KR100893621B1 - Method for manufacturing membrane electrode assemblies for an electrolytic ozone generator - Google Patents

Abstract

The present invention provides an electrochemical ozone generating membrane electrode assembly and a method of manufacturing the same, including the tantalum electrode catalyst layer on one side of the ion exchange membrane forming the electrochemical cell membrane electrode assembly for ozone generation. It is related with a chemical cell, Comprising: A positive electrode catalyst layer consists of a tantalum platinum electrode catalyst layer. According to the present invention, by using tantalum as the anode electrode catalyst, the overvoltage at the anode can be reduced to drastically reduce the operating cost during electrolysis, and the reaction efficiency can be stabilized to improve durability.

Description

Method for manufacturing membrane electrode assemblies for an electrolytic ozone generator

The present invention relates to an electrochemical cell for producing ozone, and in particular, electrochemical ozone generation configured to have a tantalum electrode catalyst layer on one side of an ion exchange membrane constituting a membrane electrode assembly for an electrochemical cell for ozone generation. It relates to a membrane electrode assembly and a method of manufacturing the same. The present invention also relates to an electrochemical cell having the membrane electrode assembly for electrochemical ozone generation as described above. That is, the present invention relates to Korean Patent Application Nos. 2005-0016642 (Method for producing membrane electrode assembly having porous electrode catalyst layer), 2005-0016639 (Method for producing membrane electrode assembly) and 2005- filed by the present inventors. As a result of the invention following 0016637 (Method for Manufacturing Membrane Electrode Assembly), the present invention relates to a membrane electrode assembly related technology suitable for an ozone generator.

Ozone is generally manufactured by a method such as a silent electric discharge process or a corona discharge, and the energy required is as follows.

The concentration of ozone produced by corona discharge is low at about 2% O ₃ (weight ratio), and nitrogen oxides such as NO _x , which are harmful to human body, are produced. On the other hand, another method of producing ozone by electrolysis may be prepared by applying a direct current to electrodes at both ends and passing an electrolyte between the electrodes. For example, when water is electrolyzed, it is decomposed into elemental components O ₂ and H ₂ , and under appropriate conditions, ozone (O ₃ ) is also produced.

The energy required for the production of O ₃ by electrolysis is as follows.

Comparing Scheme 1 and Scheme 2, it can be seen that ΔH_ ₂₉₈ of the electrolytic method is about 6 times larger than the silent discharge or corona discharge method. This means that the energy cost of the ozone production method by electrolysis is about 6 times greater.

In general, the electrochemical ozone generation method has a higher operating cost due to the higher electrical energy consumption than the discharge method, but a lot of research and product development has been made since it is possible to manufacture a very high concentration of ozone.

The production of ozone by electrochemical methods has a history of more than 100 years, and some literature reports that up to 35% can achieve electrochemical efficiency (current efficiency). Current efficiency is the ratio of the energy used to generate ozone to the electrical energy supplied to the electrolyte. For example, 35% current efficiency means that 35% of the ozone (O ₂ ) and ozone (O ₃ ) gas generated from the anode is 35% by the supplied electrical energy. However, in order to obtain such an electrochemical efficiency, it was possible to keep the operating temperature low at -30 ° C to -65 ° C. In order to maintain the low temperature, not only expensive refrigeration equipment but also a lot of energy was added to the operation.

An electrolytic cell is a device that generates chemical reactions by receiving electrical energy from the outside. The core of the chemical reactions in the electrolytic cell are oxidation reactions that give up electrons and reduction reactions that accept electrons. This reaction occurs at the interface between the electrode and the solution, and the electrode must be a good conductor of conductivity. In electrolyzer operation, the electrodes in the electrolyzer are connected by an external power source and a circuit, and electrons move between the positive electrode and the negative electrode through the external circuit. In order to form a complete electrical circuit for an electrolyzer, charge transfer paths must be internal. This means that at least one electrolyte must be present so that charge can be transferred by ion conduction, and the electrolyte must be low in conductivity to prevent short circuiting in the electrolytic cell. The simplest electrolyzer requires at least two electrodes and one or more electrolytes.

In order to cause an electrochemical reaction, electricity must be supplied to the electrodes (anode and cathode). The potential required for the electrolysis reaction is determined from about 2 to 3 volts DC (direct current), regardless of the shape and structure of the electrode, and the current is in the range of 0.1 A / cm ² to 1.5 A / cm ^{2 on the} basis of the current density.

An ozone generating cell is an apparatus that generates ozone including hydrogen and oxygen by electrochemically decomposing water. For example, a proton exchange membrane electrolysis cell serves to produce hydrogen gas, oxygen and ozone gas by electrochemically decomposing water.

1 is a conceptual diagram of a typical electrolysis cell that electrochemically decomposes water to produce hydrogen gas and oxygen and ozone gas. As shown in FIG. 1, water (H ₂ 0) is supplied to the anode 110 to supply oxygen gas (O ₂ ) and ozone gas (O ₃ ), electrons (e ⁻ ), and hydrogen ions (H ⁺ ) (protons). Decompose to At this time, a portion of the water (H ₂ 0) is discharged to the outside of the electrolysis cell 100 together with the oxygen gas (O ₂ ) and ozone gas (O ₃ ). The decomposed hydrogen ions (H ⁺ ) pass through the hydrogen ion exchange membrane 120 and move to the cathode 130 (hydrogen electrode), along the external circuit 140 connecting the anode 110 and the cathode 130. moving the electron (e ^-) is reacted with hydrogen gas (H _2). In addition, the water (H ₂ 0) passing through the hydrogen ion exchange membrane 120 in conjunction with the hydrogen gas (H ₂ ) and hydrogen ions (H ⁺ ) flows out of the electrolysis cell 100. In this case, the electrochemical reactions occurring in the anode 110 and the cathode 130, respectively, are represented by Equations 3, 4, and 5.

At room temperature, the ideal supply voltage for Scheme 4 would be 1.51V based on the hydrogen standard electrode, and the theoretical generation energy required for ozone generation corresponding to 1.51V would be 5.06 kWh / O ₃ kg. However, the actual ozone generating energy is about 10 times higher than the ion generating energy due to the overvoltage loss.

The energy produced for ozone production is calculated as:

Equation 1 is a formula for calculating the current efficiency η related to ozone generation, where F is Faraday's constant [C / mol], Q is the amount of ozone generated in liquid and gas phase [kg / h], and M is the molecular weight of ozone [g / mol], I is the current [A] supplied to the electrochemical reactor. In addition, the current efficiency related to oxygen generation is obtained when the right side molecule 6 of the equation is 4, M is the oxygen molecular weight [g / mol], and Q is the oxygen generation amount.

Equation 2 is an equation for calculating the ozone generating energy Ep (energy consumed to produce 1 kg of ozone), which is determined by the ozone concentrations in the gas and liquid phases and the voltage and current characteristics of the electrochemical reactor. Where I is the current [A] supplied to the electrolyzer and V is the voltage across both the anode and cathode of the electrochemical reactor [V], Q _g Is the ozone concentration in the gas phase [kg / L], v _g Is the gas volumetric flow rate [L / h], Q _aq Is the liquid ozone concentration [kg / L], v _aq Represents the flow rate of water [L / h].

In Equation 1 and Equation 2, the electrolytic cell voltage requires a voltage higher than the theoretical voltage 1.51V. In general, the difference between the actual voltage and the theoretical voltage is called an overvoltage, and the overvoltage is the sum of the overvoltages of each element generated in the ion exchange membrane, the anode, the cathode, and the electrolyte constituting the electrolysis cell.

Figure 2 is composed of an electric circuit by decomposing the electrolytic cell voltage into the electrolytic cell component voltage, the conventional electrolytic cell voltage for ozone generation, as shown in equation (3) of each of the elements generated in each of the positive electrode, the negative electrode, the ion exchange membrane and the electrolyte It is the sum of overvoltages.

Where I is the current [A] supplied to the electrolytic cell, and V is the voltage [V] across the positive and negative electrodes of the electrochemical reactor.

In FIG. 2 and Equation 3, R _a represents the overvoltage associated with the anode, and R _am represents the voltage drop between the anode and the cation exchange membrane, which is the distance between the anode and the cation membrane, and between the anode and the cation exchange membrane. It is affected by the gas bubbles present in it. R _m is the voltage drop of the cation exchange membrane, R _mb is the voltage drop between the cation exchange membrane and the cathode, which is influenced by the distance between the cation exchange membrane and the cathode, gas bubbles between the cation exchange membrane and the cathode. Receives. R _b represents the overvoltage associated with the cathode.

The ozone over-voltage element in case of Looking at the ratio of the voltage across the R _a is 35%, R _am is 25%, R _m is 10%, R _mb is 15%, R _b is 15%.

The ozone gas generator by electrolysis can be easily manufactured, but lowering the energy generated for ozone production is an important technology for industrialization, and it is important to increase the generation efficiency of ozone and lower the ozone generated energy.

Up to now, the development has been mainly focused on the development of electrode materials to reduce ozone generation efficiency and ozone generation energy. That is, there is a method of developing a catalyst with a high oxygen overvoltage or adding an additive for inhibiting an oxygen evolution reaction as a cocatalyst. For example, PbO ₂ , DSA, glassy carbon, boron-doped diamond, and Ti / IrO ₂ electrodes were explored.

These studies are to study the positive and negative electrodes, such as R _a (overvoltage component related to anode) and R _b (resistance component related to cathode), which account for 35% of total electricity consumption, to reduce the electrical energy required for ozone production. Only concentrated research has been conducted.

Therefore, the above research alone could not effectively reduce the electrical energy required for ozone generation.

The present invention has been made to solve the problems of the prior art as described above, in the method for producing ozone by electrolysis of water in order to lower the electrical energy required during ozone generation, the resistance between the positive electrode, positive electrode and cation exchange membrane, cation It is an object of the present invention to provide a membrane electrode assembly for electrochemical ozone generation, a method of manufacturing the same, and an electrochemical cell having the same, which reduces resistance between the exchange membrane and the cathode and resistance associated with the cathode.

According to one feature of the present invention for achieving the above object, in the electrochemical ozone generating membrane electrode assembly (Membrane Electrode Assembly) having a positive electrode and a negative electrode catalyst layer for forming electrodes on both surfaces of the electrolyte membrane, the anode electrode catalyst layer It is characterized by consisting of a tantalum platinum electrode catalyst layer.

According to another feature of the invention, in the method of manufacturing an electrochemical ozone generating membrane electrode assembly (Membrane Electrode Assembly) having a positive electrode and a negative electrode catalyst layer to form electrodes on both surfaces of the electrolyte membrane, the pretreatment step of cleaning the electrolyte membrane And impregnating the pretreated electrolyte membrane into a solution containing the electrode catalyst ions to immobilize the ions by penetrating into and into the surface of the electrolyte membrane, and reducing the electrode catalyst ions fixed on the electrolyte membrane with a catalyst using a reducing agent to form an electrode catalyst layer. It is characterized in that it comprises a step of adsorption reduction, the step of electroplating tantalum plating one side of the electrolyte membrane coated on both surfaces of the electrode catalyst layer, and the post-treatment step of washing the electrolyte membrane.

In the adsorption reduction step of the present invention, the electrode catalyst may be any one or a mixture of iridium, manganese, cobalt, nickel, palladium, chromium, platinum.

According to another feature of the present invention, an electrochemical ozone generating membrane electrode assembly (electrode) and a reactant and a product having a positive electrode and a negative electrode catalyst layer respectively forming electrodes on both surfaces of the electrolyte membrane, a form capable of supplying and discharging products In an electrochemical cell including a packing, a separator, and a frame arranged based on a membrane electrode assembly, the anode electrode catalyst layer is characterized by consisting of a tantalum platinum electrode catalyst layer.

As described in detail above, the present invention improves electrolysis efficiency by using a platinum tantalum catalyst in the electrode catalyst layer, which can drastically reduce operating costs (half the level of the conventional one) and stabilize the reaction efficiency to improve durability. It works.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of an electrochemical ozone generating membrane electrode assembly and a method for manufacturing the same and an electrochemical cell having the same according to the present invention will be described in detail.

Figure 3 is a block diagram showing the manufacturing process of the electrochemical ozone generating membrane electrode assembly according to an embodiment of the present invention. The manufacturing process of the membrane electrode assembly according to the present invention will be described with reference to FIG. 3.

The method for producing a membrane electrode assembly according to the present invention is classified into three steps by using an adsorption reduction method and an electroplating method. The first step is the pretreatment step of the ion exchange membrane, the second step is the adsorption reduction step of coating the platinum catalyst by the adsorption reduction method, the third step is to electroplating iridium on the membrane electrode assembly having the platinum catalyst prepared in the second step It consists of an electroplating step. The second step is composed of two steps 2-1 and 2-2 as follows. In step 2-1, the ion exchange membrane is impregnated in the solution containing the platinum electrocatalyst ions to remove ions of the platinum catalyst. Adsorption step of immobilization by penetrating into the surface and inside of the ion exchange membrane, and step 2-2 is a reduction step of reducing the metal ions fixed in the ion exchange membrane to the metal catalyst using a reducing agent.

As the ion exchange membrane suitable for the preparation of the membrane electrode assembly according to the present invention, the perfloonated sulfonic acid cation exchange membrane is most preferred.

The first step, the pretreatment step, is as follows.

First, the surface is roughened with sand blasting or sand paper to increase the reaction surface area of the ion exchange membrane. After roughening the surface of the ion exchange membrane as described above, the washing and washing steps are repeated to remove impurities and the like in the ion exchange membrane. In order to remove foreign substances on the surface of the ion exchange membrane, the cleaning method may be added to pure water or heated, or may use auxiliary equipment such as an ultrasonic cleaner, and the washing step may include heating in an acid solution such as hydrochloric acid or sulfuric acid. At this time, the most preferable acid is hydrochloric acid. The pretreatment step includes a process of roughening the surface of the ion exchange membrane, a process of washing with pure water, a process of heating in an acid, and the like, and these components are preferably subjected to at least one iteration process.

Adsorption step 2-1 is as follows.

The adsorption step of the catalyst ion is to impregnate the ion exchange membrane in a solution containing a metal compound having an electrochemical catalyst function at a predetermined temperature for a predetermined time to diffuse and penetrate into the ion exchange membrane capable of metal ion. This affects the physical properties of the ion exchange membrane.

At this time, as an applicable electrochemical catalyst, any one or one or more mixtures of iridium, manganese, cobalt, nickel, palladium, chromium, and platinum are known. Compound Pt (NH ₃ ) ₄ Cl ₂ , RuCl ₃ , IrCl ₃ , Mn (NO ₃ ) ₂ , Co (NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , SnCl ₃ , PdCl ₂ , CrCl _3, etc. It is desirable to. As an electrode catalyst, the platinum catalyst which can be applied simultaneously to an anode and a cathode is preferable.

The concentration of the platinum catalyst reagent is preferably from 0.01mmole to 5mmole. At this time, if the concentration is lower than 0.01mmole, the catalytic ion component is difficult to penetrate into the ion exchange membrane, and at 5mmole or more, an unreacted catalyst is present to waste expensive precious metals.

The suitable temperature in the metal ion adsorption step is 10 ~ 80 ℃, it is difficult to penetrate the catalyst ions in the ion exchange membrane below 10 ℃, it is difficult to operate due to severe deformation of the ion exchange membrane above 80 ℃, more preferred temperature is 40-60 degreeC.

Reduction step (platinum ion reduction process) of the 2-2 step is as follows.

The reduction process is a process of reducing the fixed metal catalyst ions by penetrating the ion exchange membrane to the metal catalyst using a reducing agent (for example, NaBH ₄ ) and a reducing accelerator (for example, NH ₄ OH, NaOH). At this time, a reducing agent having a reducing function and a reducing accelerator (alkali component) for promoting reduction are added to a constant temperature bath at a constant temperature, and the solution is stirred at a low speed. At this time, the preferred reduction temperature is 20 ~ 80 ℃, below 20 ℃, the reaction rate of the reducing agent and the elution function and the alkaline component to promote the reduction of the reduction efficiency is reduced, above 80 ℃ deformation of the ion exchange membrane like the adsorption step Severe difficulties in operation. More preferred reduction temperature is 40 ~ 70 ℃.

The third step, the electroplating step, is as follows.

In the electroplating step, the tantalum plating solution is placed between the membrane electrode assembly and the anode by using the platinum-coated membrane electrode assembly prepared in the second step, using the numerically stable electrode coated with tantalum oxide as the cathode as the anode. Electroplating tantalum to one side of a platinum catalyst coated membrane electrode assembly by applying electricity.The concentration of electrolyte, applied voltage, temperature, pH and regulator, current density, type of anode, size of anode and membrane electrode assembly. The performance of the membrane electrode assembly is determined by the ratio. At this time, the concentration of the preferred tantalum compound is 1gr / liter ~ 30gr / liter, less than 1gr / liter coating density of tantalum is lower, 30gr / liter or more loss of expensive tantalum chemicals. More preferred concentrations of tantalum are 10 gr / liter to 30 gr / liter.

The preferred applied voltage at the time of plating is 0.5Volt ~ 5Volt, when the applied voltage is 0.5Volt or less, the electroplating efficiency is drastically reduced, and at 5Volt or more side reactions other than the plating reaction occurs to reduce the efficiency. At this time, the preferred voltage range is 2 to 3 Volt. The temperature of the plating liquid is 25 ~ 80 ℃, the plating efficiency is reduced at 25 ℃ or less due to the activity of ions, and above 80 ℃ it is difficult to maintain the concentration of the plating liquid due to the evaporation of the plating liquid. At this time, preferable plating temperature is 40-60 degreeC.

The pH of the plating liquid should be kept acidic, preferably 1 to 2.5, and the pH adjusting agent is hydrochloric acid or sulfuric acid. If the pH is maintained at alkali, the tantalum compound of the plating liquid reacts with the alkali (OH) component to form a solid. The current density applied per electrode area during plating is 0.1 ~ 3.0A / dm ² , plating is difficult to occur under the current density condition of 0.1A / dm ² or less, and non-plating side reaction of tantalum at the current density of 3.0A / dm ² or more (eg For example, the decomposition reaction of water molecules occurs to decrease the efficiency. Preferred conditions for the current density are 0.3 to 1.5 A / dm ² .

As the anode used for electroplating, a dimensionally stable electrode (Dimensional Stable Anode) coated with a platinum group on titanium is used. Tantalum or tantalum oxide is preferable as a catalyst for the preferred anode. The size ratio of the positive electrode to the membrane electrode assembly is 0.5 to 1.5, and if it is larger than 1.5 (if the size of the anode is small), it is difficult to obtain uniform tantalum in the entire area of the membrane electrode assembly, and if it is smaller than 0.5 (the size of the anode is large) ) Tantalum is plated thickly at the end of the membrane electrode assembly. The preferred size ratio of the positive electrode to the membrane electrode assembly is one.

When the electroplating step is completed, a post-treatment step of washing and storing with water or hydrochloric acid is performed.

As described above, the present invention may repeat the second step, the adsorption reduction step, the third step, the electroplating step and the post-treatment step after the post-treatment step to increase the impregnation amount of the catalyst.

4 is a structural diagram of a unit electrochemical cell having a membrane electrode assembly prepared according to the present invention. As shown in FIG. 4, the unit electrochemical cell of the present invention is configured with a membrane electrode assembly configured to have a tantalum platinum electrode catalyst layer as the anode catalyst as described above. Here, the membrane electrode assembly 400 includes an ion exchange membrane 420, an anode 410 having an electrode catalyst layer composed of tantalum and platinum on one side of the ion exchange membrane 420, and a cathode 430 having a platinum catalyst layer on the other side. do. In this case, the anode chamber 41 and the cathode chamber 43 formed by the anode 410 and the cathode 430 are places having a product and a reactant and have a form facing each other.

The anode chamber 41 is formed to be cut off from the outside by the frame 411 and the separator 412, and has a cathode 410 and an anode chamber membrane electrode assembly support 413. At this time, a gasket (packing) 414 is installed between the frame 411 and the separator 412 to prevent external leakage of reactants and products in the anode chamber 41.

The cathode chamber 43 is formed to be cut off from the outside by the frame 431 and the separator 432, and the cathode 430, the cathode chamber membrane electrode assembly support 433, and the cathode chamber membrane electrode assembly support 433. ) And a pressure pad 434 positioned between the separator plate 432. Here, the pressure pad 434 is made of a material suitable for the environment of the electrochemical cell, and functions to adjust the pressure in the unit electrochemical cell to be uniform, and does not always have to be installed. In addition, a gasket (packing) 435 is installed between the frame 431 and the separator 432 to prevent external leakage of reactants and products in the cathode chamber 43.

Among the components constituting the unit electrochemical cell, the frames 411 and 431, the separator plates 412 and 432, and the gaskets 414 and 435 are suitable holes to facilitate the inflow and outflow of reactants or products through the unit electrochemical cell. Has

Hereinafter, an example in which the performance of the membrane electrode assembly manufactured by the method of the related art and the membrane electrode assembly manufactured by the method according to an embodiment of the present invention will be described. However, the scope of the present invention is not limited to this example.

Invention Example Tantalum Platinum Anode Catalyst Layer (Ta-Pt) / Cathode Catalyst Layer (Pt)

1. Manufacturing Process of Membrane Electrode Assembly

First step (pretreatment step)

The ion exchange membrane is a perfluorosulfonic cation exchange membrane, using Nafion from DuPont, and roughly treated on both sides with sandpaper (Norton 600A), soaked in ultrapure water for about 1 hour, and cut out to a certain size. It was used. In order to remove organic matter present in the ion exchange membrane cut to a predetermined size, the ion exchange membrane is heated in an aqueous solution of H ₂ O ₂ (3%) for about 40 minutes and then washed with pure water. In addition, the ion exchange membrane was heated in a 1M H ₂ SO ₄ solution for about 30 minutes, washed with pure water, and then heated in ultrapure water for about 1 hour.

Second step (sorption reduction step)

Step 2-1 (Sorption Step)

Methanol containing 0.5 mM pt (NH ₃ ) ₄ Cl ₂ (tetra-amine platinum chloride hydrate, 98%) and water were mixed at a volume ratio of 1: 3 to form a mixed solution, and then mixed into the mixed solution. The ion exchange membrane cleaned in the pretreatment step is introduced for about 40 minutes to allow the platinum ions to diffuse and adsorb into the ion exchange membrane.

Step 2-2 (Reduction Stage)

NaBH ₄ is mixed with a solution of pH 13 preheated to 50 ° C. to form a 1 mM reducing solution. An ion exchange membrane is added to the reducing solution to remove the platinum solution adsorbed in the adsorption step. Perform for hours.

3rd stage (electroplating stage)

A plating bath 500 for coating tantalum is configured as shown in FIG. 5. 5 is a structural diagram of a plating bath for electroplating tantalum for implementing the membrane electrode assembly according to the present invention. As shown in FIG. 5, the plating bath 500 is designed to plate only one side of the membrane electrode assembly 540 having the platinum catalyst prepared through the first to third steps. The plating bath 500 includes a storage tank 522 for storing a solution and a lower end 524 for fixing the membrane electrode assembly. The membrane electrode assembly 540 having a platinum catalyst is used as the cathode, and only one surface thereof is exposed. As the anode 530, a numerically stable electrode coated with tantalum oxide on titanium is used. A positive lead 532 is connected to a positive terminal 536 of the DC power supply 560 in the positive electrode 530, and the membrane electrode assembly 540, which is a negative electrode, serves to supply current to the membrane electrode assembly. The negative lead wire 544 is connected to the negative terminal 546 of the supply unit 542 and the DC power supply 560. The size ratio of the anode 530 and the membrane electrode assembly 540 is equal to one.

The concentration of the tantalum compound TaCl ₄ is 10 gr / liter, the pH is adjusted to 2.0 using hydrochloric acid, and the plating solution 502 is filled in the storage tank 522. The heater 514, the temperature sensor 512, and the temperature controller ( 510) is used to adjust the plating solution to 50 ° C. When the temperature of the plating solution reaches 50 ° C., a direct current is applied under a condition of 3 Volt and a current density of 0.3 A / dm ² in the DC power supply 560 to prepare a membrane electrode assembly having a tantalum platinum electrochemical catalyst. Then, the exchange membrane was stored by impregnating 0.5 M H ₂ SO ₄ for 2 hours and ultrapure water for 1 hour.

2. Evaluation of Unit Electrochemical Cells

end. Experimental system

The performance of the unit electrochemical cell having the membrane electrode assembly prepared through the above steps was evaluated using the experimental system as shown in FIG. 6. The unit electrochemical cell used in the experiment of the present invention is configured as shown in FIG.

6 is a process diagram of an experimental system used to evaluate electrochemical cells having membrane electrode assemblies prepared according to the prior art and the present invention. As shown in FIG. 6, DC current was supplied to the electrochemical cell 400 using the DC power supply 610, but distilled water of 1 Mega ohm cm or more was used as a raw material of water. At this time, the water is supplied to the anode chamber through the pump 620, the ozone and unreacted water generated in the anode chamber is separated from the water reservoir 630, the water level of the water reservoir 630 is detected by the level sensor 631 Inflow of water was controlled via an on-off valve 632. Hydrogen generated in the cathode chamber was separated from the gas-liquid separator 640 of water and hydrogen and discharged. At this time, the water level of the gas-liquid separator 640 was detected through the level sensor 641 and adjusted through the on-off valve 642. And the temperature of the electrolyte was set to be 80 ℃ by measuring the temperature of the electrochemical cell 400 with the sensor 650, controlled by the electric heater 670 through the regulator 660, the voltage generated at this time (CV , Cell Voltage, and Unit) were measured. The electrical energy and current efficiency needed to produce 1 kg of ozone were calculated through Equation 2 and Equation 3.

I. Ozone analysis method [A.D. Eaton, L.S. Clesceri, A.E. Greenberg, Section 4500-Cl B, Iodometric method I, Standard Methods for the Examination of Water and Wastewater, 19th ed., American Public Health Association, Washington, DC, 1995, ISBN 0-87553-223-3, 4 / 38- /39.18]

Ozone was measured by the iodometric method. After ozone was absorbed in 200 ml of 2% KI solution for 10 minutes, titration analysis was performed with 0.005N Na ₂ S ₂ O ₃ standard solution, and the actual ozone generation amount was calculated by the following Equation 4.

Where A is the amount of Na ₂ S ₂ O ₃ used in the titration sample (ml), B is the amount of Na ₂ S ₂ O ₃ used in the blank test of the absorbent solution (ml), and N is Na ₂ S ₂ O ₃ Normal concentration.

3. Results

7 is a graph comparing the performance results of the comparative examples and the invention example experimented with the experimental system of FIG. 6, the measured value is the electrical energy required to generate 1 kg of ozone, and FIG. 9 is a graph comparing long-term operation values to evaluate stability, and FIG. 9 is a graph comparing long-term operation values to evaluate current efficiency of the present invention and Comparative Example 1. FIG.

Comparative Example 1 Anode Catalyst Layer (Pt) / Cathode Catalyst Layer (Pt)

1. Preparation of membrane electrode assembly

First step (pretreatment step)

It is the same as the pretreatment step of the invention example.

Second step (sorption reduction step)

It is the same as the adsorption reduction step of the invention example.

2. Evaluation of Unit Electrochemical Cells

The performance was evaluated by the evaluation method of the invention example.

3. Results

Experimental results related to electrical energy required to generate 1 kg of ozone are represented by data of Comparative Example 1 of FIG. 7, experimental results related to voltage are represented by data of Comparative Example 1 of FIG. 8, and experimental results related to current efficiency are illustrated. It was shown by the data of the comparative example 1 of 9.

[Comparative Example 2] Information described in the Model ozone generator catalog of Lynntech, Inc. 7610 Eastmark Drive College Station, Texas 77840

According to the information described in the catalog, it can be seen that the electric energy required for 1 kg of ozone is about 13 kWH (http://www.lynntech.com/licensing/ozone/index.shtml).

As can be seen from FIG. 7 showing the experimental results of the Inventive Example and Comparative Examples 1 and 2, the Inventive Example corresponding to the present invention consumes less electric energy used to prepare 1 kg of ozone than Comparative Examples 1 and 2. It means that the present invention has improved performance over the prior art.

8 and 9 show a trend of electrolytic voltage and electrolysis efficiency (current efficiency) when operated for a long time, and it can be seen that the present invention is more stable than the conventional Comparative Example 1.

In the above description, a membrane electrode assembly having a platinum tantalum electrode catalyst layer of the present invention, a method of manufacturing the same, and an electrochemical cell having the same are described together with the accompanying drawings, which are illustrative examples of the best embodiments of the present invention. It does not limit the invention.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations within the scope of the appended claims without departing from the scope of the technical idea of the present invention.

1 is a conceptual diagram of a typical electrolysis cell which electrochemically decomposes water to produce hydrogen gas and oxygen and ozone gas,

2 is a schematic diagram of an electric circuit by decomposing an electrolytic cell voltage into an electrolytic cell component voltage,

3 is a block diagram showing a manufacturing process of an electrochemical ozone generating membrane electrode assembly according to an embodiment of the present invention,

4 is a structural diagram of a unit electrochemical cell having a membrane electrode assembly prepared according to the present invention;

5 is a structural diagram of a plating bath for electroplating tantalum for implementing the membrane electrode assembly according to the present invention,

6 is a process diagram of an experimental system used to evaluate electrochemical cells having membrane electrode assemblies prepared according to the prior art and the present invention,

7 is a graph comparing the performance results of the comparative examples and the invention example experimented with the experimental system of FIG.

8 is a graph comparing long-term operation values to evaluate the stability of the voltage of the present invention and Comparative Example 1,

9 is a graph comparing long-term operation values in order to evaluate the current efficiency of the present invention and Comparative Example 1.

Claims (4)

delete In the manufacturing method of the electrochemical ozone generating membrane electrode assembly (Membrane Electrode Assembly) each having an anode and a cathode electrode catalyst layer for forming electrodes on both surfaces of the electrolyte membrane, A pretreatment step of cleaning the electrolyte membrane, The pretreated electrolyte membrane is impregnated in a solution containing electrocatalyst ions to penetrate and immobilize ions into the surface and the inside of the electrolyte membrane. Forming an adsorption reduction step, Tantalum plating the one surface of the electrolyte membrane with the electrode catalyst layer coated on both surfaces thereof by an electroplating method, and And a post-treatment step of washing the electrolyte membrane. The method according to claim 2, In the adsorption reduction step, the electrode catalyst is a method for producing an electrochemical ozone generating membrane electrode assembly, characterized in that using any one or one or more of iridium, manganese, cobalt, nickel, palladium, chromium, platinum. delete

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