Continuous chlorination reaction method and equipment for pesticide intermediate

Abstract

The invention relates to the technical field of pesticide intermediate production, and discloses a pesticide intermediate continuous chlorination reaction method and equipment, and the method comprises the following steps: dehydrating an o-nitrotoluene raw material, preheating to 60-70 DEG C, filtering a ferric trichloride / diluted hydrochloric acid solution with the concentration of 10-15 wt%, continuously injecting into a reaction system, and reacting for 2-4 hours; the o-nitrotoluene pretreated in the step a, the ferric trichloride solution obtained in the step b and dry chlorine are introduced into the reaction equipment according to the flow velocity of 8-10 L / h, 1.0-1.5 L / h and 0.8-1.0 m < 3 > / h, the reaction temperature is controlled to be 60-70 DEG C, the system pressure is 0.4-0.6 MPa, and the retention time is 30-40 minutes. The device has the following advantages and effects: full-automatic regulation and control from raw material dehydration to tail gas emission are realized, the requirements of automatic chlorination production are met, gas-liquid two-phase segmented mixing is realized in a manner of efficient mass and heat transfer and multiple interfaces, the reaction efficiency is improved, dichloro side reaction is inhibited in a manner of multi-segment temperature control, and the selectivity of monochlorinated products is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide intermediate production, and particularly relates to a continuous chlorination reaction method and equipment for pesticide intermediates. Background Art

[0002] With the growth of the global population and the challenges of climate change, food security has become the focus of global attention. Pesticide intermediates, as key elements in pesticide production, contribute to ensuring the stability and sustainability of food production by enhancing the efficacy and safety of pesticides. Highly effective pesticides can reduce the damage of pests and diseases to crops, thereby increasing food yields and ensuring an adequate and stable food supply.

[0003] In the synthesis process of the pesticide intermediate methylaniline, the chlorination reaction is a key step. Currently, the industry mainly uses batch chlorination processes or microchannel continuous chlorination processes for pesticide intermediates. However, in long-term production operations, it has gradually been found that the batch chlorination process has poor efficiency and many by-products, while in the microchannel continuous process, the catalyst deactivates quickly, the equipment reliability is poor, and there is a lack of real-time quality monitoring means, making it difficult to achieve closed-loop control.

[0004] Based on the above situation, the present inventors have proposed a continuous chlorination reaction method and equipment for pesticide intermediates to improve the current problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a continuous chlorination reaction method and equipment for pesticide intermediates, which have the effects of high reaction efficiency, automatic precision.

[0006] The above technical purpose of the present invention is achieved through the following technical solutions: A continuous chlorination reaction method for pesticide intermediates, the method comprising the following steps:

[0007] Step a: Dehydrate the o-nitrotoluene raw material and preheat it to 60 - 70 °C;

[0008] Step b: Filter the ferric chloride / dilute hydrochloric acid solution with a concentration of 10 - 15 wt% and continuously inject it into the reaction system;

[0009] Step c: Feed the o-nitrotoluene pretreated in step a, the ferric chloride solution in step b, and dry chlorine gas into the reaction equipment at flow rates of 8 - 10 L / h, 1.0 - 1.5 L / h, and 0.8 - 1.0 m 3 / h, control the reaction temperature at 60 - 70 °C, the system pressure at 0.4 - 0.6 MPa, and the residence time at 30 - 40 minutes;

[0010] Step d: Perform gas-liquid separation on the reaction mixture, collect the liquid-phase product after on-line analysis, and subject the unreacted chlorine gas and hydrogen chloride gas to two-stage alkali washing treatment;

[0011] Step e: Continuously remove the ferrous ion impurities in the ferric chloride solution through the electrodialysis module, maintain the Fe 2+ concentration ≤ 50 ppm, and conduct product analysis.

[0012] A further setting of the present invention is that the molar ratio of the chlorine gas to the o-nitrotoluene is 1.05:1 to 1.1:1.

[0013] A further setting of the present invention is that the water content of the dehydrated o-nitrotoluene ≤ 0.1%.

[0014] A further setting of the present invention is that the operating current density of the electrodialysis module is 15 - 25 mA / cm 2 , and the regeneration cycle operates once every 48 - 72 hours. After regeneration, the Fe in the ferric chloride solution 3+ / Fe 2+ molar ratio ≥ 200:1.

[0015] A continuous chlorination reaction device for a pesticide intermediate, comprising a raw material pretreatment system, a reaction system, a catalyst injection system, a chlorine gas distribution system, a gas-liquid separation tank and a tail gas treatment system. The raw material pretreatment system is sequentially connected to the reaction system, the gas-liquid separation tank and the tail gas treatment system through pipelines. The output ends of the catalyst injection system and the chlorine gas distribution system are connected to the reaction system. The raw material pretreatment system includes a dehydration tank, a dehydration treatment module connected thereto and a preheater. The reaction system includes a tubular reactor and a cooling system and a reaction module provided on the tubular reactor.

[0016] A further setting of the present invention is that the dehydration treatment module includes a feed pipe with an outer wall fixed to the dehydration tank, a positioning sleeve provided below the feed pipe, and a dehydration ball with an outer wall in sliding contact with the positioning sleeve. A hot nitrogen inlet pipe and a rotating mechanism are provided on the dehydration ball. The dehydration ball is used to place A molecular sieve. After the hot nitrogen inlet pipe is introduced into the dehydration ball, the dehydration ball is driven to rotate by the rotating mechanism;

[0017] The reaction module includes a reaction pipe and an isothermal pipe connected in sequence, and a heat insulation sheet is provided between the reaction pipe and the isothermal pipe.

[0018] By adopting the above technical solution, stepped heating is formed to reduce the axial temperature coupling interference.

[0019] A further setting of the present invention is that leakage holes are provided on the surface of the dehydration ball, and a protruding retaining strip is fixedly provided on the bottom surface of the inner wall of the dehydration ball. Exchange holes are provided on the surface of the retaining strip, and a sealing structure is provided between the adjacent surfaces of the positioning sleeve and the dehydration ball.

[0020] By adopting the above technical solution, when the dehydration ball rotates, the water flowing out from the inside of the dehydration ball can be blocked, and it is cooperated with hot nitrogen for adsorption and drying.

[0021] A further setting of the present invention is that the input end of the cooling system corresponds to the position of the different-temperature pipe. The cooling system includes a circulation pipe with an output end connected to the inside of the reaction system, a three-way valve connected to the input end of the circulation pipe, and an external connection pipe connected to the input end of the three-way valve.

[0022] By adopting the above technical solution, the coolant can be sent into the area of the different-temperature pipe.

[0023] A further setting of the present invention is that the moisture sensor and the positioning sleeve are successively connected above the preheater. The catalyst injection system includes a storage tank, an acid-resistant diaphragm pump, and a conductivity detector connected in sequence through pipes. The output end of the conductivity detector is connected to the tubular reactor through a pipe.

[0024] By adopting the above technical solution, it precipitates at low temperature, so that the FeCl 3 / HCl solution can flow into the first-stage reaction tube and react with o-nitrotoluene.

[0025] A further setting of the present invention is that the chlorine distribution system includes a titanium sintered head and a control and monitoring module connected in sequence through pipes. The control and monitoring module is connected to the tubular reactor through a pipe below. The gas-liquid separation tank includes a gas-liquid separation tank pipe connected to the output end of the tubular reactor. An automatic sampler is provided at the discharge end of the gas-liquid separation tank pipe, and the gas-liquid separation tank pipe is connected to the tail gas treatment system through a tail gas discharge pipe.

[0026] By adopting the above technical solution, the automatic sampler collects samples every minute, and sends the tail gas into the tail gas treatment system through the tail gas discharge pipe.

[0027] The beneficial effects of the present invention are:

[0028] 1. Realize full-automatic regulation from raw material dehydration to tail gas emission, meeting the needs of automatic chlorination production;

[0029] 2. High-efficiency mass transfer and heat transfer, multi-interface method, realize segmented mixing of gas-liquid two phases, improve reaction efficiency, suppress dichlorination side reactions through multi-stage temperature control method, and improve the selectivity of monochlorination products;

[0030] 3. Facilitate environmental protection, reduce the generation of reaction by-products, optimize reaction safety, harmless treatment of tail gas, and be suitable for large-scale green production. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of a continuous chlorination reaction device for a pesticide intermediate provided by an embodiment of the present invention;

[0033] Figure 2 It is a schematic structural diagram of each system in an embodiment of the present invention;

[0034] Figure 3 It is a schematic structural diagram of a dehydration tank in an embodiment of the present invention;

[0035] Figure 4 It is a schematic structural diagram of a rotating mechanism in an embodiment of the present invention;

[0036] Figure 5 It is a schematic structural diagram of a sealing structure in an embodiment of the present invention;

[0037] Figure 6 It is a schematic structural diagram of a tubular reactor in an embodiment of the present invention.

[0038] In the figure, 1, raw material pretreatment system; 2, reaction system; 3, catalyst injection system; 4, chlorine gas distribution system; 5, gas-liquid separation tank; 11, dehydration tank; 12, preheater; 13, feed pipe; 14, positioning sleeve; 15, dehydration ball; 16, hot nitrogen inlet pipe; 17, rotating mechanism; 18, moisture sensor; 111, partition board; 141, through hole; 142, inlay ring; 151, leakage hole; 152, stop bar; 153, exchange hole; 154, inlay hole; 171, rotating rod; 172, gear; 173, rack; 174, support rod; 175, push cylinder; 21, tubular reactor; 22, cooling system; 211, heater; 221, circulation pipe; 222, three-way valve; 223, external connection pipe; 231, heat insulation sheet; 231, reaction tube; 232, isothermal tube; 233, heat insulation sheet; 31, storage tank; 32, acid-resistant diaphragm pump; 33, conductivity detector; 41, titanium sintered head; 42, control and monitoring module; 51, gas-liquid separation tank pipe; 52, automatic sampler; 53, tail gas discharge pipe. Detailed implementation manners

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0040] The embodiment of the present invention specifically provides a continuous chlorination reaction method for a pesticide intermediate, and the method includes the following steps:

[0041] Step a: Dehydrate the o-nitrotoluene raw material and preheat it to 60 - 70 °C;

[0042] Step b: Filter the ferric chloride / dilute hydrochloric acid solution with a concentration of 10 - 15 wt% and continuously inject it into the reaction system;

[0043] Step c: Feed the o-nitrotoluene pretreated in step a, the ferric chloride solution in step b, and dry chlorine into the reaction equipment at a flow rate of 8 - 10 L / h, 1.0 - 1.5 L / h, and 0.8 - 1.0 m 3 / h, control the reaction temperature at 60 - 70 °C, the system pressure at 0.4 - 0.6 MPa, and the residence time at 30 - 40 minutes;

[0044] Step d: Perform gas-liquid separation on the reaction mixture, collect the liquid-phase product after on-line analysis, and subject the unreacted chlorine and hydrogen chloride gas to two-stage alkali washing treatment;

[0045] Step e: Continuously remove the ferrous ion impurities in the ferric chloride solution through an electrodialysis module, maintain the Fe 2+ concentration ≤ 50 ppm, and perform product analysis to extend the service life of FeCl 3 ;

[0046] Among them, the molar ratio of chlorine to o-nitrotoluene is 1.05:1 to 1.1:1.

[0047] Among them, the water content of the dehydrated o-nitrotoluene is ≤ 0.1%.

[0048] Among them, the operating current density of the electrodialysis module is 15 - 25 mA / cm 2 , the regeneration cycle runs once every 48 - 72 hours, and the molar ratio of Fe 3+ / Fe 2+ in the regenerated ferric chloride solution is ≥ 200:1.

[0049] Furthermore, the continuous chlorination reaction method for the pesticide intermediate further includes a reaction device. Please refer to Figures 1-6, its structure includes a raw material pretreatment system 1, a reaction system 2, a catalyst injection system 3, a chlorine gas distribution system 4, a gas-liquid separation tank 5, and a tail gas treatment system.

[0050] Specifically, the raw material pretreatment system 1 is sequentially connected to the reaction system 2, the gas-liquid separation tank 5, and the tail gas treatment system through pipelines. Liquid adjacent-nitrotoluene is transported into the raw material pretreatment system 1 by a corrosion-resistant centrifugal pump, with the flow rate set at 8 - 10 L / h, and the heat tracing temperature of the transport pipeline can be set at 62 - 68 °C;

[0051] The output ends of the catalyst injection system 3 and the chlorine gas distribution system 4 are connected to the reaction system 2. The catalyst injection system 3 is mainly used to inject FeCl 3 / HCl solution. The raw material pretreatment system 1 includes a dehydration tank 11, a dehydration treatment module connected thereto, and a preheater 12. The reaction system 2 includes a tubular reactor 21 and a cooling system 22 and a reaction module provided on the tubular reactor 21.

[0052] Among them, the dehydration treatment module includes a feed pipe 13 whose outer wall is fixed to the dehydration tank 11, a positioning sleeve 14 provided below the feed pipe 13, and a dehydration ball 15 whose outer wall is in sliding contact with the positioning sleeve 14. The inner wall of the positioning sleeve 14 is a spherical structure, so that the outer wall of the dehydration ball 15 can be in sliding contact with the positioning sleeve 14;

[0053] The feed pipe 13 is used to be connected to the liquid adjacent-nitrotoluene transport pipeline. The number of the positioning sleeves 14 is set at two places, upper and lower, and the positioning sleeves 14 are symmetrically distributed above and below with the center of the dehydration ball 15 as the reference. An opening 141 is provided on the upper positioning sleeve 14. The bottom end of the feed pipe 13 is coaxially fixed to the positioning sleeve 14, and the opening 141 is coaxially distributed with the feed pipe 13, so that the liquid adjacent-nitrotoluene can smoothly flow into the dehydration ball 15 after passing through the feed pipe 13.

[0054] During implementation, a hot nitrogen inlet pipe 16 and a rotating mechanism 17 are provided on the dehydration ball 15. The outer wall of the hot nitrogen inlet pipe 16 is in rotational contact with the dehydration ball 15, and the outer wall of the hot nitrogen inlet pipe 16 is also fixed to the dehydration tank 11. A rotary seal 161 is provided at the adjacent position of the hot nitrogen inlet pipe 16 and the dehydration ball 15. The rotary seal 161 is a prior art and can be obtained through customization. It is used to improve the connection airtightness between the hot nitrogen inlet pipe 16 and the dehydration ball 15. The outer end of the hot nitrogen inlet pipe 16 is connected to the hot nitrogen transport pipeline to input nitrogen into the dehydration tank 11.

[0055] Among them, the dehydration ball 15 is used to place 3A molecular sieve. By selectively adsorbing water molecules with 3A molecular sieve and not adsorbing adjacent-nitrotoluene, the adjacent-nitrotoluene is dehydrated.

[0056] After introducing the hot nitrogen inlet pipe 16 into the dehydration sphere 15, the rotation mechanism 17 drives the dehydration sphere 15 to rotate, and the moisture is desorbed by purging with hot nitrogen. The temperature of the hot nitrogen is controlled at 200 °C, so as to regenerate the 3A molecular sieve after water absorption, improve its service life, and the regeneration period is once every 48 hours. The inner wall of the dehydration tank 11 should be connected to the hot nitrogen output pipeline, so that the hot nitrogen can be sent out through the output pipeline after blowing out of the dehydration sphere 15.

[0057] Specifically, leakage holes 151 are formed on the surface of the dehydration sphere 15, and a protruding retaining strip 152 is fixedly arranged on the bottom surface of the inner wall of the dehydration sphere 15. The leakage holes 151 correspond to the positions of the through holes 141 on the positioning sleeve 14 respectively. The lower positioning sleeve 14 is connected to the conveying pipeline. When o-nitrotoluene is sent into the through hole 141 of the upper positioning sleeve 14 through the feed pipe 13 and falls into the interior of the dehydration sphere 15 through the leakage holes 151 for dehydration treatment, the dehydrated o-nitrotoluene then flows downward from the through hole 141 of the lower positioning sleeve 14 through the leakage holes 151 below and into the conveying pipeline.

[0058] Among them, exchange holes 153 are formed on the surface of the retaining strip 152. The arrangement of the retaining strip 152 is such that when the dehydration sphere 15 rotates, the 3A molecular sieve can be driven to move through the retaining strip 152, so that it vibrates and spills in the dehydration sphere 15, improving the contact effect with the hot nitrogen. And when o-nitrotoluene contacts the 3A molecular sieve, the o-nitrotoluene can gradually flow to the leakage holes 151 below through the exchange holes 153.

[0059] Furthermore, to assist the rotation of the dehydration sphere 15, a partition 111 extending upward is fixedly arranged on the inner bottom surface of the dehydration tank 11. The rotation mechanism 17 includes a rotating rod 171 whose outer wall is rotatably connected to the partition 111, a gear 172 coaxially fixed to the end of the rotating rod 171 away from the dehydration sphere 15, a rack 173 meshing with the outside of the gear 172, a support rod 174 whose top end is fixedly connected to the rack 173, and a push cylinder 175 whose piston rod is fixedly connected to the support rod 174. The bottom end of the push cylinder 175 is fixed to the dehydration tank 11. The rotating rod 171 is fixedly connected to the outer wall of the dehydration sphere 15, and the rotating rod 171 is coaxial with the hot nitrogen inlet pipe 16. When the rotating rod 171 drives the dehydration sphere 15 to rotate, the hot nitrogen inlet pipe 16 is coaxial with the rotation fulcrum of the dehydration sphere 15;

[0060] During implementation, the piston rod is driven to move up and down by the push cylinder 175, so that the rack 173 can repeatedly push the gear 172 to rotate forward and backward upward or downward, so that the dehydration sphere 15 rotates forward and backward, oscillating the 3A molecular sieve inside it, and then the dehydration sphere 15 can be reset by the push cylinder 175.

[0061] Specifically, to improve the internal sealing performance when the dehydration sphere 15 rotates, a sealing structure is provided between the adjacent surfaces of the positioning sleeve 14 and the dehydration sphere 15. The sealing structure includes an inlay ring 142 fixed to the inner wall of the positioning sleeve 14. There are two inlay rings 142, which are spaced apart at the left and right parts of the dehydration sphere 15. Embedding holes 154 corresponding to the positions of the inlay rings 142 are formed on the surface of the dehydration sphere 15. The inlay ring 142 is rotatably arranged in the embedding hole 154, and the inlay ring 142 is in contact with the inner wall of the embedding hole 154. The inlay ring 142 is coaxial with the rotating rod 171. Thus, when the dehydration sphere 15 rotates, it can block the moisture flowing out from the inside of the dehydration sphere 15 and cooperate with hot nitrogen adsorption and drying.

[0062] Further, the reaction module includes a reaction tube 231 and a different-temperature tube 232 connected in sequence. An electric heating module is provided on the outer wall of the reaction tube 231 to heat the reaction tube 231 through the electric heating module. A heat insulation sheet 233 is arranged between the reaction tube 231 and the different-temperature tube 232. The number of reaction tubes 231 is three sections, and the different-temperature tube 232 has two ends. The input end of the first section and the output end of the third section are respectively connected to the raw material pretreatment system 1 and the gas-liquid separation tank 5. The reaction tube 231 and the different-temperature tube 232 are coaxial;

[0063] The heat insulation sheet 233 is made of ceramic fiber material, and the thermal resistance > 1m 2 ·K / W, having strong heat resistance performance, can reduce the heat conduction performance between the reaction tube 231 and the different-temperature tube 232. The outer side of the heat insulation sheet 233 is fixedly attached to the inner wall of the tubular reactor 21, so that the areas where the reaction tube 231 and the different-temperature tube 232 are located can be separated from each other, forming a stepped heating to reduce the axial temperature coupling interference.

[0064] Among them, the input end of the cooling system 22 corresponds to the position of the different-temperature tube 232. The cooling system 22 includes a circulation tube 221 with an output end connected to the inside of the reaction system 2, a three-way valve 222 connected to the input end of the circulation tube 221, and an external connection tube 223 connected to the input end of the three-way valve 222. One cooling system 22 is provided on each side of the tubular reactor 21. The circulation tubes 221 on both sides are respectively communicated with the areas inside the tubular reactor 21 that belong to the different-temperature tube 232, so that the coolant can be sent into and out of the different-temperature tube 232 area for circulation;

[0065] During implementation, from left to right, the control range of the temperature gradient of the reaction tube 231 and the different-temperature tube 232 is: 70°C → 68°C → 65°C → 63°C → 60°C, so that when the reaction liquid flows from the reaction tube 231 into the different-temperature tube 232, it can be gradually cooled slightly to reduce the situation where crystals may precipitate when the temperature difference between the reaction tube 231 and the different-temperature tube 232 > 5°C when the reaction liquid flows out of the reaction tube 231. 3 solution may precipitate.

[0066] Among them, above the preheater 12, it is successively connected to a moisture sensor 18 and a positioning sleeve 14. A three-way solenoid valve is provided between the moisture sensor 18 and the preheater 12. The moisture of the material at the outlet of the positioning sleeve 14 is monitored in real time through the moisture sensor 18. If it is > 0.1%, the solenoid valve is triggered to close the lower pipeline, so that the raw material cannot flow to the preheater 12, and the pipeline is opened and closed through the three-way valve, so that the external dehydration tower can extract and process the unreasonably dehydrated material, improving the reaction accuracy and reducing the risk of mistakes;

[0067] If the moisture is qualified, the raw material is heated by the preheater 12 and transported into the tubular reactor 21.

[0068] During implementation, the catalyst injection system 3 includes a storage tank 31, an acid-resistant diaphragm pump 32, and a conductivity detector 33 that are successively connected by pipelines. The number of storage tanks 31 is set to two, which respectively store FeCl 3 and HCl solution. The output end of the conductivity detector 33 is connected to the tubular reactor 21 through a pipeline. FeCl 3 is dissolved in 10% dilute hydrochloric acid, and the concentration is monitored by an on-line conductivity meter. The concentration target value is 12 ± 0.5 wt%. The whole conveying pipeline is accompanied by heat, and the temperature is controlled at 70°C to prevent FeCl 3 from precipitating at low temperature, so that the FeCl 3 / HCl solution can flow into the first-stage reaction tube 231 and react with o-nitrotoluene. When the FeCl 3 / HCl solution is injected, it forms a 30° angle jet mixing with o-nitrotoluene, and the flow rate is 1.0 - 1.5 L / h.

[0069] Among them, the chlorine gas distribution system 4 includes a titanium sintered head 41 and a control and monitoring module 42 that are successively connected by pipelines. The control and monitoring module 42 includes a dew point monitor connected thereto and a mass flow controller connected to the tubular reactor 21. The lower part of the control and monitoring module 42 is connected to the tubular reactor 21 through a pipeline, that is, connected to the second-stage reaction tube 231. During operation, it is detected in real time through the dew point monitor to ensure that the chlorine gas dew point ≤ -40°C. The mass flow controller adjusts the flow rate according to the molar ratio of Cl 2 :o-nitrotoluene = 1.05:1. If the temperature of the reactor 231 > 70°C, the Cl 2 flow rate is automatically reduced by 5%.

[0070] Specifically, the gas-liquid separation tank 5 includes a gas-liquid separation tank pipe 51 connected to the output end of the tubular reactor 21. An automatic sampler 52 is provided at the discharge end of the gas-liquid separation tank pipe 51. The gas-liquid separation tank pipe 51 is connected to the tail gas treatment system through a tail gas discharge pipe 53. Samples are collected every 15 minutes through the automatic sampler, and the tail gas is sent into the tail gas treatment system through the tail gas discharge pipe 53. The tail gas treatment system includes a primary falling film absorption tower and a secondary alkali washing tower. HCl is recovered through dilute hydrochloric acid, and the residual Cl 2 is neutralized by the secondary alkali washing tower to meet the emission standards.

[0071] The control method of the present invention is automatically controlled by a controller. The control circuit of the controller can be realized by simple programming by those skilled in the art. The provision of power also belongs to the common knowledge in the art. Moreover, the present invention mainly aims to protect mechanical devices, so the control method and circuit connection of the present invention will not be explained in detail herein.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for continuous chlorination of pesticide intermediates, characterized in that: The method comprises the following steps: Step a: dehydrating the o-nitrotoluene raw material and preheating it to 60-70° C.; Step b: filtering a 10-15 wt% ferric chloride / dilute hydrochloric acid solution and continuously injecting it into the reaction system; Step c: The o-nitrotoluene pretreated in step a, the ferric chloride solution in step b and dry chlorine are mixed at 8-10 L / h, 1.0-1.5 L / h and 0.8-1.0 m 3 / h flow rate into the reaction equipment, control the reaction temperature to 60-70°C, the system pressure to 0.4-0.6MPa, and the residence time to 30-40 minutes; Step d: separating the mixture after the reaction by gas-liquid separation, collecting the liquid phase product after online analysis, and treating the unreacted chlorine and hydrogen chloride gas by two-stage alkali washing; Step e: Continuously remove ferrous ion impurities in the ferric chloride solution through an electrodialysis module to maintain the Fe2+ concentration ≤ 50 ppm, and perform product analysis.

2. A method and apparatus for continuous chlorination of a pesticide intermediate according to claim 1, characterized in that: The molar ratio of the chlorine gas to the o-nitrotoluene is 1.05:1 to 1.1:

1.

3. A method and apparatus for continuous chlorination of pesticide intermediates according to claim 2, characterized in that: The water content of the o-nitrotoluene after dehydration is ≤0.1%.

4. A method and apparatus for continuous chlorination of pesticide intermediates according to claim 3, characterized in that: The operating current density of the electrodialysis module is 15-25 mA / cm 2 The regeneration cycle runs once every 48-72 hours, and the Fe3+ / Fe2+ molar ratio in the ferric chloride solution after regeneration is ≥200:

1.

5. A continuous chlorination reaction equipment for pesticide intermediates, characterized in that: A method for realizing the continuous chlorination reaction of pesticide intermediates as claimed in any one of claims 1 to 4, wherein the method comprises a raw material pretreatment system (1), a reaction system (2), a catalyst injection system (3), a chlorine distribution system (4), a gas-liquid separation tank (5) and an exhaust gas treatment system, wherein the raw material pretreatment system (1) is connected to the reaction system (2), the gas-liquid separation tank (5) and the exhaust gas treatment system in sequence through pipelines, the output ends of the catalyst injection system (3) and the chlorine distribution system (4) are connected to the reaction system (2), the raw material pretreatment system (1) comprises a dehydration tank (11), a dehydration treatment module and a preheater (12) connected thereto, and the reaction system (2) comprises a tubular reactor (21) and a cooling system (22) and a reaction module arranged on the tubular reactor (21).

6. A pesticide intermediate continuous chlorination reaction equipment according to claim 5, characterized in that: The dehydration treatment module comprises a feed pipe (13) whose outer wall is fixed to a dehydration tank (11), a positioning sleeve (14) arranged below the feed pipe (13), and a dehydration ball (15) whose outer wall is in sliding contact with the positioning sleeve (14); a hot nitrogen inlet pipe (16) and a rotating mechanism (17) are arranged on the dehydration ball (15); the dehydration ball (15) is used to place a 3A molecular sieve; after the hot nitrogen inlet pipe (16) is passed into the dehydration ball (15), the dehydration ball (15) is driven to rotate by the rotating mechanism (17); The reaction module comprises a reaction tube (231) and a different temperature tube (232) which are connected in sequence, and a heat insulating sheet (233) is arranged between the reaction tube (231) and the different temperature tube (232).

7. A pesticide intermediate continuous chlorination reaction equipment according to claim 6, characterized in that: The surface of the dehydration ball (15) is provided with a leakage hole (151), and the inner wall bottom surface of the dehydration ball (15) is fixedly provided with a protruding retaining bar (152), and the surface of the retaining bar (152) is provided with an exchange hole (153), and a sealing structure is provided between the adjacent surfaces of the positioning sleeve (14) and the dehydration ball (15).

8. A pesticide intermediate continuous chlorination reaction equipment according to claim 7, characterized in that: The input end of the cooling system (22) corresponds to the position of the different temperature pipe (232), and the cooling system (22) comprises a circulation pipe (221) whose output end is connected to the inside of the reaction system (2), a three-way valve (222) connected to the input end of the circulation pipe (221), and an external pipe (223) connected to the input end of the three-way valve (222).

9. A pesticide intermediate continuous chlorination reaction equipment according to claim 8, characterized in that: The upper portion of the preheater (12) is connected in sequence to a moisture sensor (18) and a positioning sleeve (14); the catalyst injection system (3) comprises a storage tank (31), an acid-resistant diaphragm pump (32) and a conductivity detector (33) which are connected in sequence through pipelines; the output end of the conductivity detector (33) is connected to the tubular reactor (21) through a pipeline.

10. A pesticide intermediate continuous chlorination reaction equipment according to claim 9, characterized in that: The chlorine gas distribution system (4) comprises a titanium sintering head (41) and a control monitoring module (42) which are connected in sequence through a pipeline. The lower part of the control monitoring module (42) is connected to the tubular reactor (21) through a pipeline. The gas-liquid separation tank (5) comprises a gas-liquid separation tank pipe (51) connected to the output end of the tubular reactor (21). An automatic sampler (52) is provided at the discharge end of the gas-liquid separation tank pipe (51). The gas-liquid separation tank pipe (51) is connected to the tail gas treatment system through a tail gas discharge pipe (53).

Images