Process for producing 2-chloropropene nitrile by multistage reaction and device thereof

Abstract

This invention provides a multi-stage reaction production process and apparatus for 2-chloroacrylonitrile, relating to the field of 2-chloroacrylonitrile production technology. The process includes: using acrylonitrile as raw material in a chlorination reactor, a crude 2,3-dichloropropionitrile is produced by electrophilic addition reaction with chlorine gas under the action of a chlorination catalyst; the crude 2,3-dichloropropionitrile is fed into a vacuum degassing module to remove dissolved hydrogen chloride and unreacted chlorine gas; the degassed crude 2,3-dichloropropionitrile enters an elimination reactor, where it is further treated with a 10% sodium hydroxide solution to obtain crude 2-chloroacrylonitrile. By using a cleaning tube scraping method, the detection error of the temperature sensor due to the accumulation of impurities over time is reduced, ensuring that the temperature sensor can detect the temperature inside the chlorination reactor in real time and accurately. This solves the problem that the surface of the temperature sensor gradually accumulates impurities over time, leading to increased measurement error.

Description

Technical Field

[0001] This invention relates to the field of 2-chloroacrylonitrile production technology, and in particular to a multi-stage reaction production process and apparatus for 2-chloroacrylonitrile. Background Technology

[0002] 2-Chloroacrylonitrile is an important fine chemical intermediate. Its molecular structure contains a carbon-carbon double bond and a cyano difunctional group, allowing it to undergo various reactions such as addition, polymerization, and cyclization. It is widely used in pharmaceuticals, pesticides, dyes, and polymer modification. In the pesticide field, 2-chloroacrylonitrile is a key intermediate for synthesizing novel insecticides and fungicides, enabling the preparation of highly effective and low-toxicity neonicotinoid pesticides and heterocyclic fungicides. In the pharmaceutical field, it can be used as an intermediate in the synthesis of antiviral and antitumor drugs. In the polymer field, it can be used as a comonomer to improve the flame retardancy, weather resistance, and adhesion properties of polyacrylonitrile and acrylate polymers, and market demand continues to grow.

[0003] In the existing technology, the production process of 2-chloroacrylonitrile requires high temperature control accuracy in each processing step. However, during continuous production, the surface of the temperature sensor gradually becomes contaminated with impurities over time. The accumulation of impurities increases their thickness and interferes with the accuracy of the temperature sensor, leading to increased measurement errors. When there are significant temperature fluctuations, the error between the actual temperature reported by the temperature sensor and the detected temperature is large, which directly affects the processing quality of 2-chloroacrylonitrile in different processes and ultimately affects the production purity of 2-chloroacrylonitrile. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multi-stage reaction production process and apparatus for 2-chloroacrylonitrile, thereby solving the problems mentioned in the background section.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a multi-stage reaction production process and apparatus for 2-chloroacrylonitrile, specifically including the following steps: 1. Preparation of raw materials, including acrylonitrile, chlorination catalyst, chlorine gas, polymerization inhibitor, elimination catalyst, and 10% sodium hydroxide solution. Second, chlorination reaction: Acrylonitrile is used as raw material in a chlorination reactor and undergoes an electrophilic addition reaction with chlorine gas under the action of a chlorination catalyst to produce crude 2,3-dichloropropionitrile. Third, degassing treatment: the crude product 2,3-dichloropropionitrile is fed into the vacuum degassing module, the vacuum degree is controlled at -0.07MPa, and degassing is carried out at room temperature for 30 minutes to remove dissolved hydrogen chloride and unreacted chlorine. Fourth, elimination reaction: the degassed crude 2,3-dichloropropionitrile is fed into the elimination reaction vessel, where a polymerization inhibitor and elimination catalyst are added, and then crude 2-chloropropionitrile is obtained by passing it through a 10% sodium hydroxide solution. Fifth, fractionation and purification treatment: the crude 2-chloroacrylonitrile is sent into the fractionation reactor, the temperature of the fractionation reactor is controlled, and 2-chloroacrylonitrile is obtained after condensation.

[0006] Furthermore, in step two, acrylonitrile and a chlorination catalyst, such as a PD catalyst, are sequentially added to the interior of the chlorination reactor. Ice water is injected into the interior of the guide tank to control the reaction temperature inside the chlorination reactor at 30-35°C. Chlorine gas is then injected through a high-precision chlorine injection pipe for 4 hours. The mixture is then stirred for 1 hour by a stirring assembly to obtain crude 2,3-dichloropropionitrile.

[0007] Furthermore, in step four, the crude 2,3-dichloropropionitrile inside the elimination reactor is heated to 105-110°C, and the polymerization inhibitor and elimination catalyst are added sequentially. The stirring assembly is used to stir until the crude 2,3-dichloropropionitrile is completely mixed. Then, 10% sodium hydroxide solution is added to control the pH value of the crude 2,3-dichloropropionitrile to be stable at 7.5-8.5. A pH monitor is installed inside the elimination reactor to detect the pH value in real time. After 3 hours, the elimination reaction is ensured to be complete, and the mixture is cooled to room temperature to obtain crude 2-chloropropionitrile.

[0008] Furthermore, in step five, the crude 2-chloroacrylonitrile in the fractionation reactor is heated to 110-130°C, while the temperature at the top of the column is stabilized at 85°C. The vapor is guided through the evaporation tube into the interior of the fractionation chamber, and the high-purity vapor enters the condenser tube for condensation to obtain high-purity 2-chloroacrylonitrile.

[0009] Furthermore, it includes: a flow guiding tank, an elimination reaction vessel, and a fractionation reaction vessel. The flow guiding tank has a cylindrical structure, and a water-cooled refrigeration module is installed on the outside of the flow guiding tank. A water inlet pipe is installed on the output end of the water-cooled refrigeration module, and a water outlet pipe is installed on the input end of the water-cooled refrigeration module. A uniform flow guiding shroud is installed on the outside of the flow guiding tank. The side end of the water inlet pipe is connected to the outside of the uniform flow guiding shroud. The side end of the water outlet pipe is connected to the other side of the flow guiding tank. Multiple uniformly distributed water flow diversion plates are installed on the inside of the flow guiding tank. A chlorination reaction vessel is installed on the side of the water flow diversion plate, wherein the chlorination reaction vessel is located in the middle of the flow guiding tank. A high-precision chlorine gas injection pipe is installed on one side of the top of the chlorination reaction vessel. The chlorination reaction vessel, the elimination reaction vessel, and the fractionation reaction vessel all have heating modules and wastewater discharge pipes. Three uniformly distributed drive levers are installed on the inside of the chlorination reaction vessel and the elimination reaction vessel.

[0010] Furthermore, a support bracket is installed on the top of the elimination reaction vessel; a servo motor is installed at the middle position of the top of both the chlorination reaction vessel and the support bracket, and a rotating rod is installed on the output end of the bottom of the servo motor; a stirring assembly is installed on the outer side of the rotating rod; a rotating vertical rod is rotatably installed on the inner side of the stirring assembly, wherein a temperature sensor is installed on the rotating vertical rod, and a cleaning scraper is installed on the inner side of the stirring assembly; the cleaning scraper is located outside the rotating vertical rod and the temperature sensor; a rotating guide wheel is installed at the top of the rotating vertical rod, penetrating the top of the stirring assembly; the side end of the drive lever is rotatably installed on the side of the rotating guide wheel.

[0011] Furthermore, a primary flow guide pipe is installed on one side of the elimination reaction vessel, and a secondary flow guide pipe is installed on the other side of the elimination reaction vessel; a drive pump is installed on both the primary and secondary flow guide pipes, a vacuum degassing module is installed on the primary flow guide pipe, and the side end of the primary flow guide pipe passes through the outside of the flow guide tank and connects to the bottom of one side of the chlorination reaction vessel.

[0012] Furthermore, the inner top of the elimination reaction vessel is equipped with a storage tank and a guide rail connected in four directions; one side of the storage tank is connected to the side end of the guide rail; a sealing plate is slidably installed at the bottom of the storage tank; a drive rod is installed at the top of one end of the sealing plate, and the sealing plate is also slidably installed on the top of the guide rail.

[0013] Furthermore, the side end of the secondary guide pipe is connected to the fractionation reactor; a cleaning pipe is installed on one side of the fractionation reactor, and a reactor vertical cylinder is installed on the top of the fractionation reactor; an evaporation pipe is installed on the top of the reactor vertical cylinder; and the side end of the evaporation pipe is connected to the fractionation chamber.

[0014] Furthermore, a reflux pipe is installed on one side of the bottom of the fractionation chamber, and a condenser pipe is installed on one side of the top of the fractionation chamber; the side end of the reflux pipe is connected to the vertical cylinder of the reaction vessel; a sleeve-type condenser assembly is installed on the outside of the condenser pipe.

[0015] This invention provides a multi-stage reaction process and apparatus for the production of 2-chloroacrylonitrile, which has the following beneficial effects: In use, during the rotation of the stirring assembly, the drive plate side end moves the rotating guide wheel at the top of the rotating vertical rod, causing the rotating vertical rod to rotate on the side of the cleaning scraper. This allows the cleaning scraper to continuously scrape and clean the impurities attached to the surface of the temperature sensor. By scraping with the cleaning tube, the detection error of the temperature sensor due to the accumulation of impurities over a long period of time is reduced. This ensures that the temperature sensor can detect the temperature inside the chlorination reactor in real time and accurately, providing a reliable guarantee for the precise control of the reaction temperature and helping to improve the production quality and purity of 2-chloroacrylonitrile.

[0016] Furthermore, during the elimination reaction stage, the iron powder stored in the storage tank inside the elimination reactor is added in batches by rotating the sealing plate through a drive rod. This batch addition allows for better control of the reaction rate, reduces the problem of iron powder agglomeration and incomplete reaction, and makes the reaction more complete. At the same time, polymerization inhibitors and elimination catalysts are continuously added during the reaction process, and the pH value of the reaction system is monitored in real time by an online pH monitor. An appropriate amount of sodium hydroxide solution is added to stabilize the pH value of the entire reaction process at 7.5-8.5. Precise pH control helps to improve the efficiency and selectivity of the elimination reaction, ensures that the reaction is completed, and obtains higher quality crude 2-chloroacrylonitrile. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0018] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0019] In the attached diagram: Figure 1 A production process flow diagram of the present invention is shown; Figure 2 A flow chart of the fractionation and purification process of the present invention is shown; Figure 3 This diagram shows a three-dimensional structural layout of the flow guide tank, the elimination reaction vessel, and the fractionation reaction vessel of the present invention. Figure 4 A schematic cross-sectional view of the flow guide tank of the present invention is shown; Figure 5 A schematic cross-sectional view of the chlorination reactor of the present invention is shown; Figure 6 A three-dimensional structural diagram of the cleaning scraper of the present invention is shown; Figure 7 A schematic cross-sectional view of the elimination reaction vessel of the present invention is shown; Figure 8 A three-dimensional structural diagram of the guide rail of the present invention is shown; Figure 9 A three-dimensional structural diagram of the bottom of the sealing plate of the present invention is shown.

[0020] List of reference numerals 1. Flow guiding tank; 101. Water-cooled refrigeration module; 102. Uniform flow guiding shroud; 103. Water inlet pipe; 104. Water outlet pipe; 105. Water flow divider plate; 106. Chlorination reactor; 107. High-precision chlorine gas injection pipe; 108. Drive lever; 109. Rotating rod; 1010. Stirring assembly; 1011. Rotating vertical rod; 1012. Cleaning scraper; 1013. Rotating guide wheel; 2. Elimination reactor; 201. Primary flow guide pipe; 202. Secondary flow guide pipe; 203. Support bracket; 204. Storage tank; 205. Guide rail; 206. Sealing plate; 207. Drive rod; 3. Fractionation reactor; 301. Cleaning pipes; 302. Reactor vertical cylinder; 303. Evaporation tube; 304. Fractionation chamber; 305. Reflux tube; 306. Condenser tube; 307. Shell-and-tube condenser assembly. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please refer to Figures 1 to 9 : Example 1: This invention proposes a multi-stage reaction production process and apparatus for 2-chloroacrylonitrile, comprising the following steps: 1. Preparation of raw materials, including acrylonitrile, chlorination catalyst, chlorine gas, polymerization inhibitor, elimination catalyst, and 10% sodium hydroxide solution. Second, chlorination reaction: Acrylonitrile is used as raw material in chlorination reactor 106. Under the action of chlorination catalyst, it undergoes an electrophilic addition reaction with chlorine to produce crude 2,3-dichloropropionitrile. Third, degassing treatment: the crude product 2,3-dichloropropionitrile is fed into the vacuum degassing module, the vacuum degree is controlled at -0.07MPa, and degassing is carried out at room temperature for 30 minutes to remove dissolved hydrogen chloride and unreacted chlorine. Fourth, elimination reaction: the degassed crude 2,3-dichloropropionitrile is fed into elimination reaction vessel 2, where polymerization inhibitor and elimination catalyst are added, and then crude 2-chloropropionitrile is obtained by passing it through 10% sodium hydroxide solution. Fifth, fractionation and purification: Crude 2-chloroacrylonitrile is fed into a fractionation reactor 3, and the temperature of the fractionation reactor 3 is controlled. After condensation, 2-chloroacrylonitrile is obtained. In step two, acrylonitrile and a chlorination catalyst, such as a PD catalyst, are added sequentially to the chlorination reactor 106. Ice water is injected into the guide tank 1 to control the reaction temperature inside the chlorination reactor 106 at 30-35°C. Chlorine gas is then injected through a high-precision chlorine injection pipe 107 for 4 hours. The mixture is stirred for 1 hour by the stirring assembly 1010 to obtain crude 2,3-dichloropropionitrile. In step four, the crude 2,3-dichloropropionitrile inside the elimination reactor 2 is heated to 105-110°C, and simultaneously, acrylonitrile is added sequentially. Inhibitors and elimination catalysts are added, and the mixture is stirred in stirring unit 1010 until the crude 2,3-dichloropropionitrile is completely mixed. Then, 10% sodium hydroxide solution is added to control the pH value of the crude 2,3-dichloropropionitrile to be stable at 7.5-8.5. The pH value is monitored in real time inside the elimination reaction vessel 2. After 3 hours, the elimination reaction is ensured to be complete, and the mixture is cooled to room temperature to obtain crude 2-chloropropionitrile. In step five, the crude 2-chloropropionitrile in the fractionation reaction vessel 3 is heated to 110-130°C, while the temperature at the top of the column is stabilized at 85°C. The vapor is guided through evaporation tube 303 to the interior of fractionation chamber 304. The high-purity vapor enters the condenser tube 306 and is condensed to obtain high-purity 2-chloropropionitrile. The multi-stage reaction production apparatus for 2-chloroacrylonitrile includes: a flow guide tank 1, an elimination reaction vessel 2, and a fractionation reaction vessel 3. The flow guide tank 1 has a cylindrical structure, and a water-cooled refrigeration module 101 is installed on the outside of the flow guide tank 1. A water inlet pipe 103 is installed on the output end of the water-cooled refrigeration module 101, and a water outlet pipe 104 is installed on the input end of the water-cooled refrigeration module 101. A uniform flow guide shroud 102 is installed on the outside of the flow guide tank 1. The side end of the water inlet pipe 103 is connected to... The outer side of the uniform flow guide shroud 102 is connected; the side end of the outlet pipe 104 is connected to the other side of the flow guide tank 1; multiple uniformly distributed water flow diversion plates 105 are installed on the inner side of the flow guide tank 1; a chlorination reactor 106 is installed on the side of the water flow diversion plate 105, wherein the chlorination reactor 106 is located in the middle of the flow guide tank 1; a high-precision chlorine gas injection pipe 107 is installed on one side of the top of the chlorination reactor 106; the chlorination reactor 106 and the elimination reactor 2 are connected... Both the fractionation reactor 3 and the distillation reactor 2 have heating modules and wastewater discharge pipes; the inner sides of the chlorination reactor 106 and the elimination reactor 2 are each equipped with three evenly distributed drive plates 108; the top of the elimination reactor 2 is equipped with a support bracket 203; a servo motor is installed at the middle position of the top of the chlorination reactor 106 and the support bracket 203, and a rotating rod 109 is installed on the output end of the bottom of the servo motor; a stirring assembly 1010 is installed on the outer side of the rotating rod 109; a rotating vertical rod 1011 is rotatably installed on the inner side of the stirring assembly 1010, wherein a temperature sensor is installed on the rotating vertical rod 1011, and a cleaning scraper 1012 is installed on the inner side of the stirring assembly 1010; the cleaning scraper 1012 is located outside the rotating vertical rod 1011 and the temperature sensor; a rotating guide wheel 1013 is installed through the top of the rotating vertical rod 1011 and through the top of the stirring assembly 1010; the side end of the drive plate 108 is rotatably installed on the side of the rotating guide wheel 1013.

[0023] In this embodiment of the invention, during the production of 2-chloroacrylonitrile, the prepared raw materials are sequentially added into the chlorination reactor 106. When acrylonitrile, as the main raw material and chlorination catalyst, is added into the chlorination reactor 106, the servo motor at the top of the chlorination reactor 106 drives the rotating rod 109 to rotate. The rotating rod 109 drives the outer stirring assembly 1010 to rotate. The stirring assembly 1010 stirs and mixes the acrylonitrile raw material and the added water to form a solution of appropriate concentration. The solution is then injected into the chlorination reactor 106 through the high-precision chlorine injection pipe 107 at the top of the chlorination reactor 106. Chlorine gas is continuously injected into the reactor 106, and the stirring assembly 1010 rotates continuously to carry out the chlorination reaction. The temperature inside the chlorination reactor 106 is detected by a temperature sensor on the rotating vertical rod 1011. As the rotating rod 109 drives the stirring assembly 1010 to rotate, the side end of the drive plate 108 pushes the rotating guide wheel 1013 at the top of the rotating vertical rod 1011, causing the rotating guide wheel 1013 to drive the rotating vertical rod 1011 to rotate on the side of the cleaning scraper 1012, so that the cleaning scraper 1012 cleans the residue adhering to the temperature sensor on the rotating vertical rod 1011. Impurities are scraped and cleaned to prevent the temperature sensor from accumulating impurities over time, ensuring the accuracy of the temperature sensor's detection of the internal temperature of the chlorination reactor 106. Simultaneously, the water-cooled refrigeration module 101 on the outside of the guide tank 1 operates, cooling the water flow through the inlet pipe 103 into the interior of the uniform flow guide shroud 102. The uniform flow guide shroud 102 has multiple slots on its interior and the side of the guide tank 1, allowing the water to flow evenly into the interior of the guide tank 1. Furthermore, multiple evenly distributed water flow diversion plates 10 on the inner side of the guide tank 1 further contribute to this process. 5. Further divert and guide the water flow so that it flows evenly through the outside of the chlorination reactor 106, thereby controlling the temperature of the chlorination reactor 106. The water then flows back into the water-cooled refrigeration module 101 through the outlet pipe 104 for recirculation, keeping the temperature inside the chlorination reactor 106 at 30-35°C. After 4 hours of continuous chlorination, online GC detection showed that the acrylonitrile residue was 0.32%, reaching the reaction endpoint. Chlorination was then stopped, and the mixture was kept warm and stirred for another hour to obtain crude 2,3-dichloropropionitrile.

[0024] In Example 2, based on Example 1, a primary guide pipe 201 is installed on one side of the elimination reaction vessel 2, and a secondary guide pipe 202 is installed on the other side. Both the primary and secondary guide pipes 201 and 202 are equipped with drive pumps. A vacuum degassing module is installed on the primary guide pipe 201. The side end of the primary guide pipe 201 penetrates the outside of the guide tank 1 and connects to the bottom of one side of the chlorination reaction vessel 106. A storage tank 204 and a guide rail 205 are installed on the top inner side of the elimination reaction vessel 2, connected in four directions. One side of the storage tank 204 is connected to the side end of the guide rail 205. A sealing plate 206 is slidably installed at the bottom of the storage tank 204. One side of the sealing plate 206... A drive rod 207 is installed at the top of the end, and a sealing plate 206 is also slidably installed on the top of the guide rail 205. During the production of 2-chloroacrylonitrile, the crude product 2,3-dichloropropionitrile produced in the chlorination reactor 106 is drawn into the vacuum degassing module by the drive pump on the primary guide pipe 201. The chlorination reactor 106 is equipped with a chlorine content detection module, which allows the vacuum degassing module to dechlorinate the chlorine in the crude product 2,3-dichloropropionitrile. The vacuum degree is controlled at -0.07MPa, and degassing is performed at room temperature for 30 minutes to remove dissolved hydrogen chloride and unreacted chlorine. The degassed crude product 2,3-dichloropropionitrile is then sent into the elimination reactor 2. In the elimination reactor 2, the 2,3-dichloropropionitrile is dechlorinated. Propanolonium and water are mixed at a weight ratio of 1:1.5. Iron powder is stored inside the storage tank 204. A drive rod 207 rotates the sealing plate 206 at the bottom of the storage tank 204, causing the stored iron powder to be added in batches into the elimination reactor 2. The temperature is raised to 105-110°C. A servo motor at the top center of the support bracket 203 drives the rotating rod 109 to rotate, which in turn drives the outer stirring assembly 1010 to rotate. The stirring assembly 1010 stirs the crude 2,3-dichloropropionitrile. The temperature inside the chlorination reactor 106 is monitored by a temperature sensor on the rotating vertical rod 1011. As the rotating rod 109 drives the stirring assembly 1010 to rotate... When the reaction is complete, the side end of the drive plate 108 moves the rotating guide wheel 1013 at the top of the rotating vertical rod 1011, causing the rotating guide wheel 1013 to drive the rotating vertical rod 1011 to rotate on the side of the cleaning scraper 1012. This allows the cleaning scraper 1012 to scrape and clean the impurities attached to the temperature sensor on the rotating vertical rod 1011, preventing the accumulation of impurities on the temperature sensor over a long period of time and ensuring the accuracy of the temperature sensor in detecting the internal temperature of the elimination reaction vessel 2. Simultaneously, the polymerization inhibitor and elimination catalyst are continuously added and stirred. The pH value is detected by the online pH monitor installed on the elimination reaction vessel 2, and an appropriate amount of sodium hydroxide solution is added to stabilize the pH value at 7.5-8 throughout the reaction process.5. The total residence time of the reaction solution is 3 hours to ensure complete elimination of the reaction. After standing and separating the layers, the aqueous phase is removed to obtain crude 2-chloroacrylonitrile. The crude 2-chloroacrylonitrile is then guided to the interior of the fractionation reactor 3 under the guidance of the secondary flow pipe 202 for fractionation and purification.

[0025] In Example 3, based on Example 1, the side end of the secondary guide pipe 202 is connected to the fractionation reactor 3; a cleaning pipe 301 is installed on one side of the fractionation reactor 3, and a reactor vertical cylinder 302 is installed on the top of the fractionation reactor 3; an evaporation pipe 303 is installed on the top of the reactor vertical cylinder 302; the side end of the evaporation pipe 303 is connected to the fractionation chamber 304; a reflux pipe 305 is installed on one side of the bottom of the fractionation chamber 304, and a condenser pipe 306 is installed on one side of the top of the fractionation chamber 304; the side end of the reflux pipe 305 is connected to the reactor vertical cylinder 302; a sleeve-type condenser assembly 307 is installed on the outside of the condenser pipe 306. During the production of 2-chloroacrylonitrile, crude 2-chloroacrylonitrile enters the interior of the fractionation reactor 3. The cleaning pipe 301 is sealed to facilitate subsequent cleaning. The reactor 3 is heated to 110-130℃, and the temperature is detected by a temperature sensor installed on the fractionation reactor 3. The temperature at the top of the tower is 85℃, which is the temperature at the top of the reactor vertical cylinder 302. This causes the vapor generated after the crude 2-chloroacrylonitrile evaporates to flow upward through the reactor vertical cylinder 302. The vapor rises and flows through the evaporation pipe 303 into the interior of the fractionation chamber 304. The fractionation chamber 304 integrates an online GC real-time detection module. The vapor with higher purity flows outward through the condenser pipe 306 and is cooled into liquid 2-chloroacrylonitrile with higher purity by the action of the sleeve-type condenser component 307. The vapor with lower purity accumulates in the fractionation chamber 304 and flows back into the interior of the fractionation reactor 3 through the reflux pipe 305 along the reactor vertical cylinder 302 for fractionation and purification, ensuring the purity of the 2-chloroacrylonitrile fractionation.

[0026] The working principle of this embodiment is as follows: Acrylonitrile, as the main raw material, and chlorination catalyst are added into the chlorination reactor 106. The servo motor at the top of the chlorination reactor 106 drives the rotating rod 109 to rotate, which in turn drives the outer stirring assembly 1010 to rotate, mixing the acrylonitrile raw material with the added water to form a solution of appropriate concentration. Chlorine gas is continuously injected into the chlorination reactor 106 through the high-precision chlorine gas injection pipe 107. The stirring assembly 1010 continues to rotate to carry out the chlorination reaction. The temperature inside the chlorination reactor 106 is detected by the temperature sensor on the rotating vertical rod 1011. As the rotating rod 109 drives the stirring assembly 1010 to rotate, the drive plate 108 moves the rotating guide wheel 1013. The rotating vertical rod 1011 rotates on the side of the cleaning scraper 1012, which scrapes and cleans impurities adhering to the temperature sensor, ensuring the accuracy of the temperature sensor's detection of the internal temperature of the chlorination reactor 106. Simultaneously, the water-cooled refrigeration module 101 on the outside of the flow guide tank 1 cools the water, which then flows through the inlet pipe 103 into the uniform flow guide shroud 102 before flowing into the interior of the flow guide tank 1. Multiple evenly distributed water flow dividers 105 further divert and guide the water flow, ensuring it flows evenly across the outside of the chlorination reactor 106. The internal temperature of the chlorination reactor 106 is controlled at 30–35°C. Online GC testing shows that the acrylonitrile residue is 0.32%. Upon reaching the reaction endpoint, chlorination is stopped, and the mixture is kept at a constant temperature and stirred for another hour to obtain crude 2,3-dichloropropionitrile. The crude 2,3-dichloropropionitrile is then pumped into a vacuum degassing module via a pump driven by the primary guide pipe 201 for dechlorination. The degassed crude 2,3-dichloropropionitrile is then fed into an elimination reaction vessel 2, where it is mixed with water. Iron powder is stored inside a storage tank 204. The drive rod 207 is moved to rotate the sealing plate 206 at the bottom of the storage tank 204, allowing the stored iron powder to be added to the elimination reaction vessel 2 in batches. A servo motor at the top center of the support bracket 203 drives the stirring assembly 1010 outside the rotating rod 109 to rotate. The crude 2,3-dichloropropionitrile is stirred in component 1010. The temperature inside the chlorination reactor 106 is detected by a temperature sensor on the rotating vertical rod 1011. The side end of the drive plate 108 moves the rotating guide wheel 1013, causing the rotating vertical rod 1011 to rotate on the side of the cleaning scraper 1012. The cleaning scraper 1012 scrapes and cleans the impurities attached to the temperature sensor on the rotating vertical rod 1011, preventing the accumulation of impurities on the temperature sensor over a long period of time. The polymerization inhibitor and the elimination catalyst are continuously added and stirred to carry out the elimination reaction. The pH value is detected by an online pH monitor installed on the elimination reactor 2. An appropriate amount of sodium hydroxide solution is added to stabilize the pH value at 7.5-8 throughout the reaction process.5. The total residence time of the reaction solution is 3 hours to ensure complete elimination of the reaction. After standing and separating, the aqueous phase is removed to obtain crude 2-chloroacrylonitrile. The crude 2-chloroacrylonitrile enters the fractionation reactor 3 through the secondary guide pipe 202. The fractionation reactor 3 is heated to 110-130℃, and the temperature at the top of the column is 85℃, which is the temperature at the top of the vertical cylinder 302 of the reactor. The vapor generated after evaporation flows upward through the vertical cylinder 302 of the reactor and flows through the evaporation pipe 303 into the fractionation chamber 304. The fractionation chamber 304 integrates an online GC real-time monitoring module. The high-purity vapor flows outward through the condenser pipe 306 and is cooled into high-purity liquid 2-chloroacrylonitrile by the shell-and-tube condenser component 307, ensuring the purity of the 2-chloroacrylonitrile fractionation.

[0027] The following points should be noted in this article: 1. The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention; other structures can refer to general designs.

[0028] 2. Where there is no conflict, the embodiments of the present invention and the features thereof can be combined with each other to obtain new embodiments.

[0029] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-stage reaction process for producing 2-chloroacrylonitrile, characterized in that, Includes the following steps:

1. Preparation of raw materials: acrylonitrile, chlorination catalyst, chlorine gas, polymerization inhibitor, elimination catalyst, and 10% sodium hydroxide solution. Second, chlorination reaction: in the chlorination reactor (106), acrylonitrile is used as raw material and undergoes an electrophilic addition reaction with chlorine gas under the action of chlorination catalyst to produce crude product 2,3-dichloropropionitrile; Third, degassing treatment: the crude product 2,3-dichloropropionitrile is fed into the vacuum degassing module, the vacuum degree is controlled at -0.07MPa, and degassing is carried out at room temperature for 30 minutes to remove dissolved hydrogen chloride and unreacted chlorine. Fourth, elimination reaction: the crude product 2,3-dichloropropionitrile after degassing is put into elimination reaction vessel (2), and polymerization inhibitor and elimination catalyst are added. Then, crude product 2-chloropropionitrile is obtained by passing through 10% sodium hydroxide solution. Fifth, fractionation and purification treatment: crude 2-chloroacrylonitrile is sent into a fractionation reactor, the temperature of the fractionation reactor (3) is controlled, and 2-chloroacrylonitrile is obtained after condensation.

2. The multi-stage reaction production process for 2-chloroacrylonitrile according to claim 1, characterized in that, In step two, acrylonitrile and chlorination catalyst are added to the chlorination reactor (106) in sequence. Ice water is injected into the flow guide tank (1) to control the reaction temperature inside the chlorination reactor (106) at 30-35°C. Chlorine is then injected through the high-precision chlorine injection pipe (107) for 4 hours. The mixture is stirred for 1 hour by the stirring assembly (1010) to obtain crude 2,3-dichloropropionitrile.

3. The multi-stage reaction production process for 2-chloroacrylonitrile according to claim 1, characterized in that, In step four, the crude 2,3-dichloropropionitrile inside the elimination reaction vessel (2) is heated to 105-110°C, and the polymerization inhibitor and elimination catalyst are added sequentially. The stirring component (1010) is used to stir until the crude 2,3-dichloropropionitrile is completely mixed. Then, 10% sodium hydroxide solution is added to control the pH value of the crude 2,3-dichloropropionitrile to be stable at 7.5-8.

5. A pH monitor is installed inside the elimination reaction vessel (2) to detect the pH value in real time. After 3 hours, the elimination reaction is ensured to be complete, and the product is cooled to room temperature to obtain crude 2-chloropropionitrile.

4. The multi-stage reaction production process for 2-chloroacrylonitrile according to claim 1, characterized in that, In step five, the crude 2-chloroacrylonitrile in the fractionation reactor (3) is heated to 110-130°C, while the temperature at the top of the column is stabilized at 85°C. The steam is guided through the evaporation tube (303) to the interior of the fractionation chamber (304). The high-purity steam enters the condenser tube (306) and is condensed to obtain high-purity 2-chloroacrylonitrile.

5. An apparatus for implementing the multi-stage reaction production process of 2-chloroacrylonitrile according to any one of claims 1-4, characterized in that, include: The system comprises a flow guide tank (1), an elimination reaction vessel (2), and a fractionation reaction vessel (3). A water-cooled refrigeration module (101) is mounted on the outside of the flow guide tank (1). An inlet pipe (103) is installed on the output end of the water-cooled refrigeration module (101), and an outlet pipe (104) is installed on the input end of the water-cooled refrigeration module (101). A uniform flow guide shroud (102) is mounted on the outside of the flow guide tank (1). The side end of the inlet pipe (103) is connected to the outside of the uniform flow guide shroud (102). The side end of the outlet pipe (104) is connected to the other side of the flow guide tank (1). The inner side of the flow tank (1) is equipped with multiple evenly distributed water flow diversion plates (105); a chlorination reactor (106) is installed on the side of the water flow diversion plate (105), wherein the chlorination reactor (106) is located in the middle of the flow tank (1); a high-precision chlorine gas injection pipe (107) is installed on one side of the top of the chlorination reactor (106); the chlorination reactor (106), the elimination reactor (2), and the fractionation reactor (3) are all equipped with heating modules and wastewater discharge pipes; three evenly distributed drive levers (108) are installed on the inner side of the chlorination reactor (106) and the elimination reactor (2).

6. The multi-stage reaction production apparatus for 2-chloroacrylonitrile according to claim 5, characterized in that, A support bracket (203) is installed on the top of the elimination reaction vessel (2); a servo motor is installed at the middle position of the top of the chlorination reaction vessel (106) and the support bracket (203), and a rotating rod (109) is installed on the output end of the bottom of the servo motor; a stirring assembly (1010) is installed on the outside of the rotating rod (109); a rotating vertical rod (1011) is rotatably installed on the inside of the stirring assembly (1010), wherein a temperature sensor is installed on the rotating vertical rod (1011), and a cleaning scraper (1012) is installed on the inside of the stirring assembly (1010); the cleaning scraper (1012) is located outside the rotating vertical rod (1011) and the temperature sensor; a rotating guide wheel (1013) is installed through the top of the rotating vertical rod (1011) and through the top of the stirring assembly (1010); the side end of the drive lever (108) is rotatably installed on the side of the rotating guide wheel (1013).

7. A multi-stage reaction production apparatus for 2-chloroacrylonitrile according to claim 5, characterized in that, A primary flow guide pipe (201) is installed on one side of the elimination reaction vessel (2), and a secondary flow guide pipe (202) is installed on the other side of the elimination reaction vessel (2); a drive pump is installed on both the primary flow guide pipe (201) and the secondary flow guide pipe (202); a vacuum degassing module is installed on the primary flow guide pipe (201); and the side end of the primary flow guide pipe (201) passes through the outside of the flow guide tank (1) and is connected to the bottom of one side of the chlorination reaction vessel (106).

8. A multi-stage reaction production apparatus for 2-chloroacrylonitrile according to claim 7, characterized in that, The inner top of the elimination reaction vessel (2) is equipped with a storage tank (204) and a guide rail (205) connected in four directions; one side of the storage tank (204) is connected to the side end of the guide rail (205); a sealing plate (206) is slidably installed on the bottom of the storage tank (204); a drive rod (207) is installed on the top of one end of the sealing plate (206), and the sealing plate (206) is also slidably installed on the top of the guide rail (205).

9. A multi-stage reaction production apparatus for 2-chloroacrylonitrile according to claim 7, characterized in that, The side end of the secondary guide pipe (202) is connected to the fractionation reactor (3); a cleaning pipe (301) is installed on one side of the fractionation reactor (3), and a reactor vertical cylinder (302) is installed on the top of the fractionation reactor (3); an evaporation pipe (303) is installed on the top of the reactor vertical cylinder (302); and a fractionation chamber (304) is connected to the side end of the evaporation pipe (303).

10. A multi-stage reaction production apparatus for 2-chloroacrylonitrile according to claim 9, characterized in that, A reflux pipe (305) is installed on one side of the bottom of the fractionation chamber (304), and a condenser pipe (306) is installed on one side of the top of the fractionation chamber (304); the side end of the reflux pipe (305) is connected to the vertical cylinder (302) of the reactor; a sleeve-type condenser assembly (307) is installed on the outside of the condenser pipe (306).

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