Methyl glyoxal preparation device and method

Abstract

The invention relates to a methyl glyoxal preparation device and method. The device comprises a supply system and a reaction flow pipe system, wherein the supply system is connected with the reaction flow pipe system; the supply system comprises a chlorine supply module, a hydroxyacetone supply module and an oxygen supply module; the reaction flow pipe system comprises a reaction flow pipe, and the reaction flow pipe comprises a first connecting section, a second connecting section and a third connecting section; a photolysis module is arranged on the periphery of the first connecting section and comprises a light source assembly and a light reflection enhancing assembly. The light reflection enhancing assembly is arranged on the light propagation path; the chlorine supply module is connected with the first connecting section, the hydroxyacetone supply module is connected with the second connecting section, and the oxygen supply module is connected with the third connecting section. The device is simple and convenient to operate and mild in reaction condition, continuous flow synthesis can be realized, and the reaction efficiency and the product yield are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, and in particular to a methylglyoxal preparation apparatus and method. Background Technology

[0002] Methylglyoxal (CH3COCHO) is a typical intermediate product in the oxidation process of various volatile organic compounds (VOCs) in the atmosphere. It plays a crucial role in the formation mechanisms of secondary pollution, including the atmospheric oxidation cycle, ozone (O3) and free radical reactions, and the formation of secondary organic aerosols (SOA). Therefore, it is of great significance in air pollution research. Currently, various spectroscopic techniques have been applied to the detection of methylglyoxal, but the lack of standard gases for measurement calibration, comparison, and experimental verification limits the accuracy and comparability of related studies. Therefore, the preparation of methylglyoxal standard gases is crucial for a deeper understanding of the formation mechanisms of secondary atmospheric pollution.

[0003] The main methods for preparing methylglyoxal include atmospheric chemical reaction, bio-fermentation, and chemical oxidation. Among these, atmospheric chemical reaction has attracted much attention due to its mild reaction conditions, high controllability, high selectivity, high efficiency, and environmental friendliness. Bio-fermentation utilizes microbial metabolic activity to produce methylglyoxal, but it is limited by natural metabolism, resulting in high costs, poor microbial community stability, difficulty in control, and low yields, making it less economical. Chemical oxidation converts the precursor into methylglyoxal through redox reactions, but it suffers from high costs and separation difficulties. In comparison, atmospheric chemical reaction, based on the photochemical oxidation pathway, has widely available raw materials, mild reaction conditions, and lower catalyst costs, making it more suitable for the laboratory and industrial-scale preparation of methylglyoxal.

[0004] In the field of standard gas preparation, current research mainly focuses on several chemical oxidation routes, including acetone oxidation, propionaldehyde oxidation, and hydroxyacetone oxidation. Although these methods have been studied, they each have their own limitations. 1) The acetone oxidation method, as an important method for the preparation of methylglyoxal, has the advantages of high product selectivity, wide availability of acetone as a raw material, and relatively low price. Under the action of a catalyst, the methyl group in the acetone molecule is gradually oxidized to an aldehyde group by an oxidant, thereby generating methylglyoxal. Commonly used oxidants include selenium dioxide (SeO2), and the reaction needs to be carried out under specific temperature and pressure conditions to obtain high-quality methylglyoxal standard gas. However, the selenium dioxide used in this method is toxic and expensive, increasing production costs. Furthermore, the reaction process may generate selenium-containing waste, causing environmental pollution. In addition, this method requires extremely strict control of reaction conditions, which is not conducive to large-scale industrial production and widespread application.

[0005] 2) The propionaldehyde oxidation method is similar in principle to the acetone oxidation method. In the propionaldehyde molecule, the hydrogen atom adjacent to the aldehyde group is oxidized to a second aldehyde group under the action of a catalyst and oxidant, thereby generating methylglyoxal. However, this method has problems such as low selectivity, many side reactions, high catalyst cost, and difficulty in controlling the preparation precision.

[0006] 3) Existing acetone oxidation methods typically use the reaction of acetone with oxygen to prepare methylglyoxal, oxidizing a methyl group in the acetone molecule to an aldehyde group through an oxidizing agent and catalyst. However, this reaction requires harsh conditions, including high temperature and high pressure, is prone to over-oxidation, has many side reactions, low oxidation selectivity, many by-products, and low raw material conversion rate.

[0007] Therefore, developing a high-efficiency and high-purity methylglyoxal preparation system and method is of great significance for the control of methylglyoxal. Summary of the Invention

[0008] To address the above technical problems, this invention provides an apparatus and method for preparing methylglyoxal, which offers high productivity and simple operation for preparing methylglyoxal standard gas.

[0009] In some embodiments of the present invention, an apparatus for preparing methylglyoxal is provided, comprising a supply system and a reaction flow tube system, wherein the supply system is connected to the reaction flow tube system; The supply system includes a chlorine supply module, a hydroxyacetone supply module, and an oxygen supply module; The reaction flow tube system includes a reaction flow tube, which includes a first connecting section, a second connecting section, and a third connecting section, and the first connecting section, the second connecting section, and the third connecting section are interconnected. The first connecting segment is surrounded by a photolysis module, which includes a light source component and a reflective enhancement component. The light source component can emit light in the range of 200-400nm; the reflective enhancement component is disposed on the light propagation path. The chlorine supply module is connected to the first connecting section, the hydroxyacetone supply module is connected to the second connecting section, and the oxygen supply module is connected to the third connecting section.

[0010] In some embodiments of the present invention, the light source assembly includes a light source and an aperture, the aperture being disposed on the light propagation path of the light source. The aperture, disposed on the light propagation path, is used to control the amount of light transmitted, adjust the intensity and distribution of the light, to meet the needs of subsequent optical reactions or detection. An aperture is installed in front of the xenon lamp to control the output beam with a diameter of 40mm.

[0011] In some embodiments of the present invention, the light source includes a xenon lamp, which comprises a plano-convex lens, a bulb, and a concave reflector. The bulb is located between the plano-convex lens and the concave reflector, and the concave reflector is located on the side away from the reaction flow tube. The convex surface of the plano-convex lens faces the side closer to the reaction flow tube. The internal light source chamber of the xenon lamp adopts a back-reflector structure, with a plano-convex lens on the front and a concave reflector on the rear, which can improve the collection efficiency by 60%. Simultaneously, this structure allows the light source to output a collimated beam.

[0012] In some embodiments of the present invention, the light source assembly is mounted on one side of the first connecting segment.

[0013] In some embodiments of the present invention, the light source assembly and the reflective enhancement assembly are arranged around the periphery of the first connecting segment.

[0014] In some embodiments of the present invention, the reflective enhancement component includes multiple reflectors, each of which includes a mounting component, an elastic buffer, and a reflector. The mounting component is used to mount the reflector, and the elastic buffer is disposed between the mounting component and the reflector. The reflectors are used to reflect and guide light again, optimize the light propagation path, enhance photolysis efficiency, and improve light utilization. The elastic buffer, such as a spring, applies pressure to the reflector through its own elastic deformation, achieving stable installation and fine-tuning of the reflector's attitude. The elastic buffer allows for better adjustment of the reflector angle, increases the number of reflections, significantly improves light energy utilization, and saves energy costs.

[0015] In some embodiments of the present invention, the reflector is a spherical reflector. The spherical reflective enhancement component employs a spherical reflective structure, which ensures multiple reflections of light, enhances the reflection intensity of the effective wavelength, and greatly improves light energy utilization.

[0016] In some embodiments of the present invention, the reflector is a concave reflector.

[0017] In some embodiments of the present invention, the mounting element includes bolts and a fixing plate.

[0018] In some embodiments of the present invention, the reflectivity enhancement assembly includes a first reflector assembly, a second reflector assembly, and a third reflector assembly. The first reflector assembly is mounted on the opposite side of the light source, and the second and third reflector assemblies are disposed between the first reflector assembly and the light source assembly. Each group of reflector assemblies includes two reflectors, and every three consecutive reflectors are distributed at an angle of three-eighths of a circle. The size of the reflective mirror arc surface formed by every three consecutive reflectors matches its curvature.

[0019] In some embodiments of the present invention, the first reflector assembly includes two reflectors that are mirror-symmetrically distributed, and the second reflector assembly and the third reflector assembly each independently include two reflectors that are oppositely distributed on both sides of the first connecting section.

[0020] This distribution method allows for the reflection of multiple segments of parallel light. Light emitted from the xenon lamp is reflected by two intermediate reflectors (i.e., the reflectors in the two reactors of the first reflector assembly) to two mirrors on opposite sides (with the interface being the straight line containing the diameter of the reaction flow tube perpendicular to the light source distribution direction; the mirrors in the second and third reflector assemblies are on the same side as the mirrors in the first reflector assembly). The light is then reflected again to a mirror on the side closest to the xenon lamp, and finally to a mirror on the same side, resulting in at least 3 to 5 reflections. This specific distribution method allows the reflectors to better reflect the focused light, changing the direction of light propagation and allowing more light to enter the reaction area, thus improving photolysis efficiency.

[0021] In some embodiments of the present invention, a temperature control module is provided on the second connecting segment.

[0022] In some embodiments of the present invention, the temperature control module includes a heating element and a temperature feedback element.

[0023] In some embodiments of the present invention, the heating element includes a thermal resistor.

[0024] In some embodiments of the present invention, the heating element includes a resistance wire wound around the outer wall of the second connecting section. The resistance wire is wound around the outer wall, achieving uniform heating, high energy efficiency, low cost, and high efficiency.

[0025] In some embodiments of the present invention, the temperature feedback element includes a temperature sensor installed within the second connection section.

[0026] Heating is achieved through a resistance wire, with a temperature sensor providing real-time temperature feedback. This allows for appropriate adjustment of the resistance wire power, ensuring a uniform and constant temperature within the tube.

[0027] In some embodiments of the present invention, the reaction flow tube is formed by interconnecting a first connecting section, a second connecting section and a third connecting section to form a Y-shaped structure.

[0028] In some embodiments of the present invention, the end of the third connecting segment away from the first and second connecting segments is provided with an exhaust port.

[0029] In some embodiments of the present invention, the third connecting segment is provided with a heat preservation module.

[0030] In some embodiments of the present invention, the third connecting section is a laminar flow tube.

[0031] In some embodiments of the present invention, the heat preservation module includes a heat preservation layer attached to the third connecting section. By setting a heat preservation layer (material such as foam) in the third connecting section, the temperature of the reaction system inside the flow tube is kept constant to maintain the reaction system at the most suitable temperature level during the preparation process, thereby achieving high efficiency and high purity in the production of methylglyoxal.

[0032] In some embodiments of the present invention, the chlorine supply module includes a carrier gas source I, a chlorine gas source and a supply pipeline I, wherein the carrier gas source I and the chlorine gas source are connected to a first connecting section through the supply pipeline I.

[0033] In some embodiments of the present invention, the hydroxyacetone supply module includes a carrier gas source II, a hydroxyacetone gas source, and a supply pipe II, wherein the carrier gas source and the hydroxyacetone gas source are connected to a second connecting section through the supply pipe II.

[0034] In some embodiments of the present invention, the oxygen supply module includes a carrier gas source III, an oxygen source and a supply pipeline III, wherein the carrier gas source III and the oxygen source are connected to a third connecting section through the supply pipeline III.

[0035] In some embodiments of the present invention, the oxygen supply module is connected to the end of the third connecting section away from the exhaust port.

[0036] In some embodiments of the present invention, the carrier gas sources I, II, and III may be the same or different. The carrier gas may be one or more of the following gases: nitrogen, carbon dioxide, helium, etc. (or other inert gases).

[0037] In some embodiments of the present invention, pressure gauges are provided at the connections of the first, second, and third connecting sections to the supply system. The pressure gauges are used to control the flow rate and achieve precise control of the material ratio.

[0038] In other embodiments of the invention, the above-described apparatus is provided for use in determining the concentration of methylglyoxal.

[0039] In other embodiments of the present invention, a method for preparing methylglyoxal using the above-described apparatus is also provided, comprising the following steps: Chlorine gas is introduced into the first connecting section to cause the chlorine gas to undergo a photolysis reaction; Hydroxyacetone is introduced into the second connecting section, and oxygen is introduced into the third connecting section. The photolysis products of chlorine and hydroxyacetone are introduced into the third connecting section, where they mix with oxygen and react to produce methylglyoxal.

[0040] In some embodiments of the present invention, the volume flow ratio of chlorine, hydroxyacetone, and oxygen is 1:1:1. The ratio may also be adjusted as needed.

[0041] In some embodiments of the present invention, the concentrations of chlorine, hydroxyacetone, and oxygen are each independently 5*10. 7 ~10 10 Number of molecules / cm 3 .

[0042] In some embodiments of the present invention, the concentrations of chlorine, hydroxyacetone, and oxygen are 10. 10 Number of molecules / cm 3 .

[0043] In some embodiments of the present invention, the total volumetric flow rate of chlorine, hydroxyacetone, and oxygen (including carrier gas) is 3.0~10 L / min. For example, it is 4 L / min.

[0044] In some embodiments of the present invention, the photolysis reaction takes about 30 ms.

[0045] In some embodiments of the present invention, the temperature of the system during the reaction process is 298K.

[0046] In some embodiments of the present invention, the temperature of the hydroxyacetone is 293-303 K before entering the third connecting section. Preheating the hydroxyacetone in the second connecting section to a suitable reaction temperature before entering the reaction pipeline area is more conducive to ensuring the reaction is in an optimal state.

[0047] In some embodiments of the present invention, the photolysis products of chlorine and hydroxyacetone are introduced into the third connecting section under the propulsion of a carrier gas flow.

[0048] In some embodiments of the present invention, the carrier gas flow is laminar.

[0049] Compared with the prior art, the above-mentioned technical solution of the present invention has the following advantages: The present invention provides a method for efficiently preparing methylglyoxal (CH3COCHO) by using xenon lamp to decompose chlorine gas to generate chlorine free radicals, and then combining this with heating hydroxyacetone, which is then reacted with chlorine free radicals and oxygen through a flow pipe. This apparatus is simple to operate, has mild reaction conditions, and can achieve continuous flow synthesis, significantly improving reaction efficiency and product yield. At a temperature of around 298 K, the yield of methylglyoxal can reach over 96%, demonstrating excellent reactivity and industrial application potential. Attached Figure Description

[0050] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a schematic diagram of the methylglyoxal preparation apparatus in an embodiment of the present invention.

[0051] Figure 2 This is a schematic diagram of the structure of the photolysis module in an embodiment of the present invention.

[0052] Figure 3 This is a graph showing the change in the concentration of substances in the reaction system over time in an embodiment of the present invention. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in each embodiment. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0054] The terms I, II, III, or first, second, and third used in this invention are for distinction only and are not intended to distinguish technical features. They should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0055] Example This example provides an apparatus for preparing methylglyoxal, the structure of which is as follows: Figure 1 As shown, it includes a supply system and a reaction flow tube system, with the supply system connected to the reaction flow tube system. The supply system includes a chlorine supply module, a hydroxyacetone supply module, and an oxygen supply module. The reaction flow tube system includes a reaction flow tube, which includes a first connecting section, a second connecting section, and a third connecting section, which are interconnected. A photolysis module is located around the first connecting section, and the photolysis module includes a light source component and a reflective enhancement component. The light source component can emit light in the 200-400nm range. The reflective enhancement component is located in the light propagation path. The chlorine supply module is connected to the first connecting section, the hydroxyacetone supply module is connected to the second connecting section, and the oxygen supply module is connected to the third connecting section.

[0056] The second connecting section is equipped with a temperature control module, including a resistance wire heating element and a temperature sensor. Specifically, the resistance wire heating element is uniformly wound around the outer wall of the hydroxyacetone channel. When the system is powered on and set to heating mode, the temperature sensor monitors and adjusts the temperature in real time. Hydroxyacetone enters the heating pipe at a certain flow rate and is heated until it reaches a temperature of 298K, at which point it enters the main reaction pipe. To maintain the reaction temperature at its optimal level, a foam insulation layer is attached to the outside of the main reaction mixing channel (i.e., the third connecting section) to ensure a constant internal temperature.

[0057] The third connecting section is equipped with an insulation module, which is a foam insulation layer attached to the third connecting section. Each connecting section has an anti-interference agent inlet, and the end of the third connecting section away from the first and second connecting sections has an exhaust port. The reaction flow tube is formed by interconnecting the first, second, and third connecting sections to form a Y-shaped structure. The oxygen supply module is connected to the end of the third connecting section away from the exhaust port.

[0058] Each connecting section is equipped with a pressure gauge, and temperature sensors can also be installed separately to achieve more precise temperature and pressure control.

[0059] The chlorine supply system includes chlorine cylinders that are fed into the reaction flow pipeline system via an MFC (Mass Flow Controller), and is also connected to nitrogen cylinders whose quantities are controlled by the MFC.

[0060] The hydroxyacetone supply system includes a hydroxyacetone bottle connected to an MFC and a nitrogen bottle controlled by the MFC.

[0061] The oxygen supply system includes oxygen cylinders connected to the MFC and nitrogen cylinders controlled by the MFC.

[0062] Pressure gauges are installed at the connections of the first, second, and third connecting sections to the supply system. These pressure gauges control the flow rate, thereby achieving precise control of the material ratio.

[0063] like Figure 2 As shown, the main components of the photolysis module are a xenon lamp and a reflector enhancement assembly. The xenon lamp is used to photolyze Cl2 to generate Cl free radicals. The reflector enhancement assembly mainly consists of six-sided mirrors that can reflect multiple segments of parallel light. The mirrors are concave and fixed with bolts and mounting plates, with several spring clips in the middle for adjusting the angle of the mirrors, ensuring multiple reflections and greatly improving the utilization rate of light energy. Light emitted from the xenon lamp is reflected by the two middle mirrors to two mirrors on opposite sides, then reflected by them to a mirror on the side closest to the xenon lamp, and then reflected again to the opposite mirror on the same side, resulting in at least 3 to 5 reflections. The reflector enhancement assembly includes multiple reflectors, each of which includes a mounting component, an elastic buffer, and a mirror. The mounting component is used to install the mirror, and the elastic buffer is placed between the mounting component and the mirror. The reflector enhancement assembly is installed on the outside of the xenon lamp and other light source components.

[0064] The light source assembly includes a light source and an aperture, which is positioned in the light propagation path of the light source. The aperture, positioned in the light propagation path, controls the amount of light transmitted, adjusting the intensity and distribution of the light to meet the needs of subsequent optical reactions or detection. An aperture is installed in front of the xenon lamp to control the output beam with a diameter of 40mm. The internal light source chamber of the xenon lamp employs a rear-facing reflector structure, with a plano-convex lens in front of the xenon lamp bulb and a concave reflector behind it, which can improve the collection efficiency by 60%. This light source outputs a collimated beam with a diameter of 46mm, while the aperture, installed in front of the xenon lamp, controls the output beam with a diameter of 40mm.

[0065] To address the low productivity of methylglyoxal, this invention provides a solution where methylglyoxal is produced within a flow tube with controllable flow field and reaction time. This is achieved through precise control of the reaction between hydroxyacetone (CH3COCH2OH) and Cl radicals, followed by a reaction with O2. Cl radicals are generated by photolysis of Cl2 using a xenon lamp at 200nm-400nm wavelength. Since Cl radicals are highly reactive gaseous components, their concentration can be calculated using the photolysis reaction of Cl2. A designed heating device is directly installed outside the methylglyoxal production flow tube, and an insulation layer is attached to the outside of the lower main reaction channel (i.e., the third connecting section) to achieve and maintain the optimal temperature for methylglyoxal production. The atmospheric methylglyoxal production system based on the reaction flow tube includes modules for supplying hydroxyacetone, Cl2, and O2, a reaction flow tube channel, a hydroxyacetone temperature control module, a xenon lamp, and a photolysis module.

[0066] This system can photolyze Cl2 to generate Cl radicals, and heat hydroxyacetone before proceeding with atmospheric chemical reactions through a flow pipe. The 200nm-400nm wavelength emitted by the xenon lamp used can meet the photolysis requirements of Cl2.

[0067] During the reaction, the inner diameter of the flow tube is approximately 20 mm, the length is approximately 500 mm, and the total gas flow rate is approximately 4 L / min. Under this structural design, the gas flow is laminar, which is conducive to low-resistance gas flow and complete reaction. The photolysis module uses a xenon lamp fixed to the side of the flow tube where chlorine gas is introduced. The xenon lamp mainly transmits photolysis light (λ=200nm-400nm) through the lamp, and a reflective enhancement component is installed on the outside.

[0068] The photolysis of Cl2 generates Cl radicals: Cl₂ + hv→Cl + Cl k = 1.54 * 10 -3 s -1 [Cl] = 2[Cl2]σ Cl2 φ Cl Ft In the formula, σCl2 φ is the absorption cross section of the pipe at the photolysis point of the gas. Cl Let Ft be the quantum yield of Cl radicals during photolysis, and Ft be the product of light flux and photolysis time. Therefore, the concentration of Cl radicals generated by photolysis can be determined using the Cl2 concentration.

[0069] During the preparation process, hydroxyacetone is introduced from the right-side pipe (i.e., the second connecting section). The heating device brings the hydroxyacetone to the required K of 298K for the reaction. An insulation layer is attached to the outside of the third connecting section. Cl initiates the oxidation reaction of hydroxyacetone in the third connecting section to generate the intermediate product CH3COCHOH, which further reacts with O2 to form methylglyoxal and HO2.

[0070] Hydroxyacetone reacts with Cl free radicals to produce intermediate products and hydrogen chloride: CH3COCH2OH + Cl→CH3COCHOH + HCl K = 5.6 * 10 -11 cm 3 / molecule / s(298K) The intermediate product further reacts with O2 to give methylglyoxal: CH3COCHOH + O2→CH3COCHO + HO2 K=3.0*10 -12 cm 3 / molecule / s(298K) The aforementioned temperature control system includes a resistance wire heating element and a temperature sensor. The resistance wire heating element is mounted on the outside of the hydroxyacetone flow pipe. When energized, the resistance wire heats the pipe. Hydroxyacetone flows through the pipe and merges with Cl into the lower main pipe. A foam insulation layer is attached to the outside of the lower main pipe to reduce heat loss and ensure the reaction temperature is maintained at 298K. Since methylglyoxal has the highest yield (up to 96%) at 298K, a temperature sensor is installed in the hydroxyacetone channel. Real-time temperature monitoring by the sensor allows for precise control of the reaction conditions. Real-time feedback from the temperature sensor allows for appropriate adjustment of the resistance wire power, ensuring uniform temperature within the pipe. At 298K, the yield reaches a maximum of 96%, significantly higher than at lower temperatures, with fewer byproducts. The resistance wire is wound around the outer wall, achieving uniform heating, high energy efficiency, low cost, and high efficiency. Temperature control within the flow pipe is crucial for ensuring the efficient and high-purity production of methylglyoxal.

[0071] In this invention, a xenon lamp is used to cleave Cl2 to produce Cl. A reflective enhancement component is installed to strengthen the reaction and improve the photolysis efficiency. The xenon lamp output spectrum has a high degree of overlap with the absorption peak of chlorine photolysis. The reflective enhancement component uses a spherical reflective structure, which ensures multiple reflections of light, enhances the reflection intensity of the effective wavelength, and greatly improves the utilization rate of light energy.

[0072] Simulation of laminar flow field and gas injection control in flow tube, adjusting reaction time according to gas concentration and reaction constant, thereby precisely controlling reaction products.

[0073] The method for preparing methylglyoxal using the above-described apparatus specifically includes the following steps: Chlorine gas is introduced into the first connecting section, and the xenon lamp (reference data for the xenon lamp used in this embodiment is as follows: model is LSB-X150, power is 150W, current is 8.5A, voltage is 18V, luminous flux is 3200lm, luminous intensity is 320cd, luminous area size is 0.8*2.0mm, bulb size is 127*20mm, and expected life is 1000h) is turned on to allow the chlorine gas to undergo a photolysis reaction; Hydroxyacetone is introduced into the second connecting section to heat the electric heating resistance wire to 298K, and oxygen is introduced into the third connecting section. Driven by a nitrogen gas flow, the photolysis products of chlorine and hydroxyacetone enter the third connecting section, mix with oxygen, and react (the temperature is maintained at 298K during the reaction) to obtain methylglyoxal (the production efficiency can reach 96%).

[0074] During the reaction, the total flow rate of the gases (including chlorine, hydroxyacetone, oxygen, and nitrogen) is approximately 4 L / min, and the initial concentration ratio of chlorine, hydroxyacetone, and oxygen is approximately 1:1:1, with each concentration being 10. 10 Number of molecules / cm 3 In the first 37.5 microseconds, the photolysis of chlorine gas mainly occurs in the flow pipe. The chlorine concentration decreases rapidly in an exponential manner, and the Cl concentration rises rapidly to its peak as chlorine decomposes. After 37.5 microseconds, photolysis ends, and hydroxyacetone and oxygen begin to participate in the reaction. The Cl concentration decreases rapidly as the intermediate CH3COCHOH is produced with hydroxyacetone. However, as CH3COCHOH reacts with oxygen to form methylglyoxal, the Cl concentration gradually decreases, and methylglyoxal gradually forms as the final product until hydroxyacetone is completely consumed. The concentration changes of the substances involved in the reaction are as follows: Figure 3 As shown in Table 1.

[0075] Table 1 The concentration units in Table 1 are molecules per cm³. 3 The time unit is microseconds.

[0076] From Table 1 and Figure 3 It can be seen that the reaction time directly affects the completion of the reaction process. Too short a time will result in incomplete conversion of reactants, while too long a time will easily lead to side reactions. Accurate control of the flow rate can ensure the sufficiency and efficiency of the reaction. At 272K and 252K, the production efficiency of methylglyoxal is lower than that at 298K, and the by-products increase significantly. If the reaction temperature can be precisely controlled at 298K, the production efficiency of methylglyoxal can be greatly increased to 96%.

[0077] In conclusion, controlling the reaction time and temperature are key factors in ensuring the efficiency of methylglyoxal formation. Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An apparatus for preparing methylglyoxal, characterized in that, It includes a supply system and a reaction flow tube system, wherein the supply system is connected to the reaction flow tube system; The supply system includes a chlorine supply module, a hydroxyacetone supply module, and an oxygen supply module; The reaction flow tube system includes a reaction flow tube, which includes a first connecting section, a second connecting section, and a third connecting section, and the first connecting section, the second connecting section, and the third connecting section are interconnected. The first connecting segment is surrounded by a photolysis module, which includes a light source component and a reflective enhancement component. The light source component can emit light in the range of 200-400nm; the reflective enhancement component is disposed on the light propagation path. The chlorine supply module is connected to the first connecting section, the hydroxyacetone supply module is connected to the second connecting section, and the oxygen supply module is connected to the third connecting section.

2. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The light source assembly includes a light source and an aperture, with the aperture positioned on the light propagation path of the light source.

3. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The light source assembly and the reflective enhancement assembly are arranged around the periphery of the first connecting section. The reflective enhancement assembly includes multiple reflectors, each of which includes a mounting component, an elastic buffer component, and a reflector. The mounting component is used to mount the reflector, and the elastic buffer component is disposed between the mounting component and the reflector.

4. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The reflector is a spherical reflector; and / or, the reflector is a concave reflector.

5. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The reflectivity enhancement component includes a first reflector component, a second reflector component, and a third reflector component. The first reflector component is mounted on the opposite side of the light source, and the second and third reflector components are disposed between the first reflector component and the light source component. The first reflector component includes two reflectors that are symmetrically distributed in a mirror image, and the second and third reflector components each independently include two reflectors that are oppositely distributed on both sides of the first connecting section.

6. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The second connecting section is equipped with a temperature control module, which includes a heating element and a temperature feedback element.

7. The apparatus for preparing methylglyoxal according to claim 1, characterized in that, The reaction flow tube is formed by interconnecting a first connecting section, a second connecting section, and a third connecting section to form a Y-shaped structure.

8. The use of the apparatus according to any one of claims 1 to 7 in the determination of methylglyoxal concentration.

9. A method for preparing methylglyoxal using the apparatus according to any one of claims 1 to 7, characterized in that, Includes the following steps: Chlorine gas is introduced into the first connecting section to cause the chlorine gas to undergo a photolysis reaction; Hydroxyacetone is introduced into the second connecting section, and oxygen is introduced into the third connecting section. The photolysis products of chlorine and hydroxyacetone are introduced into the third connecting section, where they mix with oxygen and react to produce methylglyoxal.

10. The method for preparing methylglyoxal according to claim 9, characterized in that, The system is at a temperature of 293~303K during the reaction process; and / or the photolysis reaction time is greater than 30s.

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