KR20200076275A - Electrode for Electrolysis - Google Patents

Abstract

The present invention provides an electrode for electrolysis that can improve overvoltage by increasing the surface area of a coating layer by using a thick metal wire as compared to a conventional electrode for electrolysis.

Description

Electrode for Electrolysis

The present invention relates to an electrode for electrolysis and a method for manufacturing the same, and relates to an electrode for electrolysis having a diameter of a wire structure of a metal base layer of an electrode of 180 to 250 μm and a method for manufacturing the same.

Technology for producing hydroxide, hydrogen, and chlorine by electrolysis of low-priced brine such as sea water is widely known. Such an electrolysis process is also commonly referred to as a chlor-alkali process, and it can be said that the performance and reliability of technology have been proven through decades of commercial operation.

The electrolysis of brine is the most widely used ion exchange membrane method that divides the electrolyzer into a cation chamber and an anion chamber by installing an ion exchange membrane inside the electrolyzer, and obtains chlorine gas at the anode and hydrogen and caustic soda at the cathode using brine as the electrolyte. This is the method used.

On the other hand, the electrolysis process of brine is made through a reaction as shown in the following electrochemical reaction formula.

Positive electrode (anode) _{^{reaction: 2Cl - → Cl 2 + 2e}} - (E 0 = +1.36 V)

A negative electrode (cathode) ^{_{reaction: 2H 2 O + 2e - →}} 2OH - + H 2 (E 0 = -0.83 V)

Total _{^{reaction: 2Cl - + 2H 2 O →}} 2OH - + Cl 2 + H 2 (E 0 = -2.19 V)

In performing the electrolysis of the brine, the electrolytic voltage must take into account the voltage required for the theoretical electrolysis of the brine, the overvoltage of the anode, the overvoltage of the cathode, the voltage due to the resistance of the ion exchange membrane, and the voltage due to the distance between the anode and the cathode. Of these voltages, the overvoltage caused by the electrode is an important variable.

Accordingly, a method capable of reducing the overvoltage of the electrode is being researched, for example, a noble metal-based electrode called DSA (Dimensionally Stable Anode) has been developed and used as an anode, and an anode with a low overvoltage and excellent durability is developed. This is required.

Stainless steel or nickel is mainly used as the negative electrode, and recently, in order to reduce overvoltage, the surface of stainless steel or nickel is coated with nickel oxide, an alloy of nickel and tin, a combination of activated carbon and oxide, ruthenium oxide, platinum, etc. Methods of use are being studied.

In addition, a method of controlling the composition using a platinum group element such as ruthenium and a lanthanide element such as cerium to increase the activity of the negative electrode by adjusting the composition of the active material has been studied. However, an overvoltage phenomenon occurs, and a problem occurs that deterioration occurs due to reverse current.

JP2003-2977967A

An object of the present invention is to provide an electrode for electrolysis having an increased coating surface area and improved overvoltage.

In order to solve the above problems, the present invention is a metal substrate layer having a wire structure; And

A coating layer comprising a ruthenium compound, a platinum compound, a lanthanide compound, and an amine-based compound,

The coating layer is formed on at least one surface of the base layer,

The diameter of the wire provides an electrode for electrolysis of 180 to 250㎛.

In addition, the present invention provides a method of manufacturing the electrode for electrolysis.

The electrode for electrolysis according to the present invention can improve overvoltage by increasing the surface area of the coating layer by using a thicker metal wire than the electrode for electrolysis.

1 is a simplified representation of a gas trap that may occur when the diameter of the wire is too thick in the electrode for electrolysis of the present invention.

Hereinafter, the present invention will be described in more detail.

The terms or words used in the specification and claims should not be interpreted as being limited to the ordinary or dictionary meanings, and the inventor can appropriately define the concept of terms in order to best describe his or her invention. Based on the principle that it should be interpreted as meanings and concepts consistent with the technical idea of the present invention.

Electrolysis electrode

The present invention is a metal substrate layer having a wire structure; And

A coating layer comprising a ruthenium compound, a platinum compound, a lanthanide compound, and an amine-based compound,

The coating layer is formed on at least one surface of the base layer,

The diameter of the wire provides an electrode for electrolysis of 180 to 250㎛.

The metal substrate may be nickel, titanium, tantalum, aluminum, hafnium, zirconium, molybdenum, tungsten, stainless steel or alloys thereof, and nickel is preferred.

The metal substrate has a wire structure, it is preferable that the diameter of the wire is 180 to 250㎛. When the metal wire has a diameter in the above range, it shows an improved overvoltage compared to the conventional electrode for electrolysis, and when the diameter of the metal wire is larger than this, gas trap in the electrolytic cell increases, which causes problems in gas desorption. Can cause As shown in FIG. 1, when the gas trap increases, this acts as a resistance, which increases the power used in the electrolysis process. In addition, when the diameter of the metal wire is too large, the thickness of the intersection point between the wires is also thick, which causes a difference in height of the electrode, which may adversely affect the flatness of the electrode.

The ruthenium compound is a material that provides ruthenium as an active material to the catalyst layer of the cathode for electrolysis. Wherein the ruthenium compound is ruthenium hexafluoride (RuF _6), ruthenium (Ⅲ) chloride (RuCl _3), ruthenium (Ⅲ) chloride hydrate _{(RuCl 3 · xH 2 O)} , ruthenium (Ⅲ) bromide (RuBr _3), ruthenium ( Ⅲ) bromide hydrate (RuBr ₃ ·xH ₂ O), ruthenium iodide (RuI ₃ ), ruthenium iodide (RuI ₃ ) and ruthenium salt may be one or more selected from the group consisting of ruthenium (III) Chloride hydrate is preferred.

The platinum compound is a material that provides platinum to the catalyst layer of the cathode for electrolysis. The platinum may improve the overvoltage phenomenon of the cathode for electrolysis. In addition, the platinum can minimize variations in the initial performance of the cathode for electrolysis and performance after a certain period of time has passed, and as a result, the cathode for electrolysis may not perform or minimize a separate activation process.

The platinum compound is chloroplatonic acid hexahydrate (H ₂ PtCl ₆ · 6H ₂ O), diamine dinitro platinum (Pt(NH ₃ ) ₂ (NO) ₂ ) and platinum(IV) chloride (PtCl ₄ ), platinum (II ) Chloride (PtCl ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ), potassium hexachloroplatinate (K ₂ PtCl ₆ ) may be one or more selected from the group consisting of platinum (IV) chloride desirable.

The catalyst composition for a cathodic electrode for electrolysis may include the platinum compound in an amount of 0.01 to 0.7 moles or 0.02 to 0.5 moles per 1 mole of the ruthenium compound, and preferably 0.02 to 0.5 moles.

If the above-described range is satisfied, the overvoltage phenomenon of the cathode for electrolysis can be remarkably improved. In addition, since the initial performance of the cathode for electrolysis and the performance after a certain period of time can be kept constant, the activation process of the cathode for electrolysis is unnecessary. Accordingly, time and cost required for the activation process of the cathode for electrolysis can be reduced.

The lanthanide compound is a material that provides a lanthanide element to the catalyst layer of the cathode for electrolysis.

The lanthanide element may improve durability of the cathode for electrolysis, thereby minimizing loss of ruthenium in the catalyst layer of the electrode for electrolysis during activation or electrolysis. Specifically, upon activation or electrolysis of the cathode for electrolysis, particles containing ruthenium in the catalyst layer become metallic Ru (metallic Ru) or partially hydrated without reduction in structure, and are reduced to active species. do. In addition, the particles containing the lanthanide group element in the catalyst layer have a structure change to form a network with particles containing ruthenium in the catalyst layer, and as a result, the durability of the cathode for electrolysis can be improved to prevent loss of ruthenium in the catalyst layer. have.

The lanthanide compound is a cerium-based compound, a placemium-based compound, a neodymium-based compound, a promethium-based compound, a samarium-based compound, a europum-based compound, a gadolinium-based compound, a terbium-based compound, a dysprosium-based compound, a holmium-based compound, an erbium-based compound It may be at least one selected from the group consisting of compounds, thulium-based compounds, ytterbium-based compounds, and ruthenium-based compounds, of which cerium-based compounds are preferred.

The cerium-based compounds are cerium(III) nitrate hexahydrate (Ce(NO ₃ ) ₃ · 6H ₂ O), cerium(IV) sulfate tetrahydrate (Ce(SO ₄ ) ₂ ·4H ₂ O) and cerium(III) Chloride heptahydrate (CeCl ₃ ·7H ₂ O) is at least one member selected from the group consisting of cerium (III) nitrate hexahydrate.

The catalyst composition for an anode for electrolysis may contain 0.01 to 0.5 moles or 0.05 to 0.35 moles of the lanthanide compound with respect to 1 mole of the ruthenium compound, and preferably 0.05 to 0.35 moles.

If the above-described range is satisfied, the durability of the cathode for electrolysis may be improved to minimize loss of ruthenium in the catalyst layer of the electrode for electrolysis during activation or electrolysis.

The amine-based compound is known to play a role of reducing the particle shape by adding it as an additive when manufacturing nanoparticles, etc., and also has an effect of making the ruthenium crystal phase small in the electrode coating. In addition, the catalyst composition for the electrolysis negative electrode contains an amine compound, so that the lanthanide element, specifically, the cerium network structure formed by increasing the size of the acicular structure of cerium, serves to fix the ruthenium particles more firmly. It improves the durability of the electrode. And, as a result, there is an effect that can significantly reduce the peeling phenomenon of the electrode even when the electrode is operated for a long time.

The catalyst composition for an anode for electrolysis may contain 0.5 to 1 mole or 0.6 to 0.9 mole of the amine-based compound with respect to 1 mole of the ruthenium compound, and it is preferable to include 0.6 to 0.9 mole of them.

When the above-mentioned content is satisfied, the amine-based compound has a structure of particles containing a lanthanide element derived from a lanthanide compound than when an amine-based compound is not used after activation of the cathode for electrolysis or electrolysis. By rapidly changing, a network can be formed in the catalyst layer, and as a result, durability of the cathode can be improved. Specifically, the amine-based compound can improve the durability of the negative electrode by increasing the acicular structure of particles containing cerium.

It is preferable that the amine compound is urea. When using urea, other amine-based compounds have advantages in that stability and safety of the coating solution are superior to those used, and the occurrence of harmful substances and odors is small even when manufacturing electrodes in a large area.

Method of manufacturing an electrode for electrolysis

The present invention comprises the steps of applying a coating composition on at least one side of a metal substrate having a wire structure; And

And drying and heat-treating the metal substrate coated with the coating composition to coat it,

The coating composition includes a ruthenium compound, a platinum compound, a lanthanide compound, and an amine compound,

The metal wire has a diameter of 180 to 250㎛ provides a method of manufacturing an electrode for electrolysis.

The metal substrate, ruthenium compound, platinum compound, lanthanide compound and amine compound used in the production method of the present invention are the same as those used in the electrode for electrolysis described above.

In the manufacturing method of the present invention, it may include the step of pre-treating the metal substrate before performing the coating step.

The pretreatment may be to form an unevenness on the surface of the metal substrate by chemical etching, blasting or thermal spraying the metal substrate.

The pre-treatment may be performed by sand blasting the surface of the metal substrate to form fine irregularities, and salt treatment or acid treatment. For example, the surface of the metal substrate may be sandblasted with alumina to form irregularities, immersed in an aqueous sulfuric acid solution, washed and dried to pretreat to form fine irregularities on the surface of the metal substrate.

The coating may be performed by a method known in the art without particular limitation as long as the catalyst composition can be applied evenly on a metal substrate.

The application may be performed by any one method selected from the group consisting of doctor blade, die casting, comma coating, screen printing, spray spraying, electrospinning, roll coating and brushing.

The drying may be performed at 50 to 300°C for 5 to 60 minutes, and preferably at 50 to 200°C for 5 to 20 minutes.

If the above conditions are satisfied, the solvent can be sufficiently removed while energy consumption can be minimized.

The heat treatment may be performed at 400 to 600°C for 1 hour or less, and is preferably performed at 450 to 550°C for 5 to 30 minutes.

If the above conditions are satisfied, impurities in the catalyst layer are easily removed, and the strength of the metal substrate may not be affected.

On the other hand, the coating may be carried out by repeating the coating, drying and heat treatment in order to be 10 g or more based on ruthenium per unit area (m 2) of the metal substrate. That is, the manufacturing method according to another embodiment of the present invention is applied to the catalyst composition on at least one surface of the metal substrate, dried and heat-treated, and then applied again on the first surface of the metal substrate coated with the catalyst composition, dried and The heat-treated coating can be repeatedly performed.

Hereinafter, examples and experimental examples will be described in more detail in order to specifically describe the present invention, but the present invention is not limited by these examples and experimental examples. Embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

material

In this example, a nickel base material (Ni purity 99% or more) manufactured by Jang Inheung Co., Ltd. was used as the metal base, and a ruthenium compound was a ruthenium chloride hydrate of Heraeus, and a platinum compound was platinum chloride (platinum(IV) chloride, 99.9%). ), as a lanthanide compound, cerium nitrate hexahydrate from Sigma-Aldrich was used, and urea was used as an amine compound.

In addition, as a solvent for the coating composition, isopropyl alcohol and 2-butoxy ethanol from Daejung Chemical Co., Ltd. were used.

Preparation of coating composition

The metal precursors RuCl ₃ ·nH ₂ O, Ce(NO ₃ ) ₃ ·6H ₂ O and PtCl ₄ are mixed in a molar ratio of 5:1:0.5 to mix isopropyl alcohol and 2-butoxyethanol in a volume ratio of 1:1. It was dissolved in the mixed solvent. Then, when the metal precursor was dissolved, an amine compound urea was added at a ratio of 3.13 moles and stirred at 50°C overnight to prepare a coating composition solution having a concentration of 100 g/L based on ruthenium.

Example 1. Preparation of an electrode for electrolysis using a nickel substrate having a diameter of 180 μm

The surface of the nickel substrate having a diameter of 180 µm was sand blasted under the condition of 0.4 MPa with oxide (120 mesh) and processed into an uneven structure. Thereafter, the processed nickel substrate was added to a 5M H ₂ SO ₄ aqueous solution at 80° C. for 3 minutes to complete the pretreatment process. Thereafter, the coating composition solution prepared prior to the pre-treated nickel substrate was coated with a brush method, placed in a convection drying oven at 180°C and dried for 10 minutes, and then placed in an electric heating furnace at 500°C for heat treatment for 10 minutes. After the coating, drying, and heat treatment were additionally performed 9 times, an electrode for electrolysis was prepared by finally heat-treating for 1 hour in an electric furnace heated to 500°C.

Example 2. Preparation of an electrode for electrolysis using a nickel substrate having a diameter of 200 μm

Electrode for electrolysis was prepared in the same manner as in Example 1, except that a nickel substrate having a diameter of 200 μm was used instead of a nickel substrate having a diameter of 180 μm.

Example 3. Preparation of an electrode for electrolysis using a nickel substrate having a diameter of 250 μm

Electrode for electrolysis was prepared in the same manner as in Example 1, except that a nickel substrate having a diameter of 250 μm was used instead of a nickel substrate having a diameter of 180 μm.

Comparative Example 1. Preparation of an electrode for electrolysis using a nickel substrate having a diameter of 150 μm

Electrode for electrolysis was prepared in the same manner as in Example 1, except that a nickel substrate having a diameter of 150 μm was used instead of a nickel substrate having a diameter of 180 μm.

Comparative Example 2. Preparation of an electrode for electrolysis without using an amine compound

Electrolysis electrodes were prepared in the same manner as in Example 1, except that urea was not used.

Comparative Example 3. Preparation of an electrode for electrolysis without using an amine compound and a platinum compound

Electrode for electrolysis was prepared in the same manner as in Example 1, except that urea and a platinum compound were not used.

The information of the electrodes prepared in Examples 1 to 3 and Comparative Examples 1 to 3 is summarized in Table 1 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Nickel wire diameter (㎛) 180 200 250 150 180 180 Composition ratio of coating layer (Ru:Ce:Pt:Urea) 5:1:0.5:3.13 5:1:0.5:3.13 5:1:0.5:3.13 5:1:0.5:3.13 5:1:0.5:0
(No urea) 5:1:0:0
(No urea and Pt)

Experimental Example 1. Performance confirmation of the prepared electrode for electrolysis

In order to confirm the performance of the electrodes prepared in Examples 1 to 3 and Comparative Examples 1 to 3, a cathode voltage measurement experiment using a half cell in a salt-electrolysis (Chlor-Alkali Electrolysis) was performed. First, the voltage was measured under the condition of current density -0.62 A/cm ² through Linear Sweep Voltammetry to measure the voltage values of Examples and Comparative Examples. A 32% NaOH aqueous solution was used as the electrolyte solution, a Pt wire as a counter electrode, and an Hg/HgO electrode as a reference electrode. The results are summarized in Table 2 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Voltage (V, at 6.2kA/cm ² ) -1.098 -1.083 -1.072 -1.111 -1.106 -1.109

Experimental Example 2. Confirmation of the composition ratio of the coating layer of the prepared electrode for electrolysis

In order to confirm the composition ratio of the coating layers of the electrodes prepared in Examples 1 to 3 and Comparative Examples 1 to 3, the electrodes for electrolysis were produced in a horizontal and vertical 0.6m standard, and equally divided into 16 pixels, X-ray fluorescence (XRF) component analysis was performed on three points for each pixel to measure the mole percent of Ru, Ce, and Pt. The dispersion and standard deviation were calculated using the following equations 1 and 2 from the mole% of each metal obtained. The results are summarized in Table 3 below.

[Equation 1]

V(x) = E(x ² )-[E(x)] ²

In Equation 1, E(x ² ) represents the mean value of the Ru mol% square in 9 pixels, and [E(x)] ² represents the square value of the Ru mol% average in 9 pixels.

[Equation 2]

σ=

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Composition ratio (% by weight) Ru 4.09 3.82 3.90 3.80 3.61 3.85 Ce 3.24 2.89 3.02 2.73 2.95 3.66 Pt 2.29 2.09 2.10 2.06 2.29 - Standard deviation (σ) Ru 0.36 0.30 0.42 0.37 0.42 0.23 Ce 0.28 0.26 0.31 0.30 0.31 0.33 Pt 0.15 0.14 0.15 0.17 0.15 -

From the above results, it was confirmed that even if the wire diameter of the metal base layer was thick, the component ratio of the electrode hardly changed.

In addition, from Experimental Examples 1 and 2, as the wire diameter of the metal base layer increased in the range of 180 to 250 μm, it was confirmed that the catalytic activity increased and the overvoltage decreased as the surface area increased, and the amine compound was added to the coating layer composition. It was confirmed that the overvoltage increases even when not included or some of the metal components are not included.

Claims (12)

A metal base layer having a wire structure; And
It includes a coating layer comprising a ruthenium compound, a platinum compound, a lanthanide compound, and an amine-based compound,
The coating layer is formed on at least one surface of the base layer,
Electrode for electrolysis, the diameter of the wire is 180 to 250㎛.
The electrode for electrolysis of claim 1, wherein the metal substrate is nickel.
According to claim 1, The ruthenium compound is ruthenium hexafluoride (RuF ₆ ), ruthenium (III) chloride (RuCl ₃ ), ruthenium (III) chloride hydrate (RuCl ₃ · xH ₂ O), ruthenium (III) bromide ( RuBr ₃ ), ruthenium (III) bromide hydrate (RuBr ₃ xH ₂ O), ruthenium iodide (RuI ₃ ), ruthenium iodide (RuI ₃ ) and at least one selected from the group consisting of ruthenium acetate Decomposition electrode
The method of claim 1, wherein the platinum compound is chloroplatonic acid hexahydrate (H ₂ PtCl ₆ · 6H ₂ O), diamine dinitro platinum (Pt(NH ₃ ) ₂ (NO) ₂ ) and platinum (IV) chloride (PtCl) ₄ ), Platinum (II) chloride (PtCl ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ), potassium hexachloroplatinate (K ₂ PtCl ₆ ) is at least one member selected from the group consisting of electrode.
The method of claim 1, wherein the lanthanide compound is a cerium-based compound, a placemium-based compound, a neodymium-based compound, a promethium-based compound, a samarium-based compound, a europium-based compound, a gadolinium-based compound, a terbium-based compound, a dysprosium-based compound, An electrode for electrolysis that is at least one member selected from the group consisting of holmium-based compounds, erbium-based compounds, thulium-based compounds, ytterbium-based compounds, and ruthenium-based compounds.
The electrode for electrolysis according to claim 1, wherein the amine compound is urea.
The electrode for electrolysis according to claim 1, wherein the electrode for electrolysis is used for electrolysis in a CA process.
Applying a coating composition on at least one side of a metal substrate having a wire structure; And
And drying and heat-treating the metal substrate coated with the coating composition to coat it,
The coating composition includes a ruthenium compound, a platinum compound, a lanthanide compound, and an amine compound,
A method of manufacturing an electrode for electrolysis, wherein the diameter of the metal wire is 180 to 250 μm.
The method of claim 8, wherein the metal substrate is nickel.
The method of claim 8, wherein the ruthenium compound is ruthenium hexafluoride (RuF _6), ruthenium (Ⅲ) chloride (RuCl _3), ruthenium (Ⅲ) chloride hydrate _{(RuCl 3 · xH 2 O)} , ruthenium (Ⅲ) bromide ( and RuBr _3), ruthenium (ⅲ) bromide hydrate _{(RuBr 3 · xH 2 O)} , ruthenium child ohdideu (RuI _3), ruthenium child ohdideu (RuI ₃₎ and at least one element selected from the group consisting of ruthenium acetate salt,
The platinum compound is chloroplatonic acid hexahydrate (H ₂ PtCl ₆ · 6H ₂ O), diamine dinitro platinum (Pt(NH ₃ ) ₂ (NO) ₂ ) and platinum(IV) chloride (PtCl ₄ ), platinum (II ) Chloride (PtCl ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ), potassium hexachloroplatinate (K ₂ PtCl ₆ ) is at least one selected from the group consisting of,
The lanthanide compounds are cerium-based compounds, placemium-based compounds, neodymium-based compounds, promethium-based compounds, samarium-based compounds, europum-based compounds, gadolinium-based compounds, terbium-based compounds, dysprosium-based compounds, holmium-based compounds, erbium-based compounds A method of manufacturing an electrode for electrolysis, which is at least one selected from the group consisting of a compound, a thlium-based compound, a ytterbium-based compound, and a ruthenium-based compound.
The method of claim 8, wherein the amine-based compound is urea.
The method of claim 8, wherein the electrode for electrolysis is used for electrolysis in a CA process.

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