ・クロリンエンジニアズ ゲー エム ベー ハー | 弾性支持要素を有する電解セル |
US11697883B2 (en) | 2018-06-14 | 2023-07-11 | thyssenkrupp nucera AG & Co. KGaA | Electrolysis cell having resilient holding elements |
Also Published As
Publication number | Publication date |
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US20150027878A1 (en) | 2015-01-29 |
EP2816141A1 (en) | 2014-12-24 |
US9506157B2 (en) | 2016-11-29 |
KR20140114023A (ko) | 2014-09-25 |
TW201343973A (zh) | 2013-11-01 |
CN104114748B (zh) | 2016-11-09 |
JPWO2013141211A1 (ja) | 2015-08-03 |
JP5670600B2 (ja) | 2015-02-18 |
KR101614639B1 (ko) | 2016-04-21 |
JP6120804B2 (ja) | 2017-04-26 |
EP2816141B1 (en) | 2016-08-03 |
CN104114748A (zh) | 2014-10-22 |
TWI471459B (zh) | 2015-02-01 |
HUE031699T2 (en) | 2017-07-28 |
ES2593354T3 (es) | 2016-12-07 |
IN2014DN07921A (ja) | 2015-05-01 |
JP2014221944A (ja) | 2014-11-27 |
EP2816141A4 (en) | 2015-03-04 |
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