A process and device for preparing sec-octyl nitrate

Abstract

The present invention belongs to the technical field of preparing nitrate esters, and particularly relates to a process and device for preparing sec-octyl nitrate. The process includes: introducing a certain amount of mixed acid and sec-octanol into a raw material distribution pipeline and a microchannel reactor in the form of continuous flow through an acid pump and an alcohol pump respectively, controlling the set temperature by a heating tank, leading the crude product out of the microchannel reactor to a post-treatment receiver after nitration reaction, separating the collected ester-acid mixture, washing the organic phase, and drying to obtain the finished product. The preparation process and device of the present invention can realize the production equipment of sec-octyl nitrate, improve the synthesis efficiency and safety of sec-octyl nitrate, reduce the generation of side reaction products, and solve the problems of high process amplification cost and great difficulty in large-scale industrial production existing in the existing microchannel reactor technology.

Description

Technical Field

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

[0002] Nitrates are multifunctional functional groups and intermediates in synthetic organic chemistry, and can be used in petrochemical industry, pharmaceuticals, energetic materials, etc. When applied in the petrochemical field, it is 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] Currently, there is no report on the nitration of sec-octanol and the large-scale production of sec-octyl nitrate. This is mainly because there are certain difficulties in the preparation and production of sec-octyl nitrate, which are mainly reflected in the following aspects:

[0004] 1. High requirement for reaction selectivity: In a secondary alcohol molecule, there is a hydrogen atom on the carbon atom connected to the hydroxyl group. Its nitration reaction may produce multiple products, including products with the hydroxyl group substituted and by-products with substitution occurring at other positions on the carbon skeleton. This requires precise control of reaction conditions during 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.

[0005] 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 using strong oxidants such as mixed acid as the nitrating agent, secondary alcohols may preferentially undergo oxidation reactions to form corresponding ketones or other oxidation products instead of the desired nitration products, thereby reducing the yield of the nitration reaction.

[0006] 3. Influence of steric hindrance: Compared with primary alcohols, the carbon atom connected to the hydroxyl group in secondary alcohols is connected to two other groups, resulting in a certain steric hindrance. This steric hindrance will prevent the nitrating reagent from attacking the hydroxyl group, making it difficult for the nitration reaction to proceed smoothly. Higher reaction activity or more suitable reaction conditions are required to overcome the influence of steric hindrance to achieve an effective nitration reaction.

[0007] 4. Strict control of reaction conditions: The nitration reaction itself is a highly exothermic reaction, and the nitration of secondary alcohols is relatively sensitive to conditions. Therefore, it is necessary to precisely control conditions such as reaction temperature, reactant concentration, and reaction time. If the temperature is too high, not only will the number of side reactions increase, but it may also cause danger; if the temperature is too low, the reaction rate will be too slow and the efficiency will be low. In addition, the dosage 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

[0008] The object 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 amplification cost and great difficulty in large-scale industrial production existing in the existing microchannel reactor technology. By using this method, the goals of high nitration reaction rate and conversion rate of sec-octanol and few side reaction products are achieved.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a sec-octyl nitrate preparation device, including:

[0011] A mixed acid unit for providing the mixed acid for the reaction of sec-octyl nitrate;

[0012] A sec-octanol unit for providing sec-octanol for the reaction of sec-octyl nitrate;

[0013] A raw material distribution pipeline. The mixed acid unit and the sec-octanol unit are respectively connected to a raw material distribution pipeline, which is used to introduce the mixed acid and sec-octanol into the corresponding raw material distribution pipeline in the form of continuous flow;

[0014] A microchannel reactor, 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;

[0015] Wherein, at least one set of Tesla valve structure mixing unit is designed in each raw material distribution pipeline and the microchannel reactor; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve, and the connection directions of the front-end Tesla valve and the rear-end Tesla valve are opposite. The mixed acid and sec-octanol are distributed through the raw material distribution pipeline and enter the microchannel reactor, and form a reflux and perform repeated collisions through the front-end Tesla valve and the rear-end Tesla valve with opposite directions to carry out the nitration reaction.

[0016] As a further improvement of the present invention, both the front-end Tesla valve and the rear-end Tesla valve are 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-earring is 5-60°, and the semi-earrings are connected end to end to form an annular three-dimensional Tesla valve flow channel.

[0017] As a further improvement of the present invention, the raw material distribution pipeline includes a mixed acid material pipeline inlet, a sec-octanol pipeline inlet, a mixed acid distribution pipeline and a corresponding number of sec-octanol distribution pipelines; the mixed acid material pipeline inlet is divided into several branches, and each branch is connected to a mixed acid distribution pipeline. The sec-octanol pipeline inlet is divided into several branches, and each branch is connected to a sec-octanol distribution pipeline; a mixed acid distribution pipeline is correspondingly connected to a sec-octanol distribution pipeline. The mixed acid distribution pipeline and the sec-octanol distribution pipeline are arranged oppositely and meet at the raw material confluence point, and the raw material confluence point is connected to the microchannel reactor at a right angle.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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:

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The device for preparing sec-octyl nitrate of the present invention introduces a certain amount of mixed acid and sec-octyl alcohol into the raw material distribution pipeline and the microchannel reactor in the form of continuous flow respectively, sets the temperature and controls it. After the nitration reaction, the crude product is led out from the microchannel reactor for post-treatment. The collected ester-acid mixture is separated. After the organic phase is washed, it is dried to obtain the finished product. By using the microchannel reactor, the raw material distribution pipeline and the microchannel reactor are provided with a Tesla valve structure mixing unit. When the raw materials flow through their respective distribution pipelines, due to the resistance generated by the front Tesla valve and the rear Tesla valve with opposite directions, the inner diameters of the Tesla valves of each pipeline, the branch pipe diameters, the diversion angles, the number of valve pairs, etc. can be adjusted to ensure that the internal resistances of each pipeline are the same, so that the material flow is evenly distributed in each pipeline without generating uneven flow, and at the same time, the problem that the system is complex and difficult to control caused by using regulating valves is avoided. During actual industrial production, multiple groups of distribution pipelines can be designed and installed according to the actual production situation to achieve the purposes of increasing production, flexible production and safe production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0029] Figure 1 It is a process flow diagram for the synthesis of sec-octyl nitrate of the present invention;

[0030] Figure 2 It is a flow channel diagram in the raw material distribution pipeline of the present invention;

[0031] Figure 3 It is a flow channel diagram in the microchannel reactor of the present invention;

[0032] Figure 4 It is a gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 1 of the present invention;

[0033] Figure 5 It is a gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 2 of the present invention;

[0034] Figure 6 It is a gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 3 of the present invention;

[0035] Figure 7 It is a gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 4 of the present invention;

[0036] Figure 8 It is a gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 5 of the present invention.

[0037] In the figure, 1 is a mixed acid tank; 2 is a sec-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 the first pump, and 8 is the second pump. Specific Embodiments

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] As a continuous-flow tubular microchannel reactor, the microchannel reactor has a larger specific surface area, efficient mixing and heat transfer characteristics, and safer operation, especially when dealing with hazardous reactants and products (such as nitrate esters); in addition, due to the relatively fast mixing speed of the materials in the pipeline, the nitration reaction can be completed in a shorter time, reducing side reactions and unnecessary by-products. Currently, the synthesis of chemicals such as nitrate esters by means of microchannel reactors has become an important method. For example, the Chinese patent application with the publication number CN109867605A, "Preparation of 1,2,4-Butanetriol Trinitrate in a Continuous-Flow Microchannel Reactor", etc. use the method of continuous microchannel synthesis to synthesize the corresponding nitrate compounds.

[0040] However, there are still many problems in the nitration of fatty alcohols in actual industrial production. First, for short-chain fatty alcohols (such as C3 and C4 alcohols), their nitration reactions are very fast, while longer-chain fatty alcohols (such as C5 and C6 alcohols) require a certain reaction residence time, which requires an extension of the pipeline length or volume, causing two problems. One is that the increase in the liquid holdup of the microchannel reactor leads to an increase in risk factors, which is not in line with the principle of safe production. The other is that the size of the microchannel reactor is small, and local accumulation problems of high-speed fluid flow are likely to occur inside. As the pipeline grows, the resistance of the fluid on the inner wall of the pipeline becomes larger, and the pressure drop increases, which may lead to an increase in the internal pressure of the pipeline and pose a safety risk, or the front-end feed pump may not be able to transport normally due to excessive pressure; second, when industrial-scale production needs to be carried out, a simple microchannel structure can only improve production capacity by simply replicating the existing process production line. With the increase in cost investment, more equipment needs to be added, which will lead to complex control of the production system and an increase in potential safety risks. If a distributed pipeline design method is used to increase the flow rate, due to uneven flow channel resistance, the fluid is prone to bypass phenomenon when flowing through the pipeline. Using the opening and closing degree of the regulating valve for flow control, the fluctuation of a single regulating valve is likely to cause the fluctuation of the overall production system flow rate and an increase in safety risks; in addition, during the nitration process, the heat released by the reaction is likely to cause nitrogen oxides gas to be generated when nitric acid is 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 posing risks of spraying and splashing of materials.

[0041] In summary, sec-octanol belongs to the long-chain alcohol. Its nitration reaction rate is slower than that of isopropanol and 1,2,4-butanetriol. Also, due to being a secondary alcohol, its nitration rate is slower than that of isooctanol. Therefore, a longer reaction pipeline is required during the reaction process.

[0042] For this reason, based on Figure 1 as shown, the first aspect of the present invention is to provide a sec-octyl nitrate preparation device, which can ensure that the internal resistance of each pipeline is the same, the flow rate is accurate, and the material mixing is uniform and sufficient. The device includes: a mixed acid unit, a sec-octanol unit, a raw material distribution pipeline, and a microchannel reactor;

[0043] Corresponding to Figure 1 in, the mixed acid tank 1 can be used as the mixed acid unit to provide the mixed acid for the sec-octyl nitrate reaction; the sec-octanol dilution tank 2 is used as the sec-octanol unit to provide sec-octanol for the sec-octyl nitrate reaction; 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 dried obtained finished product. The first pump 7 is used as the acid pump, and the second pump 8 is used as the alcohol pump.

[0044] Among them, the mixed acid unit and the sec-octanol unit are respectively connected to a raw material distribution pipeline, which is used to introduce the mixed acid and sec-octanol into the corresponding raw material distribution pipeline in a continuous flow form; 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.

[0045] Furthermore, as Figure 2 and Figure 3 shown, at least one set of Tesla valve structure mixing units is designed in each raw material distribution pipeline and the microchannel reactor; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve, and the connection directions of the front-end Tesla valve and the rear-end Tesla valve are opposite.

[0046] During actual industrial large-scale production, to ensure rapid, convenient, and safe production capacity improvement, the present invention introduces a raw material distribution pipeline and a microchannel reactor with a Tesla valve structure mixing unit to meet the requirements of flexible production and safe production.

[0047] First of all, 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 flowing through each pipeline is the same. Therefore, the distribution is guaranteed, and there will be no risk of reaction process out-of-control caused by distribution differences due to uneven flow. In addition, the number of dynamic equipment is reduced, the complexity of the reaction system is reduced, which is beneficial to operation and monitoring.

[0048] Secondly, by integrating a Tesla valve structure mixing unit, the microchannel reactor effectively controls the flow state of the fluid in the microchannel, reduces the problems of local accumulation and high-speed flow of the fluid in the pipeline, thereby reducing the pressure drop and safety risks.

[0049] 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.

[0050] In addition, this design also considers the risk of nitrogen oxide gas generated due to reaction heat. During industrial scale-up production, the microchannel reactor can be designed as small modules. Through modular design, multiple modules can be connected and used as needed at the beginning, allowing for flexible addition of reaction units without a large increase in dynamic equipment, thereby simplifying the control complexity of the production system and reducing potential safety risks. The present invention can achieve the efficient and safe preparation of sec-octyl nitrate, meeting the requirements of industrial production.

[0051] 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 with 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 impacts between sec-octanol and nitric acid, improve the mixing degree of the two, make the reaction more sufficient, and facilitate the nitration reaction.

[0052] Preferably, as Figure 2 shown, 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 head and tail of each semi-earring are connected to form an annular three-dimensional Tesla valve flow channel. When increasing the production by expanding the flow rate, the physical resistance of the fluid passing through the pipe diameter is different, affecting the heat transfer and mass transfer processes. By respectively setting "one-to-many" type Tesla valve structure mixing unit structures with different inclination angles at the inlet of the mixed acid material pipeline and the inlet of the sec-octanol pipeline, the problem of uneven distribution of pipeline resistance caused by increasing the flow rate can be avoided, ensuring accurate fluid velocity and uniform and sufficient mixing of the materials.

[0053] More preferably, the raw material distribution pipeline includes an inlet of the mixed acid material pipeline, an inlet of the sec-octanol pipeline, a mixed acid distribution pipeline, and a sec-octanol distribution pipeline; the inlet of the mixed acid material pipeline is divided into several branches, and each branch is connected to a mixed acid distribution pipeline. The inlet of the sec-octanol pipeline is divided into several branches, and each branch is connected to a sec-octanol distribution pipeline; one mixed acid distribution pipeline is correspondingly connected to one sec-octanol distribution pipeline, and the mixed acid distribution pipeline and the sec-octanol distribution pipeline are arranged oppositely and intersect at the raw material confluence point, and the raw material confluence point is connected to the microchannel reactor at a right angle.

[0054] As an example, at least one set of Tesla valve structure mixing units is designed in each mixed acid distribution pipeline and sec-octyl alcohol distribution pipeline; each set of mixed acid distribution pipelines and sec-octyl alcohol distribution pipelines are symmetrically arranged with respect to the raw material confluence point.

[0055] More specifically, the front-end Tesla valves of the mixed acid distribution pipeline, the sec-octyl alcohol pipeline inlet and the front end of the microchannel reactor are in the reverse direction, and the rear-end Tesla valves are in the forward direction. When conducting in the forward direction, the Tesla valve will guide the fluid to pass through smoothly and accelerate the fluid flow rate at each half-earring confluence point; when conducting in the reverse direction, during the processes of fluid splitting, turning, refluxing, and converging, the fluid will repeat within each Tesla valve structure mixing unit, slowing down the fluid flow rate and effectively preventing the reaction liquid from flowing back.

[0056] Through the front-end Tesla valve and the rear-end Tesla valve of the present invention, the pressure drop in each pipeline of the raw material distribution pipeline is 1 to 2 Mpa, and the pressure drop in the microchannel reactor is 2 to 3 Mpa.

[0057] During actual manufacturing, the pipe diameter of the raw material distribution pipeline is 1 mm to 4 mm, and the diameters of the mixed acid distribution pipeline and the sec-octyl alcohol distribution pipeline are 0.5 to 2 mm.

[0058] Taking the preparation of sec-octyl nitrate as an example, and of course not limited to the preparation of sec-octyl nitrate, another object of the present invention is to provide a process for preparing sec-octyl nitrate. Using the above-mentioned sec-octyl nitrate preparation device, it includes the following steps:

[0059] Introduce a certain amount of mixed acid and sec-octyl alcohol into the raw material distribution pipeline in the form of a continuous flow through an acid pump and an alcohol pump respectively, and then introduce them into the microchannel reactor. The set temperature is controlled by a heating tank. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver, and the collected ester-acid mixture is separated, washed, and dried to obtain the finished product.

[0060] The principle of the present invention is as follows: A certain amount of mixed acid and sec-octanol are respectively 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. The set temperature is controlled by a heating bath. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver. The collected ester-acid mixture is separated. After the organic phase is washed, it is dried to obtain the finished product. The present invention uses a raw material distribution pipeline and a microchannel reactor. In each raw material distribution pipeline, a "one-to-many" type raw material distribution pipeline is provided and supplemented with a Tesla valve structure mixing unit, which can effectively control the same pressure drop in each pipeline, avoid the problem of uneven distribution of pipeline resistance caused by increasing the flow rate, ensure accurate fluid flow velocity, and uniform and sufficient material distribution. A Tesla valve structure mixing unit is arranged 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 extend the residence time of the material in the microchannel reactor, ensure that the secondary alcohol group has sufficient reaction time, and improve the conversion rate of its nitration reaction. Furthermore, the present invention improves the synthesis efficiency and safety of sec-octyl nitrate, reduces the generation of side reaction products, and solves the problems of high process amplification cost and great difficulty in large-scale industrial production existing in the existing microchannel reactor technology.

[0061] 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 with 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 sec-octanol and nitric acid, improve the mixing degree of the two, make the reaction more complete, and is conducive to the nitration of the secondary alcohol group.

[0062] When preparing sec-octyl nitrate, the half-earring tilt angle (diversion angle), branch pipe diameter, and number of valve pairs of the Tesla valve structure mixing unit in the present invention are selected and designed according to the physical properties and flow principle of the material. When increasing the production by expanding the flow rate, the physical resistance of the fluid passing through the pipe diameter is different, affecting the heat transfer and mass transfer processes. "One-to-many" type Tesla valve structure mixing units with different tilt angles are respectively arranged in the mixed acid distribution pipeline and the sec-octanol distribution pipeline, which can avoid the problem of uneven distribution of pipeline resistance caused by increasing the flow rate, ensure accurate fluid flow velocity, and uniform and sufficient material mixing.

[0063] When nitrating sec - octanol with mixed acid in a microchannel reactor, a large amount of nitrogen oxide gas is generated, resulting in pipeline pressurization. In the present invention, a Tesla valve structure mixing unit is introduced into the microchannel reactor. The semi - earring in the Tesla valve structure mixing unit can be used as a repeating unit to extend the residence time of the material in the microchannel reactor, control the pressure drop, and convert the 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 in the micro - reaction channel and reducing the safety risk caused by excessive pressure during the reaction, enabling the reaction system to complete the nitration reaction process under normal, safe, and controllable conditions.

[0064] In the present invention, multiple groups of forward Tesla valves are additionally installed at the rear end of each raw material distribution pipeline and in the microchannel reactor. Its purpose is to act as a check valve. Compared with the commonly used spring - type check valve, the Tesla valve structure mixing unit is more durable and will not have deformation of key parts due to long - term contact with corrosive media, and can more effectively ensure that the mixed acid and sec - octanol will not cause "channeling reaction" due to spring deformation and leakage or large pressure difference, further enhancing the safety guarantee. Therefore, the Tesla valve can effectively prevent the "channeling reaction" caused by spring deformation and leakage of the mixed acid and sec - octanol or large pressure difference, improving the safety during the production process. The Tesla valve structure mixing unit can keep the pressure drop in each pipeline of each raw material distribution pipeline consistent, and the pressure drop range (1 - 2 Mpa) is controllable, which helps to optimize the reaction conditions and improve the reaction efficiency.

[0065] As an optional solution, the Tesla valve structure mixing unit can keep the pressure drop in each pipeline of each raw material distribution pipeline of the mixed acid and sec - octanol raw materials consistent, and the pressure drop can be controlled within 1 - 2 Mpa, and the pressure drop in the microchannel reactor can be controlled within 2 - 3 Mpa.

[0066] Preferably, the microchannel reactor of the present invention uses a heating tank for temperature control, and the post - treatment receiver is used for post - treatment process temperature control. The set temperature range of the heating tank and the post - treatment receiver helps to maintain the stability of the reaction system, and the heating tank and the receiver ensure that the reaction proceeds under appropriate 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 set temperature of the heating tank is 30 - 50 °C, and the temperature of the post - treatment receiver is 10 - 30 °C.

[0067] Further preferably, the optimization of the diameters of the mixed acid distribution pipeline and the sec - octanol pipeline helps to accurately control the flow rate of the raw materials, ensuring that the reactants enter the microchannel reactor at a predetermined ratio and speed. A smaller pipeline diameter helps 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 1 mm - 4 mm, and the diameters of the mixed acid distribution pipeline and the sec - octanol distribution pipeline are 0.5 - 2 mm.

[0068] As an alternative, the residence time of the mixed acid and sec-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, the molar ratio of nitric acid to sec-octanol is 1 - 2, the feeding temperature of the mixed acid is 30 - 50 °C, the feeding rate is 180 - 460 mL / min, the feeding temperature of sec-octanol is 30 - 50 °C, and the feeding rate is 150 - 320 mL / min. By controlling the residence time of the mixed acid and sec-octanol in the microchannel reactor, the progress of the reaction can be precisely controlled to avoid overreaction or underreaction. An appropriate residence time helps to produce high-quality products while reducing the generation of by-products. Precise 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 sec-octanol, the feeding temperature and rate of the mixed sulfuric acid and sec-octanol helps to optimize the reaction conditions, improve the efficiency and selectivity of the reaction. Precise 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.

[0069] The method of the present invention will be described in detail below with specific examples.

[0070] Example 1

[0071] 98% concentrated sulfuric acid and 65% concentrated nitric acid were mixed at a molar ratio of sulfuric acid to nitric acid of 1:1 to obtain a mixed acid. The mixed acid and sec-octanol were introduced into the raw material distribution pipeline through an acid pump and an alcohol pump respectively according to the molar ratio of nitric acid to sec-octanol of 1.05:1, and then introduced into the microchannel reactor for nitration reaction. The set temperature was controlled by a heating bath. After the nitration reaction, the crude product was led out from the microchannel reactor to a post-treatment receiver. The materials in the post-treatment receiver were separated, washed, and then dried to obtain the finished product. The mixed acid distribution pipeline was designed with a "one-to-two" type Tesla valve structure mixing unit, and two sets of front-end Tesla valves and rear-end Tesla valves with opposite directions were designed, keeping the diversion angle at 45°45'. The pressure drop in each pipeline of the mixed acid distribution pipeline was 0.15 Mpa; the sec-octanol distribution pipeline was designed with a "one-to-three" type Tesla valve structure mixing unit, and three sets of front-end Tesla valves and rear-end Tesla valves with opposite directions were designed, and the diversion angle was 55°20'. The pressure drop in each pipeline of the raw material distribution pipeline was 0.10 Mpa; a set of front-end Tesla valves and rear-end Tesla valves were arranged at the front end of the microchannel reactor, and the diversion angles were both 50°45'. The pressure drop of the microchannel reactor was controlled within 1.20 Mpa. The pipeline diameter of the raw material distribution pipeline was 4 mm, and the diameters of the mixed acid distribution pipeline and the sec-octanol distribution pipeline were 2 mm. The set temperature of the heating bath was 50 °C, and the water bath temperature of the post-treatment receiver was 10 °C. The feeding temperature of the mixed acid was 50 °C, the feeding rate was 190 mL / min, the feeding temperature of sec-octanol was 50 °C, and the feeding rate was 300 mL / min. The purity of the final product was 99.85%, and the yield was 97.23%.

[0072] In all embodiments of the present invention, the front-end Tesla valve has a forward Tesla valve structure, and the rear-end Tesla valve has a reverse Tesla valve structure.

[0073] Figure 4 This is the gas chromatogram analysis of sec-octyl nitrate prepared in Example 1 of the present invention; the analysis results are shown in Table 1 (the unit of the abscissa is min, and the unit of the ordinate is pA):

[0074] Table 1

[0075]

[0076] Through Figure 4 and the analysis of Table 1, it can be obtained that the retention time of the main component sec-octyl nitrate is 1.383 minutes, and the peak area and content both account for 99.8541%, indicating that the purity of the product is very high.

[0077] Example 2

[0078] Mix concentrated sulfuric acid with a content of 90% and concentrated nitric acid with a content of 75% in a molar ratio of sulfuric acid to nitric acid of 1.05:1 to obtain a mixed acid. According to the molar ratio of nitric acid to sec-octanol of 1.2:1, the mixed acid and sec-octanol are introduced into the raw material distribution pipeline through an acid pump and an alcohol pump respectively, and then introduced into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating bath. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver. The materials in the post-treatment receiver are separated, washed, and then dried to obtain the finished product. The mixed acid distribution pipeline is designed with a "one-to-three" type Tesla valve structure mixing unit, and three groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, keeping the diversion angle at 40°20'. The pressure drop in each pipeline of the mixed acid distribution pipeline is 0.12 Mpa; the sec-octanol distribution pipeline is designed with a "one-to-four" type Tesla valve structure mixing unit, and four groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, and the diversion angle is 50°23'. The pressure drop in each pipeline of the sec-octanol distribution pipeline is 0.09 Mpa; a group 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'. The pressure drop of the microchannel reactor is controlled at 1.44 Mpa. The pipeline diameter of the raw material distribution pipeline is 3.5 mm, and the diameters of the mixed acid distribution pipeline and the sec-octanol distribution pipeline are 1.5 mm. The set temperature of the heating bath is 45°C, and the water bath temperature of the post-treatment receiver is 15°C. The feeding temperature of the mixed acid is 45°C, and the feeding speed is 225 mL / min. The feeding temperature of sec-octanol is 45°C, and the feeding speed is 295 mL / min. The purity of the final product is 99.97%, and the yield is 98.15%.

[0079] Figure 5 This is the gas chromatogram analysis of sec-octyl nitrate prepared in Example 2 of the present invention, as shown in Table 2 specifically;

[0080] Table 2

[0081]

[0082] By Figure 5 and Table 2 analysis, it can be obtained that the main component, sec-octyl nitrate, is at 1.385 minutes, and both the peak area and content are 99.9657%, indicating that the sample purity is very high.

[0083] Example 3

[0084] Mix concentrated sulfuric acid with a content of 80% and concentrated nitric acid with a content of 80% in a molar ratio of sulfuric acid to nitric acid of 1.2:1 to obtain a mixed acid. Introduce the mixed acid and sec-octanol into the raw material distribution pipeline through an acid pump and an alcohol pump respectively according to the molar ratio of nitric acid to sec-octanol of 1.3:1, and then introduce them into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating bath. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver. The materials in the post-treatment receiver are separated, washed, and then dried to obtain the finished product. The mixed acid distribution pipeline is designed with a "one-to-four" type Tesla valve structure mixing unit, and four groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, keeping the shunt angle at 35°52'. The pressure drop in each pipeline of the mixed acid distribution pipeline is 0.10 Mpa; the sec-octanol distribution pipeline is designed with a "one-to-five" type Tesla valve structure mixing unit, and five groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, with a shunt angle of 45°50'. The pressure drop in each pipeline of the sec-octanol distribution pipeline is 0.08 Mpa; a group of front-end Tesla valves and rear-end Tesla valves are set at the front end of the microchannel reactor, and the shunt angles are both 45°29'. The pressure drop of the microchannel reactor is controlled at 1.60 Mpa. The pipeline diameter of the raw material distribution pipeline is 3 mm, and the diameters of the mixed acid distribution pipeline and the sec-octanol distribution pipeline are 1.25 mm. The set temperature of the heating bath is 40°C, and the water bath temperature of the post-treatment receiver is 20°C. The feeding temperature of the mixed acid is 40°C, and the feeding speed is 265 mL / min. The feeding temperature of sec-octanol is 40°C, and the feeding speed is 300 mL / min. The purity of the final product is 99.97%, and the yield is 97.68%.

[0085] Figure 6 This is the gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 3 of the present invention; specifically see Table 1;

[0086] Table 3

[0087]

[0088] By Figure 6 and Table 3 analysis, it can be obtained that the main component, sec-octyl nitrate, is at 1.355 minutes, and both the peak area and content are close to 100%, indicating that the sample purity is very high.

[0089] Example 4

[0090] Mix concentrated sulfuric acid with a content of 75% and concentrated nitric acid with a content of 90% at a molar ratio of sulfuric acid to nitric acid of 1.3:1 to obtain a mixed acid. Introduce the mixed acid and sec-octyl alcohol into the raw material distribution pipeline through an acid pump and an alcohol pump respectively according to the molar ratio of nitric acid to sec-octyl alcohol of 1.4:1, and then introduce them into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating bath. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver. The materials in the post-treatment receiver are separated, washed, and then dried to obtain the finished product. The mixed acid distribution pipeline is designed with a "one-to-five" type Tesla valve structure mixing unit, with five groups of front-end Tesla valves and rear-end Tesla valves with opposite directions, keeping the diversion angle at 30°11'. The pressure drop in each pipeline of the mixed acid distribution pipeline is 0.09 Mpa; the sec-octyl alcohol distribution pipeline is designed with a "one-to-six" type Tesla valve structure mixing unit, with six groups of front-end Tesla valves and rear-end Tesla valves with opposite directions, and the diversion angle is 40°22'. The pressure drop in each pipeline of the sec-octyl alcohol distribution pipeline is 0.075 Mpa; one group of front-end Tesla valves and rear-end Tesla valves are arranged at the front end of the microchannel reactor, and the diversion angles are both 40°30'. The pressure drop of the microchannel reactor is controlled at 1.80 Mpa. The pipeline diameter of the raw material distribution pipeline is 2.5 mm, and the diameters of the mixed acid distribution pipeline and the sec-octyl alcohol distribution pipeline are 1.05 mm. The set temperature of the heating bath is 35°C, and the water bath temperature of the post-treatment receiver is 25°C. The feeding temperature of the mixed acid is 35°C, and the feeding speed is 300 mL / min. The feeding temperature of sec-octyl alcohol is 35°C, and the feeding speed is 305 mL / min. The purity of the final product is 99.97%, and the yield is 98.37%.

[0091] Figure 7 This is the gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 4 of the present invention, as shown in Table 4 specifically;

[0092] Table 4

[0093]

[0094] Through Figure 7 and the analysis of Table 4, it can be obtained that the main component, sec-octyl nitrate, is at 1.385 minutes, and the peak area and content are close to 100%, indicating that the purity of the sample is very high.

[0095] Example 5:

[0096] Mix concentrated sulfuric acid with a content of 70% and concentrated nitric acid with a content of 98% according to a molar ratio of sulfuric acid to nitric acid of 1.4:1 to obtain a mixed acid. Introduce the mixed acid and sec-octyl alcohol into the raw material distribution pipeline through an acid pump and an alcohol pump respectively according to a molar ratio of nitric acid to sec-octyl alcohol of 2:1, and then introduce them into a microchannel reactor for nitration reaction. The set temperature is controlled by a heating bath. After the nitration reaction, the crude product is led out from the microchannel reactor to a post-treatment receiver. The materials in the post-treatment receiver are separated, washed, and then dried to obtain the finished product. The mixed acid distribution pipeline is designed with a "one-to-six" type Tesla valve structure mixing unit, and six groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, keeping the diversion angle at 25°11'. The pressure drop in each pipeline of the mixed acid distribution pipeline is 0.16 Mpa; the sec-octyl alcohol distribution pipeline is designed with a "one-to-seven" type Tesla valve structure mixing unit, and seven groups of front-end Tesla valves and rear-end Tesla valves with opposite directions are designed, with a diversion angle of 35°10'. The pressure drop in each pipeline of the sec-octyl alcohol distribution pipeline is 0.137 Mpa; a group of front-end Tesla valves and rear-end Tesla valves are arranged at the front end of the microchannel reactor, and the diversion angles are both 35°10'. The pressure drop of the microchannel reactor is controlled at 1.92 Mpa. The pipeline diameter of the raw material distribution pipeline is 2 mm, and the diameters of the mixed acid distribution pipeline and the sec-octyl alcohol distribution pipeline are 0.5 mm. The set temperature of the heating bath is 30 °C, and the water bath temperature of the post-treatment receiver is 30 °C. The feeding temperature of the mixed acid is 30 °C, and the feeding speed is 452 mL / min. The feeding temperature of sec-octyl alcohol is 30 °C, and the feeding speed is 312 mL / min. The purity of the final product is 99.97%, and the yield is 97.93%.

[0097] Figure 8 This is the gas chromatogram analysis chart of sec-octyl nitrate prepared in Example 5 of the present invention, as shown in Table 5 specifically.

[0098] Table 5

[0099] Through Figure 8 And analysis of Table 5 shows that the retention time of the main component of sec-octyl nitrate is 1.355 minutes, and both the peak area and the content are close to 100%, indicating that the purity of the sample is very high. The contents of other minor peaks are very low and have little impact on the results. Therefore, the purity of the sample is very high and meets the standards.

[0100] To sum up, the materials collected in the present invention are separated, and the organic phase is washed and dried to obtain the finished product. The materials collected are separated, washed, and dried to obtain the finished product, with a content of more than 99% and a yield of more than 97%.

[0101] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An apparatus for preparing sec-octyl nitrate, characterized in that Including: A mixed acid unit for providing the mixed acid for the reaction of sec-octyl nitrate; A sec-octanol unit for providing the sec-octanol for the reaction of sec-octyl nitrate; A raw material distribution pipeline. The mixed acid unit and the sec-octanol unit are respectively connected to a raw material distribution pipeline for introducing the mixed acid and sec-octanol into the corresponding raw material distribution pipeline in the form of a continuous flow; A microchannel reactor. 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; Wherein, at least one set of Tesla valve structure mixing unit is designed in each raw material distribution pipeline and the microchannel reactor; the Tesla valve structure mixing unit includes a front-end Tesla valve and a rear-end Tesla valve. The connection directions of the front-end Tesla valve and the rear-end Tesla valve are opposite. The mixed acid and sec-octanol are distributed through the raw material distribution pipeline and enter the microchannel reactor, and form a reflux and perform repeated collisions through the front-end Tesla valve and the rear-end Tesla valve with opposite directions, increasing the number of collisions between sec-octanol and nitric acid, ensuring that the internal resistance of each pipeline is the same, the pressure drop of the material flowing through each pipeline is the same, and a nitration reaction is carried out; 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 θ of the semi-earring is 5-60°. The heads and tails of each semi-earring are connected to form an annular three-dimensional Tesla valve flow channel; The raw material distribution pipeline includes a mixed acid material pipeline inlet, a sec-octanol pipeline inlet, a mixed acid distribution pipeline and a corresponding number of sec-octanol distribution pipelines; the mixed acid material pipeline inlet is divided into several branches, and each branch is connected to a mixed acid distribution pipeline. The sec-octanol pipeline inlet is divided into several branches, and each branch is connected to a sec-octanol distribution pipeline; one mixed acid distribution pipeline is correspondingly connected to one sec-octanol distribution pipeline. The mixed acid distribution pipeline and the sec-octanol distribution pipeline are arranged oppositely and meet at the raw material confluence point. The raw material confluence point is connected to the microchannel reactor at a right angle; The pipeline diameter of the raw material distribution pipeline is 1 mm to 4 mm, and the diameters of the mixed acid distribution pipeline and the sec-octanol distribution pipeline are 0.5 to 2 mm.

2. The nitric acid secondary octyl ester preparation device according to claim 1, characterized in that At least one set of Tesla valve structure mixing unit is designed in each mixed acid distribution pipeline and sec-octanol distribution pipeline; each set of mixed acid distribution pipeline and sec-octanol distribution pipeline is symmetrically arranged with respect to the raw material confluence point.

3. The nitric acid sec-octyl ester preparation device according to claim 1, characterized in that The front-end Tesla valves of the mixed acid distribution pipeline, the sec-octanol distribution pipe and the microchannel reactor are in the reverse direction, and the rear-end Tesla valves are in the forward direction.

4. The nitric acid sec-octyl ester preparation device according to claim 1, characterized in that, The pressure drop in each pipeline of the raw material distribution pipeline is 1 to 2 Mpa, and the pressure drop in the microchannel reactor is 2 to 3 Mpa.

5. A process for preparing sec-octyl nitrate, characterized in that, Using the sec-octyl nitrate preparation device according to any one of claims 1 to 4; the process includes: The mixed acid formed by sulfuric acid and nitric acid and sec-octanol are respectively introduced into the corresponding raw material distribution pipelines in the form of continuous flow, and then introduced into a microchannel reactor for nitration reaction. The mixed acid and sec-octanol are distributed into the microchannel reactor through the raw material distribution pipelines, and form a reflux and carry out repeated collisions through the front Tesla valve and the rear Tesla valve with opposite directions to carry out the nitration reaction; after the nitration reaction, the crude product is drawn out from the microchannel reactor for post-treatment, and sec-octyl nitrate is obtained after the post-treatment.

6. The process for preparing sec-octyl nitrate according to claim 5, characterized in that, The temperature of the nitration reaction is 30~50°C, and the temperature of the post-treatment is 10~30°C.

7. The process for preparing sec-octyl nitrate according to claim 5, characterized in that, The residence time of the mixed acid and sec-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 sec-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 sec-octanol is 30~50°C, and the feeding rate of sec-octanol is 150~320 mL / min.

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