A safe and environment-friendly process and device for nitrate

Abstract

The application discloses a nitrate safe and environment-friendly process and device, relates to the technical field of organic compound synthesis, and solves the problems that the existing traditional kettle type, customized micro-reactor and traditional micro-reactor have intense reaction heat release during reaction, low heat exchange efficiency, easy local overheating, induced side reactions and even safety accidents, easy generation of high-pressure gas, brown smoke and carbonization during the reaction process, and difficult product quality control. The nitration reaction is carried out in a micro-channel reactor by taking fatty alcohol and nitro-sulfur mixed acid as raw materials. After the nitration reaction, the reaction substances are subjected to ester acid separation, dried after separation and then put into a product storage tank. After separation, the inorganic acid is concentrated sulfuric acid containing a small amount of nitric acid, which is used as raw material after denitration treatment and concentration. The nitration reaction is carried out through the micro-channel reactor, the reaction raw materials are added in a multi-point feeding mode during the nitration reaction, the reaction heat is effectively controlled, and the safety during the production process is ensured.

Description

Technical Field

[0001] This invention relates to the field of organic compound synthesis, specifically to a safe and environmentally friendly process and apparatus for nitrate ester synthesis. Background Technology

[0002] Nitrate esters are organic compounds containing nitro (-NO2) and ester (-COOR) groups, with the general chemical formula RO-NO2 (R being an organic group). They are the core structure of nitrate ester drugs and have wide applications in pharmaceuticals, high-energy materials, and environmental chemistry. They are chemically reactive and readily undergo hydrolysis and reduction reactions. They are commonly prepared by reacting nitric acid with alcohols under acidic conditions, which is a key step in the preparation of nitrate ester drugs. Nitrate esters are generally prepared using equipment such as traditional batch reactors, customized microreactors, and traditional microreactors.

[0003] Traditional batch reactors, customized microreactors, and conventional microreactors all exhibit intense exothermic reactions and low heat exchange efficiency during the reaction process, which can easily lead to local overheating, causing side reactions or even safety accidents. They are also prone to generating high-pressure gases, brown fumes, and carbonization during the reaction process, making it difficult to control product quality.

[0004] The main advantage of micro-pass reactors is their high-efficiency heat exchange. However, micro-pass reactors also release a great deal of heat, so the desired effect cannot be achieved by micro-pass reactors alone. Therefore, they do not meet the current requirements. To address this, we propose a safe and environmentally friendly process and device for nitrate esters. Summary of the Invention

[0005] The purpose of this invention is to provide a safe and environmentally friendly process and apparatus for nitrate esters, in order to solve the problems mentioned in the background art, such as the violent exothermic reaction, low heat exchange efficiency, easy local overheating, side reactions or even safety accidents, high pressure gas, brown smoke and carbonization during the reaction process, and difficulty in controlling product quality. At the same time, the use of a denitrification device ensures that the inorganic acid produced can be maximized and carbon emissions can be eliminated.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a safe and environmentally friendly process for nitrate esters, comprising the following steps:

[0007] S1: Nitrate-sulfur mixed acid is added to the microchannel reactor through the main pipeline, and at the same time, fatty alcohol is added into the microchannel reactor through the secondary pipeline in a multi-point feeding manner, either against or in the direction of the reaction material flow, to carry out the nitration reaction. By adjusting the ratio of sulfuric acid to nitric acid in the reaction system, the high specific heat of sulfuric acid is used for internal heat extraction. At the same time, the microchannel reactor is placed in a cold bath device for external heat extraction and auxiliary heat exchange. The temperature of the nitration reaction is controlled by the external cold bath and the internal heat extraction of the nitrate-sulfur mixed acid.

[0008] S2: After the nitration reaction, the reacted substances are transported to the separation equipment through an ultrasonic device pipeline. After the reaction is completed, the high-frequency and low-frequency ultrasonic devices are used to promote the full mixing and rapid separation of the aqueous and oil phases, so that the unreacted raw materials can fully react. The downstream low-frequency ultrasonic device enables the complete reaction material to be rapidly separated into esters and acids.

[0009] S3: The reacted substances enter the separation equipment for complete separation of esters and acids;

[0010] S4: The separated ester phase is washed with water and dried to obtain nitrate ester products, which are then stored.

[0011] S5: By-product acid is introduced into denitrification and concentration equipment for treatment. The concentrated acid can be used as a new raw material in the reaction system for closed-loop circulation, and the water generated during the concentration process is reused as general chemical water.

[0012] Preferably, the microchannel reactor includes a reaction pipeline and multiple feed pipes, with the number of feed pipes being no less than three.

[0013] Preferably, there are four feed pipes, with the first two feed pipes using φ1-3mm pipelines and the subsequent feed pipes using φ8-10mm or thicker pipelines.

[0014] Preferably, the nitric acid-sulfur mixture comprises nitric acid and sulfuric acid, wherein the mass ratio of nitric acid to sulfuric acid is 1:3 to 1:6.

[0015] Preferably, the mass ratio of nitric acid to sulfuric acid in the nitric acid-sulfuric acid mixture is 1:3 to 1:4 nitrate ester.

[0016] Preferably, the molar ratio of fatty alcohol to nitric acid is 1:1.1 to 1:1.5.

[0017] Preferably, the diameter of the reaction channel of the microchannel reactor is 2 mm to 5 mm and the length is 3 m to 10 m.

[0018] Preferably, the reaction temperature of the nitration reaction is -10°C to 20°C, the reaction pressure of the nitration reaction is 0.5 MPa to 2.0 MPa, and the reaction residence time is 0.5 s to 120 s.

[0019] An apparatus for the safe and environmentally friendly production of nitrate esters includes a microchannel reactor, a mixed acid feed pump, and multiple raw material pumps. The inlet end of the microchannel reactor is connected to the mixed acid feed pump via a tee or a mixer. The feed pipeline of the microchannel reactor is connected to the delivery interface of the raw material pumps. The outlet end of the microchannel reactor is connected to an fatty acid separation device.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention improves the exothermic effect by adjusting the proportion of pure acid in the reaction system, allowing the system to internally heat itself using the high specific heat of sulfuric acid, while simultaneously placing the microchannel reactor in a cold bath for external heat extraction. Furthermore, the mixed nitrate-sulfur acid is added to the microchannel reactor through the main pipeline, while fatty alcohols are simultaneously added to the microchannel reactor through the secondary pipeline using a multi-point feeding method, either against or in the direction of the reactant flow. This effectively disperses the large amount of heat during the reaction process, avoids local overheating, mitigates the risk of concentrated exothermic reactions, and ensures a stable reaction.

[0022] 2. After the reaction is completed, the present invention uses high and low frequency ultrasonic devices to promote the mixing and rapid separation of the aqueous phase and the oil phase, so that the unreacted raw materials can fully react, thereby improving the conversion rate and product stability, while shortening the processing time of subsequent processes and improving efficiency.

[0023] 3. After the residual nitric acid is removed by the denitrification device, the 70-80% sulfuric acid is concentrated to 98% for recycling, achieving the environmental protection goal of zero acid discharge. The concentrated acid can be used as a new raw material to enter the reaction system for closed-loop circulation, and the water generated in the concentration process can be reused as general chemical water. The complete utilization of the by-product acid in the process cycle can achieve closed-loop raw material circulation without external discharge. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation process of the present invention;

[0025] Figure 2 This is a schematic diagram of the preparation apparatus of the present invention;

[0026] Figure 3 This is a chromatographic analysis report of Experiment 1 of the present invention;

[0027] Figure 4 This is a chromatographic analysis report of Experiment 2 of the present invention;

[0028] Figure 5 This is a chromatographic analysis report of Experiment 3 of the present invention;

[0029] Figure 6 This is a chromatographic analysis report of Experiment 4 of the present invention. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] Please see Figures 1 to 6 The present invention provides an embodiment of a safe and environmentally friendly process for nitrate esters, comprising the following steps:

[0032] S1: Nitration reaction is carried out in a microchannel reactor using fatty alcohols and mixed nitric and sulfuric acids as raw materials;

[0033] The controlled ratio of nitrate ester to nitric acid is 1.2:1.

[0034] The microchannel reactor is equipped with cooling water channels on the outside, which are spirally fitted to the outer wall of the microchannel reactor.

[0035] In this process, fatty alcohols are added into the microchannel reactor using a multi-point feeding method, either against or in the direction of material flow. The microchannel reactor includes a reaction pipeline and multiple feed pipes. The number of feed pipes is no less than 3, with 4 being the optimal choice. The first two feed pipes use φ1-3mm pipelines, and the subsequent feed pipes use φ8-10mm or thicker pipelines.

[0036] It also includes a PLC control terminal, and the reaction pipeline has a built-in temperature sensor. The feed pipe is connected to a metering pump. The temperature sensor and the metering pump are electrically connected to the PLC control terminal for real-time monitoring of the reaction temperature and precise control of the nitrate feed rate.

[0037] The diameter of the reaction channel in the microchannel reactor is 2 mm to 5 mm, and the length is 3 m to 10 m;

[0038] By adjusting the ratio of sulfuric acid to nitric acid in the reaction system, the high specific heat of sulfuric acid is used for internal heat extraction, while the microchannel reactor is placed in a cold bath device for external heat extraction and auxiliary heat exchange. The temperature of the nitration reaction is controlled by the external cold bath and the internal heat extraction of the nitrate-sulfur mixture. The nitrate-sulfur mixture is added to the microchannel reactor from the main pipe, and at the same time, fatty alcohols are added to the microchannel reactor from the secondary pipe using a multi-point feeding method in the reverse or forward direction of the reaction material flow.

[0039] The reaction system utilizes the high specific heat of sulfuric acid for internal heat extraction, while the microchannel reactor is placed in a cold bath for external heat extraction, further enhancing the exothermic effect. A mixture of nitrate and sulfuric acid is added to the microchannel reactor through the main pipeline, while fatty alcohols are simultaneously added to the microchannel reactor through a secondary pipeline using a multi-point feeding method, either against or in the direction of the reactant flow. The multi-point feeding method is a segmented feeding approach, which effectively disperses the large amount of heat during the reaction process, avoids local overheating, mitigates the risk of concentrated exothermic reactions, and ensures a stable reaction.

[0040] S2: After the nitration reaction, the reactants are transported to the separation equipment via an ultrasonic device. After the reaction, ultrasonic devices of different frequencies are used to promote the mixing and separation of the aqueous and oil phases, so that the unreacted raw materials can fully react and the esters and acids can be quickly separated. After the nitration reaction, the reactants are first passed through an 80-100 kHz ultrasonic device to promote the mixing of the aqueous and oil phases, so that the unreacted raw materials can fully react, thereby improving the conversion rate and product stability. Then, an ultrasonic device of 20-50 kHz is used to promote the rapid separation of esters and acids. Finally, the reactants are transported to the separation equipment for complete separation.

[0041] The reaction temperature for nitration is -10℃ to 20℃, the reaction pressure is 0.5MPa to 2.0MPa, and the reaction residence time is 0.5s to 120s.

[0042] S3: The reacted substances enter the separation equipment for ester-acid separation;

[0043] The separation equipment is a circulating ultrasonic extraction device, which uses ultrasound to separate fatty acids. After separation, the upper ester and the lower by-product acid are obtained. The ester is stored in the finished product storage tank, and the by-product acid is sent to the by-product acid tank.

[0044] S4: The separated ester phase is washed with water and dried to obtain nitrate ester products, which are then stored.

[0045] S5: By-product acid is introduced into denitrification and concentration equipment for treatment. After removing residual nitric acid through the denitrification device, 70-80% sulfuric acid is concentrated to 98% for recycling, achieving the environmental protection goal of zero acid emissions. The concentrated acid can be used as a new raw material in the reaction system for closed-loop circulation, and the water generated during the concentration process is reused as general chemical water. The complete utilization of by-product acid in the process cycle can achieve closed-loop raw material production without external discharge.

[0046] The by-product acid is mainly composed of concentrated sulfuric acid and contains a small amount of nitric acid. After denitrification and concentration of the obtained material, the final acid is used to prepare new nitrate-sulfur mixed acid, realizing the recycling of waste materials and saving energy and protecting the environment.

[0047] The nitrate ester feedstock is fed at multiple points, numbered 1, 2, 3, ..., n. At point 1, a small amount of alcohol reacts with a large amount of acid. As the reaction system flows through the pipeline, the temperature decreases. Simultaneously, the sulfuric acid inside the nitrate-sulfur mixture absorbs the instantaneous heat of the reaction, reducing the amount of byproducts generated during the reaction. When feeding at point 2, the acid ratio is lower than at point 1. Subsequently, feeding at point 3, the acid ratio is lower again compared to point 2. Overall, the proportion of acid in the material is higher than that of alcohol.

[0048] The temperature of the nitration reaction is controlled by the external cold bath and the internal heat recovery of the nitrate-sulfur mixture. The reaction temperature is -10℃ to 20℃, and the reaction pressure is 0MPa to 2.0MPa.

[0049] The nitric-sulfur mixed acid includes nitric acid and sulfuric acid, with a mass ratio of nitric acid to sulfuric acid of 1:3 to 1:6. The molar ratio of fatty alcohol to nitric acid is 1:1.1 to 1:1.5. By utilizing the high specific heat of sulfuric acid, the proportion of sulfuric acid in the mixed acid is increased, thereby changing the internal heat recovery of the mixed acid to lower the temperature of the reaction point. This, combined with the advantages of microchannel reaction, solves the problem of reaction heat.

[0050] As a preferred embodiment, the mass ratio of nitric acid to sulfuric acid in the nitric acid-sulfuric acid mixture is preferably 1:3 to 1:4.

[0051] The apparatus for the safe and environmentally friendly production of nitrate esters includes a microchannel reactor, a mixed acid feed pump, and multiple raw material pumps. The inlet end of the microchannel reactor is connected to the mixed acid feed pump via a tee or a mixer. The feed pipeline of the microchannel reactor is connected to the delivery interface of the raw material pumps. The outlet end of the microchannel reactor is connected to an fatty acid separation device.

[0052] To this end, preliminary experiments were conducted using fatty alcohols and nitric acid-sulfur mixtures as the main raw materials. The process parameters were initially determined by the purity of the product and the stability of the inorganic acid. Under the premise of ensuring product quality and process safety, a production increase experiment was conducted to determine the optimal process parameters.

[0053] Based on the microtube reaction process, the microtubes used are φ1-10mm pipelines with a length of 3m-6m. The reaction temperature is based on the batch reaction method in the technical literature. Related experiments were conducted, with the ratio of mnitric acid to msulfuric acid being 1:3 (sulfuric acid can be extracted in increments of 4, 5, 6, etc.). Increasing the amount of sulfuric acid increases the amount of inorganic acid in the system, so the addition of inorganic acid for recycling can be considered. The relevant experimental data are as follows:

[0054] The mixed acid used in the experiment was nitric acid and sulfuric acid in a mass ratio of 1:3, with a density of 1.834 g / cm3;

[0055] Experiment 1:

[0056] The experimental materials were mixed acid and n-butanol, with a mass ratio of n-butanol:nitric acid = 1:1.5. n-Butanol was added at four points via a multi-point feed: n-butanol I, n-butanol II, n-butanol III, and n-butanol IV, with a feed volume ratio of n-butanol I: n-butanol II: n-butanol III: n-butanol IV: mixed acid = 1:2:3:4:24. The reaction temperature was -1℃, and the discharge temperature was 13℃. The reaction process was stable, with a discharge time of 2 minutes. The volume ratios were: total volume (Vtotal) = 67 ml, organic volume (Vorganic) = 25 ml, and aqueous volume (Vaqueous) = 42 ml. After separation using a separatory funnel, the organic phase was washed with water until neutral and then analyzed by gas chromatography. The n-butyl ester content was 99.93%. The chromatographic analysis report is as follows: Figure 3 As shown, Figure 3 The component with a retention time of 7.473 is butyl nitrate, the component with a retention time of 6.48 is the byproduct butyl nitrite, the rest are short-chain byproducts, and there is no residual n-butanol.

[0057] Experiment 2:

[0058] The experimental materials were mixed acid and n-butanol, with a mass ratio of n-butanol:nitric acid = 1:1.3. n-Butanol was added at four points via a multi-point feed: n-butanol I, n-butanol II, n-butanol III, and n-butanol IV, with a feed volume ratio of n-butanol I: n-butanol II: n-butanol III: n-butanol IV: mixed acid = 1:2:3:4: mixed acid = 10:18. The reaction temperature was -2℃, and the discharge temperature was 5℃. The reaction process was stable. After 1 minute of discharge, the volume ratios were: total volume (Vtotal) = 31 ml, organic volume (Vorganic) = 13 ml, and aqueous volume (Vaqueous) = 18 ml. After separation using a separatory funnel, the organic phase was washed with water until neutral and then analyzed by gas chromatography. The n-butyl ester content was 99.92%. The chromatographic analysis report is as follows: Figure 4 As shown, Figure 4 The component with a retention time of 7.473 is butyl nitrate, the component with a retention time of 6.467 is the byproduct butyl nitrite, and the rest are short-chain byproducts. There is no residual n-butanol, the output is stable, the color is normal, and it remains stable after 2 hours of stable storage.

[0059] Experiment 3:

[0060] The experimental materials were mixed acid and n-butanol, with a mass ratio of n-butanol:nitric acid = 1:1.1. n-Butanol was added at four points via a multi-point feed: n-butanol I, n-butanol II, n-butanol III, and n-butanol IV, with a feed volume ratio of n-butanol I: n-butanol II: n-butanol III: n-butanol IV: mixed acid = 1:2:3:4:16. The reaction temperature was 0℃, and the discharge temperature was 3℃. The reaction process was stable, with a discharge time of 2 minutes. The volume ratios were: total volume (Vtotal) = 61 ml, organic volume (Vorganic) = 24 ml, and aqueous volume (Vaqueous) = 37 ml. After separation using a separatory funnel, the organic phase was washed with water until neutral and then analyzed by gas chromatography. The n-butyl ester content was 99.72%. The chromatographic analysis report is as follows: Figure 5 As shown, Figure 5 The component with a retention time of 7.433 is butyl nitrate, the component with a retention time of 6.413 is the byproduct butyl nitrite, the component with a retention time of 1.72 is unreacted butanol, and the rest are short-chain byproducts. There is no residual n-butanol, but there are impurity peaks, which are byproducts formed by the oxidation of some alcohols. It is determined that mixed acid is used as raw material and the alcohol-nitrate ratio is 1:1.3 for increased production.

[0061] Experiment 4:

[0062] The experimental materials were mixed acid and n-butanol, with a mass ratio of n-butanol:nitric acid = 1:1.3. The flow rate was increased by two times. n-Butanol was added at four points via a multi-point feed: n-butanol I: n-butanol II: n-butanol III: n-butanol IV, with a feed volume ratio of n-butanol I: n-butanol II: n-butanol III: n-butanol IV: mixed acid = 2:4:6:8:36. The reaction temperature was 0℃, and the discharge temperature was 8-10℃. High-pressure gas was ejected during the reaction. Timed and quantitative counting of the organic and inorganic phases was not performed in this experiment. After separation using a separatory funnel, the organic phase was washed with water until neutral and then analyzed by gas chromatography. The n-butyl ester content was 99.85%. The chromatographic analysis report is as follows: Figure 6 As shown, Figure 6 The component with a retention time of 7.427 is butyl nitrate, the component with a retention time of 6.407 is the byproduct butyl nitrite, the component with a retention time of 1.8 is unreacted butanol, the component with a retention time of 5.133 is the remaining short-chain byproduct, and there is no residual n-butanol.

[0063] Experiment 5:

[0064] The experimental materials were mixed acid and n-butanol, with a mass ratio of n-butanol:nitric acid = 1:1.3. The flow rate was increased fourfold. The n-butanol was fed at four points: n-butanol I, n-butanol II, n-butanol III, and n-butanol IV, with a feed volume ratio of n-butanol I: n-butanol II: n-butanol III: n-butanol IV: mixed acid = 4:8:12:16:72. The reaction temperature was -3℃, and the discharge temperature was 8-10℃. The reaction was vigorous after 30 seconds of feeding, with brownish-yellow fumes being released and high-pressure gas continuously spraying from the pipeline. The analysis showed that the main reason was that the heat exchange at the reaction point was not timely, resulting in an excessively high temperature of the reactants and a sudden increase in pipeline pressure, leading to the termination of the experiment.

[0065] The conclusion is that the process parameters for n-butyl nitrate were determined through multiple sets of process optimization and repeated verification experiments: n-butanol:n-nitric acid = 1:1.3, m-nitric acid:m-sulfuric acid = 1:3, the maximum feed rate V-butanol:V-mixed acid = 20:36 (unit: ml / min), the cold bath temperature was 0℃, the reaction pipeline used was a φ3 pipeline, and the residence time was approximately 0.5 min. The optimal process yielded a product with a purity of 99.85%, no n-butanol impurity peaks, and the product was a colorless and transparent liquid.

[0066] The process system is stable and has been repeatedly verified. The content of the prepared product is stable. The crude ester and mixed acid can be stored stably for 2 hours. The mixed acid is basically stable after storage and no unstable decomposition phenomenon was observed after 4 hours. The mass loss rate of the entire reaction system is about 4.74%, mainly due to multiple water washings, which is within the error range. According to the material balance calculation, the mass loss of sulfuric acid is 13.35%, and the material balance of nitric acid is basically balanced.

[0067] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A safe and environmentally friendly process for nitrate esters, characterized in that: Includes the following steps: S1: Nitrate-sulfur mixed acid is added to the microchannel reactor through the main pipeline, and at the same time, fatty alcohol is added into the microchannel reactor through the secondary pipeline in a multi-point feeding manner, either against or in the direction of the reaction material flow, to carry out the nitration reaction. By adjusting the ratio of sulfuric acid to nitric acid in the reaction system, the high specific heat of sulfuric acid is used for internal heat extraction. At the same time, the microchannel reactor is placed in a cold bath device for external heat extraction and auxiliary heat exchange. The temperature of the nitration reaction is controlled by the external cold bath and the internal heat extraction of the nitrate-sulfur mixed acid. S2: After the nitration reaction, the reactants are transported to the separation equipment through an ultrasonic device pipeline. After the reaction is completed, ultrasonic devices of different frequencies are used to promote the mixing and separation of the aqueous phase and the oil phase, so that the unreacted raw materials can fully react and the ester acid can be quickly separated after the reaction. S3: The reacted substances enter the separation equipment for ester-acid separation; S4: The separated ester phase is washed with water and dried to obtain nitrate ester products, which are then stored. S5: By-product acid is introduced into denitrification and concentration equipment for treatment. The concentrated acid can be used as a new raw material in the reaction system for closed-loop circulation, and the water generated during the concentration process is reused as general chemical water.

2. The safe and environmentally friendly process for producing nitrate esters according to claim 1, characterized in that: The microchannel reactor includes a reaction pipeline and multiple feed pipes, with no fewer than three feed pipes.

3. The safe and environmentally friendly process for nitrate esters according to claim 2, characterized in that: The number of feed pipes is preferably four, with the first two feed pipes using φ1-3mm pipelines and the subsequent feed pipes using φ8-10mm or thicker pipelines.

4. The safe and environmentally friendly process for nitrate esters according to claim 3, characterized in that: The nitric acid-sulfur mixture includes nitric acid and sulfuric acid, with a mass ratio of nitric acid to sulfuric acid of 1:3 to 1:

6.

5. The safe and environmentally friendly process for nitrate esters according to claim 4, characterized in that: The mass ratio of nitric acid to sulfuric acid in the nitric acid-sulfuric acid mixture is 1:3 to 1:

4.

6. The safe and environmentally friendly process for nitrate esters according to claim 5, characterized in that: The molar ratio of the fatty alcohol to nitric acid is 1:1.1 to 1:1.5 nitrate ester.

7. The safe and environmentally friendly process for producing nitrate esters according to claim 6, characterized in that: The diameter of the reaction channel of the microchannel reactor is 2 mm to 5 mm, and the length is 3 m to 10 m.

8. The safe and environmentally friendly process for nitrate esters according to claim 7, characterized in that: The nitration reaction temperature is -10℃ to 20℃, the nitration reaction pressure is 0MPa to 2.0MPa, and the reaction residence time is 0.5s to 120s.

9. An apparatus for the safe and environmentally friendly production process of nitrate esters as described in claim 8, characterized in that: It includes a microchannel reactor, a mixed acid feed pump, and multiple raw material pumps. The inlet end of the microchannel reactor is connected to the mixed acid feed pump via a tee or a mixer. The feed pipeline of the microchannel reactor is connected to the delivery interface of the raw material pumps. The outlet end of the microchannel reactor is connected to an fatty acid separation device.

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