Process and device for preparing sec-octyl nitrate

Abstract

The invention belongs to the technical field of preparation of nitrate, and particularly relates to a process and a device for preparing sec-octyl nitrate. The process comprises the following steps: respectively introducing a certain amount of mixed acid and sec-octanol into a raw material distribution pipeline and a micro-channel reactor in a continuous flow form through an acid pump and an alcohol pump, controlling the set temperature by a heating tank, leading a crude product after nitration reaction into a post-treatment receiver from the micro-channel reactor, separating the collected ester-acid mixture, and obtaining the sec-octanol. And washing the organic phase, and drying to obtain a finished product. According to the preparation process and the device, production equipment of the sec-octyl nitrate can be realized, the synthesis efficiency and the safety of the sec-octyl nitrate are improved, the generation of side reaction products is reduced, and the problems of high process amplification cost and high difficulty in large-scale industrial production in the existing micro-channel reactor technology are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of nitrate synthesis, and particularly relates to a process and a device for preparing secondary octyl nitrate. Background Art

[0002] Nitrate esters are multifunctional functional groups and intermediates in synthetic organic chemistry and can be used in petrochemicals, pharmaceuticals, energetic materials, etc. When used in the field of petrochemicals, they are mainly used as a diesel additive to increase the cetane number of diesel, improve the ignition performance of diesel, and thus improve the combustion efficiency of diesel in internal combustion engines.

[0003] At present, there are no reports on the nitration of sec-octanol and the large-scale production of sec-octyl nitrate. The main reason is that there are certain difficulties in the preparation and production of sec-octyl nitrate, which are mainly reflected in the following aspects: 1. High requirements for reaction selectivity: In the secondary alcohol molecule, there is a hydrogen atom on the carbon atom to which the hydroxyl group is connected. Its nitration reaction may generate a variety of products, including products in which the hydroxyl group is replaced and by-products in which other positions on the carbon skeleton are replaced. This requires precise control of the reaction conditions in the reaction to improve the selectivity of the target product and obtain the desired nitro secondary alcohol compound, which increases the difficulty of the reaction.

[0004] 2. Prone to side reactions such as oxidation: Secondary alcohols are more easily oxidized than primary alcohols. Under the strong acidic conditions of the nitration reaction, especially when strong oxidants such as mixed acids are used as nitrating agents, secondary alcohols may preferentially undergo oxidation reactions to generate corresponding ketones or other oxidation products rather than the desired nitration products, thereby reducing the yield of the nitration reaction.

[0005] 3. Steric hindrance: Compared with primary alcohols, the carbon atom to which the hydroxyl group of secondary alcohols is connected is connected to two other groups, which produces a certain amount of steric hindrance. This steric hindrance will hinder the attack of the nitrating agent on the hydroxyl group, making it difficult for the nitration reaction to proceed smoothly. Higher reactivity or more suitable reaction conditions are required to overcome the influence of steric hindrance in order to achieve an effective nitration reaction.

[0006] 4. Strict control of reaction conditions: The nitration reaction itself is a violent exothermic reaction, and the nitration of secondary alcohols is sensitive to conditions, so it is necessary to accurately control the reaction temperature, reactant concentration, reaction time and other conditions. If the temperature is too high, it will not only lead to an increase in side reactions, but also may cause danger; if the temperature is too low, the reaction rate will be too slow and the efficiency will be low. In addition, the amount and concentration of the nitrating agent also need to be strictly controlled, otherwise it will affect the selectivity and yield of the reaction. Summary of the invention

[0007] The purpose of the present invention is to provide a process and device for preparing sec-octyl nitrate, so as to solve the problems of high process scale-up cost and great difficulty in large-scale industrial production in the existing microchannel reactor technology. The method is used to achieve the goals of high nitration reaction rate and conversion rate of sec-octanol and less side reaction products.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a device for preparing secondary octyl nitrate, comprising: A mixed acid unit, used for providing mixed acid for the reaction of secondary octyl nitrate; The sec-octanol unit is used to provide sec-octanol for the reaction of sec-octyl nitrate; A raw material distribution pipeline, wherein the mixed acid unit and the octanol unit are respectively connected to a raw material distribution pipeline, and are used to introduce the mixed acid and the octanol into the corresponding raw material distribution pipeline in the form of a continuous flow; A microchannel reactor, wherein the inlet end of the microchannel reactor is connected to the raw material confluence point of the raw material distribution pipeline, and the terminal end is connected to the material outlet channel; Among them, each raw material distribution pipeline and microchannel reactor is designed with at least one group of Tesla valve structure mixing units; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve, and the front-end Tesla valve and the rear-end Tesla valve are connected in opposite directions. The mixed acid and para-octanol are distributed into the microchannel reactor through the raw material distribution pipeline, and reflux is formed through the front-end Tesla valve and the rear-end Tesla valve in opposite directions and repeatedly collide to carry out nitration reaction.

[0009] As a further improvement of the present invention, the front-end Tesla valve and the rear-end Tesla valve are both composed of a bend and a straight channel in parallel, and the overall shape is a plurality of semi-earrings arranged in sequence, the inclination angle θ of the semi-earrings is 5~60°, and the semi-earrings are connected end to end to form a ring-shaped three-dimensional Tesla valve flow channel.

[0010] As a further improvement of the present invention, the raw material distribution pipeline includes a mixed acid material pipeline inlet, a secondary octanol pipeline inlet, a mixed acid distribution pipeline and a corresponding number of secondary octanol distribution pipelines; the mixed acid material pipeline inlet is divided into several branches, each branch is connected to a mixed acid distribution pipeline, the secondary octanol pipeline inlet is divided into several branches, each branch is connected to a secondary octanol distribution pipeline; one mixed acid distribution pipeline is correspondingly connected to one secondary octanol distribution pipeline, the mixed acid distribution pipeline and the secondary octanol distribution pipeline are arranged opposite to each other and intersect at a raw material confluence point, and the raw material confluence point is connected to the microchannel reactor at a right angle.

[0011] As a further improvement of the present invention, at least one group of Tesla valve structure mixing units are designed in each mixed acid distribution pipeline and the secondary octanol distribution pipeline; each group of mixed acid distribution pipelines and the secondary octanol distribution pipelines are symmetrically arranged around the raw material confluence point.

[0012] As a further improvement of the present invention, the front-end Tesla valves of the mixed acid distribution pipe, the secondary octanol distribution pipe and the microchannel reactor are in reverse direction, and the rear-end Tesla valves are in forward direction.

[0013] As a further improvement of the present invention, the pressure drop in each pipeline in the raw material distribution pipeline is 1-2 MPa, and the pressure drop in the microchannel reactor is 2-3 MPa.

[0014] As a further improvement of the present invention, the diameter of the raw material distribution pipeline is 1 mm to 4 mm, and the diameters of the mixed acid distribution pipeline and the secondary octanol distribution pipeline are 0.5 to 2 mm.

[0015] In a second aspect, the present invention provides a process for preparing secondary octyl nitrate, using the secondary octyl nitrate preparation device; the process comprises: The mixed acid formed by sulfuric acid and nitric acid and 2-octanol are respectively introduced into the corresponding raw material distribution pipeline in the form of continuous flow, and then introduced into the microchannel reactor for nitration reaction. The mixed acid and 2-octanol are distributed into the microchannel reactor through the raw material distribution pipeline, and reflux is formed through the front Tesla valve and the rear Tesla valve in opposite directions and repeatedly collide to carry out nitration reaction; after the nitration reaction, the crude product is drawn out from the microchannel reactor for post-treatment, and 2-octyl nitrate is obtained after the post-treatment.

[0016] As a further improvement of the present invention, the temperature of the nitration reaction is 30-50°C, and the temperature of the post-treatment is 10-30°C.

[0017] As a further improvement of the present invention, the residence time of the mixed acid and the secondary octanol in the microchannel reactor is 0.5-3 min, the molar ratio of sulfuric acid to nitric acid in the mixed acid is 1-1.4, and the molar ratio of nitric acid to secondary octanol is 1-2; the feeding temperature of the mixed acid is 30-50° C., and the feeding rate of the mixed acid is 180-460 mL / min; the feeding temperature of the secondary octanol is 30-50° C., and the feeding rate of the secondary octanol is 150-320 mL / min.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: The nitrate ester preparation device of the present invention introduces a certain amount of mixed acid and octanol into the raw material distribution pipeline and the microchannel reactor in the form of continuous flow, sets the temperature and controls it, and the crude product after the nitration reaction is drawn out from the microchannel reactor for post-treatment, and the collected ester acid mixture is separated, and the organic phase is washed and dried to obtain the finished product. By using a microchannel reactor, the raw material distribution pipeline and the microchannel device reaction are provided with a Tesla valve structure mixing unit. When the raw material flows through each distribution pipeline, due to the presence of the front Tesla valve and the rear Tesla valve in opposite directions, the resistance is generated. The Tesla valve diameter, branch diameter, diversion angle, valve pair number, etc. of each pipeline can be adjusted to ensure that the internal resistance of each pipeline is the same, so that the material flow is evenly distributed in each pipeline without generating bias flow, and the problem of complex and difficult to control system caused by the use of a regulating valve is avoided. In actual industrial production, multiple groups of distribution pipelines can be designed and installed according to the actual production situation to achieve the purpose of increasing output, flexible production and safe production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1 The schematic diagram of the process flow of the synthesis of 2-octyl nitrate of the present invention; Figure 2 It is a schematic diagram of the flow channel in the raw material distribution pipeline of the present invention; Figure 3 It is a schematic diagram of the flow channel in the microchannel reactor of the present invention; Figure 4 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 1 of the present invention; Figure 5 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 2 of the present invention; Figure 6 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 3 of the present invention; Figure 7 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 4 of the present invention; Figure 8 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 5 of the present invention.

[0021] In the figure, 1 is a mixed acid tank; 2 is a 2-octanol dilution tank; 3 is a reaction device; 4 is a separation tank; 5 is a washing tank; 6 is a finished product tank; 7 is a first pump; and 8 is a second pump. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] As a continuous flow pipeline microchannel reactor, the microchannel reactor has a larger specific surface area, efficient mixing and heat transfer characteristics, and safer operation, especially when involving dangerous reactants and products (such as nitrates); in addition, since the materials are mixed in the pipeline at a faster speed, the nitration reaction can be completed in a shorter time, reducing side reactions and unnecessary by-products. At present, the synthesis of chemicals such as nitrates with the help of microchannel reactors has become an important method. For example, the Chinese patent application "Preparation of 1,2,4-butanetriol trinitrate in a continuous flow microchannel reactor" with publication number CN109867605A uses a microchannel continuous synthesis method to synthesize the corresponding nitrate compounds.

[0024] However, there are still many problems in the actual industrial production of nitration of fatty alcohols. First, for short-chain fatty alcohols (such as C3 and C4 alcohols), the nitration reaction is very fast, while longer-chain fatty alcohols (such as C5 and C6 alcohols) require a certain reaction residence time, which requires the extension of pipeline length or volume, which causes two problems. First, the increase in the liquid holding capacity of the microchannel reactor leads to an increase in risk factors, and the principle of safe production is not utilized. Second, the microchannel reactor is small in size, and the internal fluid is prone to local accumulation of high-speed flow. As the pipeline grows, the resistance of the fluid on the inner wall of the pipeline increases, and the pressure drop increases, which may lead to an increase in the internal pressure of the pipeline, resulting in safety risks, or the front-end feed pump cannot be transported normally due to excessive pressure; secondly, when it is needed When industrial-scale production is carried out, a simple microchannel structure can only achieve capacity improvement by simply copying the existing process production line. As the cost investment increases, more equipment will be needed, which will make the production system control complex and increase safety risks. If a distributed pipeline design is used to expand the flow rate, the fluid is prone to bias when flowing through the pipeline due to uneven flow resistance. The flow rate is controlled by the opening and closing degree of the regulating valve. The fluctuation of a single regulating valve is likely to cause fluctuations in the flow of the entire production system, increasing safety risks. In addition, during the nitration process, the exothermic reaction can easily cause nitric acid to produce nitrogen oxide gas when heated. The gas will push the material to move rapidly in the pipeline, resulting in insufficient reaction residence time in the pipeline, and at the same time creating the risk of spraying and splashing.

[0025] In summary, 2-octanol is a relatively long carbon chain alcohol, and its nitration rate is slower than that of isopropanol and 1,2,4-butanetriol. Because it is a secondary alcohol, its nitration rate is also slower than that of isooctanol, so a longer reaction pipeline is required during the reaction process.

[0026] To this end, based on Figure 1 As shown, the first aspect of the present invention is to provide a device for preparing 2-octyl nitrate, which can ensure that the internal resistance of each pipeline is the same, the flow rate is accurate, and the materials are mixed evenly and fully. The device includes: a mixed acid unit, a 2-octanol unit, a raw material distribution pipeline and a microchannel reactor; correspond Figure 1 In the process, the mixed acid tank 1 can be used as a mixed acid unit to provide mixed acid for the reaction of secondary octyl nitrate; the secondary octanol dilution tank 2 can be used as a secondary octanol unit to provide secondary octanol for the reaction of secondary octyl nitrate; the reaction device 3 mainly includes a microchannel reactor; the separation tank 4 separates the collected ester acid mixture, the washing tank 5 is used to wash the separated ester acid mixture, and the finished product tank 6 is used to store the finished product obtained by drying. The first pump 7 is used as an acid pump, and the second pump 8 is used as an alcohol pump.

[0027] Among them, the mixed acid unit and the 2-octanol unit are respectively connected to a raw material distribution pipeline, which is used to introduce the mixed acid and 2-octanol into the corresponding raw material distribution pipeline in the form of a continuous flow; the inlet end of the microchannel reactor is connected to the raw material confluence point of the raw material distribution pipeline, and the end is connected to the material outlet channel.

[0028] Furthermore, Figure 2 and Figure 3 As shown, each raw material distribution pipeline and microchannel reactor is designed with at least one group of Tesla valve structure mixing units; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve, and the front-end Tesla valve and the rear-end Tesla valve are connected in opposite directions.

[0029] In actual large-scale industrial production, in order to ensure that the output can be increased quickly, conveniently and safely, the present invention introduces a raw material distribution pipeline and a microchannel reactor containing a Tesla valve structure mixing unit to meet the needs of flexible production and safe production.

[0030] Firstly, the raw material distribution pipeline integrates the Tesla valve structure mixing unit to ensure that the internal resistance of each pipeline is the same, and the pressure drop of the material when flowing through each pipeline is the same, so the distribution is guaranteed, and there will be no risk of loss of control of the reaction process due to distribution differences caused by bias flow. In addition, the number of moving equipment is reduced, the complexity of the reaction system is reduced, and it is convenient for operation and monitoring.

[0031] Secondly, the microchannel reactor integrates a Tesla valve structure mixing unit to effectively control the flow state of the fluid in the microchannel, reduce the local accumulation and high-speed flow problems of the fluid in the pipeline, thereby reducing pressure drop and safety risks.

[0032] At the same time, by designing the internal structure of the microchannel reactor as a Tesla valve structure mixing unit, the residence time of the reactants in the reaction pipeline is ensured to achieve an ideal nitration reaction effect.

[0033] In addition, the design also takes into account the risk of generating nitrogen oxide gas due to reaction heat. During industrial scale-up production, the microchannel reactor can be designed as a small module. Through modular design, multiple modules can be connected and used as needed, allowing for flexible addition of reaction units without adding a large number of moving equipment, thereby simplifying the control complexity of the production system and reducing safety risks. The present invention can achieve efficient and safe preparation of 2-octyl nitrate and meet the needs of industrial production.

[0034] More specifically, when the distributed raw materials enter the microchannel reactor for reaction and flow through the microchannel reactor, the front-end Tesla valve and the rear-end Tesla valve in opposite directions form a reflux effect, breaking the original laminar flow state to form a vortex mixing state. This repeated collision can increase the number of collisions between 2-octanol and nitric acid, improve the mixing degree of the two, make the reaction more complete, and facilitate the nitration reaction.

[0035] Preferably, if Figure 2 As shown in the figure, both the front-end Tesla valve and the rear-end Tesla valve are composed of a bend and a straight channel in parallel. The overall shape is a plurality of semi-earrings arranged in sequence. The inclination angle (diversion angle) θ of the semi-earrings is 5~60°. The semi-earrings are connected end to end to form a ring-shaped three-dimensional Tesla valve flow channel. When the output is enlarged by expanding the flow rate, the physical resistance of the fluid passing through the pipe diameter is different, which affects the heat transfer and mass transfer process. The "one-to-many" Tesla valve structure mixing unit with different inclination angles is set at the inlet of the mixed acid material pipeline and the inlet of the 2-octanol pipeline, which can avoid the problem of uneven distribution of pipeline resistance caused by increasing the flow rate, and ensure that the fluid flow rate is accurate and the material is mixed evenly and fully.

[0036] More preferably, the raw material distribution pipeline includes a mixed acid material pipeline inlet, a secondary octanol pipeline inlet, a mixed acid distribution pipeline and a secondary octanol distribution pipeline; the mixed acid material pipeline inlet is divided into several branches, each branch is connected to a mixed acid distribution pipeline, and the secondary octanol pipeline inlet is divided into several branches, each branch is connected to a secondary octanol distribution pipeline; one mixed acid distribution pipeline is correspondingly connected to one secondary octanol distribution pipeline, and the mixed acid distribution pipeline and the secondary octanol distribution pipeline are arranged opposite to each other and intersect at a raw material confluence point, and the raw material confluence point is connected to the microchannel reactor at a right angle.

[0037] As an example, each mixed acid distribution pipeline and the 2-octanol distribution pipeline is designed with at least one group of Tesla valve structure mixing units; each group of mixed acid distribution pipelines and the 2-octanol distribution pipelines are symmetrically arranged around the raw material confluence point.

[0038] More specifically, the front Tesla valves of the mixed acid distribution pipeline, the inlet of the 2-octanol pipeline and the microchannel reactor are in reverse direction, and the rear Tesla valves are in forward direction. When conducting in forward direction, the Tesla valve will guide the fluid to pass smoothly and accelerate the fluid flow rate at each half-earring intersection; when conducting in reverse direction, during the process of diversion, diversion, reflux and convergence, the fluid will repeat in each Tesla valve structure mixing unit, slowing down the fluid flow rate and effectively preventing the reaction liquid from flowing back.

[0039] Through the front-end Tesla valve and the rear-end Tesla valve of the present invention, the pressure drop in each pipeline in the raw material distribution pipeline is 1-2Mpa, and the pressure drop in the microchannel reactor is 2-3Mpa.

[0040] In actual manufacturing, the diameter of the raw material distribution pipeline is 1 mm to 4 mm, and the diameters of the mixed acid distribution pipeline and the secondary octanol distribution pipeline are 0.5 to 2 mm.

[0041] Taking the preparation of secondary octyl nitrate as an example, it is certainly not limited to the preparation of secondary octyl nitrate. Another object of the present invention is to provide a process for preparing secondary octyl nitrate, adopting the above-mentioned secondary octyl nitrate preparation device, comprising the steps of: A certain amount of mixed acid and 2-octanol are introduced into the raw material distribution pipeline in the form of continuous flow through an acid pump and an alcohol pump respectively, and then introduced into the microchannel reactor. The set temperature is controlled by a heating tank. The crude product after nitration reaction is led out from the microchannel reactor to a post-processing receiver. The collected ester acid mixture is separated, washed, and dried to obtain a finished product.

[0042] The principle of the present invention is: a certain amount of mixed acid and sec-octanol are introduced into the raw material distribution pipeline and the microchannel reactor in the form of continuous flow through an acid pump and an alcohol pump respectively, and the set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn from the microchannel reactor to the post-processing receiver, and the collected ester acid mixture is separated. After washing, the organic phase is dried to obtain the finished product. The present invention uses a raw material distribution pipeline and a microchannel reactor, and a "one-to-many" raw material distribution pipeline is set in each raw material distribution pipeline and supplemented with a Tesla valve structure mixing unit, which can effectively control the pressure drop of each pipeline to be the same, avoid the problem of uneven distribution of pipeline resistance caused by increasing the flow rate, and ensure that the fluid flow rate is accurate and the material distribution is uniform and sufficient. The Tesla valve structure mixing unit is set in the microchannel reactor. On the one hand, it increases the number of collisions between sec-octanol and nitric acid, improves the mixing degree of the two, and is conducive to the nitration of the secondary alcohol group; on the other hand, the Tesla valve structure mixing unit can prolong the residence time of the material in the microchannel reactor, ensure that the secondary alcohol group has enough reaction time, and improve its nitration reaction conversion rate. Therefore, the present invention improves the synthesis efficiency and safety of secondary octyl nitrate, reduces the generation of side reaction products, and solves the problems of high process scale-up cost and great difficulty in large-scale industrial production in the existing microchannel reactor technology.

[0043] As an example of the present invention, when the distributed raw materials enter the microchannel reactor for reaction and flow through the microchannel reactor, the front Tesla valve and the rear Tesla valve in opposite directions form a reflux effect, breaking the original laminar flow state to form a vortex mixing state. This repeated collision can increase the number of collisions between secondary octanol and nitric acid, improve the mixing degree of the two, make the reaction more complete, and facilitate the nitration of the secondary alcohol group.

[0044] When preparing 2-octyl nitrate, the semi-earring inclination angle (diversion angle), branch pipe diameter, and valve pair number of the Tesla valve structure mixing unit in the present invention are selected and designed according to the physical properties of the material and the flow principle. When the output is enlarged by expanding the flow rate, the physical resistance of the fluid is different when passing through the pipe diameter, which affects the heat transfer and mass transfer process. The "one-to-many" Tesla valve structure mixing units with different inclination angles are respectively set in the mixed acid distribution pipeline and the 2-octanol distribution pipeline, which can avoid the problem of uneven distribution of pipeline resistance caused by increasing the flow rate, ensure the accuracy of the fluid flow rate, and ensure that the materials are mixed evenly and fully.

[0045] When 2-octanol and mixed acid are subjected to nitration reaction in a microchannel reactor, a large amount of nitrogen oxide gas will be generated, resulting in pipeline pressurization. In the present invention, by introducing a Tesla valve structure mixing unit in a microchannel reactor, the Tesla valve structure mixing unit uses a semi-earring as a repeating unit to prolong the residence time of the material in the microchannel reactor, control the pressure drop, and realize the conversion of nitrogen oxide gas (especially nitric oxide) generated during the nitration reaction into nitrogen dioxide gas soluble in the material flow, effectively reducing the air pressure of the micro-reaction channel, reducing the safety risk caused by excessive pressure during the reaction, and allowing the reaction system to complete the nitration reaction process under normal, safe and controllable conditions.

[0046] The present invention adds multiple sets of forward Tesla valves at the rear end of each raw material distribution pipeline and in the microchannel reactor, the purpose of which is to play the role of a one-way valve. Compared with the commonly used spring-type one-way valve, the Tesla valve structure mixing unit is more durable, and will not cause deformation of key parts due to long-term contact with corrosive media. It can also ensure that the mixed acid and 2-octanol will not cause "crossflow reaction" due to spring deformation leakage or large pressure difference, further improving safety. Therefore, the Tesla valve can effectively prevent the "crossflow reaction" caused by spring deformation leakage or large pressure difference between mixed acid and 2-octanol, thereby improving the safety of the production process. The Tesla valve structure mixing unit can keep the pressure drop in each pipeline in each raw material distribution pipeline consistent, and the pressure drop range (1~2Mpa) is controllable, which helps to optimize the reaction conditions and improve the reaction efficiency.

[0047] As an optional solution, the Tesla valve structure mixing unit can maintain the same pressure drop in each pipeline in the mixed acid and 2-octanol raw material distribution pipelines, and the pressure drop can be controlled at 1~2Mpa, and the pressure drop in the microchannel reactor can be controlled at 2~3Mpa.

[0048] Preferably, the microchannel reactor of the present invention adopts a heating tank for temperature control, and a post-processing receiver for temperature control of the post-processing process. The setting range of the temperature of the heating tank and the post-processing receiver helps to maintain the stability of the reaction system, and the heating tank and the receiver ensure that the reaction is carried out under suitable conditions. Appropriate temperature setting can increase the reaction rate and reduce the generation of by-products, thereby improving the purity and yield of the product. The setting temperature of the heating tank is 30-50°C, and the temperature of the post-processing receiver is 10-30°C.

[0049] Further preferably, the optimization of the diameter of the mixed acid distribution pipeline and the octanol distribution pipeline helps to accurately control the flow of the raw materials, ensuring that the reactants enter the microchannel reactor at a predetermined ratio and speed. Smaller pipeline diameters help to enhance the mixing effect of the raw materials and improve the uniformity and efficiency of the reaction. Therefore, the pipeline diameter of the raw material distribution pipeline is 1mm~4mm, and the diameter of the mixed acid distribution pipeline and the octanol distribution pipeline is 0.5~2mm.

[0050] As an optional scheme, the residence time of the mixed acid and 2-octanol in the microchannel reactor is 0.5-3min, the molar ratio of sulfuric acid to nitric acid in the mixed acid is 1-1.4, the molar ratio of nitric acid to 2-octanol is 1-2, the feed temperature of the mixed acid is 30-50°C, the feed rate is 180-460mL / min, and the feed temperature of 2-octanol is 30-50°C, and the feed rate is 150-320mL / min. By controlling the residence time of the mixed acid and 2-octanol in the microchannel reactor, the degree of reaction can be accurately controlled to avoid overreaction or underreaction. The appropriate residence time helps to produce high-quality products while reducing the generation of by-products. Accurate control of parameters such as the molar ratio of sulfuric acid to nitric acid in the mixed acid, the molar ratio of nitric acid to 2-octanol, the feed temperature and speed of the mixed sulfur, mixed acid and 2-octanol helps to optimize the reaction conditions and improve the efficiency and selectivity of the reaction. Accurate control of the raw material ratio and temperature can ensure the consistency and stability of the product and improve the controllability of the production process.

[0051] The method of the present invention is described in detail below with reference to specific embodiments.

[0052] Example 1 98% concentrated sulfuric acid and 65% concentrated nitric acid are mixed at a molar ratio of sulfuric acid to nitric acid of 1:1 to obtain a mixed acid. The mixed acid and the 2-octanol are introduced into a raw material distribution pipeline through an acid pump and an alcohol pump respectively at a molar ratio of nitric acid to 2-octanol of 1.05:1, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn from the microchannel reactor to a post-processing receiver. The material in the post-processing receiver is separated, washed, and dried to obtain a finished product. The mixed acid distribution pipeline is designed with a "one-to-two" Tesla valve structure mixing unit, and two sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed to maintain the diversion angle of 45°45′, and the pressure drop in each pipeline in the mixed acid distribution pipeline is 0.15 Mpa; the 2-octanol distribution pipeline is designed with a "one-to-three" Tesla valve structure mixing unit, and three sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed, with a diversion angle of 55°20′, and the pressure drop in each pipeline in the raw material distribution pipeline is 0.10 Mpa; a set of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the diversion angle is 50°45′, and the pressure drop of the microchannel reactor is controlled within 1.20 Mpa. The pipe diameter of the raw material distribution pipeline is 4mm, and the diameter of the mixed acid distribution pipeline and the 2-octanol distribution pipeline is 2mm. The heating tank is set at 50℃, and the water bath temperature of the post-treatment receiver is 10℃. The mixed acid feed temperature was 50°C, the feed rate was 190 mL / min, the secondary octanol feed temperature was 50°C, the feed rate was 300 mL / min. The final product purity was 99.85%, and the yield was 97.23%.

[0053] The front-end Tesla valve in all embodiments of the present invention is a forward Tesla valve structure, and the rear-end Tesla valve is a reverse Tesla valve structure.

[0054] Figure 4 The gas chromatography analysis chart of 2-octyl nitrate obtained in Example 1 of the present invention is shown in Table 1 (the horizontal axis unit is min, and the vertical axis unit is pA): Table 1

[0055] pass Figure 4 From the analysis in Table 1, it can be seen that the main component, 2-octyl nitrate, has a retention time of 1.383 minutes, and the peak area and content account for 99.8541%, indicating that the purity of the product is very high.

[0056] Example 2 90% concentrated sulfuric acid and 75% concentrated nitric acid are mixed at a molar ratio of sulfuric acid to nitric acid of 1.05:1 to obtain a mixed acid. The mixed acid and the 2-octanol are introduced into a raw material distribution pipeline through an acid pump and an alcohol pump respectively at a molar ratio of nitric acid to 2-octanol of 1.2:1, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn out from the microchannel reactor to a post-processing receiver. The material in the post-processing receiver is separated, washed, and dried to obtain a finished product. The mixed acid distribution pipeline is designed with a "one-to-three" Tesla valve structure mixing unit, and three sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed to maintain the diversion angle of 40°20′, and the pressure drop in each pipeline in the mixed acid distribution pipeline is 0.12 Mpa; the 2-octanol distribution pipeline is designed with a "one-to-four" Tesla valve structure mixing unit, and four sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed, with a diversion angle of 50°23′, and the pressure drop in each pipeline in the 2-octanol distribution pipeline is 0.09 Mpa; a set of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the diversion angles are both 48°41′, and the pressure drop of the microchannel reactor is controlled at 1.44 Mpa. The pipe diameter of the raw material distribution pipeline is 3.5 mm, and the diameter of the mixed acid distribution pipeline and the 2-octanol distribution pipeline is 1.5 mm. The heating tank is set at 45°C, and the water bath temperature of the post-treatment receiver is 15°C. The mixed acid feed temperature was 45°C, the feed rate was 225 mL / min, the secondary octanol feed temperature was 45°C, the feed rate was 295 mL / min. The final product purity was 99.97%, and the yield was 98.15%.

[0057] Figure 5 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 2 of the present invention is shown in Table 2; Table 2

[0058] pass Figure 5 From the analysis in Table 2, it can be seen that the peak area and content of the main component, 2-octyl nitrate, are both 99.9657% at 1.385 minutes, indicating that the sample purity is very high.

[0059] Example 3 80% concentrated sulfuric acid and 80% concentrated nitric acid are mixed at a molar ratio of sulfuric acid to nitric acid of 1.2:1 to obtain a mixed acid. The mixed acid and the 2-octanol are introduced into a raw material distribution pipeline through an acid pump and an alcohol pump respectively at a molar ratio of nitric acid to 2-octanol of 1.3:1, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn out from the microchannel reactor to a post-processing receiver. The material in the post-processing receiver is separated, washed, and dried to obtain a finished product. The mixed acid distribution pipeline is designed with a "one-to-four" Tesla valve structure mixing unit, and four sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed to maintain the diversion angle of 35°52′, and the pressure drop in each pipeline in the mixed acid distribution pipeline is 0.10 Mpa; the 2-octanol distribution pipeline is designed with a "one-to-five" Tesla valve structure mixing unit, and five sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed, with a diversion angle of 45°50′, and the pressure drop in each pipeline in the 2-octanol distribution pipeline is 0.08 Mpa; a set of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the diversion angle is 45°29′, and the pressure drop of the microchannel reactor is controlled at 1.60 Mpa. The pipe diameter of the raw material distribution pipeline is 3mm, and the diameter of the mixed acid distribution pipeline and the 2-octanol distribution pipeline is 1.25mm. The heating tank is set at 40℃, and the water bath temperature of the post-treatment receiver is 20℃. The mixed acid feed temperature was 40°C, the feed rate was 265 mL / min, the secondary octanol feed temperature was 40°C, the feed rate was 300 mL / min. The final product purity was 99.97%, and the yield was 97.68%.

[0060] Figure 6 The gas chromatographic analysis chart of 2-octyl nitrate obtained in Example 3 of the present invention is shown in Table 1; Table 3

[0061] pass Figure 6 From the analysis in Table 3, it can be seen that the peak area and content of the main component, 2-octyl nitrate, are close to 100% at 1.355 minutes, which indicates that the purity of the sample is very high.

[0062] Example 4 75% concentrated sulfuric acid and 90% concentrated nitric acid are mixed at a molar ratio of sulfuric acid to nitric acid of 1.3:1 to obtain a mixed acid. The mixed acid and the 2-octanol are introduced into a raw material distribution pipeline through an acid pump and an alcohol pump respectively at a molar ratio of nitric acid to 2-octanol of 1.4:1, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn out from the microchannel reactor to a post-processing receiver. The material in the post-processing receiver is separated, washed, and dried to obtain a finished product. The mixed acid distribution pipeline is designed with a "one-to-five" Tesla valve structure mixing unit, and five sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed to maintain the diversion angle of 30°11′, and the pressure drop in each pipeline in the mixed acid distribution pipeline is 0.09 Mpa; the 2-octanol distribution pipeline is designed with a "one-to-six" Tesla valve structure mixing unit, and six sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed, with a diversion angle of 40°22′, and the pressure drop in each pipeline in the 2-octanol distribution pipeline is 0.075 Mpa; a set of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the diversion angle is 40°30′, and the pressure drop of the microchannel reactor is controlled at 1.80 Mpa. The pipe diameter of the raw material distribution pipeline is 2.5mm, and the diameter of the mixed acid distribution pipeline and the 2-octanol distribution pipeline is 1.05mm. The heating tank is set at 35℃, and the water bath temperature of the post-treatment receiver is 25℃. The mixed acid feed temperature was 35°C, the feed rate was 300 mL / min, the secondary octanol feed temperature was 35°C, the feed rate was 305 mL / min. The final product purity was 99.97%, and the yield was 98.37%.

[0063] Figure 7 The gas chromatographic analysis chart of sec-octyl nitrate obtained in Example 4 of the present invention is shown in Table 4; Table 4

[0064] pass Figure 7 From the analysis in Table 4, it can be seen that the peak area and content of the main component, 2-octyl nitrate, are close to 100% at 1.385 minutes, indicating that the sample is of high purity.

[0065] Embodiment 5: 70% concentrated sulfuric acid and 98% concentrated nitric acid are mixed at a molar ratio of sulfuric acid to nitric acid of 1.4:1 to obtain a mixed acid. The mixed acid and the 2-octanol are introduced into a raw material distribution pipeline through an acid pump and an alcohol pump respectively at a molar ratio of nitric acid to 2:1, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is drawn from the microchannel reactor to a post-processing receiver. The material in the post-processing receiver is separated, washed, and dried to obtain a finished product. The mixed acid distribution pipeline is designed with a "one-to-six" Tesla valve structure mixing unit, and six sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed to maintain the diversion angle of 25°11′. The pressure drop in each pipeline in the mixed acid distribution pipeline is 0.16 Mpa; the 2-octanol distribution pipeline is designed with a "one-to-seven" Tesla valve structure mixing unit, and seven sets of front-end Tesla valves and rear-end Tesla valves in opposite directions are designed, with a diversion angle of 35°10′, and the pressure drop in each pipeline in the 2-octanol distribution pipeline is 0.137 Mpa; a set of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the diversion angle is 35°10′, and the pressure drop of the microchannel reactor is controlled at 1.92 Mpa. The pipe diameter of the raw material distribution pipeline is 2mm, and the diameter of the mixed acid distribution pipeline and the 2-octanol distribution pipeline is 0.5mm. The heating tank is set at 30℃, and the water bath temperature of the post-treatment receiver is 30℃. The mixed acid feed temperature was 30°C, the feed rate was 452 mL / min, the secondary octanol feed temperature was 30°C, the feed rate was 312 mL / min. The final product purity was 99.97%, and the yield was 97.93%.

[0066] Figure 8 The gas chromatographic analysis chart of sec-octyl nitrate obtained for Example 5 of the present invention is specifically shown in Table 5.

[0067] Table 5 pass Figure 8 According to the analysis in Table 5, the retention time of the main component of 2-octyl nitrate is 1.355 minutes, and the peak area and content are close to 100%, indicating that the sample purity is very high. The content of other minor peaks is very low and has little effect on the results. Therefore, the purity of the sample is very high and meets the standard.

[0068] In summary, the collected materials of the present invention are separated, and the organic phase is washed and dried to obtain a finished product. The collected materials are separated, washed and dried to obtain a finished product, with a content of more than 99% and a yield of more than 97%.

[0069] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A device for preparing secondary octyl nitrate, characterized in that: include: A mixed acid unit, used for providing mixed acid for the reaction of secondary octyl nitrate; The sec-octanol unit is used to provide sec-octanol for the reaction of sec-octyl nitrate; A raw material distribution pipeline, wherein the mixed acid unit and the octanol unit are respectively connected to a raw material distribution pipeline, and are used to introduce the mixed acid and the octanol into the corresponding raw material distribution pipeline in the form of a continuous flow; A microchannel reactor, wherein the inlet end of the microchannel reactor is connected to the raw material confluence point of the raw material distribution pipeline, and the terminal end is connected to the material outlet channel; Among them, each raw material distribution pipeline and microchannel reactor is designed with at least one group of Tesla valve structure mixing units; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve, and the front-end Tesla valve and the rear-end Tesla valve are connected in opposite directions. The mixed acid and para-octanol are distributed into the microchannel reactor through the raw material distribution pipeline, and reflux is formed through the front-end Tesla valve and the rear-end Tesla valve in opposite directions and repeatedly collide to carry out nitration reaction.

2. The device for preparing secondary octyl nitrate according to claim 1, characterized in that: The front-end Tesla valve and the rear-end Tesla valve are both composed of a bend and a straight channel in parallel, and the overall shape is a plurality of semi-earrings arranged in sequence, the inclination angle θ of the semi-earrings is 5~60°, and the semi-earrings are connected end to end to form a ring-shaped three-dimensional Tesla valve flow channel.

3. The device for preparing secondary octyl nitrate according to claim 1, characterized in that: The raw material distribution pipeline includes a mixed acid material pipeline inlet, a secondary octanol pipeline inlet, a mixed acid distribution pipeline and a corresponding number of secondary octanol distribution pipelines; the mixed acid material pipeline inlet is divided into several branches, each branch is connected to a mixed acid distribution pipeline, the secondary octanol pipeline inlet is divided into several branches, each branch is connected to a secondary octanol distribution pipeline; one mixed acid distribution pipeline is correspondingly connected to one secondary octanol distribution pipeline, the mixed acid distribution pipeline and the secondary octanol distribution pipeline are arranged opposite to each other and intersect at a raw material confluence point, and the raw material confluence point is connected to the microchannel reactor at a right angle.

4. The device for preparing secondary octyl nitrate according to claim 3, characterized in that: Each mixed acid distribution pipeline and the 2-octanol distribution pipeline is designed with at least one group of Tesla valve structure mixing units; each group of mixed acid distribution pipelines and the 2-octanol distribution pipelines are symmetrically arranged around the raw material confluence point.

5. The device for preparing secondary octyl nitrate according to claim 3, characterized in that: The front-end Tesla valves of the mixed acid distribution pipeline, the secondary octanol distribution pipe and the microchannel reactor are in the reverse direction, and the rear-end Tesla valves are in the forward direction.

6. The device for preparing secondary octyl nitrate according to claim 3, characterized in that: The pressure drop in each pipeline in the raw material distribution pipeline is 1-2 MPa, and the pressure drop in the microchannel reactor is 2-3 MPa.

7. The device for preparing secondary octyl nitrate according to claim 3, characterized in that: The diameter of the raw material distribution pipeline is 1 mm to 4 mm, and the diameters of the mixed acid distribution pipeline and the secondary octanol distribution pipeline are 0.5 to 2 mm.

8. A process for preparing secondary octyl nitrate, characterized in that: The device for preparing secondary octyl nitrate according to any one of claims 1 to 7 is used; the process comprises: The mixed acid formed by sulfuric acid and nitric acid and 2-octanol are respectively introduced into the corresponding raw material distribution pipeline in the form of continuous flow, and then introduced into the microchannel reactor for nitration reaction. The mixed acid and 2-octanol are distributed into the microchannel reactor through the raw material distribution pipeline, and reflux is formed through the front Tesla valve and the rear Tesla valve in opposite directions and repeatedly collide to carry out nitration reaction; after the nitration reaction, the crude product is drawn out from the microchannel reactor for post-treatment, and 2-octyl nitrate is obtained after the post-treatment.

9. The process for preparing secondary octyl nitrate according to claim 8, characterized in that: The temperature of the nitration reaction is 30-50°C, and the temperature of the post-treatment is 10-30°C.

10. The process for preparing secondary octyl nitrate according to claim 8, characterized in that: The residence time of the mixed acid and the secondary octanol in the microchannel reactor is 0.5-3 min, the molar ratio of sulfuric acid to nitric acid in the mixed acid is 1-1.4, and the molar ratio of nitric acid to the secondary octanol is 1-2; the feeding temperature of the mixed acid is 30-50° C., and the feeding speed of the mixed acid is 180-460 mL / min; the feeding temperature of the secondary octanol is 30-50° C., and the feeding speed of the secondary octanol is 150-320 mL / min.

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