BR112019010219A2 - electrolysis electrode, method for producing the electrolysis electrode, and electrolyser. - Google Patents

Abstract

This electrolysis electrode is provided with a conductive base material and a catalyst layer which is formed on the surface of the conductive base material. the catalyst layer contains elemental ruthenium, elemental iridium, elemental titanium and at least one first transition metal element selected from the group consisting of sc, v, cr, fe, co, ni, cu and zn; the content ratio of the first transition metal element contained in the catalyst layer relative to 1 mol of elemental titanium is 0,25 mol% or more but less than 3,4 mol%; and the value d serving as an index for the double-layer electrical capacity of this electrolysis electrode is 120 c / m2 to 420 c / m2 (inclusive).

Description

ELECTRODE FOR ELECTROLYSIS, METHOD TO PRODUCE THE ELECTRODE FOR ELECTROLYSIS, AND, ELECTROLYZER

Technical Field [001] The present invention relates to an electrolysis electrode and a method for producing the same, and an electrolyser comprising the electrolysis electrode.

Fundamentals of the Technique [002] Electrolysis in sodium chloride by the ion exchange membrane process is a method to electrolyze brine using electrodes for electrolysis to thereby produce caustic soda, chlorine and hydrogen. For the sodium chloride electrolysis process using the ion exchange membrane process, a technique that can keep electrolysis voltage low over a long period of time is required to reduce energy consumption.

[003] When the decomposition of the electrolysis voltage is analyzed in detail, it becomes clear that in addition to the theoretically necessary electrolysis voltage, the voltage resulting from the resistance of the ion exchange membrane and the structural resistance of the electrolyzer, the anode and of the cathode, which are electrodes for electrolysis, the voltage resulting from the distance between the anode and the cathode, and the like are included. In addition, when electrolysis is continued for a long period of time, increased voltage and the like induced by various causes such as impurities in the brine can occur.

[004] Among the various electrolysis voltages described above, studies have been conducted for the purpose of reducing the overvoltage of the chlorine generator anode. For example, Patent Literature 1 discloses the technique of an insoluble anode obtained by coating a titanium substrate with an oxide of a platinum group metal such as ruthenium. This anode is referred to as DSA (registered trademark, Dimmable Stable Anode). In addition, Non-Patent Literature 1 describes historical developments in

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2/44 soda electrolysis techniques using DSA.

[005] With respect to the DSA described above, also until now, several improvements have been made and studies on the improvement in performance have been conducted.

[006] For example, Patent Literature 2 reports a chlorine generating electrode obtained from the production of platinum and palladium alloys, paying attention to the low chlorine overvoltage and high oxygen overvoltage of the palladium in the platinum group. Patent Literature 3 and Patent Literature 4 propose an electrode obtained by subjecting the surface of a platinum-palladium alloy to oxidation treatment to form palladium oxide on the surface. In addition, Patent Literature 5 proposes an electrode coated with an external catalyst layer containing a tin oxide as the main component and containing oxides of ruthenium, iridium, palladium and niobium. With this electrode, an attempt is made to suppress an oxygen generation reaction at the anode that occurs simultaneously with chlorine generation, in order to obtain high purity chlorine having a low oxygen concentration.

Citation List

Patent Literature

Patent Literature 1: Japanese Patent Publication No. 46-021884

Patent Literature 2: Japanese Patent Publication No.

45-11014

Patent Literature 3: Japanese Patent Publication No.

45-11015

Patent Literature 4: Japanese Patent Publication No.

48-3954

Patent Literature 5: National Publication of the Application for

International Patent No. 2012-508326

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3/44

Non-Patent Literature

Non-Patent Literature 1: Hiroaki Aikawa, “National Museum of Nature and Science, Survey Reports on the Systemization of Technologies No. 8”, published by the Independent Administrative Institution National Museum of Nature and Science, March 30, 2007, p 32 Summary Invention Technical Problem [007] However, a problem with conventional anodes such as

DSA described in Patent Literature 1 is that overvoltage immediately after the start of electrolysis becomes high, and a certain period is required before stabilization at low overvoltage due to the activation of the catalyst, and therefore loss in energy consumption occurs during electrolysis.

[008] In addition, the chlorine-generating electrodes described in

Patent literature 2 to 4 may have high overvoltage and low durability. In addition, in the production of the electrodes described in Patent Literature 3 and 4, it is necessary to use an alloy for the substrate itself, and in addition, a complicated step is required, such as forming an oxide on the substrate by thermal decomposition followed by production of alloys by reduction and in addition the formation of palladium oxide by electrolytic oxidation; great improvement is therefore required both practically and in terms of the production method.

[009] The electrode described in Patent Literature 5 has a certain effect on the improvement in the duration of palladium electrolysis (electrode life) (Note: palladium is considered to be unsatisfactory in chemical resistance), but cannot be said to decrease sufficiently overvoltage in chlorine generation. [0010] As described above, the techniques described in Patent Literature 1 to 5 and Non-Patent Literature 1 cannot provide an electrolysis electrode that has sufficiently low overvoltage in the initial stage of electrolysis and allows electrolysis to be performed under voltage low and low

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4/44 energy consumption over a long period of time.

[0011] The present invention was made in order to solve the problems described above. Therefore, an objective of the present invention is to provide an electrolysis electrode that can reduce overvoltage in the initial stage of electrolysis and allow electrolysis to be carried out at low voltage and low energy consumption over a long period of time, and a method for producing the same, and an electrolyzer comprising the electrode for electrolysis.

Solution to the Problem [0012] The present inventors studied diligently in order to solve the above problems. As a result, the present inventors have found that by adjusting, in a particular range, a numerical value that is an indicator of the capacitance of the double electrical layer of an electrolysis electrode having a catalyst layer containing predetermined metallic elements in a predetermined ratio, overvoltage in the initial electrolysis stage can be reduced, and electrolysis can be carried out at low voltage and low energy consumption over a long period of time, thus completing the present invention.

[0013] Specifically, the present invention is as follows.

[0014] [1] An electrolysis electrode comprising:

a conductive substrate; and a catalyst layer formed on a surface of the conductive substrate, wherein the catalyst layer comprises the ruthenium element, the iridium element, the titanium element, and at least one first transition metal element selected from the group consisting of Sc , V, Cr, Fe, Co, Ni, Cu, and Zn, a content ratio of the first transition metal element contained in the catalyst layer based on 1 mol of the element

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5/44 titanium is 0.25 mol% or more and less than 3.4 mol%, and a D value being an indicator of a capacitance of the double electrode electrode layer for electrolysis is 120 C / m ² or more and 420 C / m ² or less.

[0015] [2] The electrolysis electrode according to [1], in which the first transition metal element forms a solid solution with a solid solution of a ruthenium oxide, an iridium oxide, and a titanium oxide .

[0016] [3] The electrolysis electrode according to [1] or [2], wherein the first transition metal element comprises at least one metallic element selected from the group consisting of vanadium, cobalt, copper, and zinc.

[0017] [4] The electrolysis electrode according to any one of [1] to [3], in which the first transition metal element comprises the vanadium element.

[0018] [5] The electrolysis electrode according to any one of [1] to [4], in which a content ratio of the first transition metal element based on all metallic elements contained in the catalyst layer is 10 mol% or more and 30 mol% or less.

[0019] [6] The electrolysis electrode according to any of [1] to [5], in which a content ratio of the first transition metal element contained in the catalyst layer based on 1 mol of the ruthenium element is 0.3 mol or more and less than 2 mol.

[0020] [7] The electrolysis electrode according to any of [1] to [6], where the D value is 120 C / m ² or more and 380 C / m ² or less.

[0021] [8] A method for producing the electrolysis electrode according to any of [1] to [7], comprising the steps of:

prepare a coating liquid comprising a ruthenium compound, an iridium compound, a titanium compound and a

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6/44 compound comprising the first transition metal element;

coating at least one surface of the conductive substrate with the coating liquid to form a coating film; and calcining the coating film under an oxygen-containing atmosphere to form the catalyst layer.

[0022] [9] An electrolyser comprising the electrolysis electrode according to any of [1] to [7].

Advantageous Effects of the Invention [0023] The present invention provides an electrolysis electrode that can reduce overvoltage in the initial electrolysis stage and allow electrolysis to be carried out at low voltage and low energy consumption over a long period of time.

Brief Description of the Drawings [0024] [Figure 1] Figure 1 illustrates a schematic cross-sectional view according to an example of an electrolyzer of the present embodiment.

[0025] [Figure 2] Figure 2 illustrates a graph showing the results of plotting and linearly approximating the measured V / Ti values obtained by XPS deep profile analysis and actual V / Ti values added to the coating liquids, for four samples having different elementary ratios (molar ratios) between V and Ti.

Description of Modalities [0026] A modality for carrying out the present invention (hereinafter simply referred to as "the present modality") will be described in detail below. The present embodiment below is an illustration to describe the present invention and is not intended to limit the present invention to the contents that follow. Appropriate modifications can be made to the present invention without departing from its spirit.

[0027] An electrode for the electrolysis of the present modality is a

Petition 870190046930, of 20/05/2019, p. 16/59 / 44 electrode for electrolysis comprising a conductive substrate; and a catalyst layer formed on a surface of the conductive substrate, wherein the catalyst layer comprises the ruthenium element, the iridium element, the titanium element, and at least one first transition metal element selected from the group consisting of scandium , vanadium, chromium, iron, cobalt, nickel, copper, and zinc (these transition metal elements are hereinafter also collectively referred to as “first transition metal elements”). In addition, the electrode for electrolysis of the present embodiment is configured such that the content ratio of the first transition metal element contained in the catalyst layer based on 1 mol of the titanium element is 0.25 mol% or more and less than than 3.4 mol%, and the D value being an indicator of the capacitance of the double electrode electrode layer for electrolysis is 120 C / m ² or more and 420 C / m ² or less.

[0028] In the present modality, using the first transition metal element in addition to the ruthenium element, the iridium element, and the titanium element in the catalyst layer provides an electrolysis electrode in which the peak position of the peak attributed to Ru 3d5 / 2 derived from RuO ₂ , measured by X-ray photoelectronic spectroscopy (XPS), changes from 280.5 eV to RuO ₂ for the high binding energy side. For XPS load correction, the correction is performed so that the Ti 2p3 / 2 binding energy is 458.4 eV. The change from the peak position of Ru 3d5 / 2 to the high bond energy side indicates a state in which Ru is more oxidized in terms of the charge, and this is considered to be due to the addition of the first transition metal element. For example, when vanadium is added as the first transition metal element, the following polarization occurs.

RuO ₂ + VO ₂ RuO ₂ ⁸⁺ + VO ₂ ⁸ [0029] RuO ₂ ^{ô +} is an active adsorption site to adsorb chlorine and promotes the adsorption of chlorine, and thus overvoltage in chlorine generation can

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8/44 be reduced.

[0030] Although limitation for the mechanism described above of action is not intended, the electrode for electrolysis of the present modality has the configuration described above, and therefore when electrolysis is performed using the electrolysis electrode, overvoltage in the initial stage of electrolysis can be reduced and electrolysis can be carried out at low voltage and low energy consumption over a long period of time. The electrolyte electrode of the present embodiment can preferably be used as a chlorine generating electrode particularly for sodium chloride electrolysis by the ion exchange membrane process.

(Conductive substrate) [0031] The electrolyte electrode of the present modality can be used in brine of a high concentration close to saturation in an atmosphere that generates chlorine gas. Therefore, as the conductive substrate material in the present embodiment, corrosion resistant valve metals are preferred. Examples of valve metals include, but are not limited to, titanium, tantalum, niobium and zirconium. From the point of view of economy and affinity for the catalyst layer, titanium is preferred.

[0032] The shape of the conductive substrate is not particularly limited, and a suitable shape can be selected according to the purpose. For example, shapes such as an expanded shape, a porous plate shape, and a wire mesh shape are preferably used. The thickness of the conductive substrate is preferably 0.1 to 2 mm.

[0033] The surface of the conductive substrate to be in contact with the catalyst layer is preferably subjected to the treatment of increasing the surface area in order to improve adhesion to the catalyst layer. Examples of the treatment method for increasing surface area include, but are not limited to, blasting treatment using

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9/44 cut, a steel grid, an alumina grid, or the like; and acid treatment using sulfuric acid or hydrochloric acid. Of these treatments, a method of forming irregularities on the surface of the conductive substrate by blasting treatment and then performing further acid treatment is preferred.

(Catalyst layer) [0034] The catalyst layer to be formed on the surface of the conductive substrate subjected to the treatment described above comprises the ruthenium element, the iridium element, the titanium element, and a first transition metal element.

[0035] The element ruthenium, the element iridium, and the element titanium are each preferably in the form of an oxide.

[0036] The examples of oxide in ruthenium include, but not are limited to, RuO ₂ . [0037] The examples of oxide in iridium include, but not are limited to, IrO ₂ . [0038] The examples of oxide in titanium include, but not are

limited to, TiO ₂ .

[0039] In the catalyst layer in the present embodiment, ruthenium oxide, iridium oxide, and titanium oxide preferably form a solid solution. When ruthenium oxide, iridium oxide, and titanium oxide form a solid solution, the durability of ruthenium oxide improves further.

[0040] A solid solution generally refers to a material in which two or more types of substances dissolve in each other, and the whole is a uniform solid phase. Examples of the substances forming the solid solution include simple metal substances and metal oxides. Particularly in the case of a solid solution of metal oxides preferred for the present modality, two or more types of metal atoms are irregularly

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10/44 arranged on equivalent points of the crystalline lattice in a single crystalline lattice in the oxide crystalline structure. Specifically, a solid replacement solution is preferred in which a ruthenium oxide, an iridium oxide, and a titanium oxide mix with each other, and in terms of ruthenium oxide, the ruthenium atoms are replaced by the atoms of iridium or titanium atoms or both. The dissolved state is not particularly limited, and a partially dissolved region may be present.

[0041] The size of the unitary crystalline lattice in the crystalline structure changes slightly due to dissolution. The degree of this change can be confirmed, for example, from the fact that when measuring X-ray powder diffraction, the diffraction pattern due to the crystalline structure does not change, and the peak position due to the size of the unitary crystalline lattice changes.

[0042] In the catalyst layer in the present embodiment, for the content ratio of the ruthenium element, the iridium element, and the titanium element, it is preferred that the content ratio of the iridium element is from 0.06 to 3 moles and the ratio titanium element content is 0.2 to 8 moles, based on 1 mol of the ruthenium element; it is more preferred that the content ratio of the iridium element is 0.2 to 3 moles and the content ratio of the titanium element is 0.2 to 8 moles, based on 1 mole of the ruthenium element; it is further preferred that the content ratio of the iridium element is 0.3 to 2 moles and the content ratio of the titanium element is 0.2 to 6 moles, based on 1 mole of the ruthenium element; and it is particularly preferred that the content ratio of the iridium element is 0.5 to 1.5 mol and the content ratio of the titanium element is 0.2 to 3 moles, based on 1 mol of the ruthenium element. By adjusting the content ratio of the three types of elements in the ranges described above, the long-lasting durability of the electrolysis electrode tends to improve further. Iridium, ruthenium, and titanium can each be contained in the catalyst layer in the form of a material other than an oxide, for example, as a simple metallic substance.

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11/44 [0043] The catalyst layer in the present embodiment comprises the first transition metal element together with the ruthenium element, the iridium element, and the titanium element described above. The form of existence of the first transition metal element is not particularly limited, and the first transition metal element must be contained in the catalyst layer if, for example, it is in the form of an oxide or is a simple metal substance or a league. In the present embodiment, from the point of view of the durability of the catalyst layer, the first transition metal element preferably forms a solid solution with the solid solution of ruthenium oxide, iridium oxide, and titanium oxide. The formation of such a solid solution can be confirmed, for example, by XRD. The above solid solution can be formed by adjusting the calcination temperature in the formation of the catalyst layer, the amount of the first transition metal element added, and the like in suitable ranges.

[0044] In the present embodiment, from the point of view of obtaining both the stress and the durability of the catalyst layer, the first transition metal element preferably comprises a metallic element selected from the group consisting of vanadium, cobalt, copper, and zinc, and the first transition metal element most preferably comprises the vanadium element.

[0045] The content ratio of the first transition metal element based on all metal elements contained in the catalyst layer in the present embodiment is preferably 10 mol% or more and 30 mol% or less, more preferably more than 10 mol% and 22.5 mol% or less, and preferably still 12 mol% or more and 20 mol% or less. When the first transition metal element comprises vanadium, the vanadium content ratio based on all the metal elements contained in the catalyst layer particularly preferably satisfies the above range.

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12/44 [0046] The content ratio above is mainly derived from the actual ratio of elements added in a coating liquid prepared in a preferred method to produce an electrolysis electrode described later, and can be confirmed by analyzing the depth profile by STEM-EDX cross-section or X-ray photoelectronic spectroscopy (XPS) described later.

[0047] When the content ratio of the first transition metal element is 10 mol% or more, the overvoltage in the generation of chlorine or electrolysis voltage tends to be able to be reduced from the initial electrolysis stage. When the content ratio of the first transition metal element is 30 mol% or less, the durability of ruthenium oxide tends to be sufficiently guaranteed.

[0048] The content ratio of the first transition metal element contained in the catalyst layer in the present embodiment based on 1 mol of the ruthenium element is preferably 0.3 mol or more and less than 2 mol, more preferably 0.5 mole or more and less than 2 moles, and preferably still 0.5 mole or more and less than 1.8 moles. When the first transition metal element comprises vanadium, the vanadium content ratio based on 1 mol of the ruthenium element contained in the catalyst layer in an especially preferable way satisfies the above range.

[0049] The content ratio above is mainly derived from the actual ratio of the elements added to the coating liquid prepared in the preferred method to produce an electrolysis electrode described later, and can be confirmed by depth profile analysis by STEM-EDX of cross section or X-ray photoelectronic spectroscopy (XPS) described later.

[0050] When the content ratio of the first transition metal element is 0.3 mol or more as the number of moles based on 1 mol of the ruthenium element, the overvoltage in chlorine generation or electrolysis stress

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13/44 tends to be able to be reduced from the initial electrolysis stage, and the D value being an indicator of the capacitance of the double electrical layer described later tends to be able to be sufficiently increased. When the content ratio of the first transition metal element is less than 2 moles, the durability of ruthenium oxide tends to be sufficiently guaranteed.

[0051] The content ratio of the first transition metal element contained in the catalyst layer in the present embodiment based on 1 mol of the titanium element, is 0.25 mol or more and less than 3.4 mol, preferably 0, 25 moles or more and less than 2.6 moles. When the first transition metal element comprises vanadium, the vanadium content ratio based on 1 mol of the titanium element contained in the catalyst layer in an especially preferable way satisfies the above range.

[0052] The content ratio above is p derived from the actual ratio of the elements added to the coating liquid prepared in the preferred method to produce an electrolysis electrode described later, and can be confirmed by STEM-EDX depth profile analysis of cross section or X-ray photoelectronic spectroscopy (XPS) described later.

[0053] When the content ratio of the first transition metal element is 0.25 mol or more as the number of moles based on 1 mol of the titanium element, the overvoltage in chlorine generation or electrolysis voltage tends to be capable to be reduced from the initial electrolysis stage, and the D value being a capacitance indicator of the double electrical layer described later tends to be able to be sufficiently increased. When the content ratio of the first transition metal element is less than 3.4 moles, the durability of ruthenium oxide tends to be sufficiently guaranteed.

[0054] The element ratio (molar ratio) between V and Ti in the catalyst layer on the electrolysis electrode can be confirmed, for example, by

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14/44 depth profile analysis by STEM-EDX cross-section or X-ray photoelectronic spectroscopy (XPS). For example, a method for obtaining the elemental ratio (molar ratio) between V and Ti in a catalyst layer comprising the ruthenium element, the iridium element, the titanium element, and the vanadium element as the first transition metal element by analysis Quantitative XPS depth profile will be shown below. Here, a Ti substrate is used as a conductive substrate. [0055] The XPS measurement conditions can be as follows.

apparatus: PHI 5000 VersaProbe II manufactured by ULVACPHI, INC., excitation source: AlKoc monochrome (15 kV x 0.3 mA), size of the analysis: about 200 μιη φ, photoelectron take-off angle: 45 °,

Pass-through Energy: 46.95 eV (narrow scan)

Air ⁺ ejection conditions can be as follows.

acceleration voltage: 2 kV, crosshair range: 2 mm square, with Zalar rotation.

[0056] For the concentration calculation method, the spectroscopic levels of photoelectron peaks used for the quantification of Ru, Ir, Ti, and V are Ru 3d, Ir 4f, Ti 2p, and V 2p3 / 2. Ru 3p3 / 2 and Ti 3s overlapping Ti 2p and Ir 4f respectively, and therefore quantification can be performed by the following procedure.

[0057] (1) Peak area intensities (hereinafter peak area intensities) of Ru 3d, Ir 4f (including Ti 3s), Ti 2p (including Ru 3p3 / 2), and V 2p3 / 2 in each projection time (each depth) is obtained using “MaltiPak” analysis software associated with the device.

[0058] (2) The intensity of the Ru 3p3 / 2 peak area is calculated with

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15/44 base on the intensity of the peak area of Ru 3d. The calculation is performed using the Corrected RSF ratio (relative sensitivity factor corrected by the pass-through energy value) in MaltiPak. This is subtracted from the intensity of the Ti 2p peak area including Ru 3p3 / 2 to calculate the intensity of the Ti 2p only peak area.

[0059] (3) The intensity of the Ti 3s peak area is calculated based on the intensity of the Ti 2p corrected peak area using the Corrected RSF ratio. This is subtracted from the intensity of the Ir 4f peak area including Ti 3s to calculate the intensity of the Ir 4f only peak area.

[0060] The measured value of the elementary ratio (molar ratio) between V and Ti in the catalyst layer obtained by the quantitative analysis of XPS depth profile is the ratio of the value obtained by adding the intensities of the peak area of V 2p3 / 2 at the depths in the depth range of the catalyst layer where V is detected and dividing the sum by the Corrected RSF of V 2p3 / 2 to the value obtained by adding the intensities of the Ti 2p peak area at the depths and dividing the sum by the RSF Corrected Ti 2p, based on the following calculation formula. The depth range of the catalyst layer in which the peak area intensities of the elements are added is, for example, the depth range of the outermost surface until the Ti signal derived from the Ti substrate begins to be detected, when the catalyst layer is a single layer. Here, when the catalyst layer is a multiple layer, the depth range is the depth range of each catalyst layer for the layers other than the catalyst layer formed directly on the Ti substrate surface, and the depth range until the Ti signal derived from the Ti substrate begins to be detected, for the catalyst layer formed directly on the surface of the Ti substrate.

the value obtained by adding the intensities of the peak area of V 2p3 / 2 in the depths and dividing the sum by the Corrected RSF of V 2p3 / 2 V-Tí ís ............. .................................................. .................................................. .................................................. ..........................

the value obtained by adding the intensities of the Ti 2p peak area after the correction in the depths and dividing the sum by the Corrected RSF of Ti 2p

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16/44 [0061] Figure 2 shows the results of the following four samples of aad having different elementary ratios (molar ratios) between V and Ti, in which the measured values of V / Ti obtained by XPS depth profile analysis by measurement method described above and actual V / Ti values for the amounts of V and Ti added to the coating liquids are plotted.

[0062] (Sample a) an electrolysis electrode having an actual V / Ti ratio added of 0.11 [0063] An electrolysis electrode obtained by the same method as in Example 1 described later except that a conductive substrate is coated using a coating liquid a formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium is 23.75: 23.75: 47.5: 5.

[0064] (Sample b) an electrolysis electrode having an added real V / Ti ratio of 0.22 [0065] An electrolysis electrode obtained by the same method as in Example 1 except that a conductive substrate is coated using a coating liquid b formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium is 22.5: 22.5: 45: 10.

[0066] (Sample c) an electrolysis electrode having an actual V / Ti ratio of 0.35 [0067] An electrolysis electrode obtained by the same method as in Example 1 described later.

[0068] (Sample d) an electrolysis electrode having an added real V / Ti ratio of 1.13 [0069] An electrolysis electrode obtained by the same method as in Example 3 described later.

[0070] Since Figure 2 showed a positive correlation between the measured and actual V / Ti values, and the elementary ratio (molar ratio) between V and Ti in

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17/44 a catalyst layer comprising the ruthenium element, the iridium element, the titanium element and the vanadium element can be obtained by referring to a calibration curve. When the components contained in the catalyst layer are exchanged, the elementary ratio (molar ratio) between V and Ti in the catalyst layer can be obtained by referring to a measured and actual V / Ti calibration curve by the same method.

[0071] In the electrode for electrolysis of the present modality, the catalyst layer can be composed of only one layer or it can be a multilayer structure of two or more layers. When the catalyst layer is a multilayer structure, the content ratio of the first transition metal element contained in at least one layer in it based on 1 mol of the titanium element must be 0.25 mol or more and less than than 3.4 mol, and other layers do not need to satisfy the content ratio.

[0072] The electrode for electrolysis of the present modality is characterized in that the D value being a capacitance indicator of the double electric layer is 120 C / m ² or more and 420 C / m ² or less. The D value is more preferably 120 C / m ² or more and 380 C / m ² or less, more preferably 150 C / m ² or more and 360 C / m ² or less. When the D value is 120 C / m ² or more, the chlorine generation overvoltage can be suppressed, and the electrolysis voltage can be reduced. When the D value is 420 C / m ² or less, the durability of ruthenium oxide can be maintained.

[0073] The value D being an indicator of the double electrical layer capacitance here is a value calculated using the double electrical layer capacitance concept, and it is considered that the larger the electrode surface area (that is, the specific surface area of the electrode) catalyst layer on the electrode) is, the higher the value. For example, by adjusting the content of the first transition metal element in the preferred range described above, the D value can be in the range described above. Particularly, increasing the content of

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18/44 first transition metal element, the D value also tends to increase. By increasing the calcination temperature in the formation of the catalyst layer (post-cooking temperature), the D value tends to decrease. Specifically, the D value can be calculated using the electrolysis current density values (A / m ² ) measured with respect to certain scan rates (V / s) by a method described in the Examples described later, that is, voltammetry cyclical. In more detail, an inherent current density difference (difference between current density during advanced scanning and current density during retrograde scanning) is obtained for each scan rate, and the data is plotted with the vertical axis being the product of difference in current density and 0.3 V, the sweep range, and the horizontal axis being the sweep rate, and the slope when the plots are linearly approximated is the D value. Here, the product of the difference in current density and 0.3 V, the scan range, is well proportional to the scan rate, and therefore the D value can be expressed by the following formula (a). By adjusting the D value as a capacitance indicator for the double electrical layer in the range described above, the overvoltage in the initial stage of electrolysis can be reduced without impairing the durability of the electrode for electrolysis obtained.

D (C / m ² ) = [difference in electrolysis current density (A / m ² ) x 0.3 (V)] 4- [scan rate (V / s)] (a) [0074] When the catalyst layer in the present embodiment contains the ruthenium element, the iridium element, the titanium element, and a first transition metal element, and in addition the content ratio of the first transition metal element and the titanium element is in a range In particular, the function as a catalyst for electrolysis associated with an increase in the D value being an indicator of the double electrical layer capacitance improves, and the overvoltage in the initial electrolysis stage can be reduced.

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19/44 [0075] The catalyst layer in the present embodiment can contain only the ruthenium element, the iridium element, the titanium element, and the first transition metal element described above, as constituent elements, or it can comprise another metallic element Besides these. Specific examples of another metallic element include, but are not limited to, elements selected from tantalum, niobium, tin, platinum, and the like. Examples of how these other metallic elements exist include being present as metal elements contained in oxides.

[0076] When the catalyst layer in the present embodiment comprises another metallic element, its content ratio is preferably 20 mol% or less, more preferably 10 mol% or less, as the molar ratio of another metallic element to all metallic elements contained in the catalyst layer.

[0077] The thickness of the catalyst layer in the present embodiment is preferably 0.1 to 5 μιη, more preferably 0.5 to 3 μιη. By adjusting the thickness of the catalyst layer to the lower limit value described above or more, the initial electrolysis performance tends to be able to be sufficiently maintained. By adjusting the thickness of the catalyst layer to the upper limit value described above or less, an electrode for excellent electrolysis in economy tends to be obtained.

[0078] The catalyst layer may comprise only one layer, or the number of layers of catalyst may be two or more.

[0079] When the number of catalyst layers is two or more, at least one of them must be the catalyst layer in the present embodiment. When the number of catalyst layers is two or more, at least the outermost layer is preferably the catalyst layer in the present embodiment. A mode of having two or more layers of catalyst in the present embodiment with the same or different compositions is also preferred.

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20/44 [0080] Even when the number of catalyst layers is two or more, the thickness of the catalyst layer in the present embodiment is preferably 0.1 to 5 μητ, more preferably 0.5 to 3 μητ, as described above .

(Method for Producing Electrode for Electrolysis) [0081] Next, an example of a method for producing an electrode for electrolysis of the present embodiment will be described in detail.

[0082] The electrolyte electrode of the present modality can be produced, for example, by forming a catalyst layer comprising the ruthenium element, the iridium element, the titanium element, and a first transition metal element on a conductive substrate subjected to to the treatment of increased surface area described above. The formation of the catalyst layer is preferably carried out by a method of thermal decomposition.

[0083] In the production method according to the thermal decomposition method, the catalyst layer can be formed by coating a conductive substrate with a coating liquid comprising a mixture of compounds (precursors) containing the above elements followed by calcination under an atmosphere containing oxygen for the thermal decomposition of components in the coating liquid. According to this method, the electrolysis electrode can be produced with high productivity in a smaller number of steps than in conventional production methods.

[0084] Thermal decomposition here means calcining metal salts or the like being precursors under an atmosphere containing oxygen to break them down into metal oxides or metals and gaseous substances. The decomposition products obtained can be controlled by the metallic species contained in the precursors combined in the coating liquid as starting materials, the types of metallic salts, the atmosphere in which the

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21/44 thermal decomposition is carried out, and the like. Usually, under an oxidizing atmosphere, many metals tend to form oxides easily. In an industrial production process for an electrolysis electrode, thermal decomposition is usually carried out in air. Also in the present modality, the range of oxygen concentration in calcination is not particularly limited, and performing calcination in air is sufficient. However, air can be fluid inside a calcination furnace, or oxygen can be supplied as needed.

[0085] As a preferred method of producing an electrolysis electrode of the present embodiment, the method preferably comprises the steps of preparing a coating liquid containing a ruthenium compound, an iridium compound, a titanium compound, and a compound comprising a first transition metal element; coating at least one surface of a conductive substrate with the coating liquid to form a coating film; and calcining the coating film under an oxygen-containing atmosphere to form a catalyst layer. The ruthenium compound, the iridium compound, the titanium compound, and the compound comprising the first transition metal element corresponds to the precursors containing the metal elements contained in the catalyst layer in the present embodiment. An electrolysis electrode having a uniform catalyst layer can be produced by the method described above.

[0086] As for the compounds contained in the coating liquid, the ruthenium compound, the iridium compound, and the titanium compound may be oxides but need not necessarily be oxides. For example, they can be metallic or similar salts. Examples of these metal salts include, but are not limited to, any selected from the group consisting of chloride salts, nitrates, dinitrodiamine complexes, nitrosyl nitrates, sulfates, acetates, and metal alkoxides.

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22/44 [0087] Examples of the metal salt of the ruthenium compound include, but are not limited to, ruthenium chloride and ruthenium nitrate.

[0088] Examples of the metal salt of the iridium compound include, but are not limited to, iridium chloride and iridium nitrate.

[0089] Examples of the metallic salt of the titanium compound include, but are not limited to, titanium tetrachloride.

[0090] As for the compounds contained in the coating liquid, the compound containing the first transition metal element may be an oxide but need not necessarily be an oxide. For example, the compound is preferably one or more selected from the group consisting of a vanadium oxo acid and a salt thereof; a vanadium chloride; and a vanadium nitrate.

[0091] Examples of contraction in the oxoacid salt above may include, but are not limited to, Na ⁺ , K ⁺ , and Ca ²⁺ .

[0092] As specific examples of such compounds, specific examples of the oxoacid or its salt may include sodium metavanadate, sodium orthovanadate, and potassium orthovanadate; specific examples of the chloride can include vanadium chloride; and specific examples of the nitrate may include vanadium nitrate.

[0093] The above compounds are appropriately selected and used according to the desired metal element ratio in the catalyst layer.

[0094] The coating liquid can comprise yet another compound other than the compounds included in the compounds described above. Examples of another compound include, but are not limited to, metallic compounds containing metallic elements such as tantalum, niobium, tin, platinum, and rhodium; and organic compounds containing metallic elements such as tantalum, niobium, tin, platinum, and rhodium.

[0095] The coating liquid is preferably a composition

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Liquid obtained by dissolving or dispersing the group of compounds above in an appropriate solvent. The solvent of the coating liquid used here can be selected according to the types of the above compounds. For example, water; and alcohols such as butanol can be used. The total concentration of compound in the coating liquid is not particularly limited but is preferably 10 to 150 g / L from the point of view of properly controlling the thickness of the catalyst layer.

[0096] The method for coating a surface on a conductive substrate with the coating liquid is not limited to the following, and, for example, an immersion method in which a conductive substrate is immersed in the coating liquid, a method in which the coating liquid is applied to a surface of a conductive substrate with a brush, a roller method in which a conductive substrate is passed over a sponge roller impregnated with the coating liquid, and an electrostatic coating method in which the atomization of spraying is carried out with a conductive substrate and the coating liquid charged with opposite charges can be used. Among these coating methods, the roller method and the electrostatic coating method are preferred from the point of view of being excellent in industrial productivity. The coating film of the coating liquid can be formed on at least one surface of a conductive substrate by these coating methods.

[0097] After the conductive substrate is coated with the coating liquid, the step of drying the coating film is preferably carried out as necessary. The coating film can be formed more firmly on the surface of the conductive substrate by this drying step. Drying conditions can be appropriately selected according to the composition and type of solvent of the coating liquid, and the like. The drying step is preferably carried out at a temperature of 10 to 90 ° C for 1 to 20 minutes.

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24/44 [0098] After the coating film of the coating liquid is formed on the surface of the conductive substrate, the coating is calcined under an atmosphere containing oxygen. The calcination temperature can be appropriately selected according to the composition and solvent type of the coating liquid. The calcination temperature is preferably 300 to 650 ° C. When the calcination temperature is less than 300 ° C, the decomposition of precursors such as the ruthenium compound is insufficient, and a catalyst layer comprising ruthenium oxide and the like may not be obtained. When the calcination temperature is greater than 650 ° C, the conductive substrate may undergo oxidation, and therefore, the adhesiveness of the interface between the catalyst layer and the substrate may decrease. This trend should be considered as particularly important when a substrate made of titanium is used as the conductive substrate.

[0099] The calcination time is preferably long. On the other hand, from the point of view of the productivity of the electrode, adjustment is preferably carried out so that the calcination time is not excessively long. Considering these, a calcination time is preferably 5 to 60 minutes.

[00100] It is possible to repeat the steps of coating, drying, and calcining the catalyst layer described above a plurality of times as necessary, to form the catalyst layer in the desired thickness. It is also possible to form the catalyst layer, and then perform long-term calcination as needed, to further improve the stability of the extremely chemical, physical, and thermally stable catalyst layer. As long-term calcination conditions, 400 to 650 ° C for about 30 minutes to 4 hours are preferred.

[00101] The electrolyte electrode of the present modality has low overvoltage even in the initial stage of electrolysis and allows electrolysis

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25/44 at low voltage and low power consumption over a long period of time. Therefore, the electrolyte electrode of the present modality can be used for various types of electrolysis. In particular, the electrode for electrolysis of the present embodiment is preferably used as a chlorine generating anode and more preferably used as an anode for electrolysis in sodium chloride by the ion exchange membrane process. (Electrolyzer) [00102] An electrolyzer of the present modality comprises the electrode for electrolysis of the present modality. In this electrolyser, the initial voltage in the electrolysis is reduced. Figure 1 shows a schematic cross-sectional view according to an example of the electrolyzer of the present modality.

[00103] An electrolyzer 200 comprises electrolyte solutions 210, a container 220 to contain electrolyte solutions 210, an anode 230 and a cathode 240 immersed in electrolyte solutions 210, an ion exchange membrane 250, and wiring 260 to connect the anode 230 and cathode 240 to a power source. In the electrolyzer 200, the space on the anode side divided by the ion exchange membrane 250 is referred to as an anodic chamber, and the space on the cathode side is referred to as a cathodic chamber. The electrolyzer of the present modality can be used for various types of electrolysis. As a typical example, a case where the electrolyzer of the present modality is used for the electrolysis of an aqueous solution of alkyl chloride will be described below.

[00104] As the electrolyte solutions 210 supplied for the electrolyzer of the present modality, for example, an aqueous solution of alkali chloride such as an aqueous solution of sodium chloride of 2.5 to 5.5 normal (N) (brine) or aqueous solution of potassium chloride can be used in the anode chamber, and a dilute aqueous solution of alkaline hydroxide (for example, aqueous sodium hydroxide solution or

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26/44 aqueous potassium hydroxide) or water can be used in the cathode chamber.

[00105] Like anode 230, the electrode for electrolysis of the present modality is used.

[00106] As the ion exchange membrane 250, for example, a fluororesin film having an ion exchange group can be used. Specific examples of this may include "Aciplex" (R) F6801 (manufactured by Asahi Kasei Corporation). Like cathode 240, a hydrogen generating cathode being an electrode obtained by coating a conductive substrate with a catalyst, or the like is used. Like this cathode, a known one can be adopted. Specific examples include a cathode obtained by coating a nickel substrate with nickel, nickel oxide, a nickel and tin alloy, a combination of activated carbon and an oxide, ruthenium oxide, platinum, or the like; and a cathode obtained by forming a coating of ruthenium oxide on a wire mesh substrate made of nickel.

[00107] The electrolyzer configuration of the present modality is not particularly limited and can be unipolar or bipolar. The materials that make up the electrolyzer are not particularly limited, but, for example, as the material of the anodic chamber, titanium and the like resistant to alkali chlorides and chlorine are preferred; and as the cathode chamber material, nickel and the like resistant to alkali hydroxides and hydrogen are preferred.

[00108] The electrolysis electrode of the present modality (anode 230) can be arranged in an appropriate interstice of the ion exchange membrane 250, and can be used without any problem even if disposed in contact with the ion exchange membrane 250. The cathode 240 can be arranged in an appropriate interstitium of the ion exchange membrane 250, and also a contact type electrolyzer without an

Petition 870190046930, of 20/05/2019, p. 36/59 / 44 ion exchange 250 (zero interstitial based electrolyzer) can be used without any problem.

[00109] The electrolysis conditions of the electrolyzer of the present modality are not particularly limited, and the electrolyzer of the present modality can be operated under known conditions. For example, electrolysis is preferably carried out with the electrolysis temperature adjusted from 50 to 120 ° C and the adjusted current density from 0.5 to 10 kA / m ² .

[00110] The electrolyte electrode of the present modality can decrease the electrolysis voltage in the sodium chloride electrolysis compared with conventional techniques. Therefore, according to the electrolyzer of the present modality comprising the electrolysis electrode, the energy consumption required for sodium chloride electrolysis can be reduced.

[00111] In addition, the electrode for electrolysis of the present modality has an extremely chemical, physical, and thermally stable catalyst layer and therefore is excellent in long-lasting durability. Thus, according to the electrolyzer of the present modality comprising the electrode for electrolysis, the catalytic activity of the electrode is kept high for a long time, and high purity chlorine can be stably produced. Examples [00112] The present embodiment will be described in more detail below based on Examples. The present embodiment is not limited to these Examples only.

[00113] First, the evaluation methods in the Examples and Comparative Examples will be shown below.

(Sodium chloride electrolysis test by the ion exchange membrane process) [00114] As an electrolytic cell, an electrolytic cell including an anodic cell having an anodic chamber, and a cathodic cell having a cathodic chamber was provided.

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28/44 [00115] Each of the electrolysis electrodes prepared in the Examples and the Comparative Examples was cut to a predetermined size (95 x 110 mm = 0.01045 m ² ) to provide a test electrode, and the test electrode was mounted on the rib in the anode chamber of the anode cell by welding and used as an anode.

[00116] As the cathode, one obtained by coating a wire mesh substrate made of nickel with a ruthenium oxide catalyst was used. First, an expanded substrate made of nickel metal, such as a current collector, was cut to the same size as the anode and welded to the rib in the cathode chamber of the cathode cell, then a damping blanket obtained by sewing nickel wires was placed , and the cathode was placed over it.

[00117] Like the gasket, a rubber gasket made of EPDM (ethylene propylene diene) was used, and an ion exchange membrane was sandwiched between the anode cell and the cathode cell. Like this ion exchange membrane, an electrolysis cation exchange membrane in sodium chloride “Aciplex” (R) F6801 (manufactured by Asahi Kasei Corporation).

[00118] In order to measure chlorine overvoltage, a platinum wire coated with PFA (vinyl ether copolymer of tetrafluoroethylene perfluoroalkyl) in which the coating of a portion of about 1 mm on one end was removed to expose the platinum was fixed to the surface of the anode opposite the ion exchange membrane by tying it with a string made of polytetrafluoroethylene, and used as a reference electrode. During the electrolysis test, the reference electrode was supposed to give chlorine generating potential due to an atmosphere saturated with the generated chlorine gas. Therefore, the result obtained by subtracting the potential of the reference electrode from the anode potential was evaluated as the chlorine overvoltage of the anode.

[00119] On the other hand, as electrolysis voltage, the difference in

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29/44 potential between the cathode and anode was measured.

[00120] In order to measure the initial electrolysis performance of the anode, for overvoltage and electrolysis voltage, the values 7 days after the start of electrolysis were respectively measured. As for electrolysis conditions, electrolysis was carried out at a current density of 6 kA / m ² , a brine concentration of 205 g / L in the anode cell, a NaOH concentration of 32% by weight in the cathode cell, and a temperature of 90 ° C. As the electrolytic rectifier, “PAD36-100LA” (manufactured by KIKUSUI ELECTRONICS CORPORATION) was used. (Acceleration Test) [00121] The same electrolytic cell as the sodium chloride electrolysis test using the ion exchange membrane process described above was used except that as the test electrode mounted on the anodic cell, a cut to size 58 x 48 mm = 0.002748 m ² was used.

[00122] As for electrolysis conditions, electrolysis was carried out at a current density of 6 kA / m ² , a brine concentration of 205 g / L in the anode cell, a NaOH concentration of 32% by weight in the cathode cell , and a temperature of 90 ° C. In order to confirm the durability of the test electrode, a series of operations, stopping the electrolysis, washing with water in the electrolytic cell (10 minutes), and starting the electrolysis, was carried out at a frequency of once every 7 days. , and the chlorine overvoltage (anode overvoltage) was measured every 7 days after the start of electrolysis. In addition, the residual ratios of Ru and Ir in the catalyst layer on the test electrode after electrolysis (100 x content before electrolysis / content after electrolysis;%) were calculated using numerical values obtained by measuring X-ray fluorescence ( XRF) of metallic components before and after electrolysis. As the XRF measuring device, Niton XL3t-800 or XL3t-800s (registered trademark, manufactured by Thermo Scientific) were used.

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30/44 (Value D Being Indicator of the Double Electric Layer Capacitance) [00123] A test electrode was cut to a size of 30 x 30 mm = 0.0009 m ² and fixed to an electrolytic cell by a screw made of titanium . A platinum mesh was used for the counter electrode, and electrolysis was performed in an aqueous NaCl solution of 85 to 90 ° C and a brine concentration of 205 g / L at the electrolysis current densities of 1 kA / m ² , 2 kA / m ² , and 3 kA / m ² for 5 minutes each and at 4 kA / m ² for 30 minutes so that the test anode develops chlorine.

[00124] After the electrolysis described above, using Ag / AgCl for a reference electrode, in the range of applied potential from 0 V to 0.3 V, at scan rates of 10 mV / s, 30 mV / s, 50 mV / s, 80 mV / s, 100 mV / s, and 150 mV / s, a cyclic voltamogram was measured, and the electrolysis current density at 0.15 V which was the center of the potential range applied during the advanced scan from 0 V to 0.3 V, and the electrolysis current density at 0.15 V that was the center of the potential range applied during the retrograde scan from 0.3 V to 0 V were measured, and the difference between two electrolysis current densities were obtained at each scan rate described above. The product of the difference in electrolysis current density obtained at each scanning rate and 0.3 V, the scanning range, was generally directly proportional to the scanning rate, and the slope was calculated as the D value (C / m ² ) being an indicator of the capacitance of the double electrical layer.

[Example 1] [00125] As a conductive substrate, an expanded substrate made of titanium in which the largest dimension (LW) of the opening was 6 mm, the smallest dimension (SW) of the opening was 3 mm, and the thickness of the plate was 1.0 mm was used. This expanded substrate was calcined in air at 540 ° C for 4 hours to form an oxide film on the surface, and then subjected to treatment with acid in 25% by weight of sulfuric acid at 85 ° C for 4

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31/44 hours for pre-treatment to provide fine irregularities on the surface of the conductive substrate.

[00126] Then, while an aqueous solution of ruthenium nitrate (manufactured by Furuya Metal Co., Ltd., ruthenium concentration 100 g / L) was cooled to 5 ° C or less with dry and stirred ice, titanium tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added in small quantities, and then an aqueous solution of iridium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, iridium concentration 100 g / L) and vanadium (III) chloride ( manufactured by KISHIDA CHEMICAL Co., Ltd.) were added in small quantities, so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 21.25: 21.25: 42.5: 15 . Thus, an Al coating liquid being an aqueous solution having a total metal concentration of 100 g / L was obtained.

[00127] This coating liquid Al was injected into the tank receiving liquid from a coating machine, a sponge roller made of EPDM was spun to absorb the coating liquid Al for impregnation, and a roller made of PVC was disposed of so as to be in contact with the upper portion of the sponge roll. Then, the conductive substrate subjected to the pretreatment was passed between the sponge roll made of EPDM and the roll made of PVC for coating. Immediately after coating, the conductive substrate after the above coating was passed between two sponge rolls made of EPDM wrapped with cloths to wipe off the excess coating liquid. Then, drying was carried out at 50 ° C for 10 minutes, and then calcination was carried out in air at 400 ° C for 10 minutes.

[00128] The cycle comprising the roll coating, drying, and calcination above was repeated above three times with the calcination temperature increased by 450 ° C, and finally calcination at 520 ° C for 1 hour was carried out additionally to form a layer catalyst

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32/44 dark brown color on the conductive substrate to manufacture an electrolysis electrode.

[Comparative Example 1] [00129] While an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) was cooled to 5 ° C or less with dry and stirred ice, titanium tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added in small quantities, and then an aqueous solution of iridium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, iridium concentration 100 g / L) was added in small quantities, of so the elementary ratio (molar ratio) of ruthenium, iridium, and titanium was 25:25:50. Thus, a BI coating liquid being an aqueous solution having a total metal concentration of 100 g / L was obtained. An electrolysis electrode was manufactured by the same method as in Example 1 except that this BI coating liquid was used, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set to 440 ° C and then repeated three times with the calcination temperature increased by 475 ° C, and finally calcination at 520 ° C for 1 hour was carried out additionally.

[Example 2] [00130] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A2 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium , and vanadium was 25.45: 25.45: 30: 19.1. [Example 3] [00131] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A3 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium , and vanadium was 28.75: 28.75: 20: 22.5.

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33/44 [Example 4] [00132] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A4 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 32.05: 32.05: 10: 25.9. [Example 5] [00133] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A5 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium , and vanadium was 17.5: 17.5: 35: 30.

[00134] Table 1 shows the configuration (the metallic composition of the coating liquid used for the formation of the catalyst layer) of each of the electrolysis electrodes manufactured in Examples 1 to 5 and Comparative Example 1 respectively, together with the measured value D being a capacitance indicator of the double electrical layer. The unit “% by mol” in the table means the molar percentage (actual value of the ratio of the elements added) based on all the metallic elements contained in the formed catalyst layer. A value of the first transition metal element / Ru and a value of the first transition metal element / Ti were values calculated from the real value of the ratio of the elements added.

[Table 1]

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Metallic elements [mol%] Element of the first metallic transition / Ru First transition metal / Ti element D value [C / m ² ] Ru Go You First metallic transition Example 1 21.25 21.25 42.5 15 0.71 0.35 296 Comparative Example 1 25 25 50 0 0 0 48 Example 2 25.45 25.45 30 19.1 0.75 0.64 161 Example 3 28.75 28.75 20 22.5 0.78 1.13 222 Example 4 32.05 32.05 10 25.9 0.81 2.59 251 Example 5 17.5 17.5 35 30 1.71 0.86 353

34/44

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35/44 [Sodium Chloride Electrolysis Test by the Ion Exchange Membrane Process] [00135] The electrolysis test on sodium chloride by the ion exchange membrane process was carried out using the electrolysis electrodes manufactured in Examples 1 to 5 and Comparative Example 1 respectively. The results are shown in Table 2.

[Table 2]

Electrolysis voltage [V] 6 kA / nT Anodic overvoltage [V] 6 kA / nr Example 1 2.94 0.032 Comparative Example 1 2.99 0.057 Example 2 2.94 0.034 Example 3 2.92 0.032 Example 4 2.92 0.032 Example 5 2.91 0.031

[00136] The electrolysis voltage at a current density of 6 kA / m ² was 2.94 V for examples 1 and 2, 2.92 V for examples 3 and 4, and 2.91 V for example 5 All were extremely low values compared to 2.99 V for Comparative Example 1.

[00137] Anode overvoltage was 0.032 V for Example 1, 0.034 V for Example 2, 0.032 V for Example 3 and Example 4, and 0.031 V for Example 5. All were low values compared with 0.057 V for the Comparative Example 1.

[Example 6] [00138] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A6 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium , and vanadium was 37: 33,35: 11,15: 18,5, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set at 310 ° C and then the increased calcination temperature 520 ° C, and in addition, calcination at

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36/44

520 ° C for 1 hour was performed.

[Example 7] [00139] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using an A7 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium , and vanadium was 31.25: 28.1: 9.4: 31.25, and the cycle comprising roller coating, drying, and calcination was performed with the first calcination temperature set at 380 ° C and then repeated three times with the calcination temperature increased by 450 ° C, and furthermore, calcination at 450 ° C for 1 hour was performed.

[Example 8] [00140] An electrolysis electrode was manufactured by the same method as in Example 1 except that an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) instead of the aqueous solution of ruthenium nitrate was used, the conductive substrate was coated using an A8 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 19.6: 20.2: 47.09 : 13.11, and the cycle comprising roll coating, drying, and calcination was repeated eight times with the calcination temperatures set at 393 ° C, and then calcination at 485 ° C for 1 hour was additionally performed.

[Example 9] [00141] An electrolysis electrode was manufactured by the same method as in Example 1 except that an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) instead of the aqueous solution of ruthenium nitrate was used, cobalt (II) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) instead of vanadium (III) chloride was used, the conductive substrate was coated using an A9 coating liquid formulated from

Petition 870190046930, of 20/05/2019, p. 46/59 / 44 so that the elementary ratio (molar ratio) of ruthenium, iridium, titanium, and cobalt was 50: 3: 30: 17, and the cycle comprising roller coating, drying, and calcination was carried out with the first temperature calcination set to 440 ° C and then repeated three times with the calcination temperature increased by 475 ° C, and finally calcination at 520 ° C for 1 hour was carried out additionally.

[Example 10] [00142] An electrolysis electrode was manufactured by the same method as in Example 1 except that copper (II) nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) instead of vanadium chloride (III ) was used, and the conductive substrate was coated using an A10 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and copper was 32.05: 32.05: 10: 25.9 .

[Example 11] [00143] An electrolysis electrode was manufactured by the same method as in Example 1 except that zinc (II) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) instead of vanadium (III) chloride ) was used, and the conductive substrate was coated using an All coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and zinc was 32.05: 32.05: 10: 25.9 .

[Comparative Example 2] [00144] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using a B2 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium were 20: 18: 60: 2, an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) was used for the formulation of the coating liquid, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature

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3% / 44 adjusted to 450 ° C, and then repeated three times with the same calcination temperatures, and in addition, calcination at 450 ° C for 1 hour was performed. [Comparative Example 3] [00145] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using a B3 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 22.7: 20.5: 34.1: 22.7, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set at 380 ° C, and then repeated three times with the same calcination temperatures, and finally calcination at 590 ° C for 1 hour was carried out additionally. [Comparative Example 4] [00146] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using a B4 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 28.6: 25.7: 42.8: 2.9, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set at 450 ° C and then repeated three times with the calcination temperature increased by 520 ° C, and furthermore, calcination at 520 ° C for 1 hour was performed.

[Comparative Example 5] [00147] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using a B5 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and vanadium was 18.5: 16.7: 55.55: 9.25, an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) was used to formulate the coating liquid, and the cycle comprising roller coating, drying, and calcination was carried out with the first

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39/44 calcination temperature adjusted to 310 ° C and then repeated three times with the calcination temperature increased by 380 ° C, and finally calcination at 590 ° C for 1 hour was carried out additionally.

[Comparative Example 6] [00148] An electrolysis electrode was manufactured by the same method as in Example 1 except that manganese nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of vanadium (III) chloride in the Example 1, and the conductive substrate was coated using a B6 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and manganese was 21.25: 21.25: 42.5: 15.

[Comparative Example 7] [00149] An electrolysis electrode was manufactured by the same method as in Example 1 except that zinc nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of vanadium (III) chloride in Example 1, and the conductive substrate was coated using a B7 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and zinc was 21.25: 21.25: 42.5: 15.

[Comparative Example 8] [00150] An electrolysis electrode was manufactured by the same method as in Example 1 except that palladium nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of vanadium (III) chloride in Example 1, the conductive substrate was coated using a B8 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, iridium, titanium, and palladium was 16.9: 15.4: 50.8: 16.9, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set at 450 ° C and then repeated three times with the increased calcination temperature of 520 ° C, and finally calcination at 590 ° C for 1 hour was performed additionally.

[Comparative Example 9]

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40/44 [00151] An electrolysis electrode was manufactured by the same method as in Example 1 except that the conductive substrate was coated using a B9 coating liquid formulated so that the elemental ratio (molar ratio) of ruthenium, titanium, and vanadium were 40:40:20, an aqueous solution of ruthenium chloride (manufactured by TANAKA KIKINZOKU KOGYO KK, ruthenium concentration 100 g / L) was used for the formulation of the coating liquid, and the cycle comprising roller coating, drying, and calcination was carried out with the first calcination temperature set at 440 ° C and then repeated three times with the increased calcination temperature of 475 ° C, and finally calcination at 520 ° C for 1 hour was carried out additionally.

[00152] Table 3 shows the configuration (the metallic composition of the coating liquid used for the formation of the catalyst layer) of each of the electrolysis electrodes manufactured in Examples 6 to 11 and Comparative Examples 2 to 9 respectively, together with the measured value D being a capacitance indicator of the double electrical layer. The unit “% by mol” in the table means molar percentage (feed rate) based on all metallic elements contained in the formed catalyst layer. A value of the first transition metal element / Ru and a value of the first transition metal element / Ti were values calculated from the feed ratio.

[Table 3]

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Metal Elements [mol%] First transition metal element / Ru First transition metal / Ti element D value Ru Go You First transition metal element V Another element ⁽⁽⁾ [C / m ² ] 37 33.35 11.15 18.5 - 0.50 1.66 139 Example 6 31.25 28.1 9.4 31.25 - 1.00 3.32 309 Example 7 19.6 20.2 47.09 13.11 - 0.67 0.28 304 Example 8 50 3 30 - 17 0.34 0.57 173 Example 9 32.05 32.05 10 25.9 0.81 2.59 260 Example 10 32.05 32.05 10 - 25.9 0.81 2.59 326 Example 11 20 18 60 2 - 0.10 0.03 48  Comparative Example 2 ’ 22.7 20.5 34.1 22.7 - 1.00 0.67 103 Comparative Example 3 28 6 25.7 42.8 2.9 - 0.10 0.07 33  Comparative Example 4 18.5 16.7 55.55 9.25 - 0.50 0.17 54 Comparative Example 5 21.25 21.25 42.5 - - - - 197  Comparative Example 6 ' 21.25 21.25 42.5 - 15 0.71 0.35 119 'Comparative Example 7 ‘ 16.9 15.4 50.8 - 16.9 1.00 0.33 35 Comparative Example 8 40 - 40 20 - 0.50 0.50 161

Comparative Example 9 (*) Co for Example 9, Cu for Example 10, Zn for Example 11, Zn for Comparative Example 7, Pd for Comparative Example 8

41/44

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42/44 [Acceleration Test] [00153] The acceleration test was performed using the electrolysis electrodes manufactured in Examples 1 to 11 and Comparative Example 1 to 9 respectively. The results are shown in Table 4. For Comparative Example 9, the durability of ruthenium was low, and therefore the evaluation results at the time point when the test was stopped after 14 days are shown.

[Table 4]

Anode overvoltage [V] 6 kA / m ² Residual ratio of R [%] Residual ratio of Ir [%] After 1 day After 21 days After 21 days After 21 days Example 1 0.031 0.032 97 98 Example 2 0.034 0.036 91 93 Example 3 0.030 0.033 88 90 Example 4 0.031 0.032 83 84 Example 5 0.030 0.031 76 78 Example 6 0.035 0.034 86 90 Example 7 0.032 0.034 52 46 Example 8 0.031 0.039 96 95 Example 9 0.044 0.030 71 80 Example 10 0.045 0.036 90 95 Example 11 0.036 0.034 89 88 Comparative Example 1 0.071 0.055 95 96 Comparative Example 2 0.070 0.064 95 98 Comparative Example 3 0.042 0.044 84 87 Comparative Example 4 0.110 0.093 95 96 Comparative Example 5 0.050 0.060 91 94 Comparative Example 6 0.072 0.048 93 96 Comparative Example 7 0.063 0.043 99 100 Comparative Example 8 0.045 0.076 92 94 Comparative Example 9 0.030 0.038 ^m 23 ® -

Comparative Example 9: a point-in-time value when the test was stopped after 14 days in the test [00154] When the 21-day acceleration test was performed, the

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Following 43/44 were discovered.

[00155] As for the electrolysis electrodes of Examples 1 to 11, the anode overvoltage 1 day after the test started was 0.030 to 0.045 V, and the anode overvoltage after 21 days was 0.030 to 0.039 V. In contrast to these, as for the electrodes for electrolysis of Comparative Examples 1 to 8, the anode overvoltage 1 day after the start of the test was from 0.042 to 0.110 V, and the anode overvoltage after 21 days was from 0.043 to 0.093 V. Thus, it was found that the Examples allowed electrolysis at low voltage and low energy consumption in the initial stage of electrolysis and over a long period of time, compared with the Comparative Examples.

[00156] Furthermore, for Examples 1 to 11, the residual ratios of Ru and Ir were both high even 21 days after the start of the test, compared to Comparative Example 9 for which the anode overvoltage was at the same level, and it was found that although the anode overvoltage was kept low, the durability in long-term electrolysis was also sufficient.

[00157] This application claims priority based on Japanese Patent Application No. 2016-227066 filed on November 22, 2016, the contents of which are incorporated herein by reference.

Industrial Applicability [00158] The electrolysis electrode of the present invention provides low overvoltage in the generation of chlorine and allows electrolysis at low voltage and low energy consumption and, therefore, can preferably be used in the field of sodium chloride electrolysis. Particularly, the electrolysis electrode of the present invention is useful as an anode for electrolysis in sodium chloride by the ion exchange membrane process, and can produce high purity chlorine gas having low oxygen gas concentration at low voltage and low energy consumption. energy over a long period of time.

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List of Reference Signs electrolyzer for electrolysis electrolyte solution anode container (electrode for electrolysis) cathode ion exchange membrane wiring

Claims (9)

1. Electrode for electrolysis, characterized by the fact that it comprises: a conductive substrate; and a catalyst layer formed on a surface of the conductive substrate, wherein the catalyst layer comprises the ruthenium element, the iridium element, the titanium element, and at least one first transition metal element selected from the group consisting of Sc , V, Cr, Fe, Co, Ni, Cu, and Zn, a content ratio of the first transition metal element contained in the catalyst layer based on 1 mol of the titanium element is 0.25 mol% or more and less than 3.4 mol%, and a D value being an indicator of a capacitance of the double electrode electrode layer for electrolysis is 120 C / m ² or more and 420 C / m ² or less. 2. Electrolyte electrode according to claim 1, characterized by the fact that the first transition metal element forms a solid solution with a solid solution of a ruthenium oxide, an iridium oxide, and a titanium oxide. 3. Electrode for electrolysis according to claim 1 or 2, characterized by the fact that the first transition metal element comprises at least one metallic element selected from the group consisting of vanadium, cobalt, copper, and zinc. Electrode for electrolysis according to any one of claims 1 to 3, characterized in that the first transition metal element comprises the vanadium element. 5. Electrolysis electrode according to any one of claims 1 to 4, characterized by the fact that a ratio of Petition 870190046930, of 20/05/2019, p. 55/59 2/2 first transition metal element based on all metal elements contained in the catalyst layer is 10 mol% or more and 30 mol% or less. An electrolysis electrode according to any one of claims 1 to 5, characterized in that the content ratio of the first transition metal element contained in the catalyst layer based on 1 mol of the ruthenium element is 0.3 mol or more and less than 2 moles. An electrolysis electrode according to any one of claims 1 to 6, characterized in that the D value is 120 C / m ² or more and 380 C / m ² or less. 8. Method for producing the electrolysis electrode as defined in any of claims 1 to 7, characterized by the fact that it comprises: preparing a coating liquid comprising a ruthenium compound, an iridium compound, a titanium compound and a compound comprising the first transition metal element; coating at least one surface of the conductive substrate with the coating liquid to form a coating film; and calcining the coating film under an oxygen-containing atmosphere to form the catalyst layer. 9. Electrolyzer, characterized by the fact that it comprises the electrolysis electrode as defined in any one of claims 1 to 7.