One]Cross-Citation with Related Applications
[2]This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0119113 dated September 26, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[3]
[4]
technical field
[5]
The present invention relates to an electrode for electrolysis capable of improving overvoltage and a method for manufacturing the same.
background
[6]
A technique for producing hydroxide, hydrogen and chlorine by electrolyzing inexpensive brine such as seawater is widely known. This electrolysis process is usually called a chlor-alkali process, and it can be said that it is a process whose performance and reliability of technology have been proven through commercial operation for several decades.
[7]
For the electrolysis of brine, an ion exchange membrane is installed inside the electrolyzer to divide the electrolyzer into a cation chamber and an anion chamber, and the ion exchange membrane method that uses brine as an electrolyte to obtain chlorine gas from the anode and hydrogen and caustic soda from the cathode is currently the most widely used method being used.
[8]
On the other hand, the electrolysis process of brine is made through a reaction as shown in the following electrochemical reaction formula.
[9]
Anode reaction: 2Cl - → Cl 2 + 2e - (E 0 = +1.36 V)
[10]
Cathode reaction: 2H 2 O + 2e - → 2OH - + H 2 (E 0 = -0.83 V)
[11]
Overall reaction: 2Cl - + 2H 2 O → 2OH - + Cl 2 + H 2 (E 0 = -2.19 V)
[12]
[13]
In carrying out the electrolysis of brine, the electrolysis voltage should consider all of the voltages required for the electrolysis of the brine in theory, 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, the overvoltage by the electrode is acting as an important variable.
[14]
Accordingly, a method for 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 excellent material with a low overvoltage and durability for the anode is also developed. this is being requested
[15]
Stainless steel or nickel has been mainly used as such anode, 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. How to use it is being studied.
[16]
In addition, in order to increase the activity of the anode by controlling the composition of the active material, a method of adjusting the composition using a platinum group element such as ruthenium and a lanthanide element such as cerium is being studied. However, an overvoltage phenomenon occurred and deterioration caused by reverse current occurred.
[17]
[18]
Prior art literature
[19]
(Patent Document 1) JP 2003-2977967A
[20]
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[21]
An object of the present invention is to provide an electrode for electrolysis capable of reducing overvoltage by improving the electrical properties of the electrode surface coating layer.
means of solving the problem
[22]
In order to solve the above problems, the present invention includes a metal base layer, and a coating layer comprising a ruthenium oxide, a platinum group oxide and a manganese oxide, wherein the coating layer is formed on at least one surface of the base layer for electrolysis electrodes are provided.
[23]
In addition, the present invention includes the steps of applying a coating composition on at least one surface of a metal substrate and coating the metal substrate to which the coating composition is applied by drying and heat treatment, wherein the coating composition is a ruthenium precursor, a platinum group precursor, and a manganese precursor It provides a method of manufacturing an electrode for electrolysis comprising a.
Effects of the Invention
[24]
The electrode for electrolysis of the present invention exhibits excellent overvoltage as the tin oxide contained in the coating layer interacts with the ruthenium oxide and the platinum group oxide contained together to improve electrical conductivity, and the basic durability is also excellent.
Best mode for carrying out the invention
[25]
Hereinafter, the present invention will be described in more detail.
[26]
The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention.
[27]
[28]
Electrode for electrolysis
[29]
The present invention provides an electrode for electrolysis comprising a metal base layer and a coating layer comprising a ruthenium oxide, a platinum group oxide and a manganese oxide, wherein the coating layer is formed on at least one surface of the base layer.
[30]
[31]
The metal substrate may be nickel, titanium, tantalum, aluminum, hafnium, zirconium, molybdenum, tungsten, stainless steel, or an alloy thereof, of which nickel is preferable. In the electrode for electrolysis of the present invention, when such a type of metal substrate is used, excellent durability and mechanical strength of the electrode can be provided to the electrode.
[32]
[33]
In the electrode for electrolysis of the present invention, the coating layer includes ruthenium oxide. The ruthenium oxide serves to provide a ruthenium element to the coating layer as an active material, and when ruthenium oxide is used for the coating layer of the electrode for electrolysis, the overvoltage phenomenon is improved, and the change in electrode performance is small with time, and thereafter, separate activation process can be minimized. The ruthenium oxide includes all kinds of oxides in which the ruthenium element and the oxygen atom are combined, and in particular, may be a dioxide or a tetraoxide.
[34]
[35]
In the electrode for electrolysis of the present invention, the coating layer includes a platinum group oxide. The platinum group oxide refers to oxides of elements other than the aforementioned ruthenium among the platinum group elements, and specifically, may be rhodium oxide, palladium oxide, osmium oxide, iridium oxide, or platinum oxide. The platinum group element provided by the platinum group oxide may act as an active material like the ruthenium element, and when the platinum group oxide and the ruthenium oxide are included in the coating layer together, it can exhibit a more excellent effect in terms of durability and overvoltage of the electrode. The platinum group oxide includes all kinds of oxides in which a platinum group element and an oxygen atom are combined, and in particular may be a dioxide or a tetraoxide, and the platinum group oxide is preferably a platinum oxide or an iridium oxide.
[36]
[37]
In the electrode for electrolysis of the present invention, the coating layer includes manganese oxide. The manganese oxide interacts with the ruthenium oxide and the platinum group oxide described above to improve the electrical conductivity of the coating layer, thereby improving the final overvoltage of the electrode for electrolysis. The manganese oxide includes all kinds of oxides in which ruthenium and an oxygen atom are bonded, and in particular, may be manganese (II, III) oxide (Mn 3 O 4 ) or manganese (III) oxide (Mn 2 O 3 ).
[38]
[39]
The weight ratio of the ruthenium element and the platinum group element included in the coating layer may be 100:40 to 100:70, preferably 100:50 to 100:65. When the weight ratio of the ruthenium element and the platinum group element included in the coating layer is within the above range, it is preferable in terms of durability and overvoltage improvement. is not advantageous from an economic point of view.
[40]
[41]
A weight ratio of elemental ruthenium and elemental manganese included in the coating layer may be 100:5 to 100:30, preferably 100:10 to 100:25. When the weight ratio of the ruthenium element and the manganese element included in the coating layer is within the above-described range, the effect of improving the electrical conductivity of the coating layer may be maximized.
[42]
[43]
In the electrode for electrolysis of the present invention, the coating layer may further include cerium oxide, and the cerium oxide serves to provide a lanthanide element to the catalyst layer of the electrode for electrolysis. The cerium element provided by the cerium oxide improves the durability of the electrode for electrolysis, thereby minimizing loss of elemental ruthenium as an active material in the catalyst layer of the electrode for electrolysis during activation or electrolysis.
[44]
Specifically, when the electrode for electrolysis is activated or electrolyzed, the particles containing the ruthenium element in the catalyst layer become metallic elements without changing their structure or partially hydrated and are reduced to active species. In addition, the particles containing the lanthanide element in the catalyst layer have a needle-like structure and act as a protective material to prevent physical drop-off of the particles containing the ruthenium element in the catalyst layer. It can prevent the loss of ruthenium element. The cerium oxide includes all kinds of oxide forms in which cerium element and oxygen atom are combined, and in particular, may be an oxide of (II), (III) or (IV).
[45]
[46]
The weight ratio of the ruthenium element and the cerium element included in the coating layer may be 100:40 to 100:90, preferably 100:45 to 100:85. When the weight ratio of the ruthenium element and the cerium element included in the coating layer is within the above-described range, the balance between the durability of the electrode for electrolysis and the electrical conductivity may be excellent.
[47]
[48]
Manufacturing method of electrode for electrolysis
[49]
The present invention comprises the steps of applying a coating composition on at least one surface of a metal substrate; and
[50]
Drying and heat-treating the metal substrate to which the coating composition is applied, comprising the steps of coating,
[51]
The coating composition provides a method for producing an electrode for electrolysis comprising a ruthenium precursor, a platinum group precursor, and a manganese precursor.
[52]
[53]
In the method of manufacturing an electrode for electrolysis of the present invention, the metal substrate may be the same as the metal substrate of the electrode for electrolysis described above.
[54]
[55]
In the method of manufacturing an electrode for electrolysis of the present invention, the coating composition may include a ruthenium precursor, a platinum group precursor, and a manganese precursor. The ruthenium precursor, the platinum group precursor, and the manganese precursor are oxidized and converted into oxides in a heat treatment step after coating.
[56]
The ruthenium precursor may be used without particular limitation as long as it is a compound capable of forming ruthenium oxide, for example, may be a hydrate, hydroxide, halide or oxide of ruthenium, specifically 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 eye Odide (RuI 3 ) and may be at least one selected from the group consisting of ruthenium acetate salt. When using the ruthenium precursors listed above, the formation of ruthenium oxide may be easy.
[57]
[58]
The platinum group precursor may be used without particular limitation as long as it is a compound capable of forming a platinum group oxide, for example, may be a hydrate, hydroxide, halide or oxide of a platinum group element, specifically chloroplatinic 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 ) At least one platinum precursor selected from the group consisting of, or iridium chloride or iridium chloride hydrate (IrCl 3 ·xH 2O) may be an iridium precursor. When the above-listed platinum group precursors are used, the formation of the platinum group oxide may be facilitated.
[59]
[60]
The manganese precursor may be used without particular limitation as long as it is a compound capable of forming manganese oxide, for example, may be a hydrate, hydroxide, halide or oxide of manganese element, specifically manganese chloride or manganese chloride hydrate, manganese (II) ) nitrate hydrate, manganese(II) nitrate tetrahydrate, and manganese precursors such as manganese(II) nitrate. When the above-listed manganese precursors are used, the formation of manganese oxide may be facilitated.
[61]
[62]
The coating composition may further include a cerium precursor for forming cerium oxide in the coating layer. The cerium precursor may be used without particular limitation as long as it is a compound capable of forming cerium oxide, for example, may be a hydrate, hydroxide, halide or oxide of cerium element, specifically 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) It may be one or more selected cerium precursors. When using the cerium precursors listed above, the formation of cerium oxide can be facilitated.
[63]
[64]
In the method of manufacturing an electrode for electrolysis of the present invention, the coating composition may further include an amine-based additive for imparting strong adhesion between the coating layer and the metal substrate. In particular, the amine-based additive improves the bonding force between the ruthenium element, the platinum group element, and the manganese element included in the coating layer, and adjusts the oxidation state of the particles containing the ruthenium element, so that the electrode can be manufactured in a form more suitable for reaction.
[65]
The amine-based additive used in the present invention is particularly suitable for use in forming a coating layer because of its high solubility in water while having an amine group. Amine-based additives that can be used in the present invention include melamine, ammonia, urea, 1-propylamine, 1-butylamine, 1-pentylamine, 1-heptylamine, 1-octylamine, 1-nonylamine, 1-dode and silamine, and at least one selected from the group consisting of these may be used.
[66]
In the electrolysis electrode of the present invention, the ruthenium element and the amine-based additive in the coating layer may be included in a molar ratio of 100:10 to 100:50, preferably 100:25 to 100:35. When the amount of the amine-based additive is less than this, the effect of improving the bonding strength by the additive is insignificant, and when the amount of the amine-based additive is included in more than this amount, precipitates are likely to occur in the coating solution, thereby reducing the uniformity of the coating and may interfere with the function of ruthenium oxide.
[67]
[68]
In the method of manufacturing an electrode for electrolysis of the present invention, an alcohol-based solvent may be used as a solvent for the coating composition. When an alcohol-based solvent is used, it is easy to dissolve the components described above, and it is possible to maintain the bonding strength of each component even at a stage in which the coating layer is formed after application of the coating composition. Preferably, at least one of isopropyl alcohol and butoxyethanol may be used as the solvent, and more preferably a mixture of isopropyl alcohol and butoxyethanol may be used. When isoprepol alcohol and butoxyethanol are mixed and used, a uniform coating can be performed compared to using alone.
[69]
[70]
In the manufacturing method of the present invention, it may include a step of pre-treating the metal substrate before performing the coating step.
[71]
The pretreatment may be to form irregularities on the surface of the metal substrate by chemical etching, blasting, or thermal spraying of the metal substrate.
[72]
The pretreatment may be performed by sandblasting the surface of the metal substrate to form fine irregularities, and treating with salt or acid. 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 pre-treat to form detailed irregularities on the surface of the metal substrate.
[73]
[74]
The application is not particularly limited as long as the catalyst composition can be evenly applied on the metal substrate and may be performed by a method known in the art.
[75]
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.
[76]
[77]
The drying may 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.
[78]
When the above conditions are satisfied, the solvent can be sufficiently removed and energy consumption can be minimized.
[79]
[80]
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.
[81]
When the above-described conditions are satisfied, impurities in the catalyst layer may be easily removed and the strength of the metal substrate may not be affected.
[82]
[83]
Meanwhile, the coating may be performed by sequentially repeating application, drying, and heat treatment so that 10 g or more of ruthenium oxide per unit area (m 2 ) of the metal substrate becomes. That is, in the manufacturing method according to another embodiment of the present invention, after coating, drying and heat treatment of the catalyst composition on at least one surface of the metal substrate, the catalyst composition is applied again on one surface of the metal substrate to which the first catalyst composition is applied. Coating with application, drying and heat treatment can be repeatedly performed.
[84]
[85]
Hereinafter, examples and experimental examples will be described in more detail to describe the present invention in detail, but the present invention is not limited by these examples and experimental examples. Embodiments according to the present invention may be modified in various other 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 completely explain the present invention to those of ordinary skill in the art.
[86]
[87]
material
[88]
In this embodiment, a nickel mesh substrate (Ni purity 99% or more, 200 μm) manufactured by Ildong Gold Mesh was used as a metal substrate, and as a ruthenium precursor, ruthenium (III) chloride hydrate (RuCl 3 ·nH 2 O), platinum group Platinum (IV) chloride as a precursor, cerium (III) nitrate hexahydrate (Ce(NO 3 ) 3 .6H 2 O) as a cerium precursor, and manganese(II) chloride tetrahydrate (MnCl 2 .4H ) as a manganese precursor 2 O) was used. Urea was used as an amine-based additive.
[89]
In addition, a mixture of 2.375 ml of isopropyl alcohol and 2.375 ml of 2-butoxyethanol was used as a solvent for the coating composition.
[90]
[91]
Pretreatment of metal substrates
[92]
Before forming the coating layer on the metal substrate, the surface of the substrate was sandblasted with aluminum oxide (White alumina, F120) at 0.4 MPa, and then placed in 5M H 2 SO 4 aqueous solution heated to 80° C. and treated for 3 minutes. After washing with distilled water, the pretreatment was completed.
[93]
[94]
Example 1
[95]
In the mixed solvent of the above materials, 2.41 mmol of ruthenium (III) chloride hydrate, 0.1928 mmol of platinum (IV) chloride, and 0.482 mmol of manganese (II) chloride tetrahydrate were sufficiently dissolved for 1 hour, and 0.045 g of urea was added and mixed. to prepare a coating composition. The coating composition was coated on the previously pretreated metal substrate using a brush, put in a convection drying oven, and dried at 180° C. for 10 minutes. After that, it was put in an electric heating furnace at 500 ° C and heat-treated for another 10 minutes, and after repeating these coating, drying and heat treatment processes 9 more times, final heat treatment was performed at 500 ° C. for 1 hour to prepare an electrode for electrolysis. .
[96]
[97]
Example 2
[98]
Electrolysis electrode was prepared in the same manner except that 0.241 mmol of cerium (III) nitrate hexahydrate was further added to the coating composition in Example 1, and 0.241 mmol of manganese (II) chloride tetrahydrate was added. prepared.
[99]
[100]
Comparative Example 1
[101]
An electrode for electrolysis was prepared in the same manner as in Example 1, except that platinum (IV) chloride was not added to the coating composition.
[102]
[103]
Comparative Example 2
[104]
An electrode for electrolysis was prepared in the same manner as in Example 2, except that platinum (IV) chloride was not added to the coating composition.
[105]
[106]
Comparative Example 3
[107]
An electrode for electrolysis was prepared in the same manner as in Example 2, except that 0.482 mmol of cerium (III) nitrate hexahydrate was added without adding manganese (II) chloride tetrahydrate.
[108]
[109]
Comparative Example 4
[110]
An electrode for electrolysis was prepared in the same manner as in Comparative Example 1, except that platinum (IV) chloride was not added to the coating composition.
[111]
[112]
The molar ratios between each precursor in the coating compositions used in Examples 1 to 2 and Comparative Examples 1 to 4 are summarized in Table 1 below.
[113]
[114]
[Table 1]
Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4
ruthenium 2.41 2.41 2.41 2.41 2.41 2.41
manganese 0.482 0.241 0.482 0.241 - -
platinum 0.1928 0.1928 - - 0.1928 -
cerium - 0.241 - 0.241 0.482 0.482
[115]
[116]
Experimental Example 1. Confirmation of the performance of the prepared electrode for electrolysis
[117]
In order to confirm the performance of the electrodes prepared in Examples 1 to 2 and Comparative Examples 1 to 4, a cathode voltage measurement experiment using a half cell in chlor-alkali electrolysis was performed. A 32% NaOH aqueous solution was used as the electrolyte, a Pt wire was used for the counter electrode, and a Hg/HgO electrode was used for the reference electrode. After the prepared electrode was immersed in the electrolyte and activated for 1 hour under a constant current density condition of -0.62A/cm 2 , the performance of each electrode was compared with the potential value at the first hour. The results are summarized in Table 2 below.
[118]
[Table 2]
division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4
Cathode potential (unit: V) -1.072 -1.077 -1.079 -1.088 -1.092 -1.104
[119]
From the above results, it was confirmed that when manganese oxide was further included in the coating layer, the effect of improving the overvoltage appeared.
[120]
[121]
Experimental Example 2. Mass analysis of the coating layer of the electrode
[122]
The weight ratio (%) of each metal component of the electrode surface coating layer prepared in Examples and Comparative Examples was analyzed through XRF. The results are shown in Table 3 below.
[123]
[Table 3]
division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4
Ru 5.76 5.49 5.65 5.78 5.49 5.63
Mn 1.29 0.72 1.32 1.64 - -
Pt 3.22 3.26 - - 3.17 -
Ce - 2.35 - 2.67 4.44 4.36
[124]
From the results of Table 3, it was confirmed that even if manganese oxide was included in the coating layer, oxide could be formed without affecting the composition ratio of other metal components.

WE CLAIMS

metal base layer; and a coating layer comprising a ruthenium oxide, a platinum group oxide, and a manganese oxide, wherein the coating layer is formed on at least one surface of the base layer.
[Claim 2]
The electrode for electrolysis according to claim 1, wherein the weight ratio of the element ruthenium and the element manganese included in the coating layer is 100:5 to 100:30.
[Claim 3]
The electrode for electrolysis according to claim 1, wherein the weight ratio of the ruthenium element and the platinum group element included in the coating layer is 100:40 to 100:70.
[Claim 4]
The electrode for electrolysis according to claim 1, wherein the coating layer further comprises cerium oxide.
[Claim 5]
The electrode for electrolysis according to claim 4, wherein the weight ratio of the ruthenium element and the cerium element included in the coating layer is 100:40 to 100:90.
[Claim 6]
applying a coating composition on at least one surface of a metal substrate; and drying and heat treating the metal substrate to which the coating composition is applied, and coating the coating composition, wherein the coating composition comprises a ruthenium precursor, a platinum group precursor, and a manganese precursor.
[Claim 7]
The method of claim 6, wherein the coating composition further comprises a cerium precursor.
[Claim 8]
According to claim 6, wherein the ruthenium precursor 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 ), and a method of manufacturing an electrode for electrolysis that is at least one selected from the group consisting of ruthenium acetate salt.
[Claim 9]
7. The method of claim 6, wherein the manganese precursor is at least one selected from the group consisting of manganese chloride, manganese chloride hydrate, manganese(II) nitrate hydrate, manganese(II) nitrate tetrahydrate, and manganese(II) nitrate. A method of manufacturing an electrode for phosphorus electrolysis.
[Claim 10]
7. The method of claim 6, wherein the platinum group precursor is chloroplatinic 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 ) for electrolysis that is at least one selected from the group consisting of A method for manufacturing an electrode.
[Claim 11]
8. The method of claim 7, wherein the cerium precursor is 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).
[Claim 12]
7. The method of claim 6, wherein the coating composition is melamine, ammonia, urea, 1-propylamine, 1-butylamine, 1-pentylamine, 1-heptylamine, 1-octylamine, 1-nonylamine and 1-dodecyl. A method of manufacturing an electrode for electrolysis further comprising at least one amine-based additive selected from the group consisting of amines.
[Claim 13]
The electrode for electrolysis of claim 12, wherein the ruthenium element and the amine-based additive of the ruthenium precursor included in the coating composition are included in a molar ratio of 100:10 to 100:50.