KR20200095963A - An electrolytic apparatus for removing nitrogen oxides, and a method for removing nitrogen oxides - Google Patents

Abstract

An objective of the present invention is to provide an apparatus for removing nitrogen oxides with high efficiency and a method therefor. Another objective of the present invention is to provide an apparatus and method for selectively producing ammonia or nitrogen from nitrogen oxides. To this end, the present invention provides an apparatus for removing nitrogen oxides including: a cathode electrode including a gas diffusion layer; an anode electrode; a reference electrode; an electrolyte; and a nitrogen oxide supply unit communicating with the cathode electrode including the gas diffusion layer. According to the present invention, it is possible to remove nitrogen oxides causing serious air pollution with high efficiency, and moreover, to produce ammonia with high utilization from nitrogen oxides in high yield. In addition, if necessary, it is possible to selectively convert to the nitrogen oxide into nitrogen harmless to the human body.

Description

An electrolytic apparatus for removing nitrogen oxides, and a method for removing nitrogen oxides.

The present invention relates to an electrolysis device for removing nitrogen oxides including a gas diffusion layer, and a method for removing nitrogen oxides using the same, and further, to an apparatus and method for selectively producing ammonia or nitrogen from nitrogen oxides through this.

Nitric Oxide (NO) is a type of nitrogen oxide (NOx) that is generally generated by oxidation of nitrogen in the combustion process, and itself causes respiratory-related diseases, and is secondary to exposure to the atmosphere to produce fine dust. (Particulate Matter, PM), photochemical smog, acid rain and ozone layer depletion, and other environmental problems. In particular, in countries that are rapidly growing economically, such as China and India, large amounts of nitrogen oxides are emitted due to excessive industrial activities, causing fine dust, and directly affecting neighboring countries. Secondary fine dust can be generated through a variety of causative substances, but it has been reported that the proportion of nitrogen oxides and sulfur oxides among the exhaust gases emitted from industrial activities is 65% or more. Due to its high water solubility and chemical reactivity, sulfur oxide treatment can be easily treated by sedimenting it as a solid at a relatively low cost like the Limestone process, whereas nitrogen monoxide has little water solubility and thus cannot be treated in water. And high-temperature reaction and the use of a noble metal catalyst and reducing agent are required.

Commercially available nitrogen oxide removal technologies include Selective Catalytic Reduction (SCR), Non-Selective Catalytic Reduction (NSCR), Lean NOx Trap (LNT), and exhaust gas. There is an Exhaust Gas Recirculation (EGR), and technologies currently under development include Electron Beam, Corona Discharge, Biological Treatment (BioDeNOx), and Solid Oxide Electrolysis. Among them, technologies that are most widely used commercially in terms of DeNOx Efficiency are mainly used in large-scale emission point pollutants such as the energy industry including power plants, petrochemicals, and steel manufacturing industries in terms of selective reduction catalysts or space securing. There is a burden of the high temperature operating conditions used and the cost of the catalyst and reducing agent used. Recently, the price of catalyst and the size of the reactor have been further improved through the improvement, and it is partially applied to mobile pollutants such as vehicles and ships using diesel, but it is difficult to apply due to lack of physical space.

On the other hand, nitrogen monoxide (NO, Nitric Oxide), which accounts for about 95% of nitrogen oxides, can be oxidized or reduced by exchanging electrons, that is, it has electrochemical activity, which supplies external electric energy and converts it into a nitrogen compound that is harmless to the environment. This suggests that this is possible. If the nitrogen oxide oxidization take the former case, the nitrite ion (NO ₂ ^-), nitrate ion (NO ₃ ^-) in a conversion and for reducing, in a switchable product is nitrous oxide (N ₂ O), nitrogen (N ₂ ), amine hydroxide (NH ₂ OH), hydrazine (N ₂ H ₄ ) and ammonia (NH ₃ ), nitrogen monoxide is converted to a specific nitrogen compound through optimization according to variables such as electrochemical reaction catalyst, electrolyte and electrical energy input. It can be selectively converted to (eg, nitrate ions, ammonia), which can be said to have an economic advantage compared to the existing denitrification technology that simply treats with nitrogen in terms of production of high value-added substances. In particular, in the case of ammonia, since it has easy safety and storage and can be used as a carrier of hydrogen, which is popular as a next-generation transport fuel, various studies on production methods and utilization methods are being conducted with a large amount of investment. In the case of the Haber process, which is a commercially available ammonia production process, it is operated at a high temperature of 500 degrees or higher and a high pressure of 15 to 25 MPa in order to break the triple bond of nitrogen, and it is necessary to supply hydrogen as a precursor. And there is a drawback of large cost consumption. To replace this, a study on the electrochemical process of producing ammonia by electrochemically reducing nitrogen and adding hydrogen ions, similarly, a study on producing ammonia using solar energy, and direct ammonia as a fuel. Research on fuel cells to be used is actively being conducted worldwide.

The production of ammonia through electrochemical nitrogen reduction has an advantage in that it is easy to operate at normal temperature and pressure, compared to the harbor process, and uses nitrogen and pure water in the atmosphere as precursors, but most of the supplied electric energy is ammonia. Since it is consumed as a side reaction, not a production, that is, a hydrogen generation reaction, the conversion efficiency is very low, less than 3% based on the water-based reaction, making it difficult to commercialize.

For example, Korean Patent Registration No. 10-1767894 is an invention related to a nitrogen circulating nitrogen oxide treatment system and method. Specifically, a nitrogen circulating nitrogen oxide treatment system using an ammonia synthesis cell, wherein the nitrogen oxide treatment The system includes an exhaust gas supply line for supplying exhaust gas including NOx and SOx to a desulfurizer; A processing gas supply line for supplying a processing gas from which SOx has been removed through the desulfurization unit to an NOx scrubber; A process gas discharge line for absorbing NOx of the process gas using an absorbent in the NOx scrubber and discharging the remaining gas; A NOx absorption solution supply line for supplying an absorption solution absorbing NOx in the NOx scrubber to a NOx and absorbent separation device; And a NOx supply line for supplying the NOx separated by the NOx and absorbent separation device to an ammonia synthesis cell but through a concentrator, wherein the ammonia synthesis cell includes an oxygen ion conductive membrane; And two electrodes coated on both surfaces of the oxygen ion conductive film, wherein the electrodes are electrically connected, and a nitrogen circulating nitrogen oxide treatment system is disclosed. However, since the above technology uses pure nitrogen oxide as a raw material in a reduction process for ammonia production, there is a problem in that a high temperature environment must be maintained for high selectivity.

In addition, Republic of Korea Patent Publication No. 10-2017-0021713 is an invention related to an electrolysis device for collecting nitrogen compounds using iron-ethylenediamine tetraacetic acid, specifically, an electrolysis device for collecting nitrogen compounds comprising the following components: ( a) a reactor body containing a compound of a divalent metal ion and a chelating agent therein; (b) anode and cathode; (c) a collection tube for collecting nitrogen compounds, including the anode therein; (d) a gas inlet for supplying a source gas containing a nitrogen compound to the reactor body; And (e) a discharge port for discharging the gas from which nitrogen compounds have been removed after being trapped inside the reactor. However, the above technology only uses a chelating agent to adsorb the nitrogen compound, and only recovers the nitrogen compound through the oxidation reaction of the anode electrode after adsorption, and the process of producing ammonia using this is specifically disclosed. Not.

On the other hand, in the case of small-scale mobile pollutants such as small ships and automobiles, a method of converting and storing ammonia is not suitable because of the limited space available, but rather, safety related problems related to leakage due to the toxicity of ammonia may be presented. Therefore, when nitrogen monoxide is converted and discharged directly into the atmosphere, it is more preferable for small pollutants to convert it to nitrogen rather than ammonia.

Accordingly, there is a need for a system and a manufacturing method capable of removing nitrogen oxides with high efficiency while performing the reaction at room temperature and pressure conditions, and selectively converting to ammonia or nitrogen according to the driving conditions of the apparatus.

An object of the present invention is to provide an apparatus and a method for removing nitrogen oxides with high efficiency. In addition, another object of the present invention is to provide an apparatus for producing ammonia from nitrogen oxides in a high yield or converting to nitrogen harmless to the human body, and a method therefor.

To this end, the present invention comprises a cathode electrode including a gas diffusion layer, an anode electrode, a reference electrode, an electrolyte, and a nitrogen oxide supply unit in communication with the cathode electrode including the gas diffusion layer. Provides.

In addition, the present invention comprises the steps of supplying nitrogen oxide to the gas diffusion layer of the cathode electrode in the electrolysis device for removing nitrogen oxides as described above; And performing an electrical reduction reaction with respect to the supplied nitrogen oxides.

Furthermore, the present invention provides an apparatus and method for producing ammonia or nitrogen from nitrogen oxides using the above apparatus and method.

According to the present invention, not only nitrogen oxides that cause serious air pollution can be removed with high efficiency, and furthermore, ammonia with high utilization can be produced in high yield from nitrogen oxides, and selectively to nitrogen, which is harmless to the human body, if necessary. There is an effect that can be converted.

1 is a schematic diagram showing the configuration of an electrolysis device for removing nitrogen oxides according to the present invention,
2A to 2E are graphs showing efficiency of removal of nitrogen monoxide and conversion to ammonia and nitrogen on a general electrode other than a gas diffusion electrode according to a comparative example of the present invention,
3A to 3E are graphs showing the efficiency of removal of nitrogen monoxide and conversion to ammonia and nitrogen in a gas diffusion electrode carrying a carbon catalyst according to an embodiment of the present invention,
4A to 4E are graphs showing the efficiency of removal of nitrogen monoxide and conversion to ammonia and nitrogen in the gas diffusion electrode supported by mixing carbon and iron catalyst according to an embodiment of the present invention,
5 is a graph showing conversion efficiency to ammonia and nitrogen according to the amount of the catalyst applied according to an embodiment of the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by an expert skilled in the art to which the present invention belongs. In general, the nomenclature used in this specification is well known and commonly used in the art.

Hereinafter, unless otherwise defined,'electrochemical system' and'electrolysis device' are used interchangeably.

It is an object of the present invention to provide an electrolysis device for removing nitrogen oxides, a method for removing nitrogen oxides using the same, and further, an ammonia or nitrogen production device and method using the same.

The present invention

A cathode electrode comprising a gas diffusion layer,

Anode electrode,

Reference electrode,

Electrolytes, and

It provides an electrolysis device for removing nitrogen oxides, characterized in that it comprises a nitrogen oxide supply unit in communication with the cathode electrode including the gas diffusion layer.

At this time, the nitrogen oxide used as the raw material or the object of removal of the present invention may be nitrogen monoxide in that nitrogen monoxide occupies about 95% of the nitrogen oxide.

Hereinafter, the electrolysis device for removing nitrogen oxides of the present invention will be described in detail for each configuration.

The electrolytic apparatus for removing nitrogen oxides of the present invention includes a cathode electrode including a gas diffusion layer. In the cathode electrode of the device of the present invention, for example, the following reduction reaction proceeds to remove nitrogen oxides.

2NO + 2H ⁺ + 2e ^-- > N ₂ O + H ₂ O… … … … … .(Scheme 1)

^{2NO + 4H + + 4e - -} > N 2 + 2H 2 O ... … … … … .(Scheme 2)

^{NO + 3H + + 3e - -} > NH 2 OH ... … … … … … … … ..(Scheme 3)

NO + 5H ⁺ 5e ^-- > NH ₃ + H ₂ O… … … … … … … ... (Scheme 4)

At this time, the cathode electrode of the present invention has the advantage of maximizing selectivity of a specific product by adjusting the ratio of the catalyst and the intensity of the applied voltage according to the desired purpose including the gas diffusion layer.

Next, the electrolytic apparatus for removing nitrogen oxides of the present invention includes an anode electrode, and the following water decomposition reaction proceeds in the anode electrode.

_{H 2 O -> ½ O 2} + 2H + + 2e - ... … … … … … … … ..(Scheme 5)

On the other hand, in the electrolytic apparatus for removing nitrogen oxides of the present invention, the anode electrode may be made of a wide variety of metals and non-metals, and specifically, at least one conductive material selected from the group consisting of graphite, platinum, titanium, nickel and gold. It may be considered to be composed of a metal and one or more mixtures or oxides selected from the group consisting of platinum, ruthenium, osmium, palladium, iridium, carbon, and transition metals. The electrode material of the anode electrode can be used without any particular limitation, but it is recommended to use iron, aluminum, copper, silver, nickel, etc., in the form of oxides, which can spontaneously undergo oxidation reactions when electric energy is introduced as the electrode material of the anode. Can be considered. It may be considered to use a platinum electrode or an insoluble electrode (Dimensional Stable Anode, DSA).

The device of the present invention may include a reference electrode, for example, a hydrogen electrode or an Ag/AgCl electrode, and a reference electrode used in other general electrochemical systems, or can be operated without a reference electrode.

The device of the present invention includes an electrolyte, and an electrolyte used in a general electrochemical system can be used without limitation.

The apparatus of the present invention includes a nitrogen oxide supply unit in communication with a cathode electrode including the gas diffusion layer. The nitrogen oxide supplied through the supply unit is supplied to the cathode electrode through the gas diffusion layer, and the reduction reaction proceeds in the electrolysis device.

In the apparatus of the present invention, the cathode electrode may further include a carbon catalyst layer. In the reduction reaction at the cathode electrode, the carbon catalyst layer increases conductivity by mixing with other metal catalysts, or directly reduces nitrogen oxides as a catalyst. At this time, the mixed metal catalysts include iron (Fe), nickel (Ni), copper (Cu), silver (Ag), zinc (Zn), gold (Au), platinum (Pt), iridium (Ir), and ruthenium ( Ru), cobalt (Co), lead (Pb), cadmium (Cd), tungsten (W), mercury (Hg), titanium (Ti), vanadium (V), and oxides thereof (MO _x ) may be used. Of these, considering the price of the catalyst, the removal efficiency of nitrogen oxides, the removal rate, and the production rate of ammonia or nitrogen by the reduction reaction, it may be preferable to use a mixed catalyst layer of carbon and iron as the cathode electrode.

Meanwhile, the apparatus of the present invention selectively converts the material produced by decomposition of nitrogen oxides into nitrogen or ammonia by adjusting the mixing ratio of carbon and iron in the mixed catalyst layer of carbon and iron included in the cathode electrode and the applied potential difference. You can decide. Accordingly, the apparatus of the present invention may further include an ammonia discharge unit or a nitrogen discharge unit depending on the material to be produced.

For example, in the case of small emission sources such as automobiles and ships, when selectively converting to ammonia, it is difficult to secure economic feasibility due to low production volume, and it may cause a risk in case of leakage. desirable. In addition, in the case of fixed pollutants that emit large amounts of nitrogen oxides, such as thermal power plants, steel mills, and cement production businesses, it is possible to suppress side reactions of nitrous oxide, which is a greenhouse gas, and selectively convert to ammonia.

In consideration of these points, the electrolytic apparatus for removing nitrogen oxides of the present invention can produce nitrogen by adjusting the weight ratio of carbon and iron in the mixed catalyst layer to 2:3 to 1:1, or the weight ratio is 1:3. To 2:5 can be adjusted to produce ammonia.

According to the apparatus of the present invention, not only nitrogen oxides can be efficiently removed, but also the material produced by the removal of nitrogen oxides can be selectively controlled with ammonia or nitrogen by adjusting the weight ratio of the mixed catalyst layer and the applied potential. There is an advantage.

In addition, the present invention

Supplying nitrogen oxides to the gas diffusion layer of the cathode electrode in the electrolysis device for removing nitrogen oxides according to the present invention; And

It provides a method for removing nitrogen oxides comprising; performing an electrical reduction reaction on the supplied nitrogen oxides.

At this time, the nitrogen oxide used as the raw material or the object of removal of the present invention may be nitrogen monoxide in that nitrogen monoxide occupies about 95% of the nitrogen oxide.

Hereinafter, the method for removing nitrogen oxides of the present invention will be described in detail for each step.

The removal method of the present invention includes the step of supplying nitrogen oxide to the gas diffusion layer of the cathode electrode in the electrolysis device for removing nitrogen oxide according to the present invention, through which nitrogen oxide is supplied to the gas diffusion layer through the nitrogen oxide supply unit. , Finally, it is removed through a reduction reaction as shown in the following reaction equation on the cathode electrode. In the removal method of the present invention, nitrogen oxide is introduced to the cathode electrode through the gas diffusion layer, thereby increasing the concentration of usable reactants around the electrode, thereby maximizing the denitration efficiency.

The removal method of the present invention includes performing an electrical reduction reaction on the supplied nitrogen oxide. In the removal method of the present invention, the electric reduction reaction for nitrogen oxides can be carried out by the following reaction equation.

2NO + 2H ⁺ + 2e ^-- > N ₂ O + H ₂ O… … … … … .(Scheme 1)

^{2NO + 4H + + 4e - -} > N 2 + 2H 2 O ... … … … … .(Scheme 2)

^{NO + 3H + + 3e - -} > NH 2 OH ... … … … … … … … ..(Scheme 3)

NO + 5H ⁺ 5e ^-- > NH ₃ + H ₂ O… … … … … … … ... (Scheme 4)

During the above reaction, by controlling the weight ratio of carbon and iron contained in the catalyst layer and the potential applied to the device, the produced material may be selectively produced as nitrogen or ammonia.

Hereinafter, the present invention will be described in more detail through Examples, Comparative Examples and Experimental Examples. However, the following is only intended to describe the present invention in detail, and is not intended to be interpreted as limiting the scope of the present invention by the following content.

<Example 1>

Electrolysis device including a cathode including a carbon catalyst layer and a gas diffusion layer, and decomposition of nitrogen oxides using the same

In order to check the nitrogen oxide removal and the production efficiency of ammonia or nitrogen in the electrolysis device according to the present invention, an electrolysis device for removing nitrogen oxides was prepared as follows. The electrolysis device is composed of an anode outer wall, an anode PEEK cell, a cathode PEEK cell, and a cathode gas injection cell.The electrolyte inlet above the anode PEEK cell is above the cathode PEEK cell, and the electrolyte inlet and gas discharge line are above the cathode PEEK cell, and Ag/AgCl standard on the side. There is an electrode (electrode void 2mm) insertion hole. There is a gas injection line above the cathode gas injection cell, and when gas is supplied, gas is supplied through a 2.5cm * 2.5cm gas diffusion electrode (cathode including a carbon catalyst layer and a gas diffusion layer) located between the cathode PEEK cell and the outer wall of the cathode. It diffuses and passes, and goes out to the gas outlet of the cathode PEEK cell. Between the outer wall of the anode and the anode PEEK cell, a 2cm *5cm platinum electrode was inserted as a counter electrode in a sandwich form. As an electrolyte, 0.5M Phosphate Buffer was used, and 1.5 mL of electrolyte was injected into the anode PEEK cell and the cathode PEEK cell, respectively, during the electrochemical reaction for nitrogen oxide conversion. For the electrochemical reaction of nitrogen monoxide proposed in the present invention, a time-varying current method was performed using a Potentiostat, an electrochemical analyzer, and gas products were analyzed by connecting the gas discharge line of the cathode PEEK cell to gas chromatography. In the case of the liquid product, after performing the time-varying current method, the electrolyte of the cathode PEEK cell was sampled and analyzed by ion chromatography. The selectivity, ammonia current density, denitrification efficiency and denitrification rate for the product were calculated based on the analysis results of the product and the current density recorded in the time versus current method.

The following experiment was performed to check the nitrogen oxide removal and the production efficiency of ammonia or nitrogen of the nitrogen oxide removal electrolysis device prepared as described above.

First, an experiment was conducted to electrochemically reduce nitrogen monoxide for each applied reduction potential by using the time-phase current method (Chronoamperommetry, CA). 3A shows the current density performed by the time vs. current method for 1 hour, and it was confirmed that more current flows as the intensity of the applied reduction potential increases. At this time, hydrogen was not produced, and as a result of analyzing the product selectivity, it was confirmed that nitrous oxide was the only product at +0.4V with respect to the hydrogen reference electrode, and nitrogen, hydroxylamine and ammonia were produced as the overvoltage increased. Was confirmed. It was confirmed that the current density of ammonia was selectively generated as 85% or more at an overvoltage greater than -0.2V with respect to the hydrogen reference electrode (FIG. 3B). Ammonia current density (Fig. 3c), denitration rate (Fig. 3d), and denitration efficiency (Fig. 3e) were calculated based on the results of the time vs. current method and product selectivity, respectively, under the voltage condition of -0.4V for the hydrogen reference electrode. It was confirmed that the ammonia current density, denitrification efficiency and denitrification rate were the best.

<Example 2>

Electrolysis device including cathode including carbon/iron mixed catalyst layer and gas diffusion layer, and decomposition of reduced oxide using the same

In order to check the nitrogen oxide removal and the production efficiency of ammonia or nitrogen in the electrolysis device according to the present invention, an electrolysis device for removing nitrogen oxides was prepared as follows. The electrolysis device is composed of an anode outer wall, an anode PEEK cell, a cathode PEEK cell, and a cathode gas injection cell.The electrolyte inlet above the anode PEEK cell is above the cathode PEEK cell, and the electrolyte inlet and gas discharge line are above the cathode PEEK cell, and Ag/AgCl standard on the side. There is an electrode (electrode void 2mm) insertion hole. There is a gas injection line above the cathode gas injection cell, and when supplying gas, a 2.5cm * 2.5cm gas diffusion electrode (cathode including a carbon/iron mixed catalyst layer and a gas diffusion layer) located between the cathode PEEK cell and the outer wall of the cathode is provided. The gas diffuses through and passes through, and goes out to the gas outlet of the cathode PEEK cell. Between the outer wall of the anode and the anode PEEK cell, a 2cm *5cm platinum electrode was inserted as a counter electrode in a sandwich form. As an electrolyte, 0.5M Phosphate Buffer was used, and 1.5 mL of electrolyte was injected into the anode PEEK cell and the cathode PEEK cell, respectively, during the electrochemical reaction for nitrogen oxide conversion. For the electrochemical reaction of nitrogen monoxide proposed in the present invention, a time-varying current method was performed using a Potentiostat, an electrochemical analyzer, and gas products were analyzed by connecting the gas discharge line of the cathode PEEK cell to gas chromatography. In the case of the liquid product, after performing the time-varying current method, the electrolyte of the cathode PEEK cell was sampled and analyzed by ion chromatography. The selectivity, ammonia current density, denitrification efficiency and denitrification rate for the product were calculated based on the analysis results of the product and the current density recorded in the time versus current method.

The same experiment as in Example 1 was performed to confirm the nitrogen oxide removal and the production efficiency of ammonia or nitrogen of the nitrogen oxide removal electrolysis device prepared as described above.

4A shows the current density performed by the time vs. current method for 1 hour, and it was confirmed that more current flows as the applied reduction potential increases. At this time, hydrogen was not produced, and as a result of analyzing the product selectivity, the reaction on the gas diffusion electrode including the carbon catalyst layer used in Example 1 was different from that of the reaction. First, at a potential higher than +0.4V with respect to the hydrogen reference electrode, nitrous oxide is the only product, and nitrogen and nitrous oxide are produced in a ratio of about 1:1 up to +0V based on the hydrogen reference electrode where overvoltage increases, resulting in a maximum nitrogen current efficiency of 50%. Was recorded, and it was confirmed that the formation of hydroxylamine was suppressed and ammonia was selectively generated by the effect of the iron catalyst at a greater overvoltage (FIG. 4b ). Based on the results of the time vs. amperometric method and product selectivity, the maximum ammonia production current density 12 mA/cm ² (Fig. 4c), the maximum denitrification rate 1.9 mole/m ² /hr (Fig. 4d), and the denitration efficiency 95% (Fig. 4e) Was achieved at -0.4 V for the hydrogen reference electrode.

<Comparative Example>

Electrolysis device including cathode not including gas diffusion electrode and decomposition of nitrogen oxides using the same

In order to check the nitrogen oxide removal and ammonia production efficiency of the electrolysis device not including the gas diffusion electrode, an electrolysis device for removing nitrogen oxides was prepared as follows.

The configuration of the electrolysis device for the experiment required in this comparative example is as follows. The electrolysis device is composed of an anode outer wall, an anode PEEK cell, a cathode PEEK cell, and a cathode outer wall.The electrolyte inlet is above the anode PEEK cell, the electrolyte inlet and gas discharge line is above the cathode PEEK cell, and a gas diffuser made of quartz material is below. The gas injection line that can be inserted has an Ag/AgCl reference electrode (electrode void 2mm) insertion hole on the side. A 2cm *5cm platinum electrode was inserted between the anode outer wall and the anode PEEK cell as a counter electrode, and a 2.5cm * 2.5cm glassy carbon electrode was sandwiched between the cathode PEEK cell and the cathode outer wall as the working electrode. As the electrolyte toward the cathode PEEK cell, 0.5 M Phosphate Buffer was used. In the electrochemical reaction for nitrogen oxide conversion, 1.5 mL of electrolyte was injected into the anode PEEK cell and the cathode PEEK cell, respectively. For the electrochemical reaction of nitrogen monoxide proposed in the present invention, a time-varying current method was performed using a Potentiostat, an electrochemical analyzer, and gas products were analyzed by connecting the gas discharge line of the cathode PEEK cell to gas chromatography. In the case of the liquid product, after performing the time-varying current method, the electrolyte of the cathode PEEK cell was sampled and analyzed by ion chromatography. The selectivity, ammonia current density, denitrification efficiency and denitrification rate for the product were calculated based on the analysis results of the product and the current density recorded in the time versus current method.

The following experiment was performed to confirm the nitrogen oxide removal and ammonia production efficiency of the nitrogen oxide removal electrolysis device prepared as described above.

First, an experiment was conducted to electrochemically reduce nitrogen monoxide for each applied reduction potential by using the time vs. current method (Chronoamperommetry, CA). 2A shows the current density performed by the time vs. current method for 1 hour, and it was confirmed that more current flows as the applied reduction potential increases. As a result of analyzing the selectivity of the product, nitrous oxide was predominantly produced at -0.24V, but unlike an electrolysis device including a cathode including a gas diffusion electrode, hydroxylamine and ammonia were also produced simultaneously. As the overvoltage increased, the selectivity of ammonia increased to -0.55V with respect to the hydrogen reference electrode, and it was confirmed that hydrogen generation reactions dominated the reduction reaction of nitrogen monoxide under overvoltage conditions greater than -0.55V with respect to the hydrogen reference electrode. Was done (Fig. 2b). Ammonia current density (FIG. 2c), denitration rate (FIG. 2d), and denitration efficiency (FIG. 2e) were calculated based on the results of the time vs. current method and product selectivity, respectively, and the highest ammonia at -0.55V for the hydrogen reference electrode. Current density was observed, and the highest denitrification efficiency and denitrification rate were shown at -0.65V. Nevertheless, it showed a low efficiency of 15% or less in terms of denitrification efficiency. On the other hand, in the case of a reaction occurring on a gas diffusion electrode including a mixed catalyst layer of carbon and iron, a maximum ammonia current density of 12 mA/cm ² (Fig. 4c), a maximum denitration rate of 1.9 mol/m ² /hr (Fig. 4d), and a denitration efficiency of 95 Since% (Fig. 4e) was achieved at -0.4V with respect to the hydrogen reference electrode, the use of a gas diffusion electrode including a mixed catalyst layer can be said to have good performance.

<Experimental Example>

Check the selectivity of the product material according to the weight ratio of the components of the mixed catalyst layer

In order to confirm the selectivity of the product material according to the weight ratio of the components constituting the mixed catalyst layer, the following experiment was performed.

An electrolysis device was prepared in the same manner as in Example 2, but the amount of iron in the components of the composite catalyst layer was adjusted to 15 to 25 mg, and the amount of nanocarbon material was mixed to 12 mg to form a composite catalyst layer, and a hydrogen reference electrode The selectivity of nitrogen according to the amount of the catalyst applied was measured at 0V. In addition, the amount of iron among the components of the composite catalyst layer is adjusted to 10 to 30 mg, and the amount of nanocarbon material is mixed at 12 mg to form a composite catalyst layer, and a reduction potential is applied to the hydrogen reference electrode at -1.0 V, and the amount of catalyst applied The selectivity of ammonia according to was measured. The results are shown in FIGS. 5A and 5B.

5A and 5B, it can be seen that nitrogen or ammonia can be selectively produced as needed by adjusting the reduction potential and the catalyst component ratio and amount.

Claims (10)

A cathode electrode comprising a gas diffusion layer,
Anode electrode,
Reference electrode,
Electrolytes, and
An electrolysis device for removing nitrogen oxides, comprising a nitrogen oxide supply unit in communication with a cathode electrode including the gas diffusion layer.
The electrolytic apparatus for removing nitrogen oxides according to claim 1, wherein the nitrogen oxides are nitrogen monoxide.
The electrolytic apparatus for removing nitrogen oxides according to claim 1, wherein the cathode electrode further comprises a carbon catalyst layer.
The electrolytic apparatus for removing nitrogen oxides according to claim 1, wherein the cathode electrode further comprises a mixed catalyst layer of carbon and iron.
The electrolytic apparatus for removing nitrogen oxides according to claim 4, wherein a weight ratio of carbon and iron in the mixed catalyst layer is 2:3 to 1:1.
The electrolytic apparatus for removing nitrogen oxides according to claim 4, wherein a weight ratio of carbon and iron in the mixed catalyst layer is 1:3 to 2:5.
The electrolytic apparatus for removing nitrogen oxides according to claim 1, wherein the apparatus further comprises an ammonia discharge unit.
The electrolytic apparatus for removing nitrogen oxides according to claim 1, wherein the apparatus further comprises a nitrogen discharge unit.
Supplying nitrogen oxides to the gas diffusion layer of the cathode electrode in the electrolysis device for removing nitrogen oxides according to claim 1; And
And performing an electrical reduction reaction on the supplied nitrogen oxides.
The method of claim 9, wherein the nitrogen oxide is nitrogen monoxide.

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