Synthetic method of nitric acid

Abstract

The invention discloses a method for synthesizing nitric acid, which comprises the following steps: placing water in a spark discharge area, ionizing the water to generate water free radical cation clusters, introducing air into a discharge reaction cavity, reacting water free radical cations with the air to obtain a product nitric acid, and collecting the nitric acid in a product collection area. By simulating the atmospheric discharge experiment, air in the atmosphere and water fully act to prepare nitric acid, so that the problems of raw material dependence, high energy consumption, high cost and the like in the existing nitric acid preparation method are solved, and efficient preparation of nitric acid is realized under relatively mild conditions by directly taking air as a raw material. The method has important practical significance and economic value.

Description

Technical Field

[0001] The present invention relates to the fields of chemical basis and green economy, and in particular to a synthesis method for preparing nitric acid by utilizing the reaction of air and water free radicals. Background Art

[0002] Nitric acid is an important chemical raw material widely used in the production of fertilizers, explosives, and nylon precursors. Currently, nitric acid is mainly produced by the Oswald oxidation of ammonia, which is produced from the reaction of N2 and H2 via the high-temperature, high-pressure, and energy-intensive Haber-Bosch synthesis. Therefore, the industrial production of nitric acid is energy-intensive and associated with significant carbon emissions. Directly converting N2 and O2 from air into HNO3 under mild conditions is considered a promising sustainable production method. However, the direct reaction of N2 and O2 to form nitrogen oxides (NOx) is thermodynamically limited at room temperature and pressure. Furthermore, the stability of the triple bond of N2 and the low activity of O2 make the synergistic activation and efficient conversion of the two molecules challenging.

[0003] Water is an essential element for life, present in a wide range of processes, daily life, and industrial production, playing a key role. Water-related research has always been a major topic in science. In-depth research into the chemical properties of gas-phase water radical cations has profound implications for understanding fundamental scientific questions such as the origin of life, aging mechanisms, energy conversion, and chemical synthesis. For example, water radical cations play a vital role in a variety of natural phenomena, including proton transfer, hydrogen bond formation, cell damage, and atmospheric and interstellar chemistry. Consequently, research on water radical cations has garnered increasing attention worldwide and is showing a growing trend. At the application level, the potential value of water radical cations in radiobiology and clinical medicine is gaining increasing attention. Furthermore, water radical cations can serve as primary ions in mass spectrometry, effectively improving detection sensitivity and selectivity. Furthermore, their high activity enables them to exhibit excellent catalytic properties in chemical reactions.

[0004] This study designed a novel reactor that simulates the ionization of water under discharge and introduces air containing 78% nitrogen to explore the generation of substances such as nitric acid, providing new insights into possible pathways for sustainable production. Studying water radical cation reactions, which are essential for the synthesis of life's fundamental building blocks, holds significant scientific value for exploring new green economic chemistry. Summary of the Invention

[0005] The present invention aims to provide a novel reaction for the rapid synthesis of nitric acid based on the reaction of water radical cations with air. This invention can provide new ideas for research related to the green and economical synthesis of nitric acid. The technical solutions of the present invention are as follows:

[0006] A method for synthesizing nitric acid comprises directly placing water in a reaction device, ionizing water molecules through discharge to generate water radical cation clusters, and simultaneously introducing air into the reaction device. Under normal temperature and pressure conditions, the water radical cations interact with the air to convert nitrogen in the air into nitric acid.

[0007] Furthermore, the discharge voltage in the reaction device is 5-8 kV.

[0008] Furthermore, the reaction device includes a reaction chamber, an array plate located in the reaction chamber, and a gas output port and a gas source inlet connected to the reaction chamber. A stainless steel reaction tank is provided in the reaction chamber, the array plate is connected to the positive electrode of the high-voltage source, the stainless steel tank is connected to the negative electrode of the high-voltage source, and a water input channel and a product output channel are provided on the stainless steel tank.

[0009] Furthermore, air is introduced into the air source inlet.

[0010] Furthermore, a plurality of discharge needles are configured in a grid on the array plate.

[0011] Furthermore, the stainless steel tank has a size of 32.4×32.4×1.5 cm.

[0012] Furthermore, the discharge needle is made of tungsten needle material, the distance between the discharge needle tip and the water level in the stainless steel tank is between 10 and 30 mm, and the curvature radius of the needle tip is between 0.01 and 0.1 mm.

[0013] Furthermore, the product output channel is also connected to a mass spectrometer and an ion chromatography detector.

[0014] Furthermore, the composition of the air is nitrogen: oxygen: rare gas: carbon dioxide = 78:21:0.939:0.03.

[0015] Furthermore, isotope D labeling and isotope 18 O labeling, through the corresponding primary mass spectrometry data and secondary mass spectrometry data analysis, it can be known that there are corresponding orders of magnitude of ions, which can determine the complex products of the reaction between water radical ions and air.

[0016] The present invention has the beneficial effect of utilizing discharge to generate water molecules into water radical cation clusters. The resulting water radical cation clusters react with air to generate nitric acid molecules, which then dissolve in a stainless steel tank to produce nitric acid. The present invention aims to provide a novel reaction for rapidly synthesizing nitric acid based on the reaction of water radical cations with air, which could provide new insights into research related to green economic chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0018] Figure 1 Schematic diagram of the structure of the nitric acid preparation device according to an embodiment of the present invention: 1 - gas output port, 2 - gas source inlet, 3 - water input channel, 4 - distance adjustment device, 5 - high-voltage source positive electrode, 6 - high-voltage source negative electrode; 7 - product output channel, 8 - adjustment scale, 9 - sealing slide bar, 10 - reaction chamber, 11 - stainless steel tank, 12 - array plate;

[0019] Figure 2 The mass spectrum of nitric acid prepared by the reaction of water radical cations with air is compared with that of standard nitric acid;

[0020] Figure 3 The ion chromatogram of nitric acid prepared by the reaction of water free radical cations with air and standard nitric acid. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0023] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0024] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0025] See also Figure 1-Figure 3, a nitric acid preparation device used in a nitric acid synthesis method proposed in one embodiment of the present invention ( Figure 1 ), specifically including a reaction chamber 10, a gas output port 1, a gas source inlet 2, a water input channel 3, a distance adjustment device 4, a high-voltage source positive electrode 5 and a product output channel 7, and a stainless steel tank 11 is provided in the reaction chamber 10.

[0026] The gas output port 1 is connected to a mechanical pump, which can be used to evacuate the gas in the sealed reaction chamber 10 to make the chamber reach a vacuum state.

[0027] The gas source inlet 2 is used to fill the air in the air bag into the reaction chamber 10 .

[0028] The water input channel 3 is connected to the product output channel 7. After water is input into the reaction chamber 10 through the input channel 3, it reacts in the stainless steel tank 11 to generate nitric acid, which is then output and collected through the product output channel 7. The stainless steel tank 11 is connected to the negative electrode 6 of the high-voltage source.

[0029] The distance adjustment device 4 is connected to the array plate 12 in the reaction chamber 10, and the distance between the needle tip and the water surface can be adjusted by adjusting the height of the array. Preferably, the distance between the needle tip and the water surface is optimized between 10-30 mm, and a height adjustment scale 8 can be provided to control the height.

[0030] The array plate 12 and the stainless steel tank 11 are respectively connected to the positive electrode and the negative electrode of a high voltage source. Preferably, the voltage of the high voltage source is 6.5 kV.

[0031] A reaction space is defined between the array plate 12 and the stainless steel tank 11 . Air is introduced into the reaction space. 900 mL of water is placed in the stainless steel tank 11 .

[0032] The array plate 12 is composed of 841 tungsten needles (with a tip diameter of 60 μm) arranged in a 29×29 grid configuration and connected to the positive electrode of the high voltage source.

[0033] The size of the stainless steel tank 11 is 32.4×32.4×1.5 cm.

[0034] Based on the above device, the method for preparing nitric acid includes:

[0035] The air in the reaction chamber 10 is pumped out by a mechanical pump through the gas outlet 1 to make the sealed reaction chamber reach a vacuum state. Then, air is input into the reaction chamber 10 through the gas source inlet 2, and water is injected into the stainless steel tank 11 in the reaction chamber 10 through the water input channel 3. Then, the height of the array plate 12 is adjusted.

[0036] The high voltage source is turned on and voltage is applied to the array plate 12, causing the needle tips of the discharge array needles to generate spark discharges and ionize the surrounding water vapor to form water radical cation clusters. The formed water radical cation clusters react with nitrogen in the air to produce nitric acid molecules, which condense into liquid and are further collected through the product output channel 7.

[0037] Specifically, by applying a high voltage (6.5kV) to the array plate, a spark discharge is generated at the tip of the discharge needle tip. At room temperature and pressure (for example, 25°C, one atmosphere of pressure), nitrogen in the air is used as a nitrogen source, and water radical cation clusters are generated through high-voltage spark discharge. The water radical cation clusters are fully in contact with the air gas and react to produce nitric acid molecules. The formed nitric acid molecules are condensed into liquid, stored in a stainless steel tank, and collected through the product output channel 7.

[0038] The following examples verify the preparation results of the above-mentioned method for preparing nitric acid:

[0039] Example 1

[0040] At room temperature and pressure, 10 L of air was introduced into the chamber of the reaction device, and 900 mL of water was measured into the discharge reaction chamber. A high voltage (6.5 kV) was applied to the discharge needle 7 and the reaction was carried out for 10 minutes. The generated nitric acid molecules were discharged through the product output channel to the sample collection area to produce nitric acid.

[0041] Example 2

[0042] At room temperature and pressure, 10 L of air was introduced into the chamber of the reaction device, and 900 mL of water was measured into the discharge reaction chamber. A high voltage (6.5 kV) was applied to the discharge needle 7 and the reaction was carried out for 20 minutes. The generated nitric acid molecules were discharged to the sample collection area through the product output channel to produce nitric acid.

[0043] Example 3

[0044] At room temperature and pressure, 10 L of air was introduced into the chamber of the reaction device, and 900 mL of water was measured into the discharge reaction chamber. A high voltage (6.5 kV) was applied to the discharge needle 7 and the reaction was carried out for 30 minutes. The generated nitric acid molecules were discharged to the sample collection area through the product output channel to produce nitric acid.

[0045] Test 1: The product of Example 3 was subjected to mass spectrometry and chromatography analysis. From the results of mass spectrometry data, the collected nitric acid product was characterized by the negative ion mode of ionization mass spectrometry, such as Figure 2 The product nitric acid m / z 62 (NO3 - ) signal, which is consistent with the results measured in the negative ion mode of the standard nitrate ( Figure 2 (b) Figure 2Figure c is a TIC diagram of online mass spectrometry research on air using the corona discharge method, as shown in Figure 4. Figure 2 As shown in (d), the signals of m / z 63 and m / z 64 can be clearly observed in the online mass spectrum, corresponding to HNO3 and H2NO3, respectively. + (Nitric acid binds one proton).

[0046] Test 2: Prepare a 20mmol / L NaOH solution as the flushing solution and identify the nitric acid produced by air through ion chromatography. Figure 3 The reaction sample exhibited a peak at 4.8 min, which was consistent with the experimental data from mass spectrometry.

[0047] In summary, according to the nitric acid synthesis method proposed in this embodiment, the entire synthesis process can be carried out at room temperature and pressure (referring to pressure), without the need for chemical catalysts, saving energy, and being green and pollution-free.

[0048] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0049] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for synthesizing nitric acid, characterized in that: Water is directly placed in the reaction device, and water molecules are ionized by discharge to produce water radical cation clusters. At the same time, air is introduced into the reaction device. Under normal temperature and pressure conditions, the water radical cations interact with the air to convert nitrogen in the air into nitric acid.

2. The method for synthesizing nitric acid according to claim 1, wherein: The discharge voltage in the reaction device is 5-8 kV.

3. The method for synthesizing nitric acid according to claim 1, wherein: The reaction device includes a reaction chamber, an array plate located in the reaction chamber, and a gas output port and a gas source inlet connected to the reaction chamber. A stainless steel reaction tank is provided in the reaction chamber. The array plate is connected to the positive electrode of the high-voltage source, the stainless steel tank is connected to the negative electrode of the high-voltage source, and a water input channel and a product output channel are provided on the stainless steel tank.

4. The method for synthesizing nitric acid according to claim 3, wherein: Air is introduced into the air source inlet.

5. The method for synthesizing nitric acid according to claim 3, wherein: A plurality of discharge needles are arranged in a grid on the array plate.

6. The method for synthesizing nitric acid according to claim 3, wherein: The stainless steel tank has a size of 32.4×32.4×1.5 cm.

7. The method for synthesizing nitric acid according to claim 5, wherein: The discharge needle is made of tungsten needle material, the distance between the discharge needle tip and the water level in the stainless steel tank is between 10 and 30 mm, and the curvature radius of the needle tip is between 0.01 and 0.1 mm.

8. The method for synthesizing nitric acid according to claim 3, wherein: The product output channel is also connected to a mass spectrometer and an ion chromatography detector.

9. The method for synthesizing nitric acid according to claim 1, wherein: The composition of the air is nitrogen: oxygen: rare gas: carbon dioxide = 78:21:0.939:0.03.

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