KR20210064729A - Ruthenium-tin based catalytic electrode for electrolysis of ballast water and preparation method thereof - Google Patents

Abstract

The present invention relates to a ruthenium-tin-based catalyst electrode having stable efficiency for ballast water electrolysis and a manufacturing method thereof. Specifically, the present invention provides a ruthenium-tin-based catalyst electrode for ballast water electrolysis, including a titanium electrode and a catalyst layer formed on the titanium electrode and including ruthenium, tin and palladium.

Description

RUTHENIUM-TIN BASED CATALYTIC ELECTRODE FOR ELECTROLYSIS OF BALLAST WATER AND PREPARATION METHOD THEREOF

The present invention relates to a ruthenium-tin-based catalyst electrode having stable efficiency for ballast water electrolysis and a method for manufacturing the same.

Ballast water refers to seawater or fresh water stored in a tank in a ship to balance the ship by lowering the center of gravity. Ballast water is filled in one port through ballasting work, transferred to another port, and discharged into the new port through deballasting work. In particular, the amount of seawater used as ballast water for international sailing ships moving around the world amounts to about 10 billion tons per year, and as about 7,000 types of marine life included in seawater move together, there is a problem of ecosystem disturbance. .

Accordingly, there is a movement to protect the marine environment. For example, the International Maritime Organization (IMO) made the Ballast Water Management Convention in 2004 to prevent disturbance of the marine ecosystem due to the discharge of ballast water, and Environmental regulations that mandate the installation of water treatment systems have been announced.

In order to solve the above-mentioned ecological disturbance problem, ballast water must be treated to kill marine organisms. Examples of such ballast water treatment include ozone sterilization treatment, disinfection treatment using hydrogen peroxide, treatment using an electrolysis method, and the like.

Among them, the ozone sterilization method has a problem in operating for a long time because the sterilization efficiency is low in turbid water and the life of the UV lamp required for ozone generation is short. Disinfection treatment using hydrogen peroxide has the advantage of strong sterilization power and low cost, but there is a possibility of residual hydrogen peroxide being discharged, which makes practical use difficult.

On the other hand, the ballast water electrolysis treatment technology is a technology necessary for sterilizing marine organisms by applying a constant current to the electrolysis tank when injecting or discharging ballast water to generate a total residual oxidant from seawater, It has the advantage of being able to control the concentration of residual oxidizing agent required for sterilization in real time.

However, since it is manufactured using precious metals (Ruthenium, Palladium, Iridium, etc.) as a material for a catalyst electrode used in seawater electrolysis, it is difficult to use in large quantities due to problems such as high price and scarcity. For this reason, it is necessary to develop a high-efficiency noble metal reduction catalyst.

In particular, in the case of a metal oxide catalyst electrode used in a conventional seawater electrolysis tank, ruthenium oxide (RuOx) and palladium oxide (PdOx) are used as main catalysts, so a catalyst electrode with 100% noble metal content must be used in the continuous electrolysis reaction. By stabilizing the redox reaction between the electrodes, the efficiency can be increased and the long operating life can be maintained. For this reason, research on mixed catalysts with non-noble metals is insufficient.

In particular, the precious metal used in the method is expensive because it is a rare metal, and palladium is one of the precious metals that is expensive enough to be priced similar to or higher than the price of gold.

Therefore, in order to develop an electrolysis tank for ballast water that is inexpensive and has a long lifespan, it is required to develop a catalyst electrode in which noble metals (Ru, Pd), which are main catalysts of the catalyst electrode, are reduced.

As a prior document related to the catalytic electrode of an electrolysis tank, Korean Patent Application Laid-Open No. 2004-0002809 discloses a one-component or two-component complex or multi-component compound composed of an alkoxide such as Ti and Zr and a chloride such as Ru and Ir is diluted with alcohol. After the hydrolysis reaction and polycondensation reaction, a coating solution is prepared, and a method of manufacturing an electrode for electrolysis pretreated with the coating solution is disclosed.

In addition, Korean Patent No. 10-0553364 discloses a metal mixed oxide electrode and a method for manufacturing the same, comprising: an electrode substrate; Iridium (Ir) compound Ruthenium (Ru) compound Tin (Sn) compound and manganese (Mn) compound Titanium (Ti) compound Molybdenum (Mo) compound Tantalum (Ta) compound At least one selected from zirconium (Zr) compound in an organic solvent Disclosed is an electrode comprising a coating layer formed by applying and drying a mixed coating solution to the electrode substrate, performing a first heat treatment process 4 to 15 times, and then performing a second heat treatment.

The present invention uses tin (Sn), a non-noble metal, as a mixed catalyst material, thereby reducing the content of expensive noble metals ruthenium (Ru) and palladium (Pd) and securing electrolysis performance for ballast water ruthenium- An object of the present invention is to provide a tin-based catalyst electrode and a method for manufacturing the same.

To this end, an object of the present invention is to provide a method capable of manufacturing a three-phase stable catalyst electrode by adding a small amount of palladium oxide rather than a mixed electrode of ruthenium and tin.

The above object is achieved by a ruthenium-tin-based catalyst electrode for ballast water electrolysis, comprising a titanium electrode and a catalyst layer comprising ruthenium, tin and palladium formed thereon.

Preferably, the ruthenium, tin and palladium may be included in an atomic ratio of 1:1 to 2:0.1 to 0.5.

Also preferably, the titanium electrode may be of a general plate material, a regular perforated network, a perforated perforated network, an expanded wire mesh type or a mesh type.

In addition, the above control comprises the steps of preparing a first coating solution in which a ruthenium compound and a tin compound and an organic solvent are mixed; preparing a second coating solution in which a palladium compound and an organic solvent are mixed; forming a catalyst layer by applying a mixed solution of the first coating solution, the second coating solution, and the binder solution on the surface of the titanium electrode and then heat-treating it at 400° C. to 500° C.; And it is achieved by the method for producing a ruthenium-tin-based catalyst electrode for ballast water electrolysis comprising the step of further sintering the electrode formed with the catalyst layer at 600 ℃ to 700 ℃.

Preferably, the step of forming the catalyst layer may be performed 4 to 6 times.

Also preferably, the organic solvent is selected from the group consisting of a lower alcohol having 1 to 4 carbon atoms, hydrochloric acid and butylcarbitol, and the binder solution is titanium methoxide, titanium ethoxide, titanium isopropoxide and titanium butoxide. It may be selected from the group consisting of.

According to the method of the present invention, by developing a catalyst electrode with an increased content of inexpensive non-noble metals (Sn) instead of expensive noble metals (Ru, Pd), the price problem that has been pointed out as a problem of insoluble electrodes for electrolysis is also provided a clue to solve at the same time. It is expected to contribute to the catalyst industry for seawater electrolysis.

1 is a diagram illustrating a cross-section of a catalyst electrode manufactured by a method according to the present invention.
Figure 2 is a schematic diagram showing the reaction occurring at the cathode (Cathode) and the anode (Anode) during the seawater electrolysis operation of the present invention.
3 is an SEM image and elemental analysis data of the electrode prepared in Example 1.
4 is an SEM image and elemental analysis data of the electrode prepared in Example 2.
5 is an SEM image and elemental analysis data of the conventional electrode prepared in Comparative Example 1.
^{6 is a continuous seawater electrolysis experiment (current density, 0.05A/cm 2} ) conducted 3 times for 10 hours by applying the catalyst electrode of Examples 1, 2, and Comparative Example 1 as the anode of the electrolysis tank. It is a graph showing the voltage change in

All technical terms used in the present invention, unless otherwise defined, have the following definitions and have the meanings as commonly understood by one of ordinary skill in the art of the present invention. In addition, although preferred methods and samples are described herein, similar or equivalent ones are also included in the scope of the present invention.

The term "about" refers to 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, means an amount, level, value, number, frequency, percentage, dimension, size, amount, weight or length varying by 4, 3, 2 or 1%.

Throughout this specification, unless the context requires otherwise, the terms "comprises" and "comprising" include the steps or elements presented, or groups of steps or elements, but any other step or element, or It is to be understood that a step or group of elements is not excluded.

The present invention relates to a ruthenium-tin-based catalyst electrode for ballast water electrolysis and a method for manufacturing the catalyst electrode.

A ruthenium-tin-based catalyst electrode for ballast water electrolysis according to the present invention includes a titanium electrode and a catalyst layer comprising ruthenium, tin and palladium formed thereon.

1 is a cross-sectional view of a catalyst electrode on which a catalyst layer (Mixed metal oxide (MOx)) of the present invention is formed. Referring to FIG. 1 , a catalyst layer (Mixed metal oxide (MOx)) is formed on the surface of a titanium electrode (Ti). The catalyst layer preferably contains ruthenium, tin and palladium in an atomic ratio of 1:1 to 2:0.1 to 0.5.

The titanium electrode used for the catalyst electrode may include a titanium metal or a titanium alloy having a purity of 100%. The titanium electrode may be of a general plate material, a regular perforated network, a perforated net, an expanded wire mesh or a mesh type. In addition, the titanium electrode may be an electrode having a rough surface treated with sand blast or the like in order to increase the reaction area during the electrolysis reaction.

According to one embodiment of the present invention, there is provided a method for producing a stable mixed catalyst electrode in seawater electrolysis containing tin, which is a non-noble metal, by reducing the contents of ruthenium and palladium, which are noble metals.

The method comprises the steps of preparing a first coating solution in which a ruthenium compound, a tin compound, and an organic solvent are mixed; preparing a second coating solution in which a palladium compound and an organic solvent are mixed; forming a catalyst layer by applying a mixed solution in which the first coating solution and the second coating solution are mixed on the surface of the titanium electrode and then heat-treating it at 400° C. to 500° C. (3 minutes to 5 minutes); and further sintering the electrode on which the catalyst layer is formed at 600° C. to 700° C. (1 hour).

In the above, the step of forming the catalyst layer is preferably performed 4 to 6 times.

The organic solvent may be selected from the group consisting of lower alcohols having 1 to 4 carbon atoms (eg, methanol, ethanol, propanol and butanol), hydrochloric acid and butylcarbitol.

The binder solution may use titanium alkoxide, preferably titanium methoxide, titanium ethoxide, titanium isopropoxide, and titanium butoxide.

In the present invention, ballast water is water stored inside to balance the ship, and may be seawater or freshwater, and more preferably seawater.

When the ballast water is seawater, the reaction that occurs during electrolysis of seawater can be explained by the following equation.

[Scheme 1]

Anode(+pole) :

2OH ^- → H ₂ O + 1/2O ₂ ↑ + 2e ^-

NaCl → Na ⁺ + Cl ^-

2Cl ^- → Cl ₂ ↑ + 2e ^- (main reaction)

Cl ₂ + H ₂ O → HClO (hypochlorous acid) + H ⁺ + Cl ^- (side reaction)

[Scheme 2]

Cathode (-pole):

2H ₂ O +2e ^- → H ₂ ↑ + 2OH ^- (main reaction)

Na ⁺ + OH ^- → NaOH (side reaction)

Mg ⁺² + Ca ⁺² + 4OH ^- → Mg(OH) ₂ + Ca(OH) ₂ (Side reaction)

Total reaction : Cl ₂ + 2NaOH → 2NaOCl + H ₂ ↑2H ₂ O +2e ^- → H ² ↑ + 2OH ^-

A schematic diagram related to the reaction is shown in FIG. 2, and as in Scheme 1, if the catalyst layer is not densely formed due _{to the generation of Cl 2} gas and O _{2 gas generated in the anode reaction during seawater electrolysis, the catalyst layer} Cracks or fragments may occur. In addition, in order for the reaction to proceed well, the reduction in seawater electrolysis efficiency can be prevented only when the conductivity of the catalyst to receive and reduce electrons is high.

According to one embodiment of the present invention, the noble metal reduction catalyst electrode of the present invention uses tin oxide (SnOx) having high catalytic efficiency among non-noble metal catalysts.

Preferably, ruthenium oxide and tin oxide may be mixed in an atomic ratio of 1:1 or 1:2. Also preferably, the method for preparing the mixed catalyst may include a small amount of palladium oxide. According to one embodiment, the catalyst layer preferably includes ruthenium, tin and palladium in an atomic ratio of 1:1 to 2:0.1 to 0.5.

When the catalyst electrode manufactured according to the method of the present invention is used in a ballast water electrolysis facility, the _{reduction in the reduction reaction efficiency of receiving electrons to reduce Cl 2} or O ₂ is prevented, so that continuous electrolysis in which ballast water is introduced or discharged is prevented. Even in the reaction, it can be used for a long time without reduction in energy efficiency and TRO generation efficiency.

Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited by these Examples.

Example 1 - Ru:Sn:Pd (atomic ratio 1:1:0.25) catalyst electrode

First, solution 1 was prepared by adding 1 g _{of RuCl 2} and 0.92 g of SnCl ₂ to 10 mL of butanol, _{and solution 2 was prepared by dissolving 1.2 g of PdCl 2 in} 5 mL of HCl (6N). As a final coating solution, 0.14 mL of solution 1 in 3 mL of butanol, 0.6 mL of titanium isopropoxide as a binder solution, 0.015 g of carbon, 6.4 mL of solution 2 and 3 mL of butyl carbitol were mixed, followed by ultrasonic bathing for 2 hours to coat the catalyst electrode. A solution was prepared.

The catalyst electrode coating solution was coated on the titanium electrode using gun spray at a rate of 1 mL/min, dried, and then heat-treated at 450° C. for 3 minutes. After this process was performed 5 times, a catalyst electrode was prepared by heat treatment at 650° C. for 1 hour.

The surface of the prepared catalyst electrode is shown in FIG. 3 . In addition, the prepared catalyst electrode was used as an anode in the electrolysis tank, and a titanium electrode of the same material was applied to the cathode without pretreatment, and a continuous seawater electrolysis experiment (current density, 0.05A) for 10 hours /cm ² ) was performed three times to show the voltage change during seawater electrolysis in FIG. 6 .

Example 2 - Ru:Sn:Pd (atomic ratio 1:2:0.25) catalyst electrode

_{First, 1 g of RuCl 2} and 1.84 g of SnCl ₂ were added to 10 mL of butanol to prepare solution 1, and _{1.2 g of PdCl 2} was dissolved in 5 mL of HCl (6N) to prepare solution 2. As the final coating solution, 0.14 mL of solution 1, 0.6 mL of titanium isopropoxide, 0.015 g of carbon, 6.4 mL of solution 2, and 3 mL of butyl carbitol were mixed in 3 mL of butanol, followed by ultrasonic bathing for 2 hours to prepare a catalyst electrode coating solution. .

The catalyst electrode coating solution was coated on a titanium electrode at a rate of 1 mL/min using a gun spray, dried and then heat-treated at 450° C. for 3 minutes. This process was performed 5 times and then at 650° C. for 1 hour. A catalyst electrode was prepared by heat treatment.

The surface of the catalyst electrode prepared above is shown in FIG. 4 . In addition, the prepared catalyst electrode was used as an anode, and a titanium electrode of the same material was applied to the cathode without pretreatment, and a continuous seawater electrolysis experiment for 10 hours (current density, 0.05A/cm ² ) The voltage change during seawater electrolysis by performing 3 times is shown in FIG. 6 .

Comparative Example 1 - Ru:Pd (atomic ratio 1:1) catalyst electrode

First, solution 1 was prepared by adding 1 g _{of RuCl 2} to 10 mL of butanol _{, and 5 g of PdCl 2} was dissolved in 5 mL of HCl (6N) to prepare solution 2. As a final coating solution, a catalyst electrode coating solution was prepared by mixing 0.14 mL of solution 1 in 3 mL of butanol, 0.6 mL of titanium isopropoxide, 0.015 g of carbon, and 6.4 mL of solution 1 and 3 mL of butyl carbitol, followed by ultrasonic bathing for 2 hours.

The catalyst electrode coating solution was coated on a titanium electrode at a rate of 1 mL/min using a gun spray, dried and then heat-treated at 450° C. for 3 minutes. After performing this process 5 times, heat treatment at 650° C. for 1 hour Thus, a catalyst electrode was prepared.

The surface of the prepared catalyst electrode is shown in FIG. 5 . In addition, the prepared catalyst electrode was used as an anode in the electrolysis tank, and a titanium electrode of the same material was applied to the cathode without pretreatment, and a continuous seawater electrolysis experiment (current density, 0.05A) for 10 hours /cm ² ) was performed three times to show the voltage change during seawater electrolysis in FIG. 6 .

Referring to FIG. 3 , the catalyst electrode prepared in Example 1 was a catalyst electrode having a ratio of Ru:Sn:Pd (atomic ratio 1:1:0.25) and a noble metal content of about 55%, and the surface gap was prepared in Comparative Example 1 It can be seen that the catalyst layer was formed with a high density because the gap gap was smaller than that of FIG.

4 is a catalyst electrode having a ratio of Ru:Sn:Pd (atomic ratio 1:2:0.25) and a noble metal content of 38% prepared in Example 2, and since it shows a surface shape similar to that of the catalyst electrode of FIG. 3, the density of the catalyst layer It can be seen that it was formed with

In the case of FIG. 5, it can be seen that the catalyst was prepared according to the method of Comparative Example 1, which is a conventional method for preparing a catalyst electrode, and only a ratio of Ru:Pd (atomic ratio 1:1) and 100% of noble metal was used as a catalyst.

6 is a voltage when a ^{continuous seawater electrolysis experiment (current density, 0.05A/cm 2} ) is performed three times for 10 hours each using the catalyst electrode of Examples 1, 2, and Comparative Example 1 as an anode; This is a graph showing the change. The conventional catalyst electrode (Comparative Example 1) seemed to decrease up to 20 hours (72,000 s) as the seawater electrolysis experiment proceeded, but electrolysis due to initial resistance upon restarting after 10 hours (36,000 s, 72,000 s) electrolysis experiment The voltage rises and then falls. However, in the case of Example 1, an overvoltage occurs during the initial electrolysis, but after the first (36,000s) and the second (72,000s) restart, the mixed catalyst electrode is activated, so that overvoltage does not occur and a stable seawater electrolysis voltage state is shown gave.

As described above in detail a specific part of the present invention, for those of ordinary skill in the art, these specific descriptions are only preferred embodiments, and it is clear that the scope of the present invention is not limited thereto. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (7)

A ruthenium-tin-based catalyst electrode for ballast water electrolysis, comprising a titanium electrode, and a catalyst layer comprising ruthenium, tin and palladium formed thereon. The ruthenium-tin-based catalyst electrode for ballast water electrolysis according to claim 1, wherein the ruthenium, tin and palladium are included in an atomic ratio of 1:1 to 2:0.1 to 0.5. The ruthenium-tin-based catalyst electrode for ballast water electrolysis according to claim 1, wherein the titanium electrode is a general plate material, a regular perforated network, a perforated net, an expanded wire mesh or a mesh type. preparing a first coating solution in which a ruthenium compound and a tin compound are mixed with an organic solvent;
preparing a second coating solution in which a palladium compound and an organic solvent are mixed;
forming a catalyst layer by applying a mixed solution of the first coating solution, the second coating solution, and the binder solution on the surface of the titanium electrode and then heat-treating it at 400° C. to 500° C.; and
A method for producing a ruthenium-tin-based catalyst electrode for ballast water electrolysis, comprising further sintering the electrode on which the catalyst layer is formed at 600° C. to 700° C. [Claim 5] The method of claim 4, wherein the step of forming the catalyst layer is performed 4 to 6 times, ruthenium-tin-based catalyst electrode for ballast water electrolysis. [Claim 5] The method of claim 4, wherein the organic solvent is selected from the group consisting of lower alcohols having 1-4 carbon atoms, hydrochloric acid and butylcarbitol. The method of claim 4, wherein the binder solution is selected from the group consisting of titanium methoxide, titanium ethoxide, titanium isopropoxide and titanium butoxide. .

Images