Method for realizing continuous synthesis and crystallization control of nitroguanidine by using continuous flow multi-stage stirring reactor

Abstract

The invention discloses a method for realizing continuous synthesis and crystallization control of nitroguanidine by using a continuous flow multi-stage stirring reactor. The method comprises the following steps: weighing perfluorinated sulfonic acid resin, placing the perfluorinated sulfonic acid resin in a catalyst cage, and mounting the catalyst cage in the continuous flow multi-stage stirring reactor; setting the temperature of a reaction section to be 20-50 DEG C and the temperature of a crystallization section to be-20-10 DEG C; introducing concentrated sulfuric acid in advance to fill an internal channel of the continuous flow multi-stage stirring reactor; guanidine nitrate and concentrated sulfuric acid are premixed and then introduced into the reactor, and the retention time of a reaction section is 0.5-10 min; water is introduced into the crystallization section, and the standing time in the crystallization section is 1-30 min; and collecting a reaction product solution, washing with cold water, and filtering. The continuous synthesis of the nitroguanidine prepared by the sulfuric acid method is realized, the mass and heat transfer efficiency is greatly improved, the reaction time is greatly shortened, the product yield is greatly improved, and the maximum yield of the nitroguanidine is 98%.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor. Background Technology

[0002] Nitroguanidine is an important industrial raw material, widely used in military applications such as propellants and explosives due to its moderate energy, low combustion temperature, and low sensitivity. It remains a common propellant in modern long-range, large-caliber artillery. Furthermore, nitroguanidine derivatives are widely used in food processing, pharmaceuticals, biology, and environmental fields. Currently, the production of nitroguanidine both domestically and internationally is mainly based on batch reactors, which have disadvantages such as large temperature fluctuations, poor stability, and large amounts of waste acid.

[0003] Patents CN112920091A and CN112778165A respectively describe a process for preparing nitroguanidine and a method for preparing ultrafine nitroguanidine, employing a continuous batch process and a batch process, respectively. Patent CN117427576A describes a continuous nitroguanidine preparation apparatus and process, using sodium nitrite, urea, benzaldehyde, sodium hydroxide, and nitric acid as raw materials. Patent CN112138614A describes a continuous nitroguanidine production system and process, employing a nitric acid process with guanidine nitrate and concentrated nitric acid as raw materials. The reaction section uses a microchannel reactor, and the crystallization section uses a crystallization vessel. The crude guanidine after crystallization requires multiple water washings and centrifugation to obtain nitroguanidine with a water content of 25%. Patent CN115160188A describes a method for preparing nitroguanidine in a microchannel, employing a microchannel reactor and a continuous crystallizer. The weight ratio of concentrated sulfuric acid to guanidine nitrate is 2–2.5:1 (i.e., a molar ratio of approximately 4.61–5.77:1), and the crystallization time is 3–10 hours. Patents CN110204461A, CN115724773A, CN115671778A, and CN115819287A respectively describe a nitroguanidine crystal and its microchannel crystallization process and apparatus, a method for preparing ultrafine nitroguanidine using a supergravity hydrolysis crystallization method, a process and apparatus for continuous preparation of ultrafine nitroguanidine, and an ultrafine columnar nitroguanidine and its preparation method, mainly focusing on the crystallization process of nitroguanidine. Summary of the Invention

[0004] The purpose of this invention is to propose a method for the continuous synthesis and crystallization control of nitroguanidine using a continuous flow multistage stirred reactor. This method uses guanidine nitrate and sulfuric acid as raw materials and utilizes a continuous flow multistage stirred reactor to achieve the continuous synthesis and crystallization of nitroguanidine. It has advantages such as high mass and heat transfer efficiency, short reaction time, high product yield, precise control of product particle size, low liquid holdup, easy catalyst recovery, low sulfuric acid consumption, environmental friendliness, and high safety, laying the foundation for large-scale production.

[0005] To achieve the above objectives, the technical solution adopted by the present invention includes: A method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multistage stirred reactor includes the following steps: weighing perfluorosulfonic acid resin and placing it in a catalyst cage, which is then installed in a continuous flow multistage stirred reactor; setting the reaction section temperature to 20–50°C and the crystallization section temperature to -20–10°C. Pre-fill the internal channels of the continuous flow multi-stage stirred reactor with concentrated sulfuric acid; Guanidine nitrate and concentrated sulfuric acid are premixed and then introduced into the reactor. The residence time in the reaction section is 0.5 to 10 minutes. Water is introduced into the crystallization section and the residence time in the crystallization section is 1 to 30 minutes. The reaction product solution is collected, washed with cold water, and filtered to obtain the final product.

[0006] Optionally, the continuous flow multistage stirred reactor has 5 to 20 stages, the mass of perfluorosulfonic acid resin in each catalyst cage is 0.1 to 2 g, and the mass hourly space velocity is 10 to 400 h⁻¹. -1 .

[0007] Optionally, the perfluorosulfonic acid resin is Nafion resin and / or Aquivion resin.

[0008] Optionally, the temperature of the reaction section is 30–50°C, and the temperature of the crystallization section is -10–10°C.

[0009] Optionally, the molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1 to 1:2.

[0010] Optionally, the molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1 to 1:1.5.

[0011] Optionally, the residence time of the reaction section is 0.5 to 5 minutes.

[0012] Optionally, the residence time of the crystallization segment is 5 to 20 minutes.

[0013] Compared with the prior art, the beneficial effects of the present invention are reflected in: (1) By using a continuous flow multi-stage stirred reactor, the continuous synthesis of nitroguanidine by the sulfuric acid method was realized, which greatly improved the mass and heat transfer efficiency, significantly shortened the reaction time, and greatly increased the product yield. The highest yield of nitroguanidine was 98%.

[0014] (2) By using a continuous flow multi-stage stirred reactor, continuous crystallization and particle size control of nitroguanidine can be achieved. By adjusting the reactor conditions, the particle size of the product can be precisely controlled and meet the national military standard particle size requirements.

[0015] (3) The use of a continuous flow multistage stirred reactor greatly reduces the liquid holdup of the reaction and improves the safety of the reaction.

[0016] (4) Combine the catalyst cage in the continuous flow multi-stage stirred reactor to achieve rapid catalyst recovery.

[0017] (5) Solid superacid perfluorosulfonic acid resin is used as catalyst. After long-term operation, the catalyst can be reused after simple treatment.

[0018] (6) By using solid superacid perfluorosulfonic acid resin catalyst, the amount of sulfuric acid used in the reaction can be greatly reduced, the cost and the amount of waste acid can be reduced, the pressure of waste liquid treatment can be greatly reduced, and the environment is friendly. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 The image shows the SEM image of nitroguanidine, the product prepared in Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] This invention utilizes a continuous-flow multi-stage stirred reactor to achieve several key advantages: First, it enables the continuous synthesis of nitroguanidine via the sulfuric acid process, significantly improving mass and heat transfer efficiency, drastically shortening reaction time, and substantially increasing product yield, with a maximum yield of 98% for nitroguanidine. Second, it achieves continuous crystallization and particle size control of nitroguanidine. By adjusting reactor conditions, precise particle size control can be achieved, meeting national military standards for particle size. Third, it significantly reduces the liquid holdup in the reaction, improving reaction safety. Fourth, the catalyst cage within the continuous-flow multi-stage stirred reactor enables rapid catalyst recovery. Fifth, it uses solid superacid perfluorosulfonic acid resin as a catalyst, which can be reused after simple treatment after long-term operation. Sixth, the use of solid superacid perfluorosulfonic acid resin catalyst greatly reduces the amount of sulfuric acid used in the reaction, lowering costs and waste acid volume, significantly alleviating waste liquid treatment pressure, and is environmentally friendly, laying the foundation for large-scale production.

[0022] The method of this invention uses guanidine nitrate and sulfuric acid as raw materials to achieve continuous synthesis and crystallization of nitroguanidine using a continuous flow multi-stage stirred reactor. It has advantages such as high mass and heat transfer efficiency, short reaction time, high product yield, precise control of product particle size, low liquid holdup, easy catalyst recovery, low sulfuric acid consumption, environmental friendliness, and high safety, laying the foundation for large-scale production.

[0023] Specifically, the method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor of the present invention includes the following steps: Solid perfluorosulfonic acid resin, a superacid, was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The reaction section temperature was set to 20–50 °C, and the crystallization section temperature to -20–10 °C. Concentrated sulfuric acid was pre-pumped into the internal channels of the continuous flow multistage stirred reactor to fill the space. Guanidine nitrate and concentrated sulfuric acid were premixed and introduced into the reactor using pump I, with a residence time of 0.5–10 min in the reaction section. Water was then introduced into the crystallization section using pump II, with a residence time of 1–30 min. The reaction product solution was collected, washed with cold water, and filtered to obtain guanidine nitrate of a specific particle size.

[0024] The continuous flow multistage stirred reactor has 5 to 20 stages, with each catalyst cage containing 0.1 to 2 g of perfluorosulfonic acid resin and a mass hourly space velocity (HSV) of 10 to 400 h⁻¹. -1 .

[0025] The perfluorosulfonic acid resin is Nafion resin and / or Aquivion resin.

[0026] The temperature of the reaction section is 30-50℃, and the temperature of the crystallization section is -10-10℃.

[0027] The molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1 to 1:2, preferably 1:1 to 1:1.5.

[0028] In the embodiments of this disclosure, the residence time of the reaction section is preferably 0.5 to 5 minutes.

[0029] In the embodiments of this disclosure, the residence time of the crystallization segment is preferably 5 to 20 minutes.

[0030] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0031] Unless otherwise specified, all materials used in the following examples and comparative examples are commercially available.

[0032] Example 1: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 40℃, and the crystallization section temperature was set to 0℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 20Hz. 226g of guanidine nitrate and 147g of 98% concentrated sulfuric acid (molar ratio 1:1.5) were premixed and introduced into the reactor using pump I (flow rate of pump I was 10mL / min). The residence time in the reaction section was 5min, and the mass hourly space velocity of guanidine nitrate was 32h⁻¹. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II: 30 mL / min), and the residence time in the crystallization section was 20 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 102 g of guanidine nitrate product, with a yield of 98% and an average particle size ≤3.3 μm.

[0033] The SEM image of the prepared product nitroguanidine is shown below. Figure 1 As shown.

[0034] Example 2: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 40℃, and the crystallization section temperature was set to 0℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 20Hz. Guanidine nitrate and 98% concentrated sulfuric acid (molar ratio 1:1.5) were premixed and introduced into the reactor using pump I (flow rate of pump I was 10mL / min). The residence time in the reaction section was 5min, and the mass hourly space velocity of nitroguanidine was 32h⁻¹. -1 Water was pumped to the crystallization section using pump II (flow rate of pump II: 30 mL / min), and the residence time in the crystallization section was 20 min. The equipment was run continuously for 100 h, and the reaction product solution was collected. After washing and filtering with cold water, guanidine nitrate was obtained with a yield of 98% and an average particle size of ≤3.3 μm.

[0035] Under the same reaction conditions as in Example 1, a long-term continuous operation was carried out for 100 hours, and the product yield remained unchanged.

[0036] The Nafion solid superacid perfluorosulfonic acid resin was removed from the catalyst cage, and after simple water washing and acidification, it was applied to the experiment according to the reaction conditions in Example 2, as shown in Table 1.

[0037] Table 1. Product yield from catalyst reuse

[0038] Under the same reaction conditions as in Example 2, the catalyst was subjected to long-term continuous operation and five recycling cycles, and the product yield remained unchanged.

[0039] Comparative Example 1: Weigh 20g of Nafion solid superacid perfluorosulfonic acid resin into a reaction flask, start stirring, and slowly add 147g of 98% concentrated sulfuric acid, cooling to 15℃. Add 226g of guanidine nitrate (molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1.5) in portions. After the addition is complete, raise the temperature to 40℃ and maintain it for 5 min. Slowly add the reaction solution to 1120g of ice water and maintain the material temperature at 0℃ for 20 min. Wash and filter the reaction product solution with cold water to obtain 30g of nitroguanidine product, with a yield of 29% and an average particle size >6.0 μm.

[0040] Compared with the results of Example 1, it was found that in the batch reaction flask, under the same reaction conditions, the product yield was significantly reduced and the product particle size was larger.

[0041] Comparative Example 2: Weigh 20g of Nafion solid superacid perfluorosulfonic acid resin into a reaction flask, start stirring, and slowly add 147g of 98% concentrated sulfuric acid, cooling to 15℃. Add 226g of guanidine nitrate (molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1.5) in portions. After the addition is complete, raise the temperature to 40℃ and maintain it for 2 hours. Slowly add the reaction solution to 1120g of ice water and maintain the material temperature at 0℃ for 4 hours. Wash and filter the reaction product solution with cold water to obtain 97.8g of nitroguanidine product, with a yield of 94% and an average particle size >6.0 μm.

[0042] Compared with the results of Example 1, it was found that in the batch reaction flask, extending the reaction time and crystallization time significantly improved the product yield, but it was still lower than the product yield of Example 1 and the product particle size was larger.

[0043] Comparative Example 3: Weigh 147g of 98% concentrated sulfuric acid into a reaction flask, turn on the stirrer, and cool to 15℃. Slowly add 226g of guanidine nitrate (molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1.5) in portions. After the addition is complete, raise the temperature to 40℃ and maintain it for 2 hours. Slowly add the reaction solution to 1120g of ice water and maintain the material temperature at 0℃ for 4 hours. After washing and filtering the reaction product solution with cold water, 44.7g of nitroguanidine product was obtained, with a yield of 43% and an average particle size >6.0 μm.

[0044] Comparison with the results of Example 1 and Comparative Example 2 revealed that in a batch reaction flask, without a solid superacid perfluorosulfonic acid resin catalyst, extending the reaction time and crystallization time significantly reduced the product yield and increased the product particle size.

[0045] Comparative Example 4: Weigh 392g of 98% concentrated sulfuric acid into a reaction flask, turn on the stirrer, and cool to 15℃. Slowly add 226g of guanidine nitrate (molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:4) in batches. After the addition is complete, raise the temperature to 40℃ and maintain it for 2 hours. Slowly add the reaction solution to 1120g of ice water and maintain the material temperature at 0℃ for 4 hours. After washing and filtering the reaction product solution with cold water, 89.4g of nitroguanidine product was obtained, with a yield of 84% and an average particle size >6.0 μm, indicating that the product particle size is relatively large.

[0046] Compared with the results of Example 1, Comparative Example 2 and Comparative Example 3, it was found that in a batch reaction flask, under the condition of no solid superacid perfluorosulfonic acid resin catalyst, increasing the amount of concentrated sulfuric acid and extending the reaction time and crystallization time resulted in a certain improvement in product yield compared with the product of Comparative Example 3, but it was still much lower than the product yield of Example 1, and the product particle size was larger.

[0047] Example 8: 20g of Aquivion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 20℃, and the crystallization section temperature was set to -20℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 15Hz. 226g of guanidine nitrate and 196g of 98% concentrated sulfuric acid (molar ratio 1:2) were premixed and introduced into the reactor using pump I (flow rate of pump I was 5mL / min). The residence time in the reaction section was 10min, and the mass hourly space velocity of guanidine nitrate was 14.4h. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II was 22 mL / min), and the residence time in the crystallization section was 30 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 91.5 g of guanidine nitrate product, with a yield of 88% and an average particle size ≤3.3 μm.

[0048] Example 9: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 50℃, and the crystallization section temperature was set to 10℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 10Hz. 226g of guanidine nitrate and 98g of 98% concentrated sulfuric acid (molar ratio 1:1) were premixed and introduced into the reactor using pump I (flow rate of pump I was 100mL / min). The residence time in the reaction section was 0.5min, and the mass hourly space velocity of guanidine nitrate was 376.7h. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II: 300 mL / min), and the residence time in the crystallization section was 2 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 86.3 g of guanidine nitrate product, with a yield of 83% and an average particle size of 3.3–6.0 μm.

[0049] Example 10: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 45℃, and the crystallization section temperature was set to 5℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 5Hz. 226g of guanidine nitrate and 137.2g of 98% concentrated sulfuric acid (molar ratio 1:1.4) were premixed and introduced into the reactor using pump I (flow rate of pump I was 12.5mL / min). The residence time in the reaction section was 4min, and the mass hourly space velocity of guanidine nitrate was 42h⁻¹. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II: 37.5 mL / min), and the residence time in the crystallization section was 16 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 99.8 g of guanidine nitrate product, with a yield of 96% and an average particle size > 6.0 μm.

[0050] Example 11: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 1g. The reaction section temperature was set to 30℃, and the crystallization section temperature was set to -10℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was 1Hz. 226g of guanidine nitrate and 117.6g of 98% concentrated sulfuric acid (molar ratio 1:1.2) were premixed and introduced into the reactor using pump I (flow rate of pump I was 6.3mL / min). The residence time in the reaction section was 8min, and the mass hourly space velocity of guanidine nitrate was 22.4h. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II was 43.7 mL / min), and the residence time in the crystallization section was 1 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 87.4 g of guanidine nitrate product, with a yield of 84% and an average particle size > 6.0 μm.

[0051] Example 12: 20g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 10 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 2g. The reaction section temperature was set to 30℃, and the crystallization section temperature was set to -10℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was set to 5Hz. 22.6g of guanidine nitrate and 11.8g of 98% concentrated sulfuric acid (molar ratio 1:1.2) were premixed and introduced into the reactor using pump I (flow rate of pump I was 2.81mL / min). The residence time in the reaction section was 8.9min, and the mass hourly space velocity of guanidine nitrate was 10h⁻¹. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II was 8 mL / min), and the residence time in the crystallization section was 1 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 92.6 g of guanidine nitrate product, with a yield of 89% and an average particle size > 6.0 μm.

[0052] Example 13: 0.5 g of Nafion solid superacid perfluorosulfonic acid resin was weighed and placed in a catalyst cage, which was then installed in a continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor had 5 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage was 0.1 g. The reaction section temperature was set to 30℃, and the crystallization section temperature was set to -10℃. Concentrated sulfuric acid was pre-pumped to fill the internal channels of the continuous flow multistage stirred reactor. The continuous flow multistage stirred reactor was started, and the vibration frequency was 5 Hz. 22.6 g of guanidine nitrate and 11.8 g of 98% concentrated sulfuric acid (molar ratio 1:1.2) were premixed and introduced into the reactor using pump I (flow rate of pump I was 2.82 mL / min). The residence time in the reaction section was 4.4 min, and the mass hourly space velocity of guanidine nitrate was 400 h⁻¹. -1 Water was pumped into the crystallization section using pump II (flow rate of pump II was 8 mL / min), and the residence time in the crystallization section was 1 min. The reaction product solution was collected, washed with cold water, and filtered to obtain 84.2 g of guanidine nitrate product, with a yield of 81% and an average particle size > 6.0 μm.

[0053] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0054] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0055] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor, characterized in that, Includes the following steps: Weigh out the perfluorosulfonic acid resin, place it in the catalyst cage, and then install it in a continuous flow multi-stage stirred reactor; set the temperature of the reaction section to 20-50℃ and the temperature of the crystallization section to -20-10℃. Pre-fill the internal channels of the continuous flow multi-stage stirred reactor with concentrated sulfuric acid; Guanidine nitrate and concentrated sulfuric acid are premixed and then introduced into the reactor. The residence time in the reaction section is 0.5 to 10 minutes. Water is introduced into the crystallization section and the residence time in the crystallization section is 1 to 30 minutes. The reaction product solution is collected, washed with cold water, and filtered to obtain the final product.

2. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1, characterized in that, The perfluorosulfonic acid resin is Nafion resin and / or Aquivion resin.

3. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1, characterized in that, The continuous flow multistage stirred reactor has 5 to 20 stages, and the mass of perfluorosulfonic acid resin in each catalyst cage is 0.1 to 2 g, with a mass hourly space velocity of 10 to 400 h⁻¹. -1 .

4. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1 or 2, characterized in that, The temperature of the reaction section is 30-50℃, and the temperature of the crystallization section is -10-10℃.

5. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1 or 2, characterized in that, The molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1 to 1:

2.

6. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1 or 2, characterized in that, The molar ratio of guanidine nitrate to concentrated sulfuric acid is 1:1 to 1:1.

5.

7. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1 or 2, characterized in that, The residence time of the reaction section is 0.5 to 5 minutes.

8. The method for continuous synthesis and crystallization control of nitroguanidine using a continuous flow multi-stage stirred reactor according to claim 1 or 2, characterized in that, The residence time of the crystallization segment is 5 to 20 minutes.

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