Process and plant for the production of nitrate

Abstract

This application relates to the field of synthesis, disclosing a method and equipment for preparing nitrate ions. The method includes: subjecting a first mixture containing a solid catalyst and a liquid substance to ultrasonic vibration or ball milling under contact with a nitrogen-containing gas to obtain a second mixture containing nitrate ions; filtering the second mixture to remove the solid catalyst to obtain a solution containing nitrate ions. This preparation method can be carried out at room temperature and pressure, greatly reducing energy consumption and achieving zero carbon emissions.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510624256.8, filed on May 14, 2025, entitled "Method and Equipment for Preparing Nitrate", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of chemical synthesis, and in particular to a method for preparing nitrate and production equipment. Background Technology

[0004] Current nitrate synthesis primarily relies on a multi-stage process involving Haber-Bosch ammonia production and Ostwald oxidation. The Haber-Bosch ammonia production process generates ammonia from nitrogen and hydrogen. This process operates at 200 atmospheres and 400-500°C, using an iron-based catalyst (such as Fe). 3+ The Ostwald oxidation process catalyzes the reaction of nitrogen and hydrogen to produce ammonia. It mainly consists of two steps: ammonia oxidation and nitric acid reduction. In the Ostwald process, ammonia is oxidized to nitrogen oxides under the action of a catalyst. These nitrogen oxides, along with oxygen, are then reduced to nitric acid by the catalyst. Nitric acid produced by the Ostwald oxidation method is widely used in industrial production, such as in the preparation of important chemicals like fertilizers, pesticides, explosives, dyes, and salts.

[0005] The Haber-Bosch process is energy-intensive, requiring the combustion of large amounts of fossil fuels and resulting in significant greenhouse gas emissions. Approximately 1%-3% of the world's energy is used in the Haber-Bosch cycle annually, representing a massive energy consumption. Summary of the Invention

[0006] This application discloses a method and equipment for preparing nitrate ions. The preparation method can be carried out at room temperature and pressure, which greatly reduces energy consumption and can achieve zero carbon emissions.

[0007] To achieve the above objectives, this application provides the following technical solution: In a first aspect, this application provides a method for preparing nitrate ions, the method comprising: A first mixture containing a solid catalyst and a liquid substance is subjected to ultrasonic vibration or ball milling under conditions of contact with a nitrogen-containing gas to obtain a second mixture containing nitrate ions. The second mixture was filtered to remove the solid catalyst, yielding a solution containing nitrate ions; The liquid substance is capable of contacting the solid catalyst to generate oxidative free radicals, which can oxidize the nitrogen gas to generate nitrate.

[0008] In the preparation method of this application, ultrasonic vibration or ball milling is provided to continuously contact and separate the solid catalyst with the liquid substance and the nitrogen-containing gas, thereby achieving contact electrification, inducing electron cloud overlap on the surface of the liquid substance and the solid catalyst, reducing the activation energy barrier of the contact catalytic reaction, and generating oxidative free radicals. The oxidative free radicals, upon contact with nitrogen gas, can oxidize the nitrogen gas to form nitrate ions.

[0009] The nitrate synthesis method described in this application can be carried out at room temperature and pressure. This method can efficiently produce nitrate, an important industrial, agricultural, and medical raw material, and has broad application potential. It is particularly effective in increasing crop yields, and its environmentally friendly, pollution-free characteristics meet modern green environmental protection requirements. The preparation method in this application pioneers a new paradigm of "air-based fertilizer production" through ultrasonic vibration or ball milling coupled with contact-electro-catalysis (CEC). This requires only mechanical energy input and eliminates the need for harsh conditions such as high temperature and high pressure. Its energy consumption per reaction is significantly lower than the traditional Haber-Bosch process, truly achieving zero carbon emissions. Experimental verification shows that the obtained nitrate solution can significantly improve the growth of mung beans.

[0010] In one embodiment, the solid catalyst comprises at least one of polymer materials, oxide materials, and composite materials, satisfying the condition that it can undergo contact electrification with the liquid substance. The liquid substance comprises at least one of inorganic solvents and organic solvents, satisfying the condition that it can undergo contact electrification with the solid catalyst. Using a highly electronegative substance as a solid catalyst to enhance its surface electron-withdrawing ability can improve the conversion efficiency of the CEC system. Using a substance with strong electron-donating ability as a solid catalyst can also improve the conversion efficiency of the CEC system.

[0011] In one embodiment, the catalyst comprises at least one selected from fluorinated ethylene propylene copolymer, polytetrafluoroethylene, nylon, ethylene cellulose, and inorganic oxides. The solid catalyst employs the above chemically inert materials; for example, high-dielectric-constant polymers such as FEP possess excellent contact charging capabilities, ensuring high efficiency of the CEC system. Simultaneously, the chemical inertness of the polymer allows it to exclude interference from other catalytic methods, focusing on CEC application scenarios.

[0012] In addition, the above solid catalysts are inexpensive. For example, FEP requires only 20 mg of catalyst in a 50 ml aqueous solution system. Compared with electrocatalysis, photocatalysis and other catalytic methods, it has significant advantages in reducing the unit price of catalyst and the amount of catalyst used, which is beneficial for controlling the cost of production processes in subsequent industrial production.

[0013] In one embodiment, the liquid substance is water, specifically deionized water. Using water as the liquid substance reduces pollution and truly achieves green and environmentally friendly production. When the liquid substance is water, the interaction between water and a solid catalyst can generate cations (H3O). + ) and hydroxyl radicals ( The above free radicals react with nitrogen (N2) to eventually form nitrate.

[0014] In one embodiment, the nitrogen-containing gas contains oxygen. When the nitrogen-containing gas also contains oxygen, the oxygen can gain electrons from the solid catalyst to form superoxide radicals, thereby promoting the formation of nitrate ions and improving the reaction efficiency of the reaction system.

[0015] In one embodiment, the mass ratio of nitrogen to oxygen is 15:1 to 1:5. When the nitrogen to oxygen ratio meets the above conditions, better conversion efficiency can be obtained.

[0016] In one embodiment, the nitrogen-containing gas is air. Using air as the reactant gas enables green and environmentally friendly production.

[0017] In one embodiment, the mass ratio of the solid catalyst to the liquid substance in the first mixture is 1:100 to 1:100000. Controlling the ratio of the solid catalyst to the liquid substance within this range can help further improve conversion efficiency. Compared to electrocatalysis, photocatalysis, and other catalytic methods, the solid catalyst content in this application is lower, which has significant advantages in reducing the unit price of the catalyst and the amount of catalyst used, thus facilitating cost control in subsequent industrial production.

[0018] In one embodiment, subjecting the first mixture containing a solid catalyst and a liquid substance to ultrasonic vibration under conditions of contact with a nitrogen-containing gas includes: The first mixture was subjected to ultrasonic vibration treatment in an air atmosphere. Alternatively, air can be introduced into the first mixture and ultrasonic vibration treatment can be applied.

[0019] A green synthesis method for preparing nitrate ions by coupling ultrasonic waves with contact electrocatalysis (CEC) has been developed, achieving for the first time the direct and efficient production of nitrate ions from air at room temperature and pressure. CEC is an emerging catalytic mechanism that utilizes the electrostatic field generated by the contact of material surfaces to induce charge transfer, triggering a redox reaction. Compared to traditional electrocatalysis that relies on external power sources or photocatalysis that relies on photoexcitation, CEC triggers catalytic activity through mechanical energy, achieving highly efficient reactions at room temperature and pressure, and offering significant advantages such as low energy consumption, zero emissions, and ease of operation. This breakthrough technology provides a novel pathway for the room-temperature oxidation of nitrogen and lays the physicochemical foundation for subsequent ultrasonic-enhanced reactions.

[0020] This technology uses ambient air as a nitrogen source, natural water as a solvent, and mechanical energy as a driving force to build a new nitrogen fertilizer production system with "zero carbon emissions, zero hydrogen consumption, and zero pollution." It not only subverts the century-old nitrogen chemical industry paradigm but also pushes green chemical agriculture into a new intelligent stage of "instant synthesis in the field and precise fertilization on demand," providing a dual solution for global food security and carbon neutrality goals.

[0021] In one embodiment, the solid catalyst includes at least one of a powder catalyst, a spherical catalyst, or a thin-film catalyst. The solid catalyst in this application can take various forms, broadening the selection range of solid catalysts.

[0022] Secondly, this application provides a production apparatus for the nitrate preparation method of this application, the production apparatus comprising: an ultrasonic vibration device or a ball milling device and a filtration device. The ultrasonic vibration device is used to perform ultrasonic vibration treatment or ball milling treatment on the first mixture. The filtration device is used to filter the second mixture to remove the solid catalyst.

[0023] The production equipment of this application can be mainly composed of an ultrasonic vibration device and a filtration device. The equipment is simple and easy to operate. Attached Figure Description

[0024] Figure 1 A comparison chart of the growth of mung beans in different control groups; Figure 2 A schematic diagram illustrating the effect of applying the liquid nitrogen fertilizer of Example 1 on the fresh weight of hydroponically grown mung beans; Figure 3 A schematic diagram illustrating the effect of applying the liquid nitrogen fertilizer of Example 1 on the fresh weight of hydroponic wheat. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] It should be noted that: Unless otherwise specified, all embodiments and preferred methods mentioned herein can be combined to form new technical solutions. Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions. Unless otherwise specified, percentages (%) or parts refer to weight percentages or parts by weight relative to the composition. Unless otherwise specified, the components involved or their preferred components can be combined to form new technical solutions. Unless otherwise specified, the numerical range "a~b" in this application represents an abbreviation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed herein; "6~22" is merely an abbreviation of these numerical combinations. The "range" disclosed in this application can be in the form of a lower limit and an upper limit, and may be one or more lower limits and one or more upper limits, respectively. Unless otherwise specified, the various reaction or operation steps in this application can be performed sequentially or in order. Preferably, the reaction methods described herein are performed sequentially.

[0027] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to a person skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this application.

[0028] The theoretical framework of contact-electro-catalysis (CEC) technology is built upon the deep coupling of charge transfer kinetics and surface chemistry. When a solid and a liquid come into contact, electron transfer tends to occur at the solid-liquid interface. Based on contact electrification, contact-electro-catalysis technology can initiate interfacial charge transfer by precisely controlling the contact-separation process between materials, pioneering a new paradigm of mechanically driven chemical reactions. The core of CEC technology lies in utilizing the instantaneous strong electric field formed during solid-liquid contact to drive electron transfer and trigger redox reactions.

[0029] Compared to the limitations of traditional catalysis, which relies on precious metals or high temperatures and pressures, the CEC technology in the nitrate preparation method of this application directly activates chemical bonds through mechanical stimulation, achieving efficient and low-energy nitrogen activation and conversion at room temperature and pressure. This breakthrough provides a new pathway for the green synthesis of nitrate and offers a glimmer of hope for solving the high carbon emission problem of the traditional nitrogen fertilizer industry.

[0030] The method for preparing nitrate in this application includes the following steps: S1. The first mixture containing a solid catalyst and a liquid substance is subjected to ultrasonic vibration or ball milling under conditions of contact with a gas containing nitrogen to obtain a second mixture containing nitrate. The liquid substance is a substance that can come into contact with the solid catalyst to generate oxidative free radicals; the oxidative free radicals can oxidize the nitrogen gas to generate nitrate.

[0031] S2. The second mixture is filtered to remove the solid catalyst to obtain a solution containing nitrate.

[0032] In the first mixture, the mass ratio of the solid catalyst to the liquid substance is 1:100 to 1:100000. For example, the mass ratio of the solid catalyst to the liquid substance can be any two values ​​between 1:100, 1:500, 1:1000, 1:5000, 1:10000, 1:5000, 1:10000, 1:50000, or 1:100000.

[0033] The solid catalyst comprises at least one of polymer materials, oxide materials, and composite materials, satisfying the condition that it can generate electricity upon contact with a liquid substance. The liquid substance comprises at least one of inorganic solvents and organic solvents, satisfying the condition that it can generate electricity upon contact with a liquid substance.

[0034] Using highly electronegative substances as solid catalysts to enhance their electron-withdrawing ability can improve the conversion efficiency of CEC systems. Similarly, using substances with strong electron-donating capabilities as solid catalysts can also improve the conversion efficiency of CEC systems.

[0035] For example, the catalyst includes at least one selected from fluorinated ethylene propylene copolymer, polytetrafluoroethylene, nylon, ethyl cellulose, and inorganic oxides. Inorganic oxides may be, for example, silicon dioxide, aluminum oxide, etc.

[0036] The form in which the solid catalyst is added is not specifically limited; for example, it may be at least one of powder catalyst, spherical catalyst, or thin film catalyst.

[0037] In one embodiment, the nitrogen-containing gas contains oxygen. The oxygen can gain electrons from the solid catalyst to form superoxide radicals, thereby promoting nitrate formation and improving the reaction efficiency of the system.

[0038] The mass ratio of nitrogen to oxygen can be between 15:1 and 1:5. For example, the mass ratio of nitrogen to oxygen can be any two values ​​between 15:1, 14:1, 13:1, 12:1, 11:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5.

[0039] For example, the nitrogen-containing gas may be air.

[0040] In one embodiment, the liquid substance is water, and the resistivity of water can be greater than 18.2 MΩ·cm. For example, the water can be deionized water.

[0041] In one embodiment of this application, subjecting the first mixture containing a solid catalyst and a liquid substance to ultrasonic vibration under conditions of contact with a nitrogen-containing gas includes: The first mixture was subjected to ultrasonic vibration treatment in an air atmosphere. Alternatively, air can be introduced into the first mixture and ultrasonic vibration treatment can be applied.

[0042] The preparation method described in this application can directly utilize ambient air and natural water as raw materials, combined with a recyclable catalyst, to form a closed-loop system of "on-site preparation - precision irrigation," perfectly meeting the low-carbon development needs of smart agriculture. This breakthrough not only provides a disruptive tool for the artificial regulation of nitrogen cycles but also marks a key turning point in the transformation of green chemical agriculture from concept to engineering application, which is of great value for ensuring food security.

[0043] In the preparation method described in this application embodiment, where pure water and air are used as raw materials to prepare nitrate ions via ultrasonic vibration, the ultrasonic waves first promote the contact-separation cycle between the solid catalyst, such as FEP powder, and the air-water interface through high-frequency mechanical vibration, achieving a contact electrification effect. Then, the ultrasonic cavitation effect forms transient high-temperature and high-pressure microregions in the solution, where the temperature can be >5000K and the pressure >100MPa. These high-temperature and high-pressure microregions induce electron cloud overlap between water molecules and the FEP surface, lowering the energy barrier for CEC activation and generating a large number of highly oxidizing ·OH radicals. Furthermore, the microjets generated by the ultrasonic cavitation effect provide sufficient energy to induce the activation of nitrogen molecules, converting them into excited-state nitrogen. Finally, these highly reactive radicals react with the excited-state nitrogen at the catalyst interface, ultimately achieving highly selective synthesis of nitrate ions through a series of oxidation pathways.

[0044] Specifically, the generation of CEC reactive oxygen species includes the following processes: In the first step, the water oxidation reaction (HOR), when the solid catalyst and the liquid substance come into contact, the electrically driven electron transfer caused by the solid-liquid contact allows the FEP to gain electrons from water molecules, transforming it into a negatively charged excited state FEP. This process simultaneously induces the formation of water radical cations. Subsequently, this extremely short-lived intermediate combines with another water molecule, undergoing rapid proton transfer to generate hydrated hydrogen ion cations (H3O). + ) and hydroxyl radicals ( OH). An exemplary chemical reaction process is shown in equation (1.1) below.

[0045] The second step, the oxygen reduction reaction (ORR), involves the negatively charged FEP. Electrons are transferred to oxygen molecules dissolved in aqueous solution, converting oxygen into superoxide radicals. O2 - At the same time, the FEP that loses electrons The reaction cycle is completed by restoring the uncharged ground state FEP.

[0046] An exemplary chemical reaction process is shown in equation (1.2) below.

[0047] (1.1), (1.2).

[0048] In the above reaction cycle, hydroxyl radicals ( The continuous generation of hydroxyl radicals (OH) plays a crucial role in nitrogen oxidation. Hydroxyl radicals possess strong oxidizing properties and, with the aid of ultrasound, can combine with nitrogen molecules. Through a series of oxidation pathways, such as the synergistic oxidation of activated nitrogen molecules with generated reactive oxygen species at the catalyst interface, nitrate (NO3) is ultimately produced. - .

[0049] Compared to traditional methods, CEC technology requires no external energy input, relying solely on mechanical energy to trigger the reaction. Furthermore, CEC operates efficiently at ambient temperature and pressure, with low energy consumption and no greenhouse gas emissions; the catalyst selection is flexible and cost-effective, and its chemical inertness avoids interference from side reactions. CEC technology is simple to operate and has integration potential, making it suitable for distributed agricultural applications, demonstrating its high efficiency in nitrate synthesis.

[0050] Furthermore, in the preparation method of this application embodiment, CEC is highly consistent with the principles of green chemistry. Its energy source is ubiquitous mechanical energy, which is often overlooked or wasted. This characteristic helps to alleviate the dependence of current production practices on traditional energy sources and reduce greenhouse gas emissions. More importantly, CEC is complementary to the electron transfer mechanisms of other catalytic mechanisms, which is conducive to the deep coupling of CEC with other catalytic mechanisms and significantly improves catalytic efficiency through synergistic effects.

[0051] Therefore, compared with the traditional process of preparing nitrate by combining Haber-Bosch ammonia production with Ostwald oxidation, the preparation method of this application can solve the following technical problems: 1) Energy and environmental benefits: By using the mechanical energy of ultrasound instead of fossil fuels relied upon by the traditional Harber-Bosch cycle and Oswald process, energy consumption and carbon emissions are reduced, which is highly consistent with the principles of sustainable development strategy and green chemistry.

[0052] 2) Limitations on the selection of catalyst materials: Traditional catalysis relies on catalyst materials with specific chemical properties, while CEC is based on the ubiquitous contact electrification effect and is almost not limited by materials, thus expanding the selection range of catalysts to chemically inert materials.

[0053] 3) Highly efficient synthesis of nitrate: CEC utilizes free radicals to oxidize nitrogen in the air to directly generate nitrate, breaking through the limitations of production conditions and environment, and can synthesize this important chemical raw material, nitrate, in almost any region.

[0054] 4) Restrictions on fertilizer transportation: Traditional fertilizers require centralized production and transportation. The nitrate solution produced by CEC can be directly used for agricultural irrigation, enabling immediate use after production and reducing dependence on infrastructure.

[0055] Therefore, the preparation method of this application is an innovative and efficient method for synthesizing nitrate.

[0056] To demonstrate the effectiveness of the preparation method in the embodiments of this application, the preparation method of this application will be further described in detail below with reference to specific embodiments.

[0057] Example 1

[0058] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: Fluorinated ethylene propylene (FEP) powder is used as a solid catalyst. FEP has excellent contact charging properties.

[0059] S2) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system at a mass ratio of 1:2500. Then, FEP was uniformly dispersed in the water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the water were monitored using ion chromatography. - The concentration change of ).

[0060] Example 2

[0061] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: Polytetrafluoroethylene (PTFE) films or spherical particles are used as solid catalysts.

[0062] S2) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system, with a mass ratio of solid catalyst to ultrapure water of 1:2500. Then, PTFE was uniformly dispersed in the water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the water were monitored using ion chromatography. - The concentration change of ).

[0063] Example 3

[0064] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: Nylon film or spherical particles are used as solid catalysts.

[0065] S2) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system, with a mass ratio of solid catalyst to ultrapure water of 1:2500. Then, nylon was uniformly dispersed in water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the water were monitored using ion chromatography. - The concentration change of ).

[0066] Table 1

[0067] As shown in Table 1, nitrate ions were obtained in Examples 1-3. This demonstrates that the method described in this application can facilitate the efficient generation of nitrate ions, and proves the feasibility of using a CEC system with different catalysts to synthesize nitrates from air via ultrasonic catalysis under mild conditions. Specifically, referring to the data from Example 1, under a 40kHz ultrasonic field, a nitrate concentration of 10.26 mg / L was obtained in a 20 mg catalyst system after 3 hours of reaction, showing a significantly improved catalytic efficiency per unit mass compared to traditional photocatalytic and electrocatalytic systems.

[0068] The test data from Examples 1-3 show that catalytic activity and the production of nitrate ions can be achieved using different catalysts, which is consistent with the widespread existence of contact electrification and confirms the broad applicability of the CEC system.

[0069] Furthermore, a comparison of the data from Examples 1 and 2 shows that catalysts with similar negative charge densities during contact charging, even with the same fluorine-containing groups, yield similar concentrations of nitrate ions. A comparison of the data from Examples 1, 2, and 3 shows that while the positive or negative charge of the catalyst during contact charging has some influence on the reaction efficiency, the effect is relatively small. This further demonstrates the general applicability of the system.

[0070] Example 4

[0071] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0072] S2) Reaction solution: Select hydrochloric acid solution with pH=2.

[0073] S3) Synthesis: First, a solid catalyst and a hydrochloric acid solution with pH=2 are injected into the reaction system at a mass ratio of 1:2500. Then, the particles are uniformly dispersed in the hydrochloric acid solution by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system is then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0074] Example 5

[0075] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0076] S2) Reaction solution: Choose a sodium hydroxide solution with pH=12.

[0077] S3) Synthesis: First, a solid catalyst and a sodium hydroxide solution at pH=12 are injected into the reaction system, with a mass ratio of solid catalyst to sodium hydroxide solution of 1:2500. Then, the particles are uniformly dispersed in the sodium hydroxide solution by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system is then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0078] Example 6

[0079] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0080] S2) Reaction solution: Select a 10mM sodium chloride solution.

[0081] S3) Synthesis: First, a solid catalyst and a 10 mM sodium chloride solution were injected into the reaction system, with a mass ratio of solid catalyst to sodium chloride solution of 1:2500. Then, FEP particles were uniformly dispersed in the sodium chloride solution by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0082] Table 2

[0083] As shown in Table 2, nitrate ions were obtained in Examples 4-6. This demonstrates that the method described in this application can facilitate the efficient generation of nitrate ions, and proves the feasibility of using a CEC system in conjunction with different liquid phase systems to synthesize nitrates from air via ultrasonic catalysis under mild conditions. Comparing Examples 4, 5, and 1, it can be seen that the catalyst efficiency of contact electrocatalysis is the highest under neutral conditions. This may be because the presence of hydrogen and hydroxide ions creates a certain charge shielding effect on contact electrification. Example 6 further corroborates this point. Furthermore, the fact that different liquid phase systems can generate nitrate ions also demonstrates the general applicability of this method.

[0084] Example 7

[0085] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0086] S2) Reaction atmosphere: Pure nitrogen (N2)

[0087] S3) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system at a mass ratio of 1:2500. Then, FEP was uniformly dispersed in the water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0088] Example 8

[0089] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0090] S2) Reaction atmosphere: Nitrogen-oxygen mixture (N2:O2=2:3)

[0091] S3) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system at a mass ratio of 1:2500. Then, FEP was uniformly dispersed in the water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0092] Example 9

[0093] This embodiment describes a method for preparing nitrate ions, which may specifically include the following steps: S1) Material selection: FEP particles are used as solid catalysts.

[0094] S2) Reaction atmosphere: Nitrogen-oxygen mixture (N2:O2=3:2)

[0095] S3) Synthesis: First, a solid catalyst and ultrapure water with a resistivity of 18.2 MΩ·cm were injected into the reaction system at a mass ratio of 1:2500. Then, FEP was uniformly dispersed in the water by ultrasonic vibration to establish a contact electrocatalytic CEC system. The system was then reacted under ambient temperature and pressure conditions, utilizing the vibration of ultrasound to continuously generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - The ultrasonic frequency was 40 kHz. Subsequently, samples were taken periodically, and nitrate ions (NO3) in the solution were monitored using ion chromatography. - The concentration change of ).

[0096] Table 3

[0097] As shown in Table 3, nitrate ions were obtained in Examples 7-9. This demonstrates that the method described in this application can facilitate the efficient generation of nitrate ions, and proves the feasibility of using the CEC system with different atmospheres to synthesize nitrates under mild conditions via ultrasonic catalysis. Example 7 demonstrates that even in the absence of oxygen, with only nitrogen present, the CEC system can still effectively fix nitrogen, although the efficiency is lower compared to an air atmosphere. Examples 7-9, along with Example 1, collectively demonstrate that the CEC system achieves the highest nitrogen fixation efficiency when the nitrogen-oxygen ratio is close to that in air, proving that air can serve as a nitrogen source that is both efficient and economical.

[0098] Based on the above data, this embodiment utilizes the unique property of ultrasound as a high-frequency mechanical wave to achieve a nitrogen oxidation process under relatively mild reaction conditions: 40 kHz ultrasound generates micron-sized cavitation bubbles (internal temperature >5000K) in the solution. The shock wave released upon the collapse of these bubbles drives FEP particles to contact and separate from water molecules at high speed. Electron transfer driven by contact electrokinetics promotes the generation of free radicals. Simultaneously, each particle dispersed in the solution can act as a reaction chamber, allowing nitrogen gas to fully contact and rapidly oxidize free radicals. Experiments show that a 3-hour reaction can generate a 10.26 mg / L nitrate solution from 20 mg of catalyst, and no byproducts such as nitrite were detected in the solution, making it suitable for direct application as liquid nitrogen fertilizer. This system achieves the direct conversion of air to nitrogen fertilizer through the propagation and precise control of mechanical energy in a liquid. The resulting nitrate solution, as verified by experiments, significantly improves the growth of mung beans. Specifically, as shown below... Figure 1 As shown.

[0099] in, Figure 1 In the diagram, (a) shows the initial growth of mung beans, and (b) shows the growth after a certain period of growth. The left cup shows the growth of mung beans treated with chemical fertilizer, the middle cup shows the growth of mung beans treated with nitrogen fertilizer according to Example 1 of this application, and the right cup shows the growth of mung beans without any fertilizer.

[0100] Figure 2 and Figure 3 The effects of applying the liquid nitrogen fertilizer of Example 1 of this application on hydroponic mung beans ( Figure 2 ) and wheat ( Figure 3 The study investigated the effect of liquid nitrogen fertilizer on the fresh weight of plants and quantitatively compared this growth-promoting effect with that of commercially available potassium nitrate fertilizer. The blank control group consisted of plants cultured in pure water without any nitrogen fertilizer. The comparison showed that the liquid nitrogen fertilizer used in this embodiment produced an effect almost equivalent to that of commercially available potassium nitrate fertilizer, significantly higher than the blank control group.

[0101] In summary, the nitrate preparation method of this application embodiment can produce nitrate ions using air as a raw material at room temperature and pressure, and effectively promotes the generation of reactive oxygen species by utilizing the contact electrostatic effect, thereby achieving efficient oxidation of nitrogen. Specifically, the preparation method of this application embodiment has the following innovative points: 1) The conversion of air to nitrate ions is achieved at normal temperature and pressure, which helps to reduce dependence on fossil fuels, reduce energy consumption, and reduce carbon emissions.

[0102] 2) Utilizing the difference in electron-binding ability between solid catalysts and liquid surfaces, nitrate ions are produced through efficient and simple ultrasonic treatment. The operation is extremely simple and easy to promote.

[0103] 3) No other gases (such as hydrogen, which is required in traditional nitrogen fixation processes) need to be introduced during the preparation process, thus reducing the emission of harmful gases.

[0104] 4) The nitrate solution prepared in this application can be directly used for crop irrigation, realizing a new smart agriculture model of "instant field synthesis - precise fertilization on demand".

[0105] Based on the same inventive objective, this application also provides a production apparatus that satisfies the above-described preparation method, comprising: an ultrasonic vibration device or a ball milling device, and a filtration device. The ultrasonic vibration device or ball milling device is used to perform ultrasonic vibration treatment or ball milling treatment on the first mixture; the filtration device is used to filter the second mixture to remove the solid catalyst.

[0106] In the production equipment of this application, the ultrasonic vibration device or ball milling device can be directly connected to the welding filtration device. Through automatic control, the second mixture obtained after reaction in the ultrasonic vibration device or ball milling device can be passed into the filtration device according to a preset time. The solid catalyst is removed by filtration. The solid catalyst can be reused and fed back into the ultrasonic vibration device or ball milling device.

[0107] Furthermore, the production equipment in this embodiment can be directly installed on-site in farmland, enabling on-demand synthesis of liquid nitrogen fertilizer. This reduces carbon emissions from traditional nitrogen fertilizer production and transportation, promoting the transformation of nitrogen fertilizer production from "centralized, high-energy-consuming" to "distributed, zero-carbon," and providing a key support for solving the global nitrogen cycle imbalance and achieving sustainable development. In addition, remote monitoring of the production equipment can be achieved by combining it with Internet of Things (IoT) technology.

[0108] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of this application. Therefore, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A method for preparing nitrate, characterized in that, include: A first mixture containing a solid catalyst and a liquid substance is subjected to ultrasonic vibration or ball milling under conditions of contact with a nitrogen-containing gas to obtain a second mixture containing nitrate ions; the second mixture is filtered to remove the solid catalyst to obtain a solution containing nitrate ions; The liquid substance is capable of contacting the solid catalyst to generate oxidative free radicals; the oxidative free radicals can oxidize the nitrogen gas to generate nitrate ions.

2. The preparation method according to claim 1, characterized in that, The solid catalyst includes at least one of polymer materials, oxide materials, and composite materials, satisfying the condition that it can generate electricity upon contact with the liquid substance; the liquid substance includes at least one of inorganic solvents and organic solvents, satisfying the condition that it can generate electricity upon contact with the solid catalyst.

3. The preparation method according to claim 2, characterized in that, The solid catalyst includes at least one of fluorinated ethylene propylene copolymer, polytetrafluoroethylene, nylon, ethyl cellulose, and inorganic oxides.

4. The preparation method according to claim 1, characterized in that, The liquid substance is water, and the water is deionized water.

5. The preparation method according to any one of claims 1-4, characterized in that, In the first mixture, the mass ratio of the solid catalyst to the liquid substance is 1:100 to 1:100000.

6. The preparation method according to any one of claims 1-4, characterized in that, The nitrogen-containing gas contains oxygen.

7. The preparation method according to claim 6, characterized in that, The mass ratio of nitrogen to oxygen is 15:1 to 1:

5.

8. The preparation method according to claim 6, characterized in that, The nitrogen-containing gas is air.

9. The preparation method according to any one of claims 1-4, characterized in that, The process of subjecting a first mixture containing a solid catalyst and a liquid substance to ultrasonic vibration under conditions of contact with a nitrogen-containing gas includes: The first mixture was subjected to ultrasonic vibration treatment in an air atmosphere. Alternatively, air can be introduced into the first mixture and ultrasonic vibration treatment can be applied.

10. The preparation method according to claim 9, characterized in that, The solid catalyst includes at least one of powder catalyst, spherical catalyst or thin film catalyst.

11. A production apparatus for use in the preparation method according to any one of claims 1-10, characterized in that, include: An ultrasonic vibration device or a ball milling device is used to perform ultrasonic vibration treatment or ball milling treatment on the first mixture; Filtration device: used to filter the second mixture to remove the solid catalyst.

Images