Nitrogen activation device and method based on ultrasonic atomization

Abstract

The invention discloses a nitrogen activation device and method based on ultrasonic atomization. The device comprises a split atomization chamber, a sample inlet, an ultrasonic atomization module, a condensation module, a gas circuit module and a detection module. The method comprises the following steps that a split type atomizing chamber is placed in a condensation module, water is added into the split type atomizing chamber, gas in the split type atomizing chamber is replaced with nitrogen-oxygen mixed gas or nitrogen-ozone mixed gas, the device is kept closed, micro-droplets are generated through an ultrasonic atomizing device, and continuous activation of nitrogen is completed; by collecting the gas and the liquid drops for analysis and detection, ppmv-level nitrous oxide and nitrate can be generated per hour; the method is simple to operate, micro-droplets can be circularly generated, and continuous reaction is promoted; according to the invention, nitrogen activation can be realized only through less electric energy; the device disclosed by the invention can stably maintain a closed state and ensure no gas leakage in a reaction process; the method is green and efficient, and nitrogen can be continuously and stably activated only in air.

Description

Technical Field

[0001] The invention belongs to the field of air pollution prevention and control and atmospheric science technology, and relates to a method and device for generating micro-droplets based on ultrasonic continuous atomization of liquid water and then activating nitrogen. Background Art

[0002] Nitrogen (N2) is the most abundant gas in the atmosphere, accounting for about 78% of the total volume of the atmosphere. However, since the N2 molecule is composed of a nitrogen-nitrogen triple bond, it is extremely stable and difficult to activate directly. Converting stable N2 into highly active and usable nitrogen-containing compounds has become an important challenge for humans to utilize nitrogen resources.

[0003] Traditional N2 resource recovery technology (such as the Haber-Bosch process) relies on high-energy consumption processes, requiring high temperature and high pressure conditions to break the triple bond structure of N2 and thus recover it. Although this process is widely used in fertilizer production, its high energy consumption and environmental impact limit its sustainable development in the future. In addition, small-scale or decentralized waste gas treatment systems are difficult to utilize such large-scale devices, so it is urgent to develop more flexible, energy-saving and efficient N2 resource recovery technology.

[0004] Microdroplets with a particle size of 1 to 100 μm have a large specific surface area, rich active substances and a strong surface electric field. Previous studies have found that the microdroplet interface can accelerate chemical reactions or make non-spontaneous reactions proceed spontaneously. Therefore, the microdroplet interface can provide a unique environment for N2 activation. Ordinary microdroplet reactions often use pneumatic spraying, which can only achieve microdroplet reactions at the microsecond to millisecond level. Therefore, there is a problem of difficulty in continuously converting N2. At the same time, due to the influence of high-speed airflow, it is difficult to ensure the airtightness of the device in this process, and there is a problem of product loss caused by airflow. Summary of the invention

[0005] In view of the limitations of the prior art, the present invention provides a method and device for continuous activation of nitrogen based on ultrasonic atomization, which overcomes the problems of high energy consumption, inability to continuously activate, and poor air tightness of traditional methods, and aims to achieve continuous activation of N2 in a green and efficient manner.

[0006] The technical solution of the present invention:

[0007] A nitrogen activation device based on ultrasonic atomization, comprising a split atomization chamber, a sample inlet, an ultrasonic atomization module, a condensation module, a gas path module and a detection module;

[0008] in,

[0009] The split type atomization chamber comprises a glass cover, a glass bottom, a flange and a gasket, wherein the flange and the gasket are used to connect the glass cover and the glass bottom; the injection port is arranged on the upper part of the glass cover;

[0010] The ultrasonic atomization module is mainly composed of an ultrasonic atomization sheet (1.7MHz / 2.4MHz / 3.0MHz) and an ultrasonic control circuit module. The ultrasonic atomization sheet is embedded in the bottom opening of the glass, and the ultrasonic control circuit module is placed on the outside, and the two are connected;

[0011] The condensation module consists of two layers, the inner layer matches the glass bottom, and the outer layer is cylindrical. The inner layer and the outer layer are connected to each other and can hold a sufficient amount of condensate. The split atomization chamber is placed in the condensation module to maintain a stable temperature.

[0012] The gas path module is connected to the sample inlet and is used to replace the gas in the split type atomization chamber;

[0013] The detection module comprises an air pump and a detection instrument, wherein the outlet of the air pump is a three-way connection, which is respectively connected to the sample inlet, the atmosphere and the detection instrument.

[0014] A N2 activation method based on ultrasonic atomization, the steps are as follows:

[0015] S1: Place the split spray chamber in the condensation module;

[0016] S2: Add water into the split nebulizer chamber from the sample inlet;

[0017] S3: Only the inlet connected to the air pump is left open, and the other inlets are closed; the air in the split-type atomization chamber is extracted by the air pump until the vacuum degree is below -0.08MPa, so that the split-type atomization chamber is vacuumed;

[0018] S4: Open the inlet connected to the gas line and deliver the nitrogen-oxygen mixed gas or nitrogen-ozone mixed gas into the split type spray chamber;

[0019] S5: Repeat steps S3 to S4 several times to ensure that there is no other gas in the split atomization chamber, and close all injection ports to ensure the airtightness of the device;

[0020] S6: Turn on the atomization module to perform ultrasonic atomization treatment;

[0021] S7: Open the inlet connected to the gas pump, and draw the gas in the split nebulizer chamber into the gas chromatograph for nitrous oxide detection, collect the nebulized liquid and perform ion chromatography to detect nitrate production.

[0022] The beneficial effects of the present invention are as follows: micro-droplets can be cyclically generated by ultrasonic atomization mechanism, and the particle size of the generated micro-droplets ranges from 1 to 100 μm. N2 first reacts with H2O·- at the interface of the micro-droplets through a reduction-oxidation mechanism, and is activated to HN2·, and then reacts with oxidizing substances, such as O2 or O3, to generate N2O and nitrates. The present invention overcomes the problems of high energy consumption, inability to continuously activate, and poor air tightness of traditional methods, and can achieve continuous activation of N2 in a green and efficient manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the whole device.

[0024] Figure 2 These are the qualitative results of the Fourier transform infrared spectroscopy (FTIR) of nitrous oxide (N2O) generation, where a is the FTIR spectrum of the N2O standard; b is the FTIR spectrum of the nitrogen (N2)-oxygen (O2)-microdroplet product; and c is the FTIR spectrum of the N2-ozone (O3)-microdroplet product.

[0025] Figure 3 These are the qualitative results of gas chromatography (GC) of N2O generation, where a is the GC chromatogram of N2O standard; b is the GC chromatogram of N2-O2-microdroplet product; and c is the GC chromatogram of N2-O3-microdroplet product.

[0026] Figure 4 These are the qualitative results of gas chromatography-mass spectrometry (GC-MS) generated for N2O, where a is the GC-MS total ion current of N2O standard; b is the GC-MS mass spectrum of N2O standard; c is the GC-MS extracted ion chromatogram of N2-O2-microdroplet product; d is the GC-MS mass spectrum of N2-O2-microdroplet product; e is the GC-MS extracted ion chromatogram of N2-O3-microdroplet product; and f is the GC-MS mass spectrum of N2-O3-microdroplet product.

[0027] Figure 5 The N2O production changes with time under different gas ratios. The gas ratio is nitrogen: other gases = 4:1, O2: O3 = 0.98: 0.02. In the figure: 1 split atomization chamber; 2 injection port; 3 ultrasonic atomization module; 4 condensation module; 5 gas path module; 6 detection module; 7 glass cover; 8 glass bottom; 9 flange and gasket; 10 ultrasonic atomization sheet; 11 ultrasonic control circuit module; 12 air pump; 13 detection instrument; 14 ozone generator. DETAILED DESCRIPTION The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions. Example 1 like Figure 1As shown, a micro-droplet generation device based on an ultrasonic mechanism includes a split atomization chamber 1, an inlet 2, an ultrasonic atomization module 3, a condensation module 4, an air path module 5 and a detection module 6. The inlet is divided into multiple ports, port a is connected to the air path pipeline, port b is used to add samples, and port c is connected to the air pump. The glass cover 7 and glass bottom 8 of the split atomization chamber 1 are connected and sealed by a flange and a gasket 9. The bottom of the glass bottom 8 is embedded with an ultrasonic atomization sheet 10 of the ultrasonic atomization device, and the split atomization chamber 1 is placed in the condensation module 4. First, add enough ice cubes and other condensed materials to the condensation module 4, add a certain amount of water to the split atomization chamber 1 through the b port of the sample inlet 2, and seal the whole device. Subsequently, open the c port, use the air pump 12 to extract the gas in the split atomization chamber 1, extract it to below -0.08Mpa, open the air path at the a port, insert the target reaction gas, that is, nitrogen (N2)-oxygen (O2) mixed gas or N2-ozone (O3) mixed gas, repeat several times until the purity of the gas in the atomization chamber reaches the target, and then close all air paths to ensure the air tightness of the device. Finally, open the atomization module, circulate and generate micro droplets in the split atomization chamber 1, and after the reaction is completed, open the c port pipeline to draw the gas into the air bag or detection instrument 13. The gas products are qualitatively analyzed by using Fourier transform infrared spectroscopy (FTIR), gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The gas products and blank gas samples were analyzed using a NicoletTM iS20 FTIR equipped with a gas chamber. The collected gas products and blank gas samples were injected into the gas chamber of the FTIR and mixed and diluted with pure N2. –1 Within the range, the sample peak is measured at 8 cm –1 The resolution was scanned 16 times. The characteristic peak of N2O is between 2300 and 2150 cm- 1 In the range, the standard FTIR spectrum ( Figure 2 a) Spectra of N2-O2-microdroplets and N2-O2-O3-microdroplets ( Figure 2 Comparison between (b) and (c) shows that the microdroplets react to generate N2O. N2O was analyzed using a Tianmei GC 7980 gas chromatograph equipped with an electron capture detector (ECD). The gas samples were separated on a PoraPlot Q capillary column (50 m × 0.53 mm id × 20 μm film thickness, Agilent Technologies). The column oven temperature was set to 70 °C for 10 min. N2 was used as the carrier gas with a constant flow rate of 27.68 mL min-1. 1The gas sample was injected in split mode with a split ratio of 3:1. The injection volume was set to 1 mL and the injection port temperature was maintained at 250 °C. The ECD detector was operated at 300 °C with N2 as makeup gas at a flow rate of 40 mL min-1. 1 The retention time of N2O is in the range of 6.6–6.8 min, as shown by the GC spectrum of the standard product ( Figure 3 a) Spectra of N2-O2-microdroplets and N2-O3-microdroplets ( Figure 3 Comparison between (b) and (c) shows that the microdroplets react to generate N2O. Agilent 6890N-5975 GC-MS was used to further identify N2O. A PoraPlot Q capillary column was used for separation, and helium was used as the carrier gas at a constant flow rate of 4.5 mL min- 1 . The initial column oven temperature was set to 50°C and maintained for 10 minutes without a temperature gradient. Manual injection was performed in splitless mode with an injection volume of 250 μL. The inlet temperature was adjusted to 150°C, and a purge flow of 60.0 mL min-1 was started 0.75 minutes after injection. The transfer line temperature of the mass spectrometer was set to 230°C. The mass spectrometer was operated in full scan mode (SCAN). The electron ionization source (EI) was operated at 230°C and the quadrupole mass filter was maintained at 150°C. The ion monitoring time was 100 ms. The retention time of N2O was in the range of 5.0–6.0 min, as shown by the total ion current and mass spectrum of the standard ( Figure 4 a, 4b) and N2-O2-microdroplet, N2-O3-microdroplet spectra ( Figure 4 c-4f) By comparison, it can be seen that the microdroplets react to produce N2O. Example 2 A standard curve was established using N2O standard gas on a GC with an ECD detector, and the changes in N2O concentration with reaction time (10, 20, 30, 40, 50 and 60 min) were measured. Figure 5 It can be seen that in the gas mixed with N2 and argon at a ratio of 4:1, the concentration of N2O remained at 0 ppbv throughout the experiment. In contrast, for the same mixed gas, the presence of microdroplets caused the N2O concentration to gradually increase from the initial 0.00 to 2.83 ppmv as the reaction time increased. The production rate of N2O was about 2.83 ± 0.41 ppmv h-1. At 1.00 mol m- 3 In the presence of O3, the production of N2O was 1.64 times that in the presence of O2, indicating that O3 was more effective than O2 in promoting the formation of N2O.

[0028] From the above results, it can be seen that the method of activating nitrogen (N2) by using micro-droplets based on the ultrasonic principle has the following advantages: (1) The reaction can be carried out continuously, and micro-droplets with a particle size range of 1 to 100 μm can be continuously circulated to promote the continuous occurrence of the reaction; (2) Low energy consumption. The present invention can continuously activate N2 and generate nitrogen oxides with only a small amount of electrical energy; (3) Good airtightness. The previous micro-droplet device requires a large amount of airflow and is difficult to maintain a closed state. The device of the present invention can stably maintain a closed state to ensure that there is no gas leakage during the reaction. (4) Green and efficient. The previous N2 activation requires catalysts, high temperature and high pressure and other means, which may lead to the generation of environmentally harmful byproducts and consume a lot of energy. The present invention can continuously and stably activate N2 only in the air.

[0029] The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions and reaction devices belonging to the present invention belong to the protection scope of the present invention. For ordinary technicians, improvements and modifications without departing from the principles and experimental schemes of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A nitrogen activation device based on ultrasonic atomization, characterized in that: The nitrogen activation device comprises a split atomization chamber, a sample inlet, an ultrasonic atomization module, a condensation module, a gas path module and a detection module; in, The split type atomization chamber comprises a glass cover, a glass bottom, a flange and a gasket, wherein the flange and the gasket are used to connect the glass cover and the glass bottom; the injection port is arranged on the upper part of the glass cover; The ultrasonic atomization module is mainly composed of an ultrasonic atomization sheet and an ultrasonic control circuit module. The ultrasonic atomization sheet is embedded in the opening of the glass bottom, and the ultrasonic control circuit module is placed on the outside, and the two are connected; The condensation module consists of two layers, and the split atomization chamber is placed in the condensation module; The gas path module is connected to the sample inlet and is used to replace the gas in the split type atomization chamber; The detection module comprises an air pump and a detection instrument, wherein the outlet of the air pump is a three-way connection, which is respectively connected to the sample inlet, the atmosphere and the detection instrument.

2. The nitrogen activation device according to claim 1, characterized in that: The frequency of the ultrasonic atomizer is 1.7 MHz, 2.4 MHz or 3.0 MHz.

3. The nitrogen activation device according to claim 1, characterized in that: The inner layer shape of the condensation module matches the glass bottom, the outer layer is cylindrical, and the inner layer is connected to the outer layer.

4. A nitrogen activation method based on ultrasonic atomization, characterized in that: Here are the steps: S1: Place the split spray chamber in the condensation module; S2: Add water into the split nebulizer chamber from the sample inlet; S3: Only the inlet connected to the air pump is left open, and the other inlets are closed; the air in the split-type atomization chamber is extracted by the air pump until the vacuum degree is below -0.08MPa, so that the split-type atomization chamber is vacuumed; S4: Open the inlet connected to the gas line and deliver the nitrogen-oxygen mixed gas or nitrogen-ozone mixed gas into the split type spray chamber; S5: Repeat steps S3 to S4 several times to ensure that there is no other gas in the split atomization chamber, and close all injection ports to ensure the airtightness of the device; S6: Turn on the atomization module to perform ultrasonic atomization treatment; S7: Open the inlet connected to the gas pump, and draw the gas in the split nebulizer chamber into the gas chromatograph for nitrous oxide detection, collect the nebulized liquid and perform ion chromatography to detect nitrate production.

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