Process for continuous production of ultrafine sodium azide

Abstract

This invention provides a continuous process for producing ultrafine sodium azide, employing either System A or System B, including a nitrite ester synthesis section, a sodium azide synthesis section, and a gravity separation section. In the nitrite ester synthesis section of System A, the reaction temperature is -5℃ to 55℃, and the pressure is atmospheric pressure; the raw material alcohol includes methanol or ethanol. In the nitrite ester synthesis section of System B, the reaction temperature is -15℃ to 5℃, the pressure is atmospheric pressure, and the separation temperature is -5℃ to 55℃; the raw material alcohol includes methanol, ethanol, propanol, or isopropanol. This invention effectively enhances the mixing and transfer of materials under strong centrifugal force, thereby accelerating the reaction and separation speed. Even the azide reaction can proceed rapidly in the aqueous phase without a phase-transfer catalyst, reducing the reaction time from several hours to minutes. The residence time of materials in the equipment is extremely short, significantly shortening the production cycle.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering and relates to the production of sodium azide, specifically to a process for the continuous production of ultrafine sodium azide. Background Technology

[0002] Sodium azide is an important chemical raw material, especially in the last two decades, widely used in pharmaceuticals, pesticides, electronic products, heat-resistant polymer materials, and military industries. There are many methods for its synthesis. Currently, the most common industrial method is the nitrite + hydrazine hydrate + sodium hydroxide method. Based on the synthesis method of the raw material nitrite, there are further methods such as sulfuric acid + nitrite + alcohol, dilute nitric acid + nitrite + alcohol, ammonia oxidation + alcohol, electrodialysis, and nitric oxide + oxygen + alcohol. Different manufacturers choose their process routes based on their budget and specific operating conditions, each with its own advantages and disadvantages. Chinese patents with application numbers 201510629438.0, 201310452735.3, 201510628267.X, 201721146705.X, and 201310451461.6 disclose synthesis processes for sodium azide and its raw material nitrite. In these processes, the sodium azide to nitrite step can use methyl ester, ethyl ester, propyl ester, butyl ester, or isoamyl ester. In actual industrial practice, ethyl ester (the boiling point of ethyl nitrite is 17°C) is more commonly used. Although methyl ester is low in cost, it is a toxic gas and difficult to control due to intermittent operation. Excessive tail gas is difficult to recover, causing environmental problems. Propyl ester, butyl ester, and isoamyl ester are more expensive and leave a high residue in the mother liquor, causing an irritating odor in the production environment. The production wastewater is also difficult to treat, so they are rarely used. Due to the solubility problem of sodium hydroxide, methanol is generally used as a solvent in the azide step, followed by ethanol. Using ethanol as a solvent in combination with ethyl nitrite makes post-processing relatively easy, but ethanol is expensive. More importantly, sodium azide has a solubility of only 0.3% in ethanol at 25°C, easily trapping impurities and leading to impure products with high levels of free alkali. Therefore, many industrial manufacturers use ethyl nitrite as a raw material and methanol as a solvent to produce qualified products in one step, resulting in lower overall costs. However, post-processing then presents the problem of separating methanol and ethanol.

[0003] Chinese patent application number 201210132140.5 discloses a method for preparing sodium azide. In this method, ethyl nitrite gas is passed into a mixture composed of hydrazine hydrate, sodium hydroxide, a catalyst, and ethanol. After the gas is introduced, the reaction is carried out at a temperature of 18-25°C for 1.5-2.5 hours. The catalyst is benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, etc. This technical route allows for the reuse of ethanol. However, this method involves a gas-liquid two-phase synthesis process, requires operation under pressure, poses a risk of gas leakage, and necessitates strict condition control.

[0004] Chinese patent application number 201210140899.8 discloses an aqueous phase synthesis method for sodium azide. Liquid ethyl nitrite is added to a reaction system consisting of hydrazine hydrate, sodium hydroxide, a phase transfer catalyst, and water. The reaction is carried out in a closed system. After the reaction is complete, unreacted ethyl nitrite, byproducts ethanol and water are recovered, and the reaction solution is then filtered to obtain sodium azide. Because this reaction has a relatively large thermal effect, using low-boiling-point liquid ethyl nitrite as a raw material in a batch reactor during a single feed can easily lead to runaway reaction, resulting in increased system pressure and potential explosion.

[0005] Chinese patent application number 201510114085.0 discloses a process for the aqueous synthesis of sodium azide using recycled n-butanol. The process involves mixing butyl nitrite, sodium hydroxide, hydrazine hydrate, a catalyst, and water to form a reaction system. After the reaction, n-butanol is recovered, and sodium azide is obtained by filtration. The recovered n-butanol is then recycled. Using n-butyl nitrite (boiling point 78℃) is relatively safe due to its high boiling point. However, the poor water solubility of butyl nitrite leads to a reaction time of up to 12 hours, resulting in low product purity. Furthermore, the generated n-butanol has an unpleasant odor and an unfriendly production environment.

[0006] Chinese patent application number 2020 1 0166694.1 discloses a continuous, safe production device and process for sodium azide in aqueous phase using a microchannel reactor. This device and process solves safety and automation problems in the sodium azide production process; however, the equipment investment is relatively large, and the energy consumption for concentrating and crystallizing the reaction product from the aqueous phase is high. Additionally, some have attempted to use microchannel reactors in organic solvents to solve safety issues in the sodium azide production process, but these attempts have been hampered by product clogging the channels, preventing smooth reaction.

[0007] All of the above methods, whether crystallizing products from the organic phase or concentrating and crystallizing products from the aqueous phase, share a common characteristic: the resulting product particles are relatively large. When sodium azide is used as a raw material to synthesize organic products (such as alkylsilane azides, benzyl azides, and acyl azides), the process is carried out in organic solvents that do not contain active hydrogen. However, these solvents cannot dissolve sodium azide, so grinding is often used to make the sodium azide very fine before the reaction can proceed. Even so, the reaction time is relatively long, and a phase transfer catalyst is required. Therefore, ultrafine sodium azide products are very suitable for this type of organic reaction. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a continuous process for producing ultrafine sodium azide, thereby solving the technical problem that the sodium azide produced by existing production methods has relatively large particle sizes, making it difficult to meet the requirements of industrial production practices.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A process for continuous production of ultrafine sodium azide, wherein the process employs a system for continuous production of ultrafine sodium azide, the system being system A.

[0011] The aforementioned System A includes a nitrite synthesis section, a sodium azide synthesis section, and a high-gravity separation section.

[0012] In the nitrite synthesis section of System A, the reaction temperature is -5℃ to 55℃, and the pressure is atmospheric pressure.

[0013] In the nitrite synthesis section of System A, the raw material alcohol includes methanol or ethanol.

[0014] The nitrite synthesis section of System A includes a high-level tank for nitrite and alcohol aqueous solution and a high-level tank for dilute acid. The high-level tank for nitrite and alcohol aqueous solution is connected to the first feed inlet of the first hypergravity bed reactor via a first metering pump and a first preheater. The high-level tank for dilute acid is connected to the second feed inlet of the first hypergravity bed reactor via a second metering pump and a second preheater.

[0015] The second outlet of the first high-gravity bed reactor is connected to the nitrite condenser.

[0016] The sodium azide synthesis section of System A includes a high-level tank for nitrite and a high-level tank for hydrazine and sodium hydroxide solution. The outlet of the nitrite condenser is connected to the high-level tank for nitrite, and the high-level tank for nitrite is connected to the third inlet of the second hypergravity bed reactor via a third metering pump. The high-level tank for hydrazine and sodium hydroxide solution is connected to the fourth inlet of the second hypergravity bed reactor via a fourth metering pump.

[0017] The third outlet of the second hypergravity bed reactor is connected to the inlet of multiple parallel crystal growth vessels, the outlet of the crystal growth vessels is connected to the inlet of a centrifuge, and the liquid outlet of the centrifuge is connected to a mother liquor storage tank.

[0018] The fourth outlet of the second hypergravity bed reactor is connected in series with two first and second condensers with different cooling temperatures. The condensate from the first condenser is returned to the fourth outlet of the second hypergravity bed reactor, and the nitrite recovered from the outlet of the second condenser is sent to the high-level nitrite tank.

[0019] The supergravity separation section of System A includes a first supergravity bed separator, and the mother liquor storage tank is connected to the fifth feed port of the first supergravity bed separator through a fifth metering pump and a third preheater.

[0020] The sixth outlet of the first ultragravity bed separator is connected to the solvent recovery condenser.

[0021] The present invention also has the following technical features:

[0022] Preferably, the crystal growth vessel can be replaced by a concentration crystallization vessel.

[0023] Furthermore, System A is replaced by System B; System B also includes a nitrite synthesis section, a sodium azide synthesis section, and a high-gravity separation section.

[0024] In the nitrite synthesis section of System B, the reaction temperature is -15℃ to 5℃, the pressure is atmospheric pressure, and the separation temperature is -5℃ to 55℃.

[0025] In the nitrite synthesis section of System B, the raw material alcohols include methanol, ethanol, propanol, or isopropanol.

[0026] The nitrite synthesis section of System B includes a high-level tank for nitrite and alcohol aqueous solution and a high-level tank for dilute acid. The high-level tank for nitrite and alcohol aqueous solution is connected to the first inlet of the first hypergravity bed reactor via a first metering pump and a first preheater. The high-level tank for dilute acid is connected to the second inlet of the first hypergravity bed reactor via a second metering pump and a second preheater.

[0027] The first discharge port of the first hypergravity bed reactor is connected to the sixth inlet of the second hypergravity bed separator through the fourth preheater, and the second discharge port of the first hypergravity bed reactor is closed.

[0028] The eighth outlet of the second gravity bed separator is connected to the nitrite ester condenser.

[0029] The sodium azide synthesis section of system B is the same as the sodium azide synthesis section of system A.

[0030] The hypergravity separation section of system B is the same as the hypergravity separation section of system A.

[0031] Preferably, in the nitrite synthesis section, the concentration of nitrite is 2-8 mol / L, the concentration of alcohol is 2-8 mol / L, and the concentration of dilute acid is 2-5 mol / L.

[0032] Preferably, in the nitrite ester synthesis section, when the raw material dilute acid is a monobasic acid, the molar ratio of nitrite, alcohol and dilute acid is 1:1.05 to 1.2:1.05; when the raw material dilute acid is a dibasic acid, the molar ratio of nitrite, alcohol and dilute acid is 1:1.05 to 1.2:0.55.

[0033] Preferably, in the nitrite ester synthesis section, the raw material dilute acid includes sulfuric acid, hydrochloric acid, or nitric acid; and the nitrite includes sodium nitrite or potassium nitrite.

[0034] Preferably, in the sodium azide synthesis section, the concentration of hydrazine hydrate is 3-5 mol / L and the concentration of sodium hydroxide is 3-5 mol / L.

[0035] Preferably, in the sodium azide synthesis section, the molar ratio of nitrite to hydrazine hydrate and sodium hydroxide is 1.05-1.2:1.05:1.0.

[0036] Preferably, in the sodium azide synthesis section, the residence time of the raw material in the second hypergravity bed reactor is 50-100 seconds, the reaction temperature is 30-55°C, and the reaction pressure is atmospheric pressure.

[0037] Preferably, in the sodium azide synthesis section, the raw material nitrite includes methyl nitrite, ethyl nitrite, propyl nitrite, or isopropyl nitrite.

[0038] Preferably, in the sodium azide synthesis section, the solvent used for the azide reaction is methanol, ethanol, n-propanol, isopropanol, water, a mixture of water and methanol in any proportion, a mixture of water and ethanol in any proportion, a mixture of water and n-propanol in any proportion, or a mixture of water and isopropanol in any proportion.

[0039] Preferably, the particle size of the ultrafine sodium azide is 50–5000 nm.

[0040] More preferably, the particle size of ultrafine sodium azide is 50–500 nm.

[0041] Compared with the prior art, the present invention has the following technical effects:

[0042] (I) The supergravity bed (1000 times gravity) continuous reactor used in this invention effectively enhances the mixing and transfer of materials under the action of strong centrifugal force, thereby accelerating the reaction and separation of materials. Even the azide reaction can be carried out in one step without phase transfer catalyst in the aqueous phase. The reaction time is shortened from several hours to minutes. The residence time of materials in the equipment is very short, the production cycle is greatly shortened, the reaction process is safer and more stable, and the production efficiency is significantly improved.

[0043] (II) The supergravity bed reactor used in this invention has the structural characteristics of small reaction space and huge specific surface area, which can enhance mass transfer in the reaction process. The entire reaction system occupies a small area and reduces equipment investment.

[0044] (III) The present invention uses two temperature conditions for reaction and separation in the ester preparation process, which effectively avoids the decomposition of intermediate product nitrous acid and further avoids the side reaction of decomposition products nitrogen oxides and hydrazine hydrate.

[0045] (IV) The entire system adopts continuous and closed operation to avoid solvent loss and VOC pollution.

[0046] (V) The sodium azide formation reaction using a spiral channel rotating bed can effectively control the reaction and crystallization process at the molecular scale compared with other reactors, thereby obtaining high-quality nanoparticles with small particle size and uniform distribution. It has the characteristics of small scale-up effect, no encapsulation of raw materials, and easy clogging.

[0047] (VI) The present invention can increase the production scale by designing the number of continuous reactors in the supergravity bed, or flexibly arrange the production volume to achieve full automation. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the overall connection relationship of system A in Example 1.

[0049] Figure 2 This is a schematic diagram of the connection relationship of the nitrite synthesis section of System A in Example 1.

[0050] Figure 3 This is a schematic diagram of the connection relationship of the sodium azide synthesis section in System A of Example 1.

[0051] Figure 4 This is a schematic diagram of the connection relationship of the supergravity separation section of System A in Example 1.

[0052] Figure 5 This is a schematic diagram of the overall connection relationship of system B in Example 2.

[0053] Figure 6 This is a schematic diagram of the connection relationship of the nitrite synthesis section of system B in Example 2.

[0054] The labels in the diagram represent: a-nitrite ester synthesis section, b-sodium azide synthesis section, and c-hypergravity separation section.

[0055] 1-High-level tank for nitrite and alcoholic aqueous solution, 2-High-level tank for dilute acid, 3-First metering pump, 4-Second metering pump, 5-First preheater, 6-Second preheater, 7-First hypergravity bed reactor, 8-Second feed inlet, 9-First feed inlet, 10-First discharge outlet, 11-Waste brine tank, 12-Waste brine pump, 13-Second discharge outlet, 14-Nitrite condenser, 15-High-level tank for nitrite, 16-High-level tank for sodium hydroxide solution, 17-Third metering pump, 18-Fourth metering pump, 19-Second hypergravity bed reactor 20-Fourth feed inlet, 21-Third feed inlet, 22-Third discharge outlet, 23-Crystallization vessel, 24-Centrifuge, 25-Mother liquor storage tank, 26-Fifth metering pump, 27-Fourth discharge outlet, 28-First condenser, 29-Second condenser, 30-Third preheater, 31-First high gravity bed separator, 32-Fifth feed inlet, 33-Fifth discharge outlet, 34-Sixth discharge outlet, 35-Solvent recovery condenser, 36-Low boiling point alcohol receiving tank, 37-Alcohol transfer pump, 38-Water receiving tank, 39-Water transfer pump.

[0056] 101-Fourth preheater, 102-Second supergravity bed separator, 103-Sixth feed inlet, 104-Seventh discharge outlet, 105-Eighth discharge outlet.

[0057] In the diagram, FE refers to the flow meter and T refers to the thermometer.

[0058] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0059] It should be noted that, unless otherwise specified, all components and equipment in this invention are based on components and equipment known in the prior art. For example, the hypergravity bed reactor is a hypergravity bed reactor known in the prior art, the hypergravity bed separator is a hypergravity bed separator known in the prior art, the wastewater treatment system is a wastewater treatment system known in the prior art, the drying system is a drying system known in the prior art, and the solvent recovery system is a solvent recovery system known in the prior art.

[0060] Analysis of existing technologies in the background section reveals four main problems in the sodium azide production process. Firstly, there is the safety issue. Current ester synthesis processes simultaneously synthesize and separate nitrite esters at or above room temperature. This process involves three reactions: nitrite reacts with acid to form nitrous acid; nitrous acid reacts with alcohol to form nitrite esters; and nitrous acid decomposes into nitric oxide and nitrogen dioxide, both of which can react with alcohols to form nitrite esters, or escape from the reaction system without reacting with alcohols. The escaped nitrogen oxides are completely oxidized to nitrogen dioxide upon contact with air. If these oxides react with hydrazine hydrate in the next stage, there is a safety hazard. Nitric acid is less likely to decompose at lower temperatures, ideally between -5°C and 5°C. In addition, the azidation reaction itself has a large heat effect, and nitrites are flammable, explosive, and toxic, so they cannot be stored in large quantities and must be used as they are produced. Secondly, there are issues with reaction rate, conversion rate, and product purity. Because sodium hydroxide, sodium azide, and nitrites have different solubilities in water and alcohol, this affects the reaction rate, conversion rate, and product purity. Thirdly, there is the issue of product particle size. Currently, large-scale production uses batch reactors in organic solvents, which makes it difficult to control the product particle size, resulting in generally large particles that are not conducive to subsequent applications. Fourthly, there is a common problem with the reported processes: the need for continuous and automated reaction processes. Solving this problem will also resolve issues related to safety, cost, and production efficiency.

[0061] This invention addresses the shortcomings of existing processes by proposing a process for producing sodium azide using a high-gravity bed reactor throughout the entire process, including ester synthesis, ester separation, sodium azide synthesis, and mother liquor recovery. This method allows for strict control of the reaction temperature and residence time, preventing runaway reactions and improving production safety. Due to the strong mass transfer effect of the high-gravity bed reactor, this invention enables continuous, safe, and efficient reaction processes, achieving automated production.

[0062] This invention employs a continuous high-gravity bed reactor to rapidly react the prepared acid with nitrite and alcohol aqueous solution, and then rapidly separates the generated ester using a high-gravity bed (the residual ester in the mother liquor is less than 50 ppm). This also makes the acid selectivity more flexible. Traditional processes use dilute sulfuric acid, while this process can also use dilute hydrochloric acid or dilute nitric acid.

[0063] This invention involves metering nitrite esters and prepared hydrazine hydrate and sodium hydroxide solutions into a high-gravity bed reactor at a specific ratio. The reactions are carried out at a certain temperature to obtain an ultrafine sodium azide dispersion. This dispersion is then crystallized in a crystallization reactor (concentration and crystallization reactor) to generate uniform ultrafine sodium azide particles. Solid-liquid separation is then performed to obtain the product, followed by drying to obtain the finished ultrafine sodium azide. The mother liquor is recovered and reused using high-gravity bed distillation.

[0064] In this invention, the condenser uses a coolant at -20°C to room temperature, the mother liquor produced is directly concentrated and crystallized to produce corresponding inorganic salts, and the tail gas from the ester synthesis is treated as waste gas.

[0065] In this invention, the tail gas from the synthesis of sodium azide undergoes two-stage condensation. The first-stage coolant is room temperature cooling water, and the second-stage coolant is a coolant ranging from -20°C to room temperature.

[0066] In this invention, the mother liquor in the centrifuge is processed and returned to the batching section, while the product goes to the finished product drying section.

[0067] In this invention, ultrafine sodium azide refers to sodium azide with a particle size of 50 to 5000 nm. Preferably, ultrafine sodium azide refers to sodium azide with a particle size of 50 to 500 nm.

[0068] In this invention, the various devices are connected by pipes, and each pipe is equipped with a valve as needed.

[0069] 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.

[0070] Example 1:

[0071] This embodiment provides a system for the continuous production of ultrafine sodium azide, which is system A;

[0072] like Figure 1 As shown, System A includes a nitrite synthesis section a, a sodium azide synthesis section b, and a high-gravity separation section c.

[0073] like Figure 2 As shown, the nitrite synthesis section a of system A includes a high-level tank 1 for nitrite and alcohol aqueous solution and a high-level tank 2 for dilute acid. The high-level tank 1 for nitrite and alcohol aqueous solution is connected to the first feed inlet 9 of the first hypergravity bed reactor 7 through a first metering pump 3 and a first preheater 5. The high-level tank 2 for dilute acid is connected to the second feed inlet 8 of the first hypergravity bed reactor 7 through a second metering pump 4 and a second preheater 6.

[0074] The second outlet 13 of the first supergravity bed reactor 7 is connected to the nitrite condenser 14.

[0075] like Figure 3As shown, the sodium azide synthesis section b of system A includes a high-level tank 15 for nitrite and a high-level tank 16 for hydrazine and sodium hydroxide solution. The outlet of the nitrite condenser 14 is connected to the high-level tank 15 for nitrite. The high-level tank 15 for nitrite is connected to the third inlet 21 of the second hypergravity bed reactor 19 via a third metering pump 17. The high-level tank 16 for hydrazine and sodium hydroxide solution is connected to the fourth inlet 20 of the second hypergravity bed reactor 19 via a fourth metering pump 18.

[0076] The third outlet 22 of the second supergravity bed reactor 19 is connected to the inlet of multiple parallel crystal growth vessels 23. The outlet of the crystal growth vessel 23 is connected to the inlet of the centrifuge 24. The liquid outlet of the centrifuge 24 is connected to the mother liquor storage tank 25.

[0077] The fourth outlet 27 of the second hypergravity bed reactor 19 is connected in series with the first condenser 28 and the second condenser 29, which have different cooling temperatures. The condensate from the first condenser 28 is returned to the fourth outlet 27 of the second hypergravity bed reactor 19, and the nitrite recovered from the outlet of the second condenser 29 is sent to the high-level nitrite tank 15.

[0078] like Figure 4 As shown, the supergravity separation section c of system A includes a first supergravity bed separator 31, and a mother liquor storage tank 25 is connected to the fifth feed port 32 of the first supergravity bed separator 31 through a fifth metering pump 26 and a third preheater 30.

[0079] The sixth outlet 34 of the first supergravity bed separator 31 is connected to the solvent recovery condenser 35.

[0080] In this embodiment, the first outlet 10 of the first supergravity bed reactor 7 in the nitrite synthesis section a is connected to the waste brine tank 11 and is connected to the wastewater treatment system through the waste brine pump 12.

[0081] In this embodiment, the solid discharge port of centrifuge 24 in sodium azide synthesis section b is used to discharge material to the drying system.

[0082] In this embodiment, the outlet of the solvent recovery condenser 35 in the supergravity separation section c is connected to the solvent recovery system.

[0083] In this embodiment, the fifth discharge port 33 of the first hypergravity bed separator 31 in the hypergravity separation section c is connected to the wastewater treatment system.

[0084] In this embodiment, the hypergravity bed reactor and hypergravity bed separator can be selected as single-drive hypergravity bed rotating packed bed, dual-drive hypergravity bed rotating packed bed, spiral channel type rotating bed, or multi-layer baffle type hypergravity bed rotating bed as needed.

[0085] In this embodiment, the high-level nitrite tank 15 is equipped with a coolant inlet and outlet.

[0086] In this embodiment, there are two or more crystal growth reactors 23. Each crystal growth reactor 23 is equipped with a heating or cooling liquid inlet / outlet.

[0087] Example 2:

[0088] This embodiment provides a system for the continuous production of ultrafine sodium azide, which is system B.

[0089] like Figure 5 As shown, System B also includes nitrite synthesis section a, sodium azide synthesis section b, and hypergravity separation section c.

[0090] like Figure 6 As shown, the nitrite synthesis section a of system B includes a high-level tank 1 for nitrite and alcohol aqueous solution and a high-level tank 2 for dilute acid. The high-level tank 1 for nitrite and alcohol aqueous solution is connected to the first feed inlet 9 of the first hypergravity bed reactor 7 through a first metering pump 3 and a first preheater 5. The high-level tank 2 for dilute acid is connected to the second feed inlet 8 of the first hypergravity bed reactor 7 through a second metering pump 4 and a second preheater 6.

[0091] The first discharge port 10 of the first supergravity bed reactor 7 is connected to the sixth inlet 103 of the second supergravity bed separator 102 through the fourth preheater 101, and the second discharge port 13 of the first supergravity bed reactor 7 is closed.

[0092] The eighth outlet 105 of the second supergravity bed separator 102 is connected to the nitrite condenser 14.

[0093] The sodium azide synthesis section b in system B is the same as the sodium azide synthesis section b in system A.

[0094] The hypergravity separation section c of system B is the same as that of system A.

[0095] In this embodiment, the seventh outlet 104 of the second high-gravity bed separator 102 in the nitrite synthesis section a is connected to the waste brine tank 11, and is connected to the wastewater treatment system via the waste brine pump 12.

[0096] In this embodiment, the solid discharge port of centrifuge 24 in sodium azide synthesis section b is used to discharge material to the drying system.

[0097] In this embodiment, the outlet of the solvent recovery condenser 35 in the supergravity separation section c is connected to the solvent recovery system.

[0098] In this embodiment, the fifth discharge port 33 of the first hypergravity bed separator 31 in the hypergravity separation section c is connected to the wastewater treatment system.

[0099] In this embodiment, the hypergravity bed reactor and hypergravity bed separator can be selected as single-drive hypergravity bed rotating packed bed, dual-drive hypergravity bed rotating packed bed, spiral channel type rotating bed, or multi-layer baffle type hypergravity bed rotating bed as needed.

[0100] In this embodiment, the high-level nitrite tank 15 is equipped with a coolant inlet and outlet.

[0101] In this embodiment, there are two or more crystal growth reactors 23. Each crystal growth reactor 23 is equipped with a heating or cooling liquid inlet / outlet.

[0102] Example 3:

[0103] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 1.

[0104] Ingredients:

[0105] 1. The concentration of sodium nitrite in the aqueous solution of sodium nitrite and methanol is 4.6 mol / L, and the concentration of methanol is 4.83 mol / L.

[0106] 2. The concentration of dilute sulfuric acid is 2.6 mol / L.

[0107] 3. The concentration of hydrazine hydrate in the hydrazine and sodium hydroxide methanol solution is 5.25 mol / L, and the concentration of sodium hydroxide is 5.0 mol / L.

[0108] The first step involves pumping the prepared sodium nitrite and methanol aqueous solution into a high-level tank 1 (equipped with a weighing module) containing nitrite and alcohol aqueous solution, and dilute sulfuric acid into a high-level tank 2 (equipped with a weighing module). The first high-gravity bed reactor 7 is then started. The two solutions, in a volume ratio of 1:1, are pumped into the first high-gravity bed reactor 7 through the first metering pump 3, the second metering pump 4, the first preheater 5, and the second preheater 6 via the first feed inlet 9 and the second feed inlet 8. The temperature of the feed solution is controlled between -5°C and 0°C, and the jacket temperature of the nitrite condenser 14 and the nitrite high-level tank 15 is controlled below -15°C. At this point, the molar ratio of sodium nitrite, methanol, and sulfuric acid is 1:1.05:0.565.

[0109] The second step involves pumping the prepared hydrazine and sodium hydroxide methanol solution into the sodium hydroxide solution high-level tank 16 equipped with a weighing module, and starting the second hypergravity reactor 19. When the ester collected in the nitrite high-level tank 15 exceeds 1 / 3 of the tank capacity, it is added at a volume ratio of 1:0.3234 (methyl nitrite density 0.991 g / cm³). 3At this point, sodium hydroxide, hydrazine, and nitrite (in a molar ratio of 1:1.05:1.05) simultaneously enter the second hypergravity bed reactor 19 through the third feed inlet 21 and the fourth feed inlet 20. Simultaneously, one crystal growth vessel 23 is opened, maintaining the temperature inside 23 at 35–40°C. When the liquid level in one crystal growth vessel 23 reaches the control level, the process is switched to the other vessel. The residence time in the crystal growth vessel 23 does not exceed one hour from the point the control level is reached. After crystal growth, the mixture is cooled to room temperature, centrifuged to obtain sodium azide solid powder, and dried to obtain an ultrafine finished powder. Analysis shows the powder particle size is 50–500 nm, the main content is 99.5%, and the free alkali is 0.3%.

[0110] In the third step, the centrifuged mother liquor is heated to 70°C by the fifth metering pump 26 and the third preheater 30 and enters the first high gravity bed separator 31 through the fifth feed port 32 to recover the solvent methanol and the wastewater is treated.

[0111] Example 4:

[0112] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 1.

[0113] Ingredients:

[0114] 1. The concentration of nitrite in the sodium nitrite and ethanol aqueous solution is 4.6 mol / L, and the concentration of ethanol is 4.83 mol / L.

[0115] 2. The concentration of dilute sulfuric acid is 2.6 mol / L.

[0116] 3. The concentration of hydrazine hydrate in the hydrazine and sodium hydroxide ethanol solution is 5.25 mol / L, and the concentration of sodium hydroxide is 5.0 mol / L.

[0117] The first step involves pumping the prepared sodium nitrite and ethanol aqueous solution into a high-level tank 1 (equipped with a weighing module) containing nitrite and ethanol aqueous solution, and dilute sulfuric acid into a high-level tank 2 (equipped with a weighing module). The first high-gravity bed reactor 7 is then started. The two solutions, in a volume ratio of 1:1, are pumped into the first high-gravity bed reactor 7 through the first metering pump 3, the second metering pump 4, the first preheater 5, and the second preheater 6 via the first feed inlet 9 and the second feed inlet 8. The temperature of the feed liquid is controlled at room temperature, and the jacket temperature of the nitrite condenser 14 and the nitrite high-level tank 15 is controlled below 0°C. At this point, the molar ratio of sodium nitrite, ethanol, and sulfuric acid is 1:1.05:0.565.

[0118] The second step involves pumping the prepared hydrazine and sodium hydroxide ethanol solution into the sodium hydroxide solution high-level tank 16 equipped with a weighing module, and then starting the second hypergravity reactor 19. When the ester collected in the nitrite high-level tank 15 exceeds one-third of the tank's capacity, it is added at a volume ratio of 1:0.3289 (the density of ethyl nitrite is 1.05 g / cm³). 3 At this point, sodium hydroxide, hydrazine, and nitrite (in a molar ratio of 1:1.05:1.05) simultaneously enter the second hypergravity bed reactor 19 through the third feed inlet 21 and the fourth feed inlet 20. Simultaneously, one crystal growth vessel 23 is opened, maintaining the temperature inside 23 at 35–40°C. When the liquid level in one crystal growth vessel 23 reaches the control level, the process is switched to the other vessel. The residence time in the crystal growth vessel 23 does not exceed one hour from the point the control level is reached. After crystal growth is complete, the mixture is cooled to room temperature, centrifuged to obtain sodium azide solid powder, and dried to obtain an ultrafine finished powder. Analysis shows the powder particle size is 50–500 nm, the main content is 99.6%, and the free alkali is 0.2%.

[0119] In the third step, the centrifuged mother liquor is heated to 90°C through the fifth metering pump 26 and the third preheater 30 and enters the first high gravity bed separator 31 through the fifth feed port 32 to recover the solvent ethanol and the wastewater is treated.

[0120] Example 5:

[0121] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 1.

[0122] This embodiment is basically the same as Embodiment 3, except that the raw material dilute acid is replaced with 5.2 mol / L dilute nitric acid, and the ester synthesis section produces wastewater containing sodium nitrate.

[0123] Example 6:

[0124] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 1.

[0125] This embodiment is basically the same as Embodiment 3, except that the nitrite is potassium nitrite, the raw material dilute acid is 5.2 mol / L dilute hydrochloric acid, and the ester synthesis section produces potassium chloride-containing wastewater.

[0126] Example 7:

[0127] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 1.

[0128] This embodiment is basically the same as embodiment 3, except that the hydrazine and sodium hydroxide solution is replaced with an aqueous solution, the crystal growth vessel 23 is replaced with a concentration crystallization vessel, the centrifuged mother liquor is returned to the concentration crystallization vessel and combined with the new reaction mixture for further concentration and crystallization, the recovered methanol back-ester synthesis section feedstock is used, and the wastewater is treated.

[0129] like Figure 3 As shown, when water is used as the solvent for the azide reaction, the crystal growth vessel 23 is changed to a concentrated crystallization vessel. The mother liquor storage tank 25 is also connected to the feed inlet of the concentrated crystallization vessel through the fifth metering pump 26. The condensate outlet of the concentrated crystallization vessel is connected to the low-boiling-point alcohol receiving tank 36 and the water receiving tank 38, respectively. The alcohol receiving tank 36 is connected to the alcohol batching system of the esterification section through the alcohol transfer pump 37, and the water receiving tank 38 is connected to the water treatment system through the water transfer pump 39.

[0130] The final product, after analysis, has a powder particle size of 1000-5000 nm, a main content of 99.4%, and a free alkali content of 0.4%.

[0131] Example 8:

[0132] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0133] Ingredients:

[0134] 1. The concentration of sodium nitrite in the aqueous solution of sodium nitrite and ethanol is 4.6 mol / L, and the concentration of ethanol is 4.83 mol / L.

[0135] 2. The concentration of dilute sulfuric acid is 2.6 mol / L.

[0136] 3. The concentration of hydrazine hydrate in the hydrazine and sodium hydroxide ethanol solution is 5.25 mol / L, and the concentration of sodium hydroxide is 5.0 mol / L.

[0137] The first step involves pumping the prepared sodium nitrite and ethanol aqueous solution into a high-level tank 1 (equipped with a weighing module) containing nitrite and ethanol aqueous solution, and dilute sulfuric acid into a high-level tank 2 (equipped with a weighing module). The first hypergravity bed reactor 7 and the second hypergravity bed separator 102 are then started. The two solutions, in a volume ratio of 1:1, are pumped into the first hypergravity bed reactor 7 through the first metering pump 3, the second metering pump 4, the first preheater 5, and the second preheater 6 via the first feed inlet 9 and the second feed inlet 8. The temperature of the feed solution is controlled at 0–5°C. The resulting mixture enters the second hypergravity bed separator 102 through the fourth preheater 101 via the sixth feed inlet 103, with the feed solution temperature controlled at 20–25°C. The jacket temperature of the nitrite condenser 14 and the nitrite high-level tank 15 is controlled below 0°C. At this point, the molar ratio of sodium nitrite, ethanol, and sulfuric acid is 1:1.05:0.565.

[0138] The second step involves pumping the prepared hydrazine and sodium hydroxide ethanol solution into the sodium hydroxide solution high-level tank 16 equipped with a weighing module, and starting the second hypergravity reactor 19. When the ester collected in the nitrite high-level tank 15 exceeds 1 / 3 of the tank capacity, it is added at a volume ratio of 1:0.3289 (the density of ethyl nitrite is 1.05 g / cm³). 3 At this point, sodium hydroxide, hydrazine, and nitrite (in a molar ratio of 1:1.05:1.05) simultaneously enter the second hypergravity bed reactor 19 through the third feed inlet 21 and the fourth feed inlet 20. Simultaneously, one crystal growth vessel 23 is opened, maintaining the temperature inside 23 at 35–40°C. When the liquid level in one crystal growth vessel 23 reaches the control level, the process is switched to the other vessel. The residence time in the crystal growth vessel 23 does not exceed one hour from the point the control level is reached. After crystal growth is complete, the mixture is cooled to room temperature, centrifuged to obtain sodium azide solid powder, and dried to obtain an ultrafine finished powder. Analysis shows the powder particle size is 50–500 nm, the main content is 99.6%, and the free alkali is 0.2%.

[0139] In the third step, the centrifuged mother liquor is heated to 90°C through the fifth metering pump 26 and the third preheater 30 and enters the first high gravity bed separator 31 through the fifth feed port 32 to recover the solvent ethanol and the wastewater is treated.

[0140] Example 9:

[0141] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0142] This embodiment is basically the same as Example 8, except that the nitrite is potassium nitrite, the raw material dilute acid is 5.2 mol / L dilute hydrochloric acid, and the ester synthesis section produces potassium chloride-containing wastewater.

[0143] Example 10:

[0144] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0145] This embodiment is basically the same as Example 8, except that the raw material dilute acid is 5.2 mol / L dilute nitric acid, and the ester synthesis section produces wastewater containing sodium nitrate.

[0146] Example 11:

[0147] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0148] This embodiment is basically the same as Embodiment 8, except that the raw material alcohol is isopropanol, the temperature of the liquid entering the second hypergravity bed separator 102 through the fourth preheater 101 is 45-50°C, the jacket temperature of the nitrite condenser 14 and the nitrite high-level tank 15 is below 20°C, and the temperature of the liquid entering the first hypergravity bed separator 31 through the third preheater 30 is 95°C. The azide reaction is a one-step feed at a volume ratio of 1:0.4098 (density of isopropanol nitrite is 1.02 g / cm³). 3 ).

[0149] Example 12:

[0150] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0151] This embodiment is essentially the same as Example 8, except that the concentration of hydrated hydrazine in the hydrazine and sodium hydroxide ethanol solution is 3.15 mol / L, and the concentration of sodium hydroxide is 3.0 mol / L. The azide reaction is carried out in a one-step feed at a volume ratio of 1:0.1973. The final product, after analysis, has a powder particle size of 50-300 nm, a main content of 99.4%, and a free alkali content of 0.2%.

[0152] Example 13:

[0153] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0154] This embodiment is basically the same as Example 8, except that the concentration of sodium nitrite in the sodium nitrite and ethanol aqueous solution is 2.3 mol / L, the concentration of ethanol is 2.76 mol / L, the concentration of dilute sulfuric acid is 1.3 mol / L, and the final product has a powder particle size of 100-400 nm, a main content of 99.5%, and a free alkali content of 0.15%.

[0155] Example 14:

[0156] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0157] This embodiment is basically the same as Embodiment 8, except that the mixed solution of sodium hydroxide and hydrazine is changed to an aqueous solution, the crystal growth vessel is changed to a concentrated crystallization vessel, the centrifuged mother liquor is returned to the concentrated crystallization vessel and combined with the new reaction mixture for further concentrated crystallization, the recycled ethanol is used for the esterification synthesis section, the wastewater is treated, and the final product has a powder particle size of 1000-5000 nm, a main content of 99.4%, and a free alkali content of 0.4%.

[0158] like Figure 3 As shown, when water is used as the solvent for the azide reaction, the crystal growth vessel 23 is changed to a concentrated crystallization vessel. The mother liquor storage tank 25 is also connected to the feed inlet of the concentrated crystallization vessel through the fifth metering pump 26. The condensate outlet of the concentrated crystallization vessel is connected to the low-boiling-point alcohol receiving tank 36 and the water receiving tank 38, respectively. The alcohol receiving tank 36 is connected to the alcohol batching system of the esterification section through the alcohol transfer pump 37, and the water receiving tank 38 is connected to the water treatment system through the water transfer pump 39.

[0159] Example 15:

[0160] This embodiment provides a process for the continuous production of ultrafine sodium azide, which uses the system for the continuous production of ultrafine sodium azide given in Example 2.

[0161] This embodiment is basically the same as embodiment 8, except that the hydrazine and sodium hydroxide solution is a methanol solution. The alcohol separated by the second supergravity bed separator is a mixture of methanol and ethanol. It cannot be directly returned to the system and needs to be further separated before being returned to the system. The final product has a powder particle size of 100-500 nm, a main content of 99.3%, and a free alkali of 0.2%.

Claims

1. A process for continuous production of ultrafine sodium azide, characterized in that, This process employs a continuous production system for ultrafine sodium azide, known as System A. The A system includes a nitrite synthesis section (a), a sodium azide synthesis section (b), and a high-gravity separation section (c); The nitrite synthesis section (a) includes a high-level tank (1) for nitrite and alcohol aqueous solution and a high-level tank (2) for dilute acid. The high-level tank (1) for nitrite and alcohol aqueous solution is connected to the first inlet (9) of the first high-gravity bed reactor (7) through a first metering pump (3) and a first preheater (5). The high-level tank (2) for dilute acid is connected to the second inlet (8) of the first high-gravity bed reactor (7) through a second metering pump (4) and a second preheater (6). The second outlet (13) of the first high gravity bed reactor (7) is connected to the nitrite condenser (14); The sodium azide synthesis section (b) includes a high-level tank for nitrite (15) and a high-level tank for hydrazine and sodium hydroxide solution (16). The outlet of the nitrite condenser (14) is connected to the high-level tank for nitrite (15). The high-level tank for nitrite (15) is connected to the third inlet (21) of the second hypergravity bed reactor (19) via a third metering pump (17). The high-level tank for hydrazine and sodium hydroxide solution (16) is connected to the fourth inlet (20) of the second hypergravity bed reactor (19) via a fourth metering pump (18). The third outlet (22) of the second supergravity bed reactor (19) is connected to the inlet of multiple parallel crystal growth vessels (23), the outlet of the crystal growth vessel (23) is connected to the inlet of the centrifuge (24), and the liquid outlet of the centrifuge (24) is connected to the mother liquor storage tank (25). The fourth outlet (27) of the second hypergravity bed reactor (19) is connected in series with the first condenser (28) and the second condenser (29) with different cooling temperatures. The condensate of the first condenser (28) is returned to the fourth outlet (27) of the second hypergravity bed reactor (19), and the nitrite recovered from the outlet of the second condenser (29) is sent to the high-level nitrite tank (15). The supergravity separation section (c) includes a first supergravity bed separator (31), and the mother liquor storage tank (25) is connected to the fifth feed port (32) of the first supergravity bed separator (31) through a fifth metering pump (26) and a third preheater (30); The sixth outlet (34) of the first high gravity bed separator (31) is connected to the solvent recovery condenser (35); In the nitrite ester synthesis section (a), the reaction temperature is -5℃ to 55℃ and the pressure is atmospheric pressure; the raw material alcohol includes methanol or ethanol. The ultrafine sodium azide has a particle size of 50–500 nm.

2. The process for continuous production of ultrafine sodium azide as described in claim 1, characterized in that, The A system is replaced by the B system; the B system also includes the nitrite synthesis section (a), the sodium azide synthesis section (b), and the hypergravity separation section (c); In the nitrite synthesis section (a) of the B system, the reaction temperature is -15℃ to 5℃, the pressure is atmospheric pressure, and the separation temperature is -5℃ to 55℃. In the nitrite synthesis section (a) of system B, the raw material alcohol includes methanol, ethanol, propanol or isopropanol; The nitrite synthesis section (a) of system B includes a high-level tank (1) for nitrite and alcohol aqueous solution and a high-level tank (2) for dilute acid. The high-level tank (1) for nitrite and alcohol aqueous solution is connected to the first inlet (9) of the first high-gravity bed reactor (7) through a first metering pump (3) and a first preheater (5). The high-level tank (2) for dilute acid is connected to the second inlet (8) of the first high-gravity bed reactor (7) through a second metering pump (4) and a second preheater (6). The first outlet (10) of the first supergravity bed reactor (7) is connected to the sixth inlet (103) of the second supergravity bed separator (102) through the fourth preheater (101), and the second outlet (13) of the first supergravity bed reactor (7) is closed. The eighth outlet (105) of the second high gravity bed separator (102) is connected to the nitrite condenser (14); The sodium azide synthesis section (b) of system B is the same as the sodium azide synthesis section (b) of system A. The hypergravity separation section (c) of system B is the same as the hypergravity separation section (c) of system A.

3. The continuous production process of ultrafine sodium azide as described in claim 1 or 2, characterized in that, In the nitrite synthesis section (a), the concentration of nitrite is 2-8 mol / L, the concentration of alcohol is 2-8 mol / L, and the concentration of dilute acid is 2-5 mol / L. In the nitrite synthesis section (a), when the raw material dilute acid is a monobasic acid, the molar ratio of nitrite, alcohol and dilute acid is 1:1.05 to 1.2:1.05; when the raw material dilute acid is a dibasic acid, the molar ratio of nitrite, alcohol and dilute acid is 1:1.05 to 1.2:0.

55.

4. The process for continuous production of ultrafine sodium azide as described in claim 1 or 2, characterized in that, In the nitrite synthesis section (a), the raw material dilute acid includes sulfuric acid, hydrochloric acid or nitric acid; the raw material nitrite includes sodium nitrite or potassium nitrite.

5. The continuous production process for ultrafine sodium azide as described in claim 1 or 2, characterized in that, In the sodium azide synthesis section (b), the concentration of hydrazine hydrate is 3-5 mol / L and the concentration of sodium hydroxide is 3-5 mol / L. In the sodium azide synthesis section (b), the molar ratio of nitrite to hydrazine hydrate and sodium hydroxide is 1.05–1.2:1.05:1.

0.

6. The process for continuous production of ultrafine sodium azide as described in claim 1 or 2, characterized in that, In the sodium azide synthesis section (b), the raw material stays in the second hypergravity bed reactor for 50 to 100 seconds, the reaction temperature is 30 to 55°C, and the reaction pressure is atmospheric pressure.

7. The continuous production process of ultrafine sodium azide as described in claim 1, characterized in that, In the sodium azide synthesis section (b), the raw material nitrite includes methyl nitrite or ethyl nitrite.

8. The process for continuous production of ultrafine sodium azide as described in claim 2, characterized in that, In the sodium azide synthesis section (b), the raw material nitrite includes methyl nitrite, ethyl nitrite, propyl nitrite, or isopropyl nitrite.

9. The process for continuous production of ultrafine sodium azide as described in claim 1 or 2, characterized in that, In the sodium azide synthesis section (b), the solvent used for the azide reaction is methanol, ethanol, n-propanol, isopropanol, water, a mixture of water and methanol in any proportion, a mixture of water and ethanol in any proportion, a mixture of water and n-propanol in any proportion, or a mixture of water and isopropanol in any proportion.

Images