An apparatus and method for producing ammonium nitrate using air and water as raw materials.

Abstract

This invention provides an apparatus and method for producing ammonium nitrate using air and water as raw materials. Compared with the prior art, the apparatus provided by this invention consists of a nitrogen generator, a plasma discharge device, a fixed-bed reactor, and an absorption tower. It employs sliding arc discharge and utilizes the heat generated by the discharge to heat the fixed-bed reactor, thereby achieving the discharge synthesis of NH3 and NO from nitrogen and water. x The method utilizes oxidation absorption to ultimately obtain ammonium nitrate solution. It uses only air and water as raw materials and avoids the high temperature and high pressure reaction conditions in the industrial synthesis of ammonium nitrate. It realizes a synthesis process driven only by renewable energy and can be applied to scenarios such as distributed energy storage and small-scale agricultural nitrogen fertilizer production.

Description

Technical Field

[0001] This invention belongs to the field of artificial nitrogen fixation technology, and particularly relates to an apparatus and method for producing ammonium nitrate using air and water as raw materials. Background Technology

[0002] Ammonium nitrate has a high nitrogen content and is inexpensive, making it an ideal nitrogen fertilizer. It can also be used to manufacture pesticides and refrigerants. Traditional industrial synthesis of ammonium nitrate requires NH3 from the Haber process as a raw material. A catalyst is used to oxidize NH3 to NO at 800-900 degrees Celsius. Nitric acid is then produced through oxidation absorption, and the remaining nitric acid is synthesized through a neutralization reaction with NH3. This process is highly centralized, relying on large-scale ammonia and hydrogen production plants, making it difficult to apply in remote areas such as high-altitude regions and deep mountains. Furthermore, ammonium nitrate is an explosive substance, posing significant safety hazards during storage and transportation. Water and air are widely present in the Earth's environment. If ammonium nitrate could be produced and used directly from water and air under mild conditions, allowing for on-site production and immediate use, thus achieving decentralized ammonium nitrate production, the above problems could be effectively solved.

[0003] In recent years, with the development of clean power technologies such as photovoltaic power generation, plasma technology driven by electricity has received widespread attention. In nitrogen plasma reactions, nitrogen molecules collide with high-energy electrons generated by discharge, which can activate them to an excited state or even a dissociated state. Therefore, plasma technology is an effective means of activating nitrogen. The combined production of ammonium nitrate using plasma discharge and other technologies has attracted attention (Yu et al., Joule, 2023, 7, 1-8). However, current research focuses on the generation of nitrogen oxides (NOx) through air discharge. x ), then NO x The ammonium nitrate is primarily reduced to NH3 via electrocatalytic reduction after absorption in the electrolyte. This method is complex, and the ammonium nitrate needs to be separated from the electrolyte, increasing the number of synthesis steps and costs. Therefore, a simpler route for the synthesis of ammonium nitrate using water and air as raw materials is needed. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an apparatus and method for producing ammonium nitrate using plasma discharge and thermocatalysis technology with air and water as raw materials.

[0005] This invention provides an apparatus for producing ammonium nitrate using air and water as raw materials, comprising: a nitrogen generator, a plasma discharge device, a fixed-bed reactor, and an absorption tower;

[0006] The nitrogen generator is connected to the plasma discharge device;

[0007] The plasma discharge device is equipped with a water vapor inlet and a gas outlet;

[0008] The gas outlet of the plasma discharge device is connected to the inlet of the fixed-bed reactor;

[0009] The fixed-bed reactor is equipped with a hydrogenation catalyst and a reducing gas outlet.

[0010] The reducing gas outlet of the fixed-bed reactor is connected to the absorption tower.

[0011] Preferably, the plasma discharge device is a sliding arc plasma discharge device;

[0012] The absorption tower is equipped with an oxidizing gas inlet.

[0013] The present invention also provides a method for producing ammonium nitrate using air and water as raw materials, comprising the following steps:

[0014] S1) Air is processed through a nitrogen generator to obtain nitrogen;

[0015] S2) Water vapor and nitrogen are mixed and treated with plasma discharge to obtain the reaction gas;

[0016] S3) The reaction gas is catalytically treated with a hydrogenation catalyst to obtain a reduced gas;

[0017] S4) The reducing gas is absorbed by the absorption liquid to obtain a solution containing ammonium nitrate.

[0018] Preferably, the molar amount of water vapor is 1% to 50% of the total molar amount of water vapor and nitrogen.

[0019] Preferably, the total flow rate of water vapor and nitrogen gas during the plasma discharge treatment is 2 to 10 slm; the discharge current of the plasma discharge treatment is 0.1 to 10 A; the discharge voltage of the plasma discharge treatment is 150 to 1000 V; and the discharge power of the plasma discharge treatment is 15 to 10000 W.

[0020] Preferably, in step S3), the hydrogenation catalyst comprises a support and noble metal particles supported on the support; the noble metal particles are selected from platinum or palladium; and the mass concentration of the noble metal particles in the hydrogenation catalyst is 0.1% to 5%.

[0021] The temperature of the catalytic treatment in step S3) is 100℃~300℃.

[0022] Preferably, in step S4), an oxidizing gas is also added; the reducing gas and the oxidizing gas are mixed and then passed through an absorption liquid to obtain a solution containing ammonium nitrate.

[0023] Preferably, the volumetric flow rate of the oxidizing gas is 0.1 to 5 times that of the reducing gas.

[0024] Preferably, the molar ratio of nitrate ions to ammonium ions in the ammonium nitrate-containing solution is 0.8 to 2:1.

[0025] Preferably, in step S4), the ammonium nitrate-containing solution obtained after the reducing gas is absorbed by the absorption liquid includes ammonium ions, nitrate ions, and nitrite ions; the total molar amount of nitrate ions and nitrite ions is less than or equal to 1 / 4 of the molar amount of ammonium ions.

[0026] Compared with existing technologies, the device provided by this invention consists of a nitrogen generator, a plasma discharge device, a fixed-bed reactor, and an absorption tower. It employs sliding arc discharge and utilizes the heat generated by the discharge to heat the fixed-bed reactor, thereby achieving the discharge synthesis of NH3 and NO from nitrogen and water. x The method utilizes oxidation absorption to ultimately obtain ammonium nitrate solution. It uses only air and water as raw materials and avoids the high temperature and high pressure reaction conditions in the industrial synthesis of ammonium nitrate. It realizes a synthesis process driven only by renewable energy and can be applied to scenarios such as distributed energy storage and small-scale agricultural nitrogen fertilizer production. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the apparatus for producing ammonium nitrate using air and water as raw materials provided by the present invention.

[0028] Figure 2 This is a schematic diagram of the plasma-fixed bed coupled reactor provided by the present invention;

[0029] Figure 3 The images shown are photographs and XRD patterns of the solution obtained in Example 1 of this invention after evaporation. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides an apparatus for producing ammonium nitrate using air and water as raw materials, comprising: a nitrogen generator, a plasma discharge device, a fixed-bed reactor, and an absorption tower;

[0032] The nitrogen generator is connected to the plasma discharge device;

[0033] The plasma discharge device is equipped with a water vapor inlet and a nitrogen oxide gas outlet;

[0034] The nitrogen oxide gas outlet of the plasma discharge device is connected to the inlet of the fixed bed reactor;

[0035] The fixed-bed reactor is equipped with a hydrogenation catalyst and a reducing gas outlet.

[0036] The reducing gas outlet of the fixed-bed reactor is connected to the absorption tower.

[0037] See Figure 1 , Figure 1 This is a schematic diagram of the apparatus for producing ammonium nitrate using air and water as raw materials, provided by the present invention.

[0038] The apparatus for producing ammonium nitrate provided by this invention includes a nitrogen generator. The function of the nitrogen generator is to separate oxygen from the air to obtain high-purity nitrogen for subsequent reactions. The principle of the nitrogen generator can be pressure swing adsorption, membrane separation, electrocatalytic oxygen reduction, etc. Any device capable of separating nitrogen from the air can be used as the nitrogen generator in this invention.

[0039] The nitrogen generator is connected to the plasma discharge device, and the nitrogen generated by the nitrogen generator is introduced into the plasma discharge device; the plasma discharge device is provided with a water vapor inlet; in the plasma discharge device, nitrogen reacts with water vapor to produce nitrogen oxides (NOx). x The plasma discharge device mainly contains NO and NO2) and H2; the plasma discharge device is preferably a sliding arc plasma discharge device; specifically, the plasma discharge device includes a discharge electrode; the discharge electrode is composed of a rod-shaped high-voltage electrode with a conical tip and an annular outer electrode; there are no particular restrictions on the inner diameter and length of the annular outer electrode, as long as the annular electrode can induce gas plasma discharge, it can be used as the discharge electrode of the plasma discharge device in this invention.

[0040] The plasma discharge device is provided with a gas outlet, which is connected to a solid bed reactor. A hydrogenation catalyst is disposed within the fixed bed reactor. The hydrogenation catalyst can be any hydrogenation catalyst well-known to those skilled in the art and is not particularly limited. In this invention, it preferably includes a support and noble metal particles loaded on the support. The support can be any support well-known to those skilled in the art and is not particularly limited. In this invention, it is preferably a metal oxide, non-metal oxide, zeolite molecular sieve, etc., and more preferably one or more of silica, alumina, titanium dioxide, HZSM5 zeolite, NaY zeolite, etc. Regarding the support... The morphology and particle size are not particularly limited, and can be amorphous particles, nanocrystals with specific crystal faces, etc.; the noble metal particles are preferably platinum and / or palladium, more preferably platinum; the present invention does not particularly limit the size of the noble metal particles and the exposed crystal faces; the mass concentration of the noble metal particles in the hydrogenation catalyst is preferably 0.1% to 5%, specifically 0.1%, 0.5%, 1%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any two of the above values; in the embodiments provided by the present invention, 0.5% to 1% is specifically used as an example; under the action of the hydrogenation catalyst, NO x It reacts with H2 to produce NH3.

[0041] In a specific embodiment of the present invention, the plasma discharge device and the fixed-bed reactor can be provided by a device that includes both a plasma discharge device and a fixed-bed reactor, namely a plasma-fixed-bed coupled reactor. Specifically, the plasma-fixed-bed coupled reactor includes a plasma discharge region and a fixed-bed reaction region. The plasma discharge region is located below the fixed-bed reaction region, and a discharge electrode is disposed within the plasma discharge region. The fixed-bed reaction region is disposed of with a hydrogenation catalyst. More specifically, the discharge electrode consists of a rod-shaped high-voltage electrode with a conical tip and an annular outer electrode. The rod-shaped high-voltage electrode is located at the bottom of the plasma discharge region, opposite to the fixed-bed reaction region. Using a plasma-fixed-bed coupled reactor allows the fixed-bed reactor to be heated to a suitable reaction temperature without the need for an external heat source, relying solely on the heat generated by the discharge reaction in the plasma discharge device. There are no specific limitations on the distance between the plasma discharge electrode and the fixed-bed reactor region, or on the shape of the connecting pipes in the plasma-fixed-bed coupled reactor. Any device structure that can effectively utilize the heat generated by the plasma discharge to heat the fixed-bed reactor can be used as the structure of the chelation reactor in the present invention. In addition, the reactor can also be equipped with an additional heating function for rapid temperature adjustment. After water and nitrogen are passed through a plasma-fixed bed coupled reactor, the resulting product gas is NO. x Mainly NH3.

[0042] In one specific embodiment of the present invention, the plasma-fixed bed coupled reactor further includes a water storage chamber, see [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of the plasma-fixed bed coupled reactor provided by the present invention, wherein 1 is the air inlet, 2 is the water storage chamber, 3 is the rod-shaped electrode with a conical tip, 4 is the annular outer electrode, 5 is the plasma moment generated by the discharge, 6 is the catalyst packing layer, and 7 is the air outlet; the nitrogen generator is connected to the plasma discharge region in the plasma-fixed bed coupled reactor through the water storage chamber, and the nitrogen generated by the nitrogen generator carries the water vapor in the water storage chamber into the plasma discharge region; in order to improve energy utilization efficiency, the heat generated by the plasma discharge region can be used not only to heat the fixed bed reaction region, but also to heat the liquid water in the water storage chamber to promote the formation of water vapor.

[0043] The reducing gas outlet of the fixed-bed reactor is connected to the absorption tower. Preferably, the reducing gas outlet of the fixed-bed reactor is connected to the absorption tower via a cooling device. The reducing gas in the fixed-bed reactor after catalysis by the hydrogenation catalyst contains ammonia, water vapor, and NO. x The reducing gas can be cooled before entering the absorption tower, condensing and separating the water vapor to increase the oxidation rate and improve the oxidation absorption effect. More preferably, the absorption tower is provided with an oxidizing gas inlet; the oxidizing gas can be any oxidizing gas well known to those skilled in the art, without special limitations, but air and / or oxygen are preferred in this invention; the reducing gas generated in the fixed-bed reactor is introduced into the absorption tower together with the oxidizing gas. Under the action of O2, excess NO... x It will be oxidized to NO2, and eventually absorbed together with NH3 to form an ammonium nitrate solution. The absorption tower is an absorption tower well known to those skilled in the art, and can be any type of device capable of achieving full absorption of the gas, such as a plate tower, bubble tower, packed tower, spray tower, etc.

[0044] The present invention also provides a method for producing ammonium nitrate using air and water as raw materials, comprising the following steps: S1) treating air with a nitrogen generator to obtain nitrogen; S2) mixing water vapor and nitrogen and treating with plasma discharge to obtain a reaction gas; S3) treating the reaction gas with a hydrogenation catalyst to obtain a reducing gas; S4) absorbing the reducing gas with an absorbent to obtain a solution containing ammonium nitrate.

[0045] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0046] Air is processed by a nitrogen generator to obtain nitrogen.

[0047] Water vapor and nitrogen are mixed and treated with plasma discharge to obtain a reactive gas. The molar amount of water vapor is preferably 1% to 50% of the total molar amount of water vapor and nitrogen, specifically 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any two of the above values; in the embodiments provided by this invention, it is specifically 30% to 40%. The total flow rate of water vapor and nitrogen during plasma discharge treatment is preferably 2 to 10 slm, specifically 2 slm, 4 slm, etc. The plasma discharge current is preferably 0.1–10A, specifically 0.1A, 0.2A, 0.5A, 1A, 2A, 3A, 5A, 8A, 10A, or any two of the above values; in the embodiments provided by this invention, 0.2–1A is specifically used as an example; the plasma discharge voltage is preferably 150–100V. 000V, specifically it can be 150V, 200V, 250V, 300V, 350V, 400V, 450V, 500V, 550V, 600V, 650V, 700V, 750V, 800V, 850V, 900V, 950V, 1000V or any two of the above values; in the embodiments provided by the present invention, 600-700V, 650-700V or 700-800V are specifically used as examples; the discharge power of the plasma discharge treatment is preferably 15-10 000W, specifically it can be 15W, 50W, 100W, 150W, 200W, 250W, 300W, 320W, 350W, 370W, 400W, 450W, 500W, 550W, 600W, 700W, 800W, 1000W, 1500W, 2000W, 3000W, 4000W, 5000W, 10000W, or a range between any two of the above values; in the embodiments provided by this invention, 320W, 200W, or 370W are specifically used as examples. NO generated by plasma discharge treatment x The molar concentrations of both NO and H2 are 0.2%–2.5%, and their molar ratio is NO x The H2 ratio is 0.7 to 1.1, and discharge will also produce NH3 and N2O with concentrations below 500 ppm.

[0048] The reactant gas is catalytically treated by a hydrogenation catalyst to obtain a reduced gas. The hydrogenation catalyst can be any hydrogenation catalyst well-known to those skilled in the art and is not particularly limited. In this invention, it preferably includes a support and noble metal particles supported on the support. The support can be any support well-known to those skilled in the art and is not particularly limited. In this invention, it is preferably a metal oxide, non-metal oxide, zeolite molecular sieve, etc., more preferably one or more of silica, alumina, titanium dioxide, HZSM5 zeolite, NaY zeolite, etc. The noble metal particles are preferably platinum and / or palladium, more preferably platinum. The mass concentration of the noble metal particles in the hydrogenation catalyst is preferably 0.1% to 5%, most preferably 0%. The ratio of the reactant gas to the hydrogenation catalyst is preferably (2-10) slm:(1-10) g, more preferably (4-8) slm:(3-4) g; in some embodiments provided by the present invention, the ratio of the reactant gas to the hydrogenation catalyst is specifically 5 slm:3 g or 8 slm:3 g; the temperature of the catalytic treatment is preferably 100℃-300℃, more preferably 150℃-250℃, and optionally 150℃, 180℃, 200℃, 250℃ or any two of the above values; after catalytic treatment with the hydrogenation catalyst, the conversion rate of H2 is 70%-100%, and the final concentration of NH3 in the gas is 0.1%-1%.

[0049] In a specific embodiment of the present invention, the total time for plasma discharge treatment and catalytic treatment can be 5 to 60 minutes, and can be optionally 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes or any two of the above values.

[0050] In a specific embodiment of the present invention, the reducing gas is absorbed by an absorbent to obtain a solution containing ammonium nitrate; the absorbent can be any aqueous medium known to those skilled in the art, and there are no special limitations, but water is preferred in the present invention; the obtained ammonium nitrate solution is mainly an ammonia-containing solution, specifically preferably including ammonium ions, nitrate ions and nitrite ions; the total molar amount of nitrate ions and nitrite ions is less than or equal to 1 / 4 of the molar amount of ammonium ions.

[0051] In another specific embodiment provided by the present invention, an oxidizing gas is also added; the reducing gas and the oxidizing gas are mixed, and after absorption by an absorbent, a solution containing ammonium nitrate is obtained; under the action of O2, excess NO... xIt will be oxidized to NO2, and eventually absorbed together with NH3 to form ammonium nitrate solution; the oxidizing gas can be any oxidizing gas well known to those skilled in the art, and there are no special limitations. In this invention, air and / or oxygen are preferred; the volumetric flow rate of the oxidizing gas is preferably 0.1 to 5 times the volumetric flow rate of the reducing gas; optionally, the volumetric flow rate of the oxidizing gas is 0.1, 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 times, or the above-mentioned volumetric flow rate of the reducing gas. The range between any two values; in the embodiments provided by the present invention, 1 to 2 times is specifically used as an example; the absorbent can be any aqueous medium well known to those skilled in the art, and there are no special restrictions, but water is preferred in the present invention; the molar ratio of nitrate ions to ammonium ions in the ammonium nitrate-containing solution obtained by passing an oxidizing gas is 0.8 to 2:1; the concentration of the ammonium nitrate-containing solution can increase with the extension of the absorption time until saturation, and the absorption time can be selected according to the actual use requirements, or the water in the solution can be evaporated to obtain solid ammonium nitrate.

[0052] As can be seen from the above, in the method provided by the present invention, the solution obtained without introducing an oxidizing gas is mainly ammonia-containing, with very little nitrate and nitrite. Only when an oxidizing gas is introduced will there be a large amount of nitrate.

[0053] According to the present invention, the gas that has not fully reacted during the oxidation absorption process can be recycled to continue the oxidation absorption process.

[0054] In this invention, in order to obtain other types of nitrates, other substances, such as carbonates, sulfates, phosphates, calcium salts, potassium salts, etc., can be added to the obtained ammonium nitrate-containing solution to obtain a solution containing multiple components. Alternatively, solid substances can be obtained by evaporation and granulation.

[0055] The method provided by this invention has fewer synthesis steps and uses air and water as raw materials, consuming only renewable energy. It eliminates the need for the high-temperature, high-pressure reaction conditions required for the Haber process to synthesize NH3 and for ammonia oxidation to NO. It can directly produce ammonium nitrate under electric power, and the reaction is continuous and easily scaled up. Furthermore, plasma discharge achieves efficient activation and conversion of nitrogen, is easy to operate, readily meets the needs of larger-scale production, and is easily applicable to distributed irrigation, small-scale nitrogen fertilizer production, and other scenarios. It also reduces the hazards associated with the transportation and storage of ammonium nitrate.

[0056] To further illustrate the present invention, the following describes in detail, with reference to embodiments, an apparatus and method for producing ammonium nitrate using air and water as raw materials.

[0057] All reagents used in the following examples are commercially available; all examples employ... Figure 2 The plasma-fixed bed coupled reactor shown.

[0058] Example 1

[0059] The reaction gas was nitrogen containing 30% water vapor at a flow rate of 5 slm. The discharge current was 0.5 A, the voltage was 600–700 V, and the power was approximately 320 W. The reactor was filled with 3 g of 0.5% Pt / Al₂O₃ catalyst. When the temperature inside the plasma-fixed bed coupled reactor stabilized at 180 degrees Celsius, after 30 minutes of discharge, the catalyst-treated gas was mixed with oxygen and fed into an absorption tower. The absorption tower was a plate tower, and the absorbent was water. The flow rates of the catalyst-treated gas and oxygen were both 5 slm. The resulting solution contained 0.0265 mol / L of ammonium nitrate. -1 The total volume of the solution obtained was 280 mL.

[0060] The solution obtained in Example 1 was evaporated to dryness and analyzed by X-ray diffraction, and its photographs and XRD patterns are shown below. Figure 3 As shown.

[0061] Example 2

[0062] The reaction gas was nitrogen containing 30% water vapor at a flow rate of 5 slm. The discharge current was 0.3 A, the voltage was 650–700 V, and the power was approximately 200 W. The reactor was filled with 3 g of 0.5% Pt / TiO2 catalyst. When the temperature inside the plasma-fixed bed coupled reactor stabilized at 150°C, after 30 minutes of discharge, the catalyst-treated gas was mixed with air and introduced into an absorption tower. The absorption tower was a plate tower, and the absorbent was water. The flow rate of the catalyst-treated gas was 5 slm, and the air flow rate was 6 slm. The concentration of ammonium nitrate in the resulting solution was 0.02 mol / L. -1 The total volume of the solution obtained was 300 mL.

[0063] Example 3

[0064] The reaction gas was nitrogen containing 30% water vapor at a flow rate of 8 slm. The discharge current was 0.5 A, the voltage was 700–800 V, and the power was approximately 370 W. The reactor was filled with 3 g of 1% Pt / TiO2 catalyst. When the temperature inside the plasma-fixed bed coupled reactor stabilized at 150°C, after 10 minutes of discharge, the catalyst-treated gas was mixed with air and introduced into an absorption tower. The absorption tower was a plate tower, and the absorbent was water. The flow rate of the catalyst-treated gas was 8 slm, and the air flow rate was 10 slm. The concentration of ammonium nitrate in the resulting solution was 0.0185 mol / L. -1 The total volume of the solution obtained was 330 mL.

[0065] Example 4

[0066] The reaction gas was nitrogen containing 30% water vapor at a flow rate of 5 slm. The discharge current was 0.5 A, the voltage was 550-650 V, and the power was approximately 300 W. The reactor was filled with 3 g of 0.5% Pt / HZSM5 catalyst. After the temperature inside the plasma-fixed bed coupled reactor stabilized at 240 degrees Celsius, and after 30 minutes of discharge, the catalyst-treated gas was mixed with air and introduced into an absorption tower. The absorption tower was a plate tower, and the absorbent was water. The flow rate of the catalyst-treated gas was 5 slm, and the air flow rate was 4 slm. The resulting solution contained 0.05 mol / L ammonium nitrate. -1 The total volume of the solution obtained was 260 mL.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for producing ammonium nitrate using air and water as raw materials, characterized in that, include: Nitrogen generator, plasma discharge device, fixed bed reactor and absorption tower; The nitrogen generator is connected to the plasma discharge device; The plasma discharge device is equipped with a water vapor inlet and a gas outlet; The gas outlet of the plasma discharge device is connected to the inlet of the fixed-bed reactor; The fixed-bed reactor is equipped with a hydrogenation catalyst and a reducing gas outlet. The reducing gas outlet of the fixed-bed reactor is connected to the absorption tower; The plasma discharge device and the fixed bed reactor are provided through a device that includes both a plasma discharge device and a fixed bed reactor, namely a plasma-fixed bed coupled reactor. The plasma-fixed-bed coupled reactor includes a plasma discharge region and a fixed-bed reaction region. The plasma discharge region is located below the fixed-bed reaction region and a discharge electrode is disposed within the plasma discharge region. The fixed-bed reaction region contains a hydrogenation catalyst. The hydrogenation catalyst includes a support and noble metal particles supported on the support. The noble metal particles are selected from platinum or palladium. The mass concentration of the noble metal particles in the hydrogenation catalyst is 0.1% to 5%. The discharge electrode consists of a rod-shaped high-voltage electrode with a tapered tip and an annular outer electrode. The rod-shaped high-voltage electrode is located at the bottom of the plasma discharge region, opposite to the fixed-bed reaction region.

2. The apparatus according to claim 1, characterized in that, The absorption tower is equipped with an oxidizing gas inlet.

3. A method for producing ammonium nitrate using air and water as raw materials in the apparatus of claim 1, characterized in that, Includes the following steps: S1) Air is processed through a nitrogen generator to obtain nitrogen; S2) Water vapor and nitrogen are mixed and treated with plasma discharge to obtain the reaction gas; S3) The reaction gas is catalytically treated with a hydrogenation catalyst to obtain a reduced gas; S4) The reducing gas is absorbed by the absorption liquid to obtain a solution containing ammonium nitrate; In step S3), the hydrogenation catalyst includes a support and noble metal particles supported on the support; the noble metal particles are selected from platinum or palladium; the mass concentration of the noble metal particles in the hydrogenation catalyst is 0.1% to 5%.

4. The method according to claim 3, characterized in that, The molar amount of water vapor is 1% to 50% of the total molar amount of water vapor and nitrogen.

5. The method according to claim 3, characterized in that, The total flow rate of water vapor and nitrogen during plasma discharge treatment is 2~10 slm; the discharge current of plasma discharge treatment is 0.1~10 A; the discharge voltage of plasma discharge treatment is 150~1000 V; and the discharge power of plasma discharge treatment is 15~10000 W.

6. The method according to claim 3, characterized in that, The temperature of the catalytic treatment in step S3) is 100℃~300℃.

7. The method according to claim 3, characterized in that, In step S4), an oxidizing gas is also added; the reducing gas and the oxidizing gas are mixed and then passed through an absorption liquid to obtain a solution containing ammonium nitrate.

8. The method according to claim 7, characterized in that, The volumetric flow rate of the oxidizing gas is 0.1 to 5 times that of the reducing gas.

9. The method according to claim 8, characterized in that, The molar ratio of nitrate ions to ammonium ions in the ammonium nitrate-containing solution is 0.8 to 2:

1.

10. The method according to claim 3, characterized in that, In step S4), the ammonium nitrate solution obtained after the reducing gas is absorbed by the absorption liquid includes ammonium ions, nitrate ions and nitrite ions; the total molar amount of nitrate ions and nitrite ions is less than or equal to 1 / 4 of the molar amount of ammonium ions.

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