Glycerol trinitrate / triethylene glycol dinitrate mixture, kettle type overflow synthesis method and application

Abstract

The invention provides a kettle type overflow synthesis method of a glycerol trinitrate / triethylene glycol dinitrate mixture. The kettle type overflow synthesis method comprises the following steps: step 1, mixing concentrated nitric acid and concentrated sulfuric acid to prepare nitric acid and sulfuric acid mixed acid; mixing glycerol with triethylene glycol to obtain mixed polyol; step 2, continuously pumping the mixed acid of nitric acid and sulfuric acid and the mixed polyol according to the formula ratio into an overflow reaction kettle by virtue of a metering pump, carrying out nitration reaction, and enabling a reaction product to flow out of an overflow port of the reaction kettle and enter a separator; step 3, separating in a separator to obtain an organic phase; 4, the organic phase enters a collecting tank after being subjected to water washing and alkali washing, and a glycerol trinitrate / triethylene glycol dinitrate mixture is obtained. According to the method disclosed by the invention, a kettle type overflow synthesis method is adopted, so that the process operation is simplified, the online amount of reaction is reduced, the safety of a nitration reaction process is improved, and the reaction yield of a glycerol trinitrate / triethylene glycol dinitrate mixture is improved.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology and relates to liquid nitrate ester mixtures, specifically to a mixture of glycerol trinitrate / triethylene glycol dinitrate, a batch overflow synthesis method, and its application. Background Technology

[0002] Glycerol trinitrate, also known as nitroglycerin (NG), is an energetic plasticizer with high plasticizing properties for nitrocellulose. It is an effective component for enhancing the energy and mechanical properties of propellant formulations. This compound is high in energy, high in density, and low in cost, making it a widely used and largest-volume energetic plasticizer, and also the most commonly used energetic plasticizer in double-base and modified double-base propellants and propellants. However, NG also has drawbacks such as high sensitivity and volatility, easily triggering explosions when exposed to external impacts or friction. Furthermore, due to its high freezing point, NG is prone to crystallization and migration at low temperatures, and it also has high mechanical sensitivity. In formulation applications, using a mixture of NG and triethylene glycol dinitrate (TEGDN) instead of NG can improve its safety and low-temperature migration.

[0003] Currently, the NG / TEGDN mixed nitrate esters used in propellants are mainly produced by separately nitrifying and post-processing NG and TEGDN to obtain individual components, which are then mixed in the required proportions. This process involves numerous steps, and the mixing of nitrate esters requires stirring, posing a high safety risk for highly sensitive nitrate esters and limiting the large-scale application of mixed nitrate esters. When using jet nitration to nitrate NG / TEGDN mixed nitrate esters, the high-speed flow of mixed acid creates negative pressure to draw in the mixed alcohol for reaction, while the mixed acid is used to control the nitration temperature. Therefore, a large amount of mixed acid is required, resulting in a significant amount of waste acid after the nitration reaction, which is detrimental to environmental protection. Furthermore, nitrate esters have a certain degree of solubility in waste acid, and a large amount of waste acid will reduce the product yield, necessitating improvement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for synthesizing a mixture of glycerol trinitrate and triethylene glycol dinitrate using a batch overflow process and its application, thereby solving the technical problems of numerous process steps and low product yield in existing synthesis methods.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate includes the following steps: Step 1: Mix concentrated nitric acid and concentrated sulfuric acid to prepare a nitric-sulfuric acid mixture; mix glycerol and triethylene glycol to obtain a mixed polyol; Step 2: Using a metering pump, the prescribed amount of nitrate-sulfur mixed acid and mixed polyol are continuously pumped into an overflow reactor for nitration reaction. The reaction products flow out of the reactor through the overflow port and enter the separator. Step 3: Separate the organic phase in the separator; Step 4: After washing with water and alkali, the organic phase is collected in a collection tank to obtain a mixture of glycerol trinitrate and triethylene glycol dinitrate.

[0007] The present invention also has the following technical features: Specifically, in step 1, the mass ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1; the mass ratio of glycerol to triethylene glycol is (1~4):1.

[0008] Furthermore, in step 2, the temperature of the nitration reaction is 10℃~20℃; the reaction time is 5min~30min; and the stirring speed of the reactor is 100 rpm~300 rpm.

[0009] Furthermore, in step 2, the nitration reaction temperature is 15°C; the reaction time is 10 min; and the stirring speed of the reactor is 200 rpm.

[0010] Furthermore, in step 2, the mass ratio of the nitrate-sulfur mixed acid and the mixed polyol entering the reactor per unit time is (3~10):1.

[0011] Furthermore, in step 4, the volumetric flow rate ratio of the organic phase to the washing water is (0.5~2):1.

[0012] Furthermore, in step 4, the volume flow rate ratio of the organic phase to the alkaline solution used for alkaline washing is (0.5~2):1.

[0013] Furthermore, in step 4, the alkaline solution is selected from any one of sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, and sodium hydroxide aqueous solution.

[0014] The present invention also protects the mixture of glycerol trinitrate / triethylene glycol dinitrate, which is prepared by the above-described batch overflow synthesis method.

[0015] The present invention also protects the use of the glycerol trinitrate / triethylene glycol dinitrate mixture prepared by the above-described batch overflow synthesis method for the preparation of propellants or propellants.

[0016] Compared with the prior art, the present invention has the following technical effects.

[0017] The method of this invention adopts a batch overflow synthesis method, which simplifies the process operation, reduces the amount of reaction in the online process, improves the safety of the nitration process, and increases the reaction yield of the glycerol trinitrate / triethylene glycol dinitrate mixture.

[0018] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, all raw materials and equipment used in this invention are those known in the prior art.

[0020] The technical concept of this invention is as follows: To address the problems of complex batch synthesis-post-treatment-mixing processes, large online volumes, and high safety risks in the preparation of liquid mixed nitrates, this study seeks a simpler, smaller-volume, and safer synthesis method. Based on the principle of continuous reaction in an overflow reactor, an overflow reactor is used for the nitration reaction, followed by continuous post-treatment, eliminating the need for additional mixing and simplifying the process.

[0021] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0022] Example 1 Following the above technical solution, this embodiment provides a batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate, including the following steps: Step 1: Mix concentrated nitric acid and concentrated sulfuric acid in a 1:1 mass ratio to prepare a nitric-sulfuric acid mixture; mix glycerol and triethylene glycol in a 3:1 mass ratio to obtain a mixed polyol; Step 2: The mixed nitrate-sulfur acid and the mixed polyol are simultaneously introduced into the overflow reactor at flow rates of 50 g / min and 10 g / min respectively through metering pumps. The reaction products flow out of the reactor through the overflow port and enter the separator. The reaction temperature is 15℃, the residence time of the nitration reaction is 10 min, and the stirring speed of the reactor is 200 rpm.

[0023] Step 3: Separate the organic phase in the separator; Step 4: After separation by the separator, the organic phase flows into the three-stage scrubber. Washing water (or alkaline solution) is introduced into the scrubber at a rate of 4 mL / min. The organic phase is then washed with water, alkaline solution, and water in sequence. The washed organic phase flows into the collection tank. After collecting the organic phase for 10 min, 149.8 g of mixed nitrate ester is obtained, with a yield of 83.6%.

[0024] The alkaline solution is selected from any one of a 10-15% sodium carbonate aqueous solution, a 10-15% sodium bicarbonate aqueous solution, and a 5-10% sodium hydroxide aqueous solution.

[0025] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 76.1% and the TEGDN content was 23.9%.

[0026] The glycerol trinitrate / triethylene glycol dinitrate mixture prepared in this embodiment can be used to prepare propellants. During preparation, the amount of glycerol trinitrate / triethylene glycol dinitrate mixture added is 20%~50%.

[0027] Example 2 This embodiment provides a batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate. The steps and raw materials used in this method are the same as in Example 1, except that in step 1, Glycerin and triethylene glycol were mixed in a 1:1 mass ratio to prepare a mixed polyol.

[0028] In this embodiment, 142.8 g of mixed nitrate esters were finally obtained, with a yield of 79.7%.

[0029] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 53.3% and the TEGDN content was 46.7%.

[0030] Example 3 This embodiment provides a batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate. The steps and raw materials used in this method are the same as in Example 1, except that in step 1, Concentrated nitric acid and concentrated sulfuric acid are mixed in a mass ratio of 3:1 to prepare a nitric acid-sulfuric acid mixture.

[0031] In this embodiment, 127.0 g of mixed nitrate ester was finally obtained, with a yield of 70.9%.

[0032] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 71.0% and the TEGDN content was 29.0%.

[0033] Example 4 This embodiment provides a batch overflow synthesis method for a mixture of glycerol trinitrate / triethylene glycol dinitrate. The steps and raw materials used in this method are the same as those in Example 1, except that in step 2, the mixed nitric acid and mixed polyol are simultaneously introduced into the overflow reactor at flow rates of 100 g / min and 10 g / min, respectively, through metering pumps for reaction.

[0034] In this embodiment, 111.5 g of mixed nitrate ester was finally obtained, with a yield of 62.2%.

[0035] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 72.7% and the TEGDN content was 27.3%.

[0036] Example 5 The example provides a batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate. The steps and raw materials used in this method are the same as those in Example 1, except that in step 2, the reaction temperature is 20°C, the residence time of the nitration reaction is 10 min, and the stirring speed of the reactor is 200 rpm.

[0037] In this embodiment, 130.4 g of mixed nitrate ester was finally obtained, with a yield of 72.7%.

[0038] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 74.0% and the TEGDN content was 26.0%.

[0039] Comparative Example 1 This comparative example provides a conventional batch reactor synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate, including the following steps: Step 1: Mix concentrated nitric acid and concentrated sulfuric acid in a 1:1 mass ratio to prepare a nitric-sulfuric acid mixture; mix glycerol and triethylene glycol in a 3:1 mass ratio to obtain a mixed polyol; Step 2: Add 500g of nitrate-sulfur mixed acid to the reactor, control the temperature at 15℃, turn on the reactor stirring at 200 rpm, add 100g of mixed polyol to the reactor through a metering pump to carry out the nitration reaction, control the feeding rate to keep the temperature at about 15℃, and continue the reaction for 10 minutes after the mixed alcohol is added, then stop stirring. Step 3: Separate the organic phase in the reactor; Step 4: Add the organic phase to the reactor, add washing water and alkali solution respectively, and wash the organic phase with water, alkali and water in sequence. After three washings, the organic phase flows into the collection tank to obtain 107.1g of mixed nitrate ester, with a yield of 59.8%.

[0040] According to the 1H NMR spectroscopy analysis, the NG content in the mixed nitrate ester was 74.4% and the TEGDN content was 25.6%.

[0041] As can be seen from Examples 1-5 and Comparative Example 1: Changing the content of nitric acid and sulfuric acid in the nitrate-sulfur mixture, adjusting the mass ratio of the nitrate-sulfur mixture to the mixed polyol, and increasing the temperature of the nitration reaction will all lead to a decrease in the yield of the nitrate ester mixture. Changing the mass ratio of glycerol to triethylene glycol in the mixed polyol will change the mass ratio of the two components in the prepared nitrate ester mixture, which will not meet the requirements of the product application.

[0042] Compared with existing batch reactor synthesis methods, the method of this invention can simplify process operation, reduce the amount of reaction in the process, improve the safety of the nitration process, and increase product yield. The reaction yield of the glycerol trinitrate / triethylene glycol dinitrate mixture can reach 83.6%.

[0043] 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.

[0044] 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.

[0045] 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 batch overflow synthesis method for a mixture of glycerol trinitrate and triethylene glycol dinitrate, characterized in that, Includes the following steps: Step 1: Mix concentrated nitric acid and concentrated sulfuric acid to prepare a nitric-sulfuric acid mixture; mix glycerol and triethylene glycol to obtain a mixed polyol; Step 2: Using a metering pump, the prescribed amount of nitrate-sulfur mixed acid and mixed polyol are continuously pumped into an overflow reactor for nitration reaction. The reaction products flow out of the reactor through the overflow port and enter the separator. Step 3: Separate the organic phase in the separator; Step 4: After washing with water and alkali, the organic phase is collected in a collection tank to obtain a mixture of glycerol trinitrate and triethylene glycol dinitrate.

2. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 1, the mass ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1; the mass ratio of glycerol to triethylene glycol is (1~4):

1.

3. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 2, the temperature of the nitration reaction is 10℃~20℃; the reaction time is 5min~30min; and the stirring speed of the reactor is 100 rpm~300 rpm.

4. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 2, the nitration reaction temperature is 15℃; the reaction time is 10 min; and the stirring speed of the reactor is 200 rpm.

5. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 2, the mass ratio of the mixed nitrate-sulfur acid and the mixed polyol entering the reactor per unit time is (3~10):

1.

6. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 4, the volumetric flow rate ratio of the organic phase to the washing water is (0.5~2):

1.

7. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 4, the volume flow rate ratio of the organic phase to the alkaline solution used for alkaline washing is (0.5~2):

1.

8. The batch overflow synthesis method for the glycerol trinitrate / triethylene glycol dinitrate mixture as described in claim 1, characterized in that, In step 4, the alkaline solution is selected from any one of sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, and sodium hydroxide aqueous solution.

9. A mixture of glycerol trinitrate and triethylene glycol dinitrate, characterized in that, It is prepared by the batch overflow synthesis method as described in any one of claims 1 to 8.

10. The use of the glycerol trinitrate / triethylene glycol dinitrate mixture prepared by the batch overflow synthesis method as described in any one of claims 1 to 8 for the preparation of propellants.