Microwave ultraviolet induced photocatalytic denitration coupling electro-catalytic ammonia production integrated method and application of microwave ultraviolet induced photocatalytic denitration coupling electro-catalytic ammonia production integrated method

Abstract

The invention discloses a microwave ultraviolet induced photocatalytic denitration coupling electrocatalytic ammonia production integrated method and application thereof, and belongs to the technical field of flue gas purification denitration and product recycling. According to the microwave ultraviolet induced photocatalytic denitration coupling electro-catalysis ammonia production integrated method provided by the invention, an oxidizing agent or a reducing agent does not need to be additionally added in the whole reaction process, so that the safety of the system is improved, and the industrial cost is reduced; the self-made copper-based catalyst is used as a working electrode of an electro-catalysis system, so that the cost is low, the preparation is easy, and the reaction efficiency and ammonia selectivity are good; by means of the integrated design of the device, gaseous pollutant nitric oxide is converted into available ammonia energy, secondary pollution is prevented, and the purposes of harmlessness and recycling of denitration products and turning waste into wealth are achieved. The whole reaction condition is mild, only renewable green electric power energy is consumed, the operation cost is low, and operation and maintenance are convenient.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas purification, denitrification and product resource utilization, and in particular relates to an integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production and its application. Background Art

[0002] Nitric oxide (NO) is one of the most significant air pollutants produced by thermal power plants. NO reacts with atmospheric water vapor to form nitric or nitrous acid, which in turn leads to the formation of acid rain. This damages aquatic ecosystems, forest ecosystems, agricultural ecosystems, building materials, and human health, posing a serious threat to the natural environment and ecosystems. Atmospheric nitric oxide reacts with hydrocarbons under ultraviolet light to produce secondary pollutants that deplete the ozone layer and form highly irritating photochemical smog, which reduces visibility and poses a health hazard, potentially causing conjunctivitis, headaches, and even blindness. Furthermore, NO readily binds to hemoglobin in human blood to form nitrosohemoglobin, which reduces the blood's oxygen transport capacity, leading to hypoxia and symptoms such as central nervous system paralysis, seizures, and movement disorders. NO pollution, caused by excessive combustion of fossil fuels, has become an increasingly serious global environmental threat to human health, prompting the introduction of stricter standards for NO emissions.

[0003] The main flue gas denitrification technologies currently used are SCR (selective catalytic reduction) and SNCR (selective non-catalytic reduction). Both methods require the additional addition of reducing agents, which increases industrial costs. There are also secondary pollution problems such as reducing agent escape and catalyst deactivation. The product after denitrification is nitrogen, which is difficult to use.

[0004] As a high-temperature, zero-carbon energy source, ammonia offers significant advantages over hydrogen in storage and transportation, making it more commercially viable. The traditional Haber process for ammonia production has drawbacks such as high N≡N dissociation energy and the requirement for high temperature and high pressure. Electrocatalytic reduction of nitrates / nitrites to produce ammonia is gaining increasing attention due to its advantages, including operating at room temperature and pressure, zero secondary pollution, and the ability to generate electricity from renewable energy sources (solar and wind). Finding a suitable nitrogen source for electrocatalytic ammonia production is a practical challenge.

[0005] In summary, the secondary pollution and product inability to be reused in flue gas denitrification technology, as well as the need for a suitable nitrogen source for electrocatalytic ammonia production, make it impossible to artificially and efficiently realize the pollutant nitrogen cycle. Summary of the Invention

[0006] To address these issues, the present invention provides an integrated method for microwave-UV-induced photocatalytic denitrification coupled with electrocatalytic ammonia production and its application. Using microwave-UV-induced photocatalysis as the denitrification method and a self-developed copper-based catalyst as the electrocatalyst for ammonia production, this method achieves an integrated operation of flue gas denitrification and ammonia production processes.

[0007] One of the technical solutions provided by the present invention:

[0008] The invention discloses an integrated device for microwave-ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production, which consists of three parts: a microwave-ultraviolet-induced photocatalytic unit, an electrocatalytic ammonia production unit and an absorption unit.

[0009] Furthermore, the microwave ultraviolet induced photocatalytic unit includes an ultraviolet electrodeless lamp and a microwave generator;

[0010] The electrocatalytic ammonia production unit includes an H-type electrolyzer and an electrochemical workstation; the H-type electrolyzer includes an anode reaction chamber and a cathode reaction chamber; the anode reaction chamber and the cathode reaction chamber are separated by a proton exchange membrane;

[0011] The absorption unit comprises an absorption bottle and a flue gas analyzer, and the absorption bottle is connected to the flue gas analyzer through a pipeline.

[0012] Furthermore, the microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device further includes a gas mixer, and the gas mixer is connected to the microwave generator through a pipeline.

[0013] Furthermore, the electrocatalytic ammonia production unit adopts a three-electrode system of a working electrode, a counter electrode and a reference electrode.

[0014] Furthermore, the structure of the integrated device of microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production is as follows:

[0015] The microwave ultraviolet induced photocatalytic system comprises a gas cylinder, a gas mixer, an ultraviolet electrodeless lamp, a microwave reaction bottle, a microwave ultraviolet induced photocatalytic reactor temperature setting display screen, a power switch, a microwave generator switch and a microwave generator;

[0016] The microwave reaction bottle is provided with a microwave reaction bottle air inlet; the gas mixer is connected to the microwave reaction bottle air inlet through an air inlet pipe; the upper end of the microwave reaction bottle is provided with an inverted cone-shaped air outlet, and the microwave reaction bottle and the inverted cone-shaped air outlet are connected through a fluororubber sealing ring; the rear end of the inverted cone-shaped air outlet is connected to a Y-shaped tube;

[0017] The electrocatalytic ammonia production device adopts a three-electrode system of a working electrode, a counter electrode and a reference electrode, which includes an H-type electrolytic cell and an electrochemical workstation; the H-type electrolytic cell includes an anode reaction chamber, a cathode reaction chamber and a cathode reaction chamber liquid inlet; the anode reaction chamber and the cathode reaction chamber are separated by a proton exchange membrane;

[0018] The absorption device includes an absorption bottle and a flue gas analyzer, and the absorption bottle is connected to the flue gas analyzer through a pipeline;

[0019] One end of the Y-shaped tube is connected to the absorption bottle, and the other end is connected to the liquid suction end of the peristaltic pump as the liquid outlet, and the liquid suction end pipeline of the peristaltic pump penetrates into the bottom of the microwave reaction bottle; the liquid outlet of the peristaltic pump is connected to the liquid inlet of the cathode reaction chamber, the reference electrode and the working electrode are placed in the cathode reaction chamber, and the counter electrode is placed in the anode reaction chamber; the electrodes of the H-type electrolytic cell are correspondingly connected to the electrode clamps of the electrochemical workstation.

[0020] Furthermore, the reference electrode is an Ag / AgCl electrode; the counter electrode is a platinum sheet; and the working electrode is a copper-based working electrode.

[0021] Furthermore, the preparation method of the copper-based working electrode includes the following steps: ultrasonically treating the initial foamed copper in hydrochloric acid, hydrogen peroxide and deionized water in sequence, taking it out and vacuum drying it at 40° C. for 6 hours to obtain the copper-based working electrode.

[0022] The copper-based working electrode provided by the present invention has the advantages of easy preparation, good catalytic effect and high economic benefit.

[0023] The second technical solution provided by the present invention is:

[0024] A microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated method is carried out by the above-mentioned microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device, gas and water are introduced into the microwave ultraviolet induced photocatalytic unit for gas-liquid reaction, NO is removed and converted into NO3 - / NO2 - The solution is transported to the electrocatalytic ammonia production unit through a peristaltic pump for electrocatalytic reduction reaction to convert NO3 - / NO2 - Electrocatalytic reduction to ammonia and a small amount of NO3 - / NO2 - The gas flows out of the air flow pipe in the form of aerosol and is intercepted by the absorption bottle; the gas includes oxygen, nitrogen and nitric oxide. The specific steps include:

[0025] Deionized water and an ultraviolet electrodeless lamp are added to the microwave reaction bottle; the inverted cone-shaped air outlet at the upper end is connected through a fluororubber sealing ring to form a sealed state except for the air inlet and the air outlet; the power switch of the microwave ultraviolet induced photocatalytic reactor is turned on, the reaction temperature is set, nitrogen, oxygen and nitric oxide pass through the gas mixer and then enter the microwave reaction bottle, and the microwave generator switch is turned on at the same time. The microwaves generated by the microwave generator excite the ultraviolet electrodeless lamp inserted in the microwave reaction bottle to release short-wavelength ultraviolet rays, forming a microwave-ultraviolet co-catalytic system, and nitric oxide is removed under this catalytic system to generate NO x - , most of the NO x - A small amount of NO remained in the aqueous solution in the microwave reaction bottle. x - As water evaporates and the air flows from one end of the Y-shaped tube at the rear end of the inverted cone-shaped outlet into the absorption bottle;

[0026] The airflow passes through the absorption bottle and enters the flue gas analyzer to measure the microwave ultraviolet photocatalytic denitrification effect;

[0027] After the microwave ultraviolet catalytic denitrification reaction is completed, the peristaltic pump is started to extract the solution in the microwave reaction bottle from the liquid outlet at the other end of the Y-tube, and flow into the cathode reaction chamber of the H-type electrolytic cell from the liquid inlet as a nitrogen source. The solution in the H-type electrolytic cell uses sodium sulfate as an electrolyte. Under the applied voltage controlled by the electrochemical workstation and the electrocatalytic conditions of the copper-based working electrode, the cathode reaction chamber contains NO x - The solution is converted into an ammonia solution.

[0028] Furthermore, the reaction temperature is 60-70° C.; 30-70 mL of deionized water is added to the microwave reaction bottle; and there are 1-3 ultraviolet electrodeless lamps in the microwave reaction bottle;

[0029] Since the increase in temperature and the number of lamps will increase the system energy consumption, but too low a temperature and too few lamps will reduce the system efficiency, from the perspective of energy saving, the preferred reaction temperature of the present invention is 60°C, and there are two ultraviolet electrodeless lamps in the microwave reaction bottle 6.

[0030] Furthermore, the core component of the microwave generator is a magnetron, which generates microwaves to induce the electrodeless lamp to release short-wavelength ultraviolet rays. The working power of the microwave generator is 200-400W.

[0031] Furthermore, the applied voltage is -1.3 to -1.4 V vs Ag / AgCl; preferably, the applied voltage is -1.3 V vs Ag / AgCl.

[0032] The third technical solution provided by the present invention is:

[0033] An application of the above-mentioned microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated method in flue gas denitrification coupled with electrocatalytic ammonia production replaces the nitric oxide in the gas cylinder with flue gas containing nitric oxide.

[0034] The applications include flue gas denitrification coupled with electrocatalytic ammonia production in thermal power generation, steelmaking or chemical industry.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] (1) The entire reaction process of the microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated method provided by the present invention does not require the addition of additional oxidants or reducing agents, which not only increases the safety of the system but also reduces industrial costs;

[0037] (2) The present invention uses a self-made copper-based catalyst as the working electrode of the electrocatalytic system, which is not only low-cost and easy to prepare but also has good reaction efficiency and ammonia selectivity;

[0038] (3) Through the integrated design of the device, the gaseous pollutant nitric oxide is converted into usable ammonia energy, preventing secondary pollution and achieving the goals of harmless denitrification products, resource utilization and "turning waste into treasure";

[0039] (4) The overall reaction conditions of the integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production provided by the present invention are mild, and only renewable green electricity is consumed, with low operating costs and easy operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is a schematic diagram of the integrated process structure of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production adopted in an embodiment of the present invention;

[0042] Among them, 1-gas cylinder; 2-gas mixer; 3-microwave reaction bottle air inlet; 4-ultraviolet electrodeless lamp; 5-peristaltic pump liquid extraction end pipeline; 6-microwave reaction bottle; 7-fluororubber sealing ring; 8-microwave ultraviolet induced photocatalytic reactor temperature setting display screen; 9-inverted cone-shaped air outlet; 10-Y-type tube; 11-microwave ultraviolet induced photocatalytic reactor power switch; 12-microwave generator switch; 13-microwave generator; 14-peristaltic pump; 15-H-type electrolytic cell cathode reaction chamber liquid inlet; 16-anode reaction chamber; 17-cathode reaction chamber; 18-electrochemical workstation; 19-absorption bottle; 20-flue gas analyzer.

[0043] Figure 2 (a) is the standard curve of nitrate concentration and absorbance; (b) is the standard curve of nitrite concentration and absorbance; (c) is the standard curve of ammonia concentration and absorbance. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] The embodiment of the present invention provides an integrated method of microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production. Figure 1 This is a schematic diagram of the integrated process structure of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production adopted in an embodiment of the present invention.

[0050] The microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated process provided in the embodiment of the present invention addresses the defects of the existing technology. The use of microwave ultraviolet induced photocatalytic denitrification has the advantages of no need to add additional reducing agents, simple operation, and resource utilization of products; a homemade copper-based catalyst is used as the working electrode of the electrocatalytic system, which is not only low in cost and easy to prepare but also has good reaction efficiency and ammonia yield. The specific operation includes the following steps: turning on the microwave ultraviolet induced photocatalytic reactor switch 11, setting the reaction temperature on the microwave ultraviolet induced photocatalytic reactor temperature setting display screen 8, and the gases in the nitrogen, oxygen, and nitric oxide gas cylinders 1 pass through the gas mixer 2 (a gas flow meter is provided on the gas mixer to monitor the gas flow) and then enter the microwave reaction bottle 6 from the air inlet 3. At the same time, the microwave generator switch 12 is turned on, and the microwaves generated by the microwave generator 13 excite the ultraviolet electrodeless lamp 4 inserted in the microwave reaction bottle 6 to release short-wavelength ultraviolet rays, forming a microwave-ultraviolet co-catalytic system, and nitric oxide is removed under this catalytic system to generate NO x - , a large amount of NO x - In the aqueous solution remaining in microwave reaction bottle 6, a small amount of NO x - As water evaporates and air flows from one end of the Y-shaped tube 10 at the rear end of the inverted cone-shaped air outlet to the absorption bottle 19; the flue gas passes through the absorption bottle 19 and enters the flue gas analyzer 20 to detect the microwave ultraviolet photocatalytic denitrification effect; after the microwave ultraviolet photocatalytic denitrification reaction is completed, the peristaltic pump 14 is started to extract the solution in the microwave reaction bottle 6 from the liquid outlet at the other end of the Y-shaped tube 10, and flows into the cathode reaction chamber 17 of the H-type electrolytic cell from the liquid inlet 15 of the cathode reaction chamber of the H-type electrolytic cell as a nitrogen source. The solution in the H-type electrolytic cell uses sodium sulfate as an electrolyte. Under the applied voltage controlled by the electrochemical workstation 18 and the electrocatalytic conditions formed by the homemade copper-based electrocatalyst, the NO-containing solution in the cathode reaction chamber 17 is converted into nitrogen. x - The solution is converted into an ammonia solution.

[0051] The reagents, raw materials and initial copper foam used in the examples of the present invention were all purchased from commercial sources.

[0052] Example 1

[0053] The microwave ultraviolet induced photocatalytic denitrification test using the above device includes the following steps:

[0054] S1. Add 50 mL of deionized water to each of the microwave reaction bottle 6 and the absorption bottle 19; place two UV electrodeless lamps 4 into the microwave reaction bottle 6;

[0055] S2. The microwave reaction bottle 6 and the inverted cone-shaped outlet 9 are connected by a fluorine rubber sealing ring, forming a sealed state except for the air inlet and outlet;

[0056] S3. Turn on the microwave UV-induced photocatalytic reactor switch 11, set the reaction temperature to 60 ° C, nitrogen, oxygen, and nitric oxide gases pass through the gas mixer 2 and enter the microwave reaction bottle 6, the gas rate is 1L / min, the oxygen concentration is 4%, and the initial NO concentration is 300mg / m 3 At the same time, turn on the microwave generator switch 12. The microwaves generated by the microwave generator 13 excite the ultraviolet electrodeless lamp 4 inserted in the microwave reaction bottle 6 to release short-wavelength ultraviolet rays, forming a microwave-ultraviolet co-catalytic system. Nitric oxide is removed under this catalytic system and NO is generated. x - , a large amount of NO x - In the aqueous solution remaining in microwave reaction bottle 6, a small amount of NO x - As water evaporates and air flows from one end of the Y-shaped tube 10 at the rear end of the inverted cone-shaped air outlet 9 to the absorption bottle; the microwave reaction bottle 6 and the inverted cone-shaped air outlet 9 are connected by a fluororubber sealing ring to form a sealed state except for the air inlet and outlet;

[0057] S4. The gas passes through the absorption bottle 19 and enters the flue gas analyzer 20 to measure the microwave ultraviolet photocatalytic denitrification effect; 0.4 mL of solution is taken from each of the microwave reaction bottle 6 and the absorption bottle 19 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 The substance concentration results were obtained (as shown); the microwave ultraviolet-induced photocatalytic denitrification reaction time was 50 min; the amount of nitrate collected in the microwave reaction bottle 6 was measured to be 0.3885 mmol, and the amount of nitrite collected in the absorption bottle 19 was 0.0304 mmol and 0.0374 mmol, respectively; the microwave ultraviolet-induced photocatalytic denitrification efficiency was 89.51%.

[0058] Example 2

[0059] The microwave ultraviolet induced photocatalytic denitrification test using the above device includes the following steps:

[0060] S1. Add 50 mL of deionized water to each of the microwave reaction bottle 6 and the absorption bottle 19; place only one UV electrodeless lamp 4 into the microwave reaction bottle 6;

[0061] S2. Same as S2 in Example 1;

[0062] S3. Same as S3 in Example 1;

[0063] S4. The gas passes through the absorption bottle 19 and enters the flue gas analyzer 20 to monitor the microwave ultraviolet photocatalytic denitrification effect; 0.4 mL of solution is taken out from the microwave reaction bottle 6 and the absorption bottle 19, diluted to 50 mL in a colorimetric tube, and the absorbance is measured using a UV-visible spectrophotometer. The absorbance is substituted into the standard curve of the corresponding ion (such as Figure 2 The substance concentration results were obtained (as shown); the microwave ultraviolet-induced photocatalytic denitrification reaction time was 50 min; the amount of nitrate collected in the microwave reaction bottle 6 was measured to be 0.2599 mmol, and the amount of nitrite was 0.0033 mmol; the amounts of nitrate and nitrite collected in the absorption bottle 19 were 0.0132 mmol and 0.0367 mmol, respectively; the microwave ultraviolet-induced photocatalytic denitrification efficiency was 88.22%.

[0064] Example 3

[0065] The microwave ultraviolet induced photocatalytic denitrification test using the above device includes the following steps:

[0066] S1. Add 50 mL of deionized water to each of the microwave reaction bottle 6 and the absorption bottle 19; place three UV electrodeless lamps 4 into the microwave reaction bottle 6;

[0067] S2. Same as S2 in Example 1;

[0068] S3. Same as S3 in Example 1;

[0069] S4. The gas passes through the absorption bottle 19 and enters the flue gas analyzer 20 to measure the microwave ultraviolet photocatalytic denitrification effect; 0.4 mL of solution is taken from each of the microwave reaction bottle 6 and the absorption bottle 19 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 The substance concentration results were obtained (as shown); the microwave ultraviolet-induced photocatalytic denitrification reaction time was 50 min; the amount of nitrate collected in the microwave bottle was measured to be 0.4107 mmol, and the amount of nitrite collected in the absorption bottle was 0.0074 mmol and 0.0186 mmol, respectively; the microwave ultraviolet-induced photocatalytic denitrification efficiency was 90.72%.

[0070] Example 4

[0071] The microwave ultraviolet induced photocatalytic denitrification test using the above device includes the following steps:

[0072] S1. Same as S1 in Example 1;

[0073] S2. Same as S2 in Example 1;

[0074] S3. Turn on the microwave UV-induced photocatalytic reactor switch 11, set the reaction temperature to 70 ° C, nitrogen, oxygen, and nitric oxide gases enter the microwave reaction bottle 6 after passing through the gas mixer 2, with a total gas velocity of 1 L / min, an oxygen concentration of 4%, and an initial NO concentration of 300 mg / m 3 At the same time, turn on the microwave generator switch 12. The microwaves generated by the microwave generator 13 excite the ultraviolet electrodeless lamp 4 inserted in the microwave reaction bottle 6 to release short-wavelength ultraviolet rays, forming a microwave-ultraviolet co-catalytic system. Nitric oxide is removed under this catalytic system and NO is generated. x - , a large amount of NO x - In the aqueous solution remaining in microwave reaction bottle 6, a small amount of NO x - As water evaporates and air flows from one end of the Y-shaped tube 10 at the rear end of the inverted cone-shaped air outlet 9 to the absorption bottle; the microwave reaction bottle 6 and the inverted cone-shaped air outlet 9 are connected by a fluororubber sealing ring to form a sealed state except for the air inlet and outlet;

[0075] S4. The gas passes through the absorption bottle 19 and enters the flue gas analyzer 20 to measure the microwave ultraviolet photocatalytic denitrification effect; 0.4 mL of solution is taken from each of the microwave reaction bottle 6 and the absorption bottle 19 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 The substance concentration results were obtained (as shown); the microwave ultraviolet-induced photocatalytic denitrification reaction time was 50 min; the amount of nitrate collected in the microwave bottle was measured to be 0.4853 mmol, and the amount of nitrite collected in the absorption bottle was 0.0273 mmol and 0.0081 mmol, respectively; the microwave ultraviolet-induced photocatalytic denitrification efficiency was 93.09%.

[0076] Comparative Example 1

[0077] The microwave ultraviolet induced photocatalytic denitrification test using the above device includes the following steps:

[0078] S1. Same as S1 in Example 1;

[0079] S2. Same as S2 in Example 1;

[0080] S3. Turn on the microwave UV-induced photocatalytic reactor switch 11, set the reaction temperature to 50 ° C, nitrogen, oxygen, and nitric oxide gases enter the microwave reaction bottle 6 after passing through the gas mixer 2, the gas rate is 1L / min, the oxygen concentration is 4%, and the initial NO concentration is 300mg / m 3 At the same time, turn on the microwave generator switch 12. The microwaves generated by the microwave generator 13 excite the ultraviolet electrodeless lamp 4 inserted in the microwave reaction bottle 6 to release short-wavelength ultraviolet rays, forming a microwave-ultraviolet co-catalytic system. Nitric oxide is removed under this catalytic system and NO is generated. x - , a large amount of NO x - In the aqueous solution remaining in microwave reaction bottle 6, a small amount of NO x - As water evaporates and air flows from one end of the Y-shaped tube 10 at the rear end of the inverted cone-shaped air outlet 9 to the absorption bottle; the microwave reaction bottle 6 and the inverted cone-shaped air outlet 9 are connected by a fluororubber sealing ring to form a sealed state except for the air inlet and outlet;

[0081] After passing through the absorption bottle 19, the S4 gas enters the flue gas analyzer 20 to measure the microwave ultraviolet photocatalytic denitrification effect; 0.4 mL of solution is taken out from the microwave reaction bottle 6 and the absorption bottle 19, diluted to 50 mL in a colorimetric tube, and the absorbance is measured using a UV-visible spectrophotometer, and the standard curve of the corresponding ion (such as Figure 2 The substance concentration results were obtained (as shown); the microwave ultraviolet-induced photocatalytic denitrification reaction time was 50 min; the amount of nitrate collected in the microwave bottle was measured to be 0.1388 mmol, and the amount of nitrite collected in the absorption bottle was 0.0041 mmol and 0.0453 mmol, respectively; the microwave ultraviolet-induced photocatalytic denitrification efficiency was 69.81%.

[0082] Determination of NO3 in solution by UV-visible spectrophotometry - 、NO2 - After the reaction is completed, 0.4 mL of solution is taken out from the reaction pool (microwave reaction bottle 6 and absorption bottle 19) and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 Table 1 shows the reaction conditions, NO removal rates, and the amount of nitrate substances in Examples 1-4 and Comparative Example 1.

[0083] The NO removal rate is calculated by the following formula:

[0084]

[0085] Where C in——initial NO concentration (mg / m 3 );

[0086] C out ——NO outlet concentration (mg / m 3 );

[0087] T——reaction time (min).

[0088] Table 1

[0089]

[0090]

[0091] The electrocatalytic ammonia production process using the above-mentioned device includes the following steps:

[0092] Example 5

[0093] S1. A 0.1-cm-thick copper foam was cut into 1×1-cm pieces and ultrasonically treated in hydrochloric acid (1 mol / L), hydrogen peroxide (20 wt.%), and deionized water for 40 min, 60 min, and 30 min, respectively. After removal, the copper-based catalyst for electrocatalytic ammonia synthesis was dried under vacuum at 40°C for 6 h. This catalyst was used as the working electrode in the cathode reaction chamber of an H-type electrolyzer.

[0094] S2. After the microwave ultraviolet catalytic denitrification reaction is completed, the peristaltic pump 5 is started to extract the solution in the microwave reaction bottle 6 in Example 1 from the liquid outlet at the other end of the Y-shaped tube 10, and the solution flows from the liquid inlet 15 of the cathode reaction chamber of the H-type electrolytic cell into the cathode reaction chamber 17 of the H-type electrolytic cell as a nitrogen source. The solution in the H-type electrolytic cell uses sodium sulfate (71 mg / mL) as an electrolyte, the copper-based catalyst prepared in S1 is used as a working electrode, the Ag / AgCl electrode is used as a reference electrode, and the platinum sheet is used as a counter electrode. After the three electrodes are connected to the corresponding electrode clamps of the electrochemical workstation 18, the electrochemical workstation 18 is turned on for electrocatalytic reaction, and the cathode reaction chamber 17 contains NO x - The solution was converted into an ammonia solution with an applied voltage of -1.3 V (vsAg / AgCl) and an electrocatalytic time of 2 h;

[0095] S3. After the electrocatalytic reaction is completed, 0.2 mL of the solution is taken out from the cathode reaction chamber 17 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 As shown in the figure, the substance concentration result was obtained and the electrocatalytic reaction NO x - The removal rate was 99.49% and the ammonia selectivity was 97.46%.

[0096] Example 6

[0097] S1. Same as S1 in Example 2;

[0098] S2. After the microwave ultraviolet catalytic denitrification reaction is completed, the peristaltic pump 5 is started to extract the solution in the microwave reaction bottle 6 in Example 1 from the liquid outlet at the other end of the Y-shaped tube 10, and the solution flows from the liquid inlet 15 of the cathode reaction chamber of the H-type electrolytic cell into the cathode reaction chamber 17 of the H-type electrolytic cell as a nitrogen source. The solution in the H-type electrolytic cell uses sodium sulfate (71 mg / mL) as an electrolyte, the copper-based catalyst prepared in S1 is used as a working electrode, the Ag / AgCl electrode is used as a reference electrode, and the platinum sheet is used as a counter electrode. After the three electrodes are connected to the corresponding electrode clamps of the electrochemical workstation 18, the electrochemical workstation 18 is turned on for electrocatalytic reaction, and the cathode reaction chamber 17 contains NO x- The solution was converted into an ammonia solution with an applied voltage of -1.4 V (vsAg / AgCl) and an electrocatalytic time of 2 h;

[0099] S3. After the electrocatalytic reaction is completed, 0.2 mL of the solution is taken out from the cathode reaction chamber 17 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2 As shown in the figure, the substance concentration result was obtained and the electrocatalytic reaction NO x - The removal rate was 98.83% and the ammonia selectivity was 98.29%.

[0100] Comparative Example 2

[0101] S1. Same as S1 in Example 2;

[0102] S2. After the microwave ultraviolet catalytic denitrification reaction is completed, the peristaltic pump 5 is started to extract the solution in the microwave reaction bottle 6 in Example 1 from the liquid outlet at the other end of the Y-shaped tube 10, and the solution flows from the liquid inlet 15 of the cathode reaction chamber of the H-type electrolytic cell into the cathode reaction chamber 17 of the H-type electrolytic cell as a nitrogen source. The solution in the H-type electrolytic cell uses sodium sulfate (71 mg / mL) as an electrolyte, the copper-based catalyst prepared in S1 is used as a working electrode, the Ag / AgCl electrode is used as a reference electrode, and the platinum sheet is used as a counter electrode. After the three electrodes are connected to the corresponding electrode clamps of the electrochemical workstation 18, the electrochemical workstation 18 is turned on for electrocatalytic reaction, and the cathode reaction chamber 17 contains NO x - The solution was converted into an ammonia solution with an applied voltage of -1.2 V vs Ag / AgCl and an electrocatalytic time of 2 h;

[0103] S3. After the electrocatalytic reaction is completed, 0.2 mL of the solution is taken out from the cathode reaction chamber 17 and diluted to 50 mL in a colorimetric tube. The absorbance is measured using a UV-visible spectrophotometer and substituted into the standard curve of the corresponding ion (such as Figure 2As shown in the figure, the substance concentration result was obtained and the electrocatalytic reaction NO x - The removal rate was 93.85% and the ammonia selectivity was 58.54%.

[0104] Table 2 shows the electrocatalytic ammonia production reaction conditions, NO x- Removal rate and ammonia selectivity. The calculation formula used in this section is as follows:

[0105] (1) Nitrate removal rate

[0106] The nitrate removal rate in the present invention represents the percentage of the nitrate concentration removed during the electrocatalytic process to the initial concentration; it is calculated according to the following formula.

[0107]

[0108] In the formula, C0 is the initial NO3 - concentration (mg / L);

[0109] C t ——NO3 after reaction - Concentration (mg / L).

[0110] (2) Ammonia yield

[0111] The ammonia yield rate (NYR) in the present invention is an indicator that measures the amount of ammonia generated per unit time and per unit area of ​​electrode material in the electrocatalytic reaction, and is calculated according to the following formula.

[0112]

[0113] Where, ——mass concentration of ammonia (mg / L);

[0114] ——Relative molecular mass of ammonia;

[0115] V——electrolyte volume (mL);

[0116] t——electrocatalytic reaction time (h);

[0117] S——cathode material area (cm 2 ).

[0118] (3) Ammonia selectivity

[0119] In this context, ammonia selectivity refers to the ratio of the amount of ammonia produced to the amount of nitrate removed during the electrocatalytic reduction reaction, typically expressed as a percentage. This metric reflects the catalyst's preference for ammonia production during the reaction. A higher selectivity indicates that a greater proportion of nitrate is effectively converted to ammonia, rather than producing other byproducts. Ammonia selectivity is calculated using the following formula.

[0120]

[0121] (4) Ammonia Faraday efficiency

[0122] In this context, ammonia Faradaic efficiency (FE) represents the ratio between the theoretical charge of synthesized ammonia and the actual charge consumed by the catalyst, typically expressed as a percentage. A high Faradaic efficiency means that more electrical energy is effectively converted into ammonia during the reaction, rather than wasted in other side reactions. It is calculated using the following formula.

[0123]

[0124] Where, F is Faraday constant, 96485 C·mol -1 ;

[0125] Q - the amount of charge consumed during the reaction (C).

[0126] Table 2

[0127]

[0128] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device, characterized in that: It consists of three parts: microwave ultraviolet induced photocatalytic unit, electrocatalytic ammonia production unit and absorption unit.

2. The microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device according to claim 1 is characterized in that: The microwave ultraviolet induced photocatalytic unit comprises an ultraviolet electrodeless lamp (4) and a microwave generator (13); The electrocatalytic ammonia production unit comprises an H-type electrolyzer and an electrochemical workstation (18); the H-type electrolyzer comprises an anode reaction chamber (16) and a cathode reaction chamber (17); the anode reaction chamber (16) and the cathode reaction chamber (17) are separated by a proton exchange membrane; The absorption unit comprises an absorption bottle (19) and a flue gas analyzer (20), and the absorption bottle (19) is connected to the flue gas analyzer (20) through a pipeline.

3. The microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device according to claim 2, characterized in that: It also includes a gas mixer (2), and the gas mixer (2) is connected to the microwave generator (13) through a pipeline.

4. The microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device according to claim 3, characterized in that: The electrocatalytic ammonia production unit adopts a three-electrode system of a working electrode, a counter electrode and a reference electrode.

5. A microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated method, characterized in that: The method is carried out by the microwave ultraviolet induced photocatalytic denitrification coupled with electrocatalytic ammonia production integrated device according to any one of claims 1 to 4, and the specific steps include: passing gas and water together into the microwave ultraviolet induced photocatalytic unit for gas-liquid reaction, and NO is removed and converted into NO3 - / NO2 - The solution is transported to the electrocatalytic ammonia production unit through a peristaltic pump for electrocatalytic reduction reaction to convert NO3 - / NO2 - Electrocatalytic reduction to ammonia and a small amount of NO3 - / NO2 - It flows out along the air flow pipe in the form of aerosol and is intercepted by the absorption bottle (19); the gas includes oxygen, nitrogen and nitric oxide.

6. The integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production according to claim 5, characterized in that: The reaction temperature is 60-70°C.

7. The integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production according to claim 5, characterized in that: The amount of water added is 30 to 70 mL.

8. The integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production according to claim 5, characterized in that: The working power of the microwave generator (13) for controlling the microwave ultraviolet induced photocatalytic unit during the gas-liquid reaction is 200-400W.

9. The integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production according to claim 5, characterized in that: In the electrocatalytic reduction reaction, the applied voltage is -1.3 to -1.4 V vs Ag / AgCl; and the electrocatalytic reduction time is 2 h.

10. Application of the integrated method of microwave ultraviolet-induced photocatalytic denitrification coupled with electrocatalytic ammonia production according to any one of claims 5 to 9 in flue gas denitrification coupled with electrocatalytic ammonia production.

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