Microreactor-based nitrosation reaction method

Abstract

The invention belongs to the technical field of nitrosation, and particularly relates to a nitrosation reaction method based on a microreactor, which comprises the following steps: step 1, adding sodium nitrite into distilled water, and stirring at constant temperature to obtain a material A; 2, adding NW acid into a hydrochloric acid aqueous solution, and uniformly stirring to obtain a material B; 3, the material A enters a reaction pipe through a reaction material inlet, the material B is introduced into an acidic material pipe, the pressure in the reaction pipe is controlled to be slightly smaller than that of the acidic material pipe, cooling water is introduced, and nitrosation liquid is obtained through a reaction. According to the invention, the blank of the existing miniaturized nitrosation reaction is solved, the microreactor is used as a reaction system, and an online small-amount mixing reaction is formed through a flow type reaction, so that the heat transfer efficiency and the reaction conversion rate are effectively improved, and the reaction risk of a nitrosation dangerous process is eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of nitrosation, and in particular relates to a nitrosation reaction method based on a microreactor. Background Art

[0002] Nitrosation refers to the reaction of nitrous acid with aromatic rings at low temperature to introduce nitroso groups on the aromatic rings. This reaction is an exothermic reaction and has recently been listed as a hazardous process. In order to improve the heat transfer efficiency of the reaction and reduce the risk of the reaction, miniaturization of reaction equipment is an effective means. With the continuous improvement of safety requirements, miniaturized reaction systems have gradually received attention. At the same time, miniaturized reactions are gradually replacing traditional industrial processes based on the characteristics of small reaction volume and strong controllability of hazards. However, although nitrosation reactions are classified as hazardous reactions, there are no records of related miniaturized reactions. Summary of the invention

[0003] In view of the problems in the prior art, the present invention provides a nitrosation reaction method based on a microreactor, which solves the gap in the existing miniaturized nitrosation reaction. The microreactor is used as the reaction system, and an online small amount of mixed reaction is formed through a flow reaction, which effectively improves the heat and mass transfer efficiency and conversion rate of the nitrosation reaction.

[0004] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0005] A nitrosation reaction method based on a microreactor comprises the following steps:

[0006] The structure of the microreactor includes a reaction tube, an acidic material tube and a guide tube, wherein the reaction tube and the acidic material tube are arranged in parallel, and the reaction tube and the acidic material tube are connected by a plurality of parallel guide tubes, and the plurality of guide tubes are arranged at intervals from top to bottom; the reaction tube includes a reaction material tube and a cooling tube, wherein the reaction material tube and the cooling tube are arranged coaxially, and the diameter of the cooling tube is smaller than the diameter of the reaction material tube, the guide tube is connected to the reaction material tube, and a reaction material inlet located at the upper end of the reaction material tube and a reaction material outlet located at the lower end of the reaction material tube are arranged on the side of the reaction material tube away from the guide tube, A first pressure gauge and a thermometer are provided between the reaction material inlet and the reaction material outlet, the first pressure gauge is used to measure the pressure in the reaction material pipe, and the thermometer is used to measure the temperature in the reaction material pipe; the upper end of the cooling pipe is a cooling water outlet, and the lower end is a cooling water inlet; a second pressure gauge is provided in the acidic material pipe, and the second pressure gauge is used to measure the pressure of the acidic material pipe; a one-way valve is provided in each of the guide pipes, and the two ends of the one-way valve are respectively connected to the reaction pipe and the acidic material pipe; a partition is provided between the reaction material pipe and the cooling pipe, and the partition is located on one side of the reaction material pipe inlet;

[0007] Step 1, adding sodium nitrite to distilled water and stirring at a constant temperature to obtain material A, wherein the mass concentration of material A is 30%, the temperature of the constant temperature stirring is 15-20° C., and the stirring speed is 200-300 r / min;

[0008] Step 2, adding NW acid to the hydrochloric acid aqueous solution and stirring uniformly to obtain material B, wherein the material B is a suspension, and the mass fraction of NW acid in the material B is 4%, the stirring speed of the uniform stirring is 200-300 r / min, and the temperature is 5-8° C.; the pH of the material B is less than 1;

[0009] Step 3, material A is introduced into the reaction tube through the reaction material inlet, material B is introduced into the acid material tube, the pressure in the reaction tube is controlled to be slightly lower than that in the acid material tube, and cooling water is introduced to react to obtain a nitrite liquid; the cooling water is an ice-water mixture, and the reaction temperature of the nitrite liquid is 5-10°C.

[0010] This process uses an ice-water mixture as a coolant, which can significantly reduce the temperature of the reaction zone in the reaction tube, ensuring that the reaction system always reacts in the range of 5-10°C, reducing the impact of temperature on the overall reaction. At the same time, the pressure in the reaction tube is lower than that in the acid material tube, which can ensure that the material in the acid material is continuously pumped into the reaction tube to achieve a mixed reaction in the reaction tube.

[0011] Furthermore, in order to improve the fluidity of material A in the entire material reaction tube and to form rapid dispersion during material mixing, the outer surface of the cooling tube is subjected to surface treatment. This surface treatment can not only effectively improve the specific surface area of ​​the cooling tube, but also increase the contact area between the cooling tube and the liquid surface, and improve the heat convection between the two, thereby better controlling the temperature in the reaction area; at the same time, the roughening after the surface treatment can increase the non-directional undercurrent in material A, provide conditions for subsequent uniform mixing, and facilitate the dispersion of material B; the surface treatment of the cooling tube includes the following steps: a1, repeatedly coating the surface of the cooling tube with an ethanol aqueous solution for 3-10 times, and rinsing with distilled water to obtain a cooling tube with a clean surface, wherein the ethanol volume ratio of the ethanol aqueous solution is 40-50%, and the coating amount of the repeated coating is 5-10mL / cm 2 , the temperature is 40-50°C; the distilled water washing speed is 3-5mL / cm 2, this step uses repeated coating to continuously cover the ethanol-water solution on the surface of the cooling tube to form a gradient penetration structure, and uses the activity of the ethanol-water at a temperature to penetrate the surface, thereby dissolving or penetrating the surface impurities; and the impurities are completely released during the distilled water rinsing process to obtain a cooling tube with a clean surface; a2, the cooling tube is subjected to surface wire drawing treatment, and then rinsed with distilled water to obtain a surface roughened cooling tube, the surface wire drawing treatment adopts a thread wire drawing process, and the thread wire drawing process is from top to bottom; the flushing flow rate is 5-10mL / min, and the temperature is 20-30℃; further, the wire drawing treatment is a small-angle thread wire drawing treatment, which can form a thread wire drawing groove on the outer surface of the cooling tube, and the wire drawing belongs to a small-angle thread wire drawing; a3, the surface of the roughened cooling tube is sprayed with acid after drying, and it is left to stand for 20-30min, and the temperature is increased and purged to obtain a pre-treated cooling tube, the drying temperature is 20-30℃, and the spray amount of the acid is 4-7mL / cm 2 , and the acid solution is a sulfuric acid-hydrochloric acid mixture with a pH of 6, the mass ratio of sulfuric acid to hydrochloric acid is 1:3-5, the standing temperature is 5-10°C, the temperature of the heating and purging is 100-120°C, and the purging adopts dry nitrogen purging; this step uses a spray method to coat the acid solution on the surface of the liquid surface, and removes impurities on the surface by standing after deposition, thereby forming micro-corrosion under the wire drawing system, forming micro-corrosion from a subtle angle, and improving the surface roughness. At the same time, during the heating and purging process, as the distilled water and hydrochloric acid are removed, the sulfuric acid concentration continues to rise, and the wire drawing forms a rough surface layer under the action of concentrated sulfuric acid and temperature, thereby forming passivation, thereby improving the overall acid resistance; a4, the surface of the pre-treated cooling tube is coated with an ethanol aqueous solution and left to stand for 20-30 minutes, and a cooling tube with a rough and passivated surface is obtained after rinsing with distilled water; the volume proportion of ethanol in the ethanol aqueous solution is 50-60%, and the coating amount is 10-15mL / cm 2 , the standing temperature is 20-30℃; the flushing speed is 2-3mL / min; this step uses ethanol aqueous solution to form a liquid film on the surface, thereby using the solubility of distilled water in sulfuric acid to achieve the removal effect, and remove the liquid film during the flushing process, thereby forming a clean surface. This surface treatment can form a threaded wire drawing on the cooling tube. When material A enters the material reaction tube, the liquid flow of material A directly impacts the surface of the cooling tube and forms a spiral liquid flow along the wire drawing groove on the surface of the cooling tube. At this time, the wire drawing groove has good guidance, which helps the directional flow of the liquid flow and provides good mixing for the subsequent entry of material B, that is, it helps the dispersed mixing of material B. At the same time, the micro-corrosiveness during the surface treatment process can effectively improve the multi-dimensional surface structure of the wire drawing groove and form surface passivation.

[0012] It can be seen from the above description that the present invention has the following advantages:

[0013] 1. The present invention solves the gap in the existing miniaturized nitrosation reaction, takes a microreactor as the reaction system, forms an online small amount of mixed reaction through a flow reaction, effectively improves the heat transfer efficiency and reaction conversion rate, and eliminates the reaction risk of the dangerous nitrosation process.

[0014] 2. The present invention uses surface treatment to roughen the surface of the cooling tube, thereby improving the fluidity of material A and the mixing effect of material A and material B, thereby achieving the purpose of improving reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0016] Figure 2 It is a horizontal cross-sectional view of the reaction material inlet in the embodiment of the present invention. DETAILED DESCRIPTION

[0017] Combination Figure 1 and Figure 2 , describes in detail a specific embodiment of the present invention, but does not limit the claims of the present invention.

[0018] Example 1

[0019] A nitrosation reaction method based on a microreactor comprises the following steps:

[0020] like Figure 1 and Figure 2As shown, the structure of the microreactor includes a reaction tube 1, an acidic material tube 2 and a guide tube 3, wherein the reaction tube 1 and the acidic material tube 2 are arranged in parallel, and the reaction tube 1 and the acidic material tube 2 are connected by a plurality of parallel guide tubes 3, and the plurality of guide tubes 3 are arranged at intervals from top to bottom; the reaction tube 1 includes a reaction material tube 1-1 and a cooling tube 1-3, wherein the reaction material tube 1-1 and the cooling tube 1-3 are coaxially arranged, and the diameter of the cooling tube 1-3 is smaller than the diameter of the reaction material tube 1-1, and the guide tube 3 is connected to the reaction material tube 1-1, and a reaction material inlet 1-12 located at the upper end of the reaction material tube 1-1 and a reaction material outlet 1-13 located at the lower end of the reaction material tube are arranged on the side of the reaction material tube 1-1 away from the guide tube 3, and the reaction material A first pressure gauge 1-11 and a thermometer 1-14 are provided between the reaction material inlet 1-12 and the reaction material outlet 1-13, the first pressure gauge 1-11 is used to measure the pressure in the reaction material pipe, and the thermometer is used to measure the temperature in the reaction material pipe; the upper end of the cooling pipe 1-3 is a cooling water outlet 1-32, and the lower end is a cooling water inlet 1-31; a second pressure gauge 2-1 is provided in the acidic material pipe 2, and the second pressure gauge is used to measure the pressure of the acidic material pipe 2; each of the flow guide pipes 3 is provided with a one-way valve 3-1, and the two ends of the one-way valve 3-1 are respectively connected to the reaction pipe 1 and the acidic material pipe 2; a partition 1-4 is provided between the reaction material pipe 1-2 and the cooling pipe 1-3, and the partition 1-4 is located on one side of the reaction material pipe inlet 1-12;

[0021] Step 1, adding sodium nitrite to distilled water and stirring at a constant temperature to obtain material A, wherein the mass concentration of material A is 30%, the constant temperature stirring temperature is 15° C., and the stirring speed is 200 r / min;

[0022] Step 2, adding NW acid to the hydrochloric acid aqueous solution and stirring uniformly to obtain material B, wherein the material B is a suspension, and the mass fraction of NW acid in the material B is 4%, the stirring speed of the uniform stirring is 200 r / min, and the temperature is 5° C.; the pH of the material B is less than 1;

[0023] Step 3, material A is introduced into the reaction tube through the reaction material inlet, material B is introduced into the acidic material tube, the pressure in the reaction tube is controlled to be slightly lower than that in the acidic material tube, and cooling water is introduced to react to obtain a nitrite liquid; the cooling water is an ice-water mixture, and the reaction temperature of the nitrite liquid is 5°C.

[0024] The surface treatment of the cooling tube comprises the following steps: a1, repeatedly coating the surface of the cooling tube with an ethanol aqueous solution for 3 times, and washing with distilled water to obtain a cooling tube with a clean surface, wherein the volume proportion of ethanol in the ethanol aqueous solution is 40%, and the coating amount of the repeated coating is 5 mL / cm 2, the temperature is 40°C; the distilled water washing speed is 3mL / cm 2 a2, the cooling tube is subjected to surface drawing treatment, and then rinsed with distilled water to obtain a surface roughened cooling tube, the surface drawing treatment adopts a thread drawing process, and the thread drawing process is from top to bottom; the flushing flow rate is 5mL / min, and the temperature is 20°C; the drawing treatment is a small-angle thread drawing treatment, a3, the surface of the roughened cooling tube is dried and sprayed with acid, left to stand for 20 minutes, and the temperature is raised and purged to obtain a pre-treated cooling tube, the drying temperature is 20°C, and the spraying amount of the acid is 4-7mL / cm 2 , and the acid solution is a sulfuric acid-hydrochloric acid mixture with a pH of 6, the mass ratio of sulfuric acid to hydrochloric acid is 1:3, the standing temperature is 5°C, the temperature of the heating and purging is 100°C, and the purging is carried out by dry nitrogen purging; a4, the surface of the pre-treated cooling tube is coated with an ethanol aqueous solution and allowed to stand for 20 minutes, and a cooling tube with a roughened and passivated surface is obtained after rinsing with distilled water; the volume proportion of ethanol in the ethanol aqueous solution is 50%, and the coating amount is 10mL / cm 2 The standing temperature is 20°C and the flushing speed is 2mL / min.

[0025] The conversion rate of the nitrosation reaction in this embodiment is 85%, which is higher than the conversion rate of about 82% in the conventional nitrosation reaction. At the same time, the obtained product particles are smaller and no large-scale equipment is required.

[0026] Example 2

[0027] A nitrosation reaction method based on a microreactor comprises the following steps:

[0028] like Figure 1 and Figure 2As shown, the structure of the microreactor includes a reaction tube 1, an acidic material tube 2 and a guide tube 3, wherein the reaction tube 1 and the acidic material tube 2 are arranged in parallel, and the reaction tube 1 and the acidic material tube 2 are connected by a plurality of parallel guide tubes 3, and the plurality of guide tubes 3 are arranged at intervals from top to bottom; the reaction tube 1 includes a reaction material tube 1-1 and a cooling tube 1-3, wherein the reaction material tube 1-1 and the cooling tube 1-3 are coaxially arranged, and the diameter of the cooling tube 1-3 is smaller than the diameter of the reaction material tube 1-1, and the guide tube 3 is connected to the reaction material tube 1-1, and a reaction material inlet 1-12 located at the upper end of the reaction material tube 1-1 and a reaction material outlet 1-13 located at the lower end of the reaction material tube are arranged on the side of the reaction material tube 1-1 away from the guide tube 3, and the reaction material A first pressure gauge 1-11 and a thermometer 1-14 are provided between the reaction material inlet 1-12 and the reaction material outlet 1-13, the first pressure gauge 1-11 is used to measure the pressure in the reaction material pipe, and the thermometer is used to measure the temperature in the reaction material pipe; the upper end of the cooling pipe 1-3 is a cooling water outlet 1-32, and the lower end is a cooling water inlet 1-31; a second pressure gauge 2-1 is provided in the acidic material pipe 2, and the second pressure gauge is used to measure the pressure of the acidic material pipe 2; each of the flow guide pipes 3 is provided with a one-way valve 3-1, and the two ends of the one-way valve 3-1 are respectively connected to the reaction pipe 1 and the acidic material pipe 2; a partition 1-4 is provided between the reaction material pipe 1-2 and the cooling pipe 1-3, and the partition 1-4 is located on one side of the reaction material pipe inlet 1-12;

[0029] Step 1, adding sodium nitrite to distilled water and stirring at a constant temperature to obtain material A, wherein the mass concentration of material A is 30%, the constant temperature stirring temperature is 20° C., and the stirring speed is 300 r / min;

[0030] Step 2, adding NW acid to the hydrochloric acid aqueous solution and stirring uniformly to obtain material B, wherein the material B is a suspension, and the mass fraction of NW acid in the material B is 4%, the stirring speed of the uniform stirring is 300 r / min, and the temperature is 8° C.; the pH of the material B is less than 1;

[0031] Step 3, material A is introduced into the reaction tube through the reaction material inlet, material B is introduced into the acidic material tube, the pressure in the reaction tube is controlled to be slightly lower than that in the acidic material tube, and cooling water is introduced to react to obtain a nitrite liquid; the cooling water is an ice-water mixture, and the reaction temperature of the nitrite liquid is 10°C.

[0032] The surface treatment of the cooling tube comprises the following steps: a1, repeatedly coating the surface of the cooling tube with an ethanol aqueous solution 10 times, and washing with distilled water to obtain a cooling tube with a clean surface, wherein the volume proportion of ethanol in the ethanol aqueous solution is 50%, and the coating amount of the repeated coating is 10 mL / cm 2, the temperature is 50°C; the distilled water washing speed is 5mL / cm 2 a2, the cooling tube is subjected to surface drawing treatment, and then rinsed with distilled water to obtain a surface roughened cooling tube, the surface drawing treatment adopts a thread drawing process, and the thread drawing process is from top to bottom; the flushing flow rate is 5-10mL / min, and the temperature is 30°C; the drawing treatment is a small-angle thread drawing treatment, a3, the surface of the roughened cooling tube is dried and sprayed with acid, left to stand for 30 minutes, and the temperature is raised and purged to obtain a pre-treated cooling tube, the drying temperature is 30°C, and the spray volume of the acid is 7mL / cm 2 , and the acid solution is a sulfuric acid-hydrochloric acid mixture with a pH of 6, the mass ratio of sulfuric acid to hydrochloric acid is 1:3-5, the standing temperature is 10°C, the temperature of the heating and purging is 120°C, and the purging is carried out by dry nitrogen purging; a4, the surface of the pre-treated cooling tube is coated with an ethanol aqueous solution and allowed to stand for 20-30 minutes, and a cooling tube with a roughened and passivated surface is obtained after rinsing with distilled water; the volume proportion of ethanol in the ethanol aqueous solution is 60%, and the coating amount is 15mL / cm 2 The standing temperature is 30°C and the flushing speed is 3 mL / min.

[0033] The conversion rate of the nitrosation reaction in this embodiment is 90%, which is higher than the conversion rate of about 82% in the conventional nitrosation reaction. At the same time, the obtained product particles are smaller and no large-scale equipment is required.

[0034] Example 3

[0035] A nitrosation reaction method based on a microreactor comprises the following steps:

[0036] like Figure 1 and Figure 2As shown, the structure of the microreactor includes a reaction tube 1, an acidic material tube 2 and a guide tube 3, wherein the reaction tube 1 and the acidic material tube 2 are arranged in parallel, and the reaction tube 1 and the acidic material tube 2 are connected by a plurality of parallel guide tubes 3, and the plurality of guide tubes 3 are arranged at intervals from top to bottom; the reaction tube 1 includes a reaction material tube 1-1 and a cooling tube 1-3, wherein the reaction material tube 1-1 and the cooling tube 1-3 are coaxially arranged, and the diameter of the cooling tube 1-3 is smaller than the diameter of the reaction material tube 1-1, and the guide tube 3 is connected to the reaction material tube 1-1, and a reaction material inlet 1-12 located at the upper end of the reaction material tube 1-1 and a reaction material outlet 1-13 located at the lower end of the reaction material tube are arranged on the side of the reaction material tube 1-1 away from the guide tube 3, and the reaction material A first pressure gauge 1-11 and a thermometer 1-14 are provided between the reaction material inlet 1-12 and the reaction material outlet 1-13, the first pressure gauge 1-11 is used to measure the pressure in the reaction material pipe, and the thermometer is used to measure the temperature in the reaction material pipe; the upper end of the cooling pipe 1-3 is a cooling water outlet 1-32, and the lower end is a cooling water inlet 1-31; a second pressure gauge 2-1 is provided in the acidic material pipe 2, and the second pressure gauge is used to measure the pressure of the acidic material pipe 2; each of the flow guide pipes 3 is provided with a one-way valve 3-1, and the two ends of the one-way valve 3-1 are respectively connected to the reaction pipe 1 and the acidic material pipe 2; a partition 1-4 is provided between the reaction material pipe 1-2 and the cooling pipe 1-3, and the partition 1-4 is located on one side of the reaction material pipe inlet 1-12;

[0037] Step 1, adding sodium nitrite to distilled water and stirring at a constant temperature to obtain material A, wherein the mass concentration of material A is 30%, the temperature of the constant temperature stirring is 18° C., and the stirring speed is 250 r / min;

[0038] Step 2, adding NW acid to a hydrochloric acid aqueous solution and stirring uniformly to obtain material B, wherein the material B is a suspension, and the mass fraction of NW acid in the material B is 4%, the stirring speed for the uniform stirring is 250 r / min, and the temperature is 7° C.; the pH of the material B is less than 1;

[0039] Step 3, material A is introduced into the reaction tube through the reaction material inlet, material B is introduced into the acidic material tube, the pressure in the reaction tube is controlled to be slightly lower than that in the acidic material tube, and cooling water is introduced to react to obtain a nitrite liquid; the cooling water is an ice-water mixture, and the reaction temperature of the nitrite liquid is 8°C.

[0040] The surface treatment of the cooling tube comprises the following steps: a1, repeatedly coating the surface of the cooling tube with an ethanol aqueous solution for 7 times, and washing with distilled water to obtain a cooling tube with a clean surface, wherein the volume proportion of ethanol in the ethanol aqueous solution is 45%, and the coating amount of the repeated coating is 8 mL / cm 2, the temperature is 45°C; the distilled water washing speed is 4mL / cm 2 a2, the cooling tube is subjected to surface drawing treatment, and then rinsed with distilled water to obtain a surface roughened cooling tube, the surface drawing treatment adopts a thread drawing process, and the thread drawing process is from top to bottom; the flushing flow rate is 8mL / min, and the temperature is 25°C; the drawing treatment is a small-angle thread drawing treatment, a3, the surface of the roughened cooling tube is dried and sprayed with acid, left to stand for 25 minutes, and the temperature is raised and purged to obtain a pre-treated cooling tube, the drying temperature is 25°C, and the spray volume of the acid is 6mL / cm 2 , and the acid solution is a sulfuric acid-hydrochloric acid mixture with a pH of 6, the mass ratio of sulfuric acid to hydrochloric acid is 1:4, the standing temperature is 8°C, the temperature of the heating and purging is 110°C, and the purging is carried out by dry nitrogen purging; a4, the surface of the pre-treated cooling tube is coated with an ethanol aqueous solution and allowed to stand for 25 minutes, and a cooling tube with a roughened and passivated surface is obtained after rinsing with distilled water; the volume proportion of ethanol in the ethanol aqueous solution is 55%, and the coating amount is 13mL / cm 2 The standing temperature is 25°C and the flushing speed is 3 mL / min.

[0041] The conversion rate of the nitrosation reaction in this embodiment is 89%, which is higher than the conversion rate of about 82% in the conventional nitrosation reaction. At the same time, the obtained product particles are smaller and no large-scale equipment is required.

[0042] It is understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.

Claims

1. A nitrosation reaction method based on a microreactor, characterized in that: The steps include: The structure of the microreactor includes a reaction tube, an acidic material tube and a guide tube, wherein the reaction tube and the acidic material tube are arranged in parallel, and the reaction tube and the acidic material tube are connected by a plurality of parallel guide tubes, and the plurality of guide tubes are arranged at intervals from top to bottom; the reaction tube includes a reaction material tube and a cooling tube, wherein the reaction material tube and the cooling tube are arranged coaxially, and the diameter of the cooling tube is smaller than the diameter of the reaction material tube, the guide tube is connected to the reaction material tube, and a reaction material inlet located at the upper end of the reaction material tube and a reaction material outlet located at the lower end of the reaction material tube are arranged on the side of the reaction material tube away from the guide tube, A first pressure gauge and a thermometer are provided between the reaction material inlet and the reaction material outlet, the first pressure gauge is used to measure the pressure in the reaction material pipe, and the thermometer is used to measure the temperature in the reaction material pipe; the upper end of the cooling pipe is a cooling water outlet, and the lower end is a cooling water inlet; a second pressure gauge is provided in the acidic material pipe, and the second pressure gauge is used to measure the pressure of the acidic material pipe; a one-way valve is provided in each of the guide pipes, and the two ends of the one-way valve are respectively connected to the reaction pipe and the acidic material pipe; a partition is provided between the reaction material pipe and the cooling pipe, and the partition is located on one side of the reaction material pipe inlet; Step 1, adding sodium nitrite into distilled water and stirring at a constant temperature to obtain material A; Step 2, adding NW acid to aqueous hydrochloric acid solution and stirring evenly to obtain material B; Step 3, material A is introduced into the reaction tube through the reaction material inlet, material B is introduced into the acid material tube, the pressure in the reaction tube is controlled to be slightly lower than that in the acid material tube, and cooling water is introduced to react to obtain a nitrite liquid.

2. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The mass concentration of material A in step 1 is 30%.

3. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The constant temperature stirring in step 1 is 15-20° C., and the stirring speed is 200-300 r / min.

4. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The material B in step 2 is a suspension, and the mass fraction of NW acid in the material B is 4%.

5. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The stirring speed for uniform stirring in step 2 is 200-300 r / min, and the temperature is 5-8° C.; the pH of material B is less than 1.

6. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The cooling water in step 3 is an ice-water mixture, and the reaction temperature of the nitrite solution is 5-10°C.

7. The nitrosation reaction method based on a microreactor according to claim 1, characterized in that: The outer surface of the cooling pipe is surface treated.

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