KR102576668B1 - Electrode for Electrolysis - Google Patents

Abstract

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

Description

Electrode for Electrolysis}

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

Technology for producing hydroxide, hydrogen, and chlorine by electrolyzing inexpensive brine such as seawater is widely known. This electrolysis process is also commonly called the chlor-alkali process, and can be said to be a process that has already proven its performance and technological reliability through decades of commercial operation.

This type of electrolysis of salt water divides the electrolyzer into a positive ion chamber and a negative ion chamber by installing an ion exchange membrane inside the electrolyzer. The ion exchange membrane method, which uses salt water as an electrolyte to obtain chlorine gas at the anode and hydrogen and caustic soda at the cathode, is currently the most widely used. This is the method being used.

Meanwhile, the electrolysis process of brine is achieved through a reaction as shown in the electrochemical equation below.

Anode reaction: 2Cl ^- → Cl ₂ + 2e ^- (E ⁰ = +1.36 V)

Cathode reaction: 2H ₂ O + 2e ^- → 2OH ^- + H ₂ (E ⁰ = -0.83 V)

Overall reaction: 2Cl ^- + 2H ₂ O → 2OH ^- + Cl ₂ + H ₂ (E ⁰ = -2.19 V)

When performing electrolysis of brine, the electrolytic voltage must take into account the voltage required for theoretical electrolysis of brine, plus 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. Among these voltages, overvoltage due to electrodes acts as an important variable.

Accordingly, methods to reduce the overvoltage of electrodes are being studied. For example, a noble metal electrode called DSA (Dimensionally Stable Anode) has been developed and used as an anode, and for the cathode, excellent materials with low overvoltage and durability are being developed. This is being demanded.

Stainless steel or nickel has been mainly used as these cathodes, and recently, in order to reduce overvoltage, the surface of stainless steel or nickel has been 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, in order to increase the activity of the negative electrode by adjusting the composition of the active material, methods of controlling the composition using platinum group elements such as ruthenium and lanthanide elements such as cerium are also being studied. However, problems such as overvoltage phenomenon and deterioration due to reverse current occurred.

JP2003-2977967A

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

In order to solve the above problems, the present invention includes a metal base layer having a wire structure; and

It includes a coating layer prepared by applying, drying, and heat-treating a coating composition containing a ruthenium compound, a platinum compound, a lanthanide compound, and an amine-based compound on the metal base layer,

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

An electrode for electrolysis is provided wherein the wire has a diameter of 180 to 250㎛.

Additionally, the present invention provides a method for manufacturing the electrode for electrolysis.

The electrolysis electrode according to the present invention uses a thicker metal wire than the conventional electrolysis electrode, thereby increasing the surface area of the coating layer and improving overvoltage.

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

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

Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

Electrode for electrolysis

The present invention relates to a metal base layer having a wire structure; and

It includes a coating layer prepared by applying, drying, and heat-treating a coating composition containing a ruthenium compound, a platinum compound, a lanthanide compound, and an amine-based compound on the metal base layer,

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

An electrode for electrolysis is provided wherein the wire has a diameter of 180 to 250㎛.

The metal substrate may be nickel, titanium, tantalum, aluminum, hafnium, zirconium, molybdenum, tungsten, stainless steel, or an alloy thereof, of which nickel is preferable.

The metal substrate has a wire structure, and the diameter of the wire is preferably 180 to 250㎛. When the metal wire has a diameter in the above range, it shows improved overvoltage compared to existing electrolysis electrodes, and when the diameter of the metal wire is larger than this, gas traps in the electrolyzer increase, causing problems with gas desorption. can cause If the gas trap increases as shown in Figure 1, there is a problem in that it acts as a resistance and increases the power used during the electrolysis process. Additionally, when the diameter of the metal wire is too large, the thickness of the intersection point between the wires also becomes thick, causing a difference in the height of the electrode, which may have a negative effect on the flatness of the electrode.

The ruthenium compound is a material that provides ruthenium, an active material, to the catalyst layer of the cathode for electrolysis. The ruthenium compounds include 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) It may be one or more selected from the group consisting of bromide hydrate (RuBr ₃ ·xH ₂ O), ruthenium iodide (RuI ₃ ), ruthenium iodide (RuI ₃ ), and ruthenium acetate salt, of which 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 can improve the overvoltage phenomenon of the cathode for electrolysis. In addition, the platinum can minimize the difference between the initial performance of the electrolysis cathode and the performance after a certain period of time, and as a result, the electrolysis cathode can no longer perform a separate activation process or can minimize it.

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

The coating composition may contain the platinum compound in an amount of 0.01 to 0.7 mol or 0.02 to 0.5 mol, based on 1 mol of the ruthenium compound, and preferably contains 0.02 to 0.5 mol.

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

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

The lanthanide element can improve the durability of the cathode for electrolysis and minimize the loss of ruthenium in the catalyst layer of the electrode for electrolysis during activation or electrolysis. Specifically, during activation or electrolysis of the cathode for electrolysis, particles containing ruthenium in the catalyst layer become metallic Ru or are partially hydrated and reduced to active species without changing the structure. do. In addition, the particles containing lanthanide elements in the catalyst layer change their structure 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 and the loss of ruthenium in the catalyst layer can be prevented. there is.

The lanthanide compound is a cerium-based compound, a placeodymium-based compound, a neodymium-based compound, a promium-based compound, a samarium-based compound, a europium-based compound, a gadolinium-based compound, a terbium-based compound, a dysprosium-based compound, a holmium-based compound, and an erbium-based compound. It may be one or more selected from the group consisting of compounds, thulium-based compounds, ytterbium-based compounds, and lutetium-based compounds, of which cerium-based compounds are preferable.

The cerium-based compounds include 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) At least one selected from the group consisting of chloride heptahydrate (CeCl ₃ ·7H ₂ O), of which cerium (III) nitrate hexahydrate is preferable.

The coating composition may contain 0.01 to 0.5 mol or 0.05 to 0.35 mol of the lanthanide compound based on 1 mol of the ruthenium compound, and preferably contains 0.05 to 0.35 mol of the lanthanide compound.

If the above-mentioned range is satisfied, the durability of the electrolysis cathode can be improved and the loss of ruthenium in the catalyst layer of the electrolysis electrode can be minimized during activation or electrolysis.

The amine-based compound is known to play a role in making the particle size smaller by being added as an additive when manufacturing nanoparticles, etc., and also has the effect of making the ruthenium oxide crystal phase smaller in electrode coating. In addition, because the coating composition contains an amine compound, the cerium network structure formed by increasing the size of the needle-like structure of the lanthanide element, specifically cerium, serves to fix the ruthenium particles more firmly, thereby increasing the durability of the electrode. improve it And, as a result, there is an effect of significantly reducing the peeling phenomenon of the electrode even when the electrode is operated for a long time.

The coating composition may contain 0.5 to 1 mole or 0.6 to 0.9 mole of the amine-based compound based on 1 mole of the ruthenium compound, and preferably contains 0.6 to 0.9 mole of the amine compound.

If the above-mentioned content is satisfied, the amine-based compound will have a structure of particles containing a lanthanide element derived from a lanthanide compound after activation of the cathode for electrolysis or during electrolysis, compared to when the amine-based compound is not used. By changing it quickly, a network can be formed within the catalyst layer, and as a result, the durability of the cathode can be improved. Specifically, the amine-based compound can improve the durability of the cathode by increasing the needle-like structure of particles containing cerium.

The amine-based compound is preferably urea. When using urea, there is an advantage that the stability and safety of the coating liquid are superior compared to those using other amine-based compounds, and the generation of harmful substances and odors is reduced even when manufacturing large-area electrodes.

Method for manufacturing electrodes for electrolysis

The present invention includes the steps of applying a coating composition on at least one surface of a metal substrate having a wire structure; and

It includes the step of coating the metal substrate to which the coating composition is applied by drying and heat treating,

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 metal wire has a diameter of 180 to 250 ㎛ is provided.

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, the step of pre-treating the metal substrate before performing the coating step may be included.

The pretreatment may be to form irregularities on the surface of the metal substrate by chemically etching, blasting, or thermally spraying the metal substrate.

The pretreatment can be performed by sandblasting the surface of the metal substrate to form fine irregularities, and then treating it with salt or acid. For example, the surface of a metal substrate can be pretreated to form irregularities by sandblasting with alumina, immersed in an aqueous sulfuric acid solution, washed and dried to form fine irregularities on the surface of the metal substrate.

The application can be performed by a method known in the art without particular limitation as long as the coating composition can be applied evenly on the 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 can be performed at 50 to 300°C for 5 to 60 minutes, and is preferably performed at 50 to 200°C for 5 to 20 minutes.

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

The heat treatment can 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-mentioned conditions are satisfied, impurities in the catalyst layer can be easily removed without affecting the strength of the metal substrate.

Meanwhile, the coating can be performed by sequentially repeating application, drying, and heat treatment to obtain 10 g or more of ruthenium per unit area (m2) of the metal substrate. That is, the manufacturing method according to another embodiment of the present invention involves applying, drying, and heat-treating the coating composition on at least one side of a metal substrate, and then applying it again on one side of the metal substrate to which the first coating composition was applied, drying, and Heat treatment coating can be performed repeatedly.

Hereinafter, the present invention will be described in more detail using examples and experimental examples to specifically illustrate the present invention, but the present invention is not limited by these examples and experimental examples. Embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described in detail below. Examples of the present invention are provided to more completely explain the present invention to those with average knowledge in the art.

ingredient

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

Additionally, isopropyl alcohol and 2-butoxy ethanol from Daejeong Chemical Company were used as solvents for the coating composition.

Preparation of coating composition

Metal precursors RuCl ₃ ·nH ₂ O, Ce(NO ₃ ) ₃ ·6H ₂ O and PtCl ₄ were mixed at a molar ratio of 5:1:0.5, and isopropyl alcohol and 2-butoxy ethanol were mixed at a volume ratio of 1:1. Dissolved in mixed solvent. After the metal precursor was dissolved, urea, an amine-based compound, was added at a molar ratio of 3.13, 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 electrode for electrolysis using nickel substrate with a diameter of 180㎛

The surface of the nickel base with a diameter of 180㎛ was processed into a structure with irregularities by sandblasting with oxide (120 mesh) under 0.4MPa conditions. Afterwards, the processed nickel substrate was placed in a 5M H ₂ SO ₄ aqueous solution at 80°C and treated for 3 minutes to complete the pretreatment process. Thereafter, the pre-treated nickel substrate was coated with the previously prepared coating composition solution using a brush method, placed in a convection drying oven at 180°C to dry for 10 minutes, and then placed in an electric heating furnace at 500°C for 10 minutes. After performing these coating, drying, and heat treatment processes 9 additional times, an electrode for electrolysis was finally manufactured by heat treatment for 1 hour in an electric heating furnace heated to 500°C.

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

An electrode for electrolysis was manufactured in the same manner as in Example 1, except that a nickel substrate with a diameter of 200 μm was used instead of a nickel substrate with a diameter of 180 μm.

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

An electrode for electrolysis was manufactured in the same manner as in Example 1, except that a nickel substrate with a diameter of 250 μm was used instead of a nickel substrate with a diameter of 180 μm.

Comparative Example 1. Manufacturing electrode for electrolysis using nickel substrate with a diameter of 150㎛

An electrode for electrolysis was manufactured in the same manner as in Example 1, except that a nickel substrate with a diameter of 150 μm was used instead of a nickel substrate with a diameter of 180 μm.

Comparative Example 2. Manufacturing electrode for electrolysis without using amine compounds

An electrode for electrolysis was manufactured in the same manner as in Example 1, except that urea was not used.

Comparative Example 3. Manufacturing electrode for electrolysis without using amine-based compounds and platinum compounds

An electrode for electrolysis was manufactured in the same manner as in Example 1, except that urea and platinum compounds were not used.

Information on the electrodes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 are 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. Confirmation of performance of manufactured electrode for electrolysis

To confirm the performance of the electrodes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3, a cathode voltage measurement experiment using a half cell in chlor-alkali electrolysis was performed. First, the voltage was measured under the condition of a current density of -0.62 A/cm ² through linear sweep voltammetry, and the voltage values of the examples and comparative examples were measured. A 32% NaOH aqueous solution was used as the electrolyte, a Pt wire was used as the counter electrode, and an Hg/HgO electrode was used as the 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 coating layer composition ratio of manufactured electrolysis electrode

In order to confirm the coating layer composition ratio of the electrodes prepared in Examples 1 to 3 and Comparative Examples 1 to 3, electrolysis electrodes were manufactured in a size of 0.6m horizontally and vertically, and divided equally into 16 pixels, XRF (X-ray fluorescence) component analysis was performed on three points for each pixel to measure the mole percentages of Ru, Ce, and Pt. Afterwards, the variance and standard deviation were calculated from the mole percentage of each metal obtained using Equations 1 and 2 below. 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 average squared value of Ru mole% within 9 pixels, and [E(x)] ² represents the squared average value of Ru mole% within 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 became thick, the component ratio of the electrode hardly changed.

In addition, from Experimental Examples 1 and 2, it was confirmed that as the wire diameter of the metal base layer increases in the range of 180 to 250㎛, the catalytic activity increases and the overvoltage decreases as the surface area increases, and the amine-based compound in the coating layer composition It was confirmed that the overvoltage increases even when it is 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 prepared by applying, drying, and heat-treating a coating composition containing a ruthenium compound, a platinum compound, a lanthanide compound, and urea on the metal base layer,
The coating layer is formed on at least one side of the base layer,
An electrode for electrolysis wherein the diameter of the wire is 180 to 250㎛.
The electrode for electrolysis according to claim 1, wherein the metal substrate is nickel.
The method of claim 1, 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 acetate, which is at least one selected from the group consisting of ruthenium salts. Electrode for disassembly.
The method of claim 1, wherein the platinum compound is chloroplatinic acid hexahydrate (H ₂ PtCl ₆ ·6H ₂ O), diamine dinitro platinum (Pt(NH ₃ ) ₂ (NO) ₂ ), platinum (IV) chloride (PtCl ₄ ), platinum (II) chloride (PtCl ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ), and potassium hexachloroplatinate (K ₂ PtCl ₆ ) for electrolysis, which is at least one selected from the group consisting of electrode.
The method of claim 1, wherein the lanthanide compound is a cerium-based compound, a placeodymium-based compound, a neodymium-based compound, a promium-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, which is at least one selected from the group consisting of holmium-based compounds, erbium-based compounds, thulium-based compounds, ytterbium-based compounds, and lutetium-based compounds.
delete The electrode for electrolysis according to claim 1, wherein the electrode for electrolysis is used for electrolysis in a chlor-alkali process.
Applying a coating composition on at least one side of a metal substrate having a wire structure; and
It includes the step of coating the metal substrate to which the coating composition is applied by drying and heat treating,
The coating composition includes a ruthenium compound, a platinum compound, a lanthanide compound, and urea,
A method of manufacturing an electrode for electrolysis wherein the metal wire has a diameter of 180 to 250㎛.
The method of manufacturing an electrode for electrolysis according to 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 ( At least one selected from the group consisting of RuBr ₃ ), ruthenium (III) bromide hydrate (RuBr ₃ ·xH ₂ O), ruthenium iodide (RuI ₃ ), ruthenium iodide (RuI ₃ ) and ruthenium acetate salt,
The platinum compounds include chloroplatinic acid hexahydrate (H ₂ PtCl ₆ ·6H ₂ O), diamine dinitro platinum (Pt(NH ₃ ) ₂ (NO) ₂ ), platinum (IV) chloride (PtCl ₄ ), and platinum (Ⅱ ) At least one selected from the group consisting of chloride (PtCl ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ), and potassium hexachloroplatinate (K ₂ PtCl ₆ ),
The lanthanide compound is a cerium-based compound, a placeodymium-based compound, a neodymium-based compound, a promium-based compound, a samarium-based compound, a europium-based compound, a gadolinium-based compound, a terbium-based compound, a dysprosium-based compound, a holmium-based compound, and an erbium-based compound. A method of manufacturing an electrode for electrolysis, comprising at least one selected from the group consisting of a compound, a thulium-based compound, a ytterbium-based compound, and a lutetium-based compound.
delete The method of claim 8, wherein the electrolysis electrode is used for electrolysis in a chlor-alkali process.