System for recycling chloroacetic acid by dechlorinating dichloroacetic acid through photocatalysis

Abstract

The utility model discloses a system for recycling chloroacetic acid by dechlorinating dichloroacetic acid through photocatalysis, which relates to the technical field of chloroacetic acid synthesis equipment and comprises a collecting tank I used for collecting mother liquor containing dichloroacetic acid during preparation of chloroacetic acid, and the collecting tank I is sequentially connected with a plurality of stages of condensers and a filter I through pipelines. A filtrate outlet I of the filter I is sequentially connected with a storage tank, a photocatalytic reaction kettle, a plurality of stages of condensers and a filter II; a filtrate outlet II of the filter II is connected with the storage tank through a reflux pipeline; stirring mechanisms are arranged in the collecting tank I and the photocatalytic reaction kettle, an ultraviolet visible light lamp is mounted in the photocatalytic reaction kettle, a material inlet of the photocatalytic reaction kettle is connected with a mother liquor supply pipeline, a water supply pipeline, a catalyst supply pipeline and a hydrogen supply pipeline, and the collecting tank I is connected with a nitrogen pipeline. The yield of chloroacetic acid prepared by an acetic anhydride catalysis method is improved, the generation of waste liquid is reduced, and the treatment cost of wastewater is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of chloroacetic acid synthesis equipment, specifically to a photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system. Background Technology

[0002] Chloroacetic acid is an important fine chemical product and organic chemical intermediate, widely used as an active compound. In the pesticide industry, chloroacetic acid can be used to synthesize more than 20 commonly used insecticides, herbicides, and plant growth regulators; in the pharmaceutical industry, chloroacetic acid and its esters are mainly used to produce vitamins, hormones, and other drugs; in the dye industry, chloroacetic acid is mainly used to synthesize reactive dyes; in addition, chloroacetic acid is also an important organic synthesis intermediate, which can be used to prepare fine chemicals such as malonic acid, malononitrile, and malonate esters.

[0003] In China, the main production processes for chloroacetic acid are sulfur catalysis and acetic anhydride catalysis. Regardless of whether it is sulfur catalysis or acetic anhydride catalysis, a large amount of mother liquor is inevitably generated during production. The composition of the mother liquor varies with the degree of chlorination, crystallization temperature and water content. It is generally composed of chloroacetic acid, dichloroacetic acid, acetic acid and chlorination intermediates.

[0004] Our company currently produces chloroacetic acid using the acetic anhydride catalytic chlorination method. This process has the advantages of convenient operation, continuous reaction, and short cycle time. However, the disadvantage of this process is that the conversion rate of primary chlorination is relatively low, and it contains more impurities such as dichloroacetic acid and acetic acid. The subsequent chloroacetic acid crystallization stage separates the components based on the melting points of the acetic acid chloride solution. After purifying chloroacetic acid, about 10% chloroacetic acid mother liquor is generated, which reduces the purity of chloroacetic acid and affects the application quality and scope of chloroacetic acid.

[0005] Therefore, relevant technical personnel are still continuously optimizing the process and production system in order to improve product yield, reduce emissions, alleviate the pressure on the post-processing section, and reduce production costs. Utility Model Content

[0006] The present invention aims to propose a novel photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system, which further treats the mother liquor containing dichloroacetic acid generated in the previous preparation of chloroacetic acid using the acetic anhydride catalytic method, thereby improving the yield of chloroacetic acid and reducing the generation of waste liquid.

[0007] To achieve the above-mentioned objectives, the technical solution of this utility model is as follows:

[0008] A photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system includes a collection tank I for collecting the mother liquor containing dichloroacetic acid during the preparation of chloroacetic acid. The collection tank I is connected in sequence to several stages of condensers and filter I via pipelines. The filtrate outlet I of filter I is connected in sequence to a storage tank, a photocatalytic reactor, several stages of condensers, and filter II. The filtrate outlet II of filter II is connected to the storage tank via a return pipeline. Both the collection tank I and the photocatalytic reactor are equipped with stirring mechanisms. The photocatalytic reactor is equipped with an ultraviolet-visible lamp. The material inlet of the photocatalytic reactor is connected to a mother liquor supply pipeline, a water supply pipeline, a catalyst supply pipeline, and a hydrogen supply pipeline. The collection tank I is connected to a nitrogen pipeline.

[0009] Furthermore, the last stage of the multi-stage condenser is a condenser that carries a medium at 20°C.

[0010] Furthermore, the multi-stage condenser is a condenser that sequentially carries media at temperatures of 60°C, 50°C, 40°C, 30°C, and 20°C.

[0011] Furthermore, both the collection tank I and the photocatalytic reactor are equipped with jackets around their outer periphery that are circulated with heat-insulating media.

[0012] Furthermore, the collection tank I, filter I, and filter II are all integrated cooling / filtration mixing tanks. The integrated cooling / filtration mixing tank is equipped with an external jacket for passing heat-insulating medium, has an internal stirring mechanism, and a solid discharge port at the bottom.

[0013] Furthermore, the integrated cooling / filtration mixing tank is connected to a vacuum line, and a pressure sensor is installed on the integrated cooling / filtration mixing tank.

[0014] Furthermore, the photocatalytic reactor is equipped with a pressure sensor and a temperature sensor.

[0015] Furthermore, the storage tank is connected to a vacuum line.

[0016] Furthermore, a booster pump I is installed on the pipeline connecting the storage tank and the photocatalytic reactor.

[0017] Furthermore, a booster pump II is installed between the photocatalytic reactor and the first-stage condenser at the rear.

[0018] The beneficial effects of this utility model are:

[0019] I. This utility model proposes a photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system, comprising a collection tank I for collecting the mother liquor containing dichloroacetic acid during the preparation of chloroacetic acid. The collection tank I is sequentially connected to several stages of condensers and filter I via pipelines. After multi-stage cooling, the mother liquor precipitates chloroacetic acid product, which is then filtered by filter I. The resulting clear liquid is sent from the filtrate outlet I of filter I to a storage tank. Then, materials are fed into the photocatalytic reactor according to its processing capacity. After photocatalytic reaction, the material is condensed by several stages of condensers to precipitate product crystals, which are then sent to filter II to separate the chloroacetic acid product. The filtrate is discharged from the filtrate outlet II of filter II and transported to the storage tank through a return pipeline. In this way, the mother liquor is processed through multiple cycles, so that dichloroacetic acid is converted into chloroacetic acid product as much as possible, reducing the generation of waste liquid.

[0020] II. In this utility model, the last stage of the preferred multi-stage condenser is a condenser with a medium at 20°C, from which chloroacetic acid crystals are precipitated.

[0021] Third, in this utility model, the multi-stage condenser is preferably a condenser that sequentially passes through media at 60°C, 50°C, 40°C, 30°C and 20°C, so that the purity of the precipitated product is high and the product yield is high.

[0022] IV. In this utility model, both the collection tank I and the photocatalytic reactor are equipped with jackets with heat-insulating media on their outer periphery, which is beneficial for heat preservation of the materials in the tank / reactor, maintaining the reaction conditions of the materials, and also for realizing the recovery and utilization of heat.

[0023] V. This utility model proposes an integrated cooling / filtration mixing tank. The tank has an external jacket for insulation, an internal stirring mechanism, and a solid discharge port at the bottom. It can replace the collection tank I and / or filter, achieving both liquid storage and filtration functions. In actual production, a filter mechanism with appropriate filtration precision can be selected based on the particle size of the crystallized product. This integrated cooling / filtration mixing tank has both insulation and stirring functions. In this photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system, there are many storage tanks and filtration devices involved. The integrated cooling / filtration mixing tank can reduce the number of devices and save space. When performing filtration, this integrated cooling / filtration mixing tank requires vacuum filtration and nitrogen pressure filtration. Therefore, it is also connected to a vacuum pipeline, requiring a gas handling device. The equipment needs to operate under pressure, placing higher demands on its sealing and pressure resistance. The equipment has a sealed operating space for filtration, excellent safety and environmental performance, and the solid discharge will not cause blockage. Operation is simple and convenient.

[0024] VI. In this utility model, the integrated cooling / filtration mixing tank is also equipped with a pressure sensor to monitor pressure changes in the device and ensure the safe operation of the equipment.

[0025] VII. In this utility model, the photocatalytic reactor is equipped with a pressure sensor and a temperature sensor. The pressure sensor and the temperature sensor are used to monitor the pressure and temperature changes in the photocatalytic reactor, which helps to ensure that the reactants are in the photocatalytic reactor under optimal reaction conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of this utility model.

[0027] Figure 2 This is a partial connection diagram of a multi-stage condenser in a photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system.

[0028] Figure 3 This is a structural diagram of a cooling / filtration integrated mixing tank.

[0029] Figure 4 This is a schematic diagram of another embodiment of the integrated cooling / filtration mixing tank.

[0030] Figure 5 This is a structural diagram of another implementation of a photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system.

[0031] Figure 6 This is a partial connection diagram of a multi-stage condenser in another embodiment of a photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system.

[0032] The components include: 1. Collection tank I; 2. Filter I; 3. Storage tank; 4. Photocatalytic reactor; 5. Filter II; 6. Reflux pipeline; 7. Stirring mechanism; 8. Ultraviolet-visible lamp; 9. Mother liquor supply pipeline; 10. Water supply pipeline; 11. Catalyst supply pipeline; 12. Hydrogen supply pipeline; 13. Nitrogen pipeline; 14. Jacket; 15. Integrated cooling / filtration stirring tank; 16. Vacuum pipeline; 17. Pressure sensor; 18. Temperature sensor; 19. Booster pump I; 20. Booster pump II; 21. Condenser for 60℃ medium; 22. Condenser for 50℃ medium; 23. Condenser for 40℃ medium. 24. Condenser; 25. Condenser with 30℃ medium; 26. Condenser with 20℃ medium; 27. Integrated cooling / filtration mixing tank I; 28. Integrated cooling / filtration mixing tank II; 29. ​​Integrated cooling / filtration mixing tank III; 30. Integrated cooling / filtration mixing tank IV; 31. Chlorine supply line; 32. Cooling medium inlet; 2.1. Filtrate outlet I; 2.2. Solid phase outlet I; 4.1. Material inlet; 5.1. Filtrate outlet II; 5.2. Solid phase outlet II; 15.1. Solid discharge port; 15.2. Liquid phase outlet; 15.3. Filtration mechanism. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0034] Example 1

[0035] A photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system relates to the technical field of chloroacetic acid synthesis equipment. It includes a collection tank I1 for collecting the mother liquor containing dichloroacetic acid during chloroacetic acid preparation. Collection tank I1 is sequentially connected to several stages of condensers and filters I2 via pipelines. The filtrate outlet I2.1 of filters I2 is sequentially connected to a storage tank 3, a photocatalytic reactor 4, several stages of condensers, and filters II5. The filtrate outlet II5.1 of filters II5 is connected to the storage tank 3 via a return pipeline 6. Both collection tank I1 and photocatalytic reactor 4 are equipped with stirring mechanisms 7. Photocatalytic reactor 4 is equipped with ultraviolet-visible lamps 8. The material inlet 4.1 of photocatalytic reactor 4 is connected to a mother liquor supply pipeline 9, a water supply pipeline 10, a catalyst supply pipeline 11, and a hydrogen supply pipeline 12. Collection tank I1 is connected to a nitrogen pipeline 13.

[0036] This embodiment is one specific implementation method. (See reference...) Figure 1 The mother liquor containing dichloroacetic acid, collected during the preparation of chloroacetic acid, is temporarily stored in collection tank I1 via chlorination replenishment pipeline 30. Preferably, collection tank I1 is equipped with a jacket 14. Cooling water is introduced into the jacket 14 to initially cool the material. The material in collection tank I1 passes through several stages of condensers in sequence. Figure 1 The diagram only shows a single-stage condenser (condenser 21 for 60℃ medium). In actual production, multi-stage condensers are preferred for gradient cooling, which is beneficial for precipitating products with higher purity and improving product yield. The mixture is then sent to filter I2. After multi-stage cooling, the mother liquor precipitates chloroacetic acid, which is then filtered through filter I2. The chloroacetic acid product is discharged from the solid phase outlet I2.2, and the resulting clear liquid is sent from the filtrate outlet I2.1 of filter I2 to storage tank 3. Material is then fed into the photocatalytic reactor 4 according to its processing capacity. After photocatalytic reaction, the material is condensed through several stages of condensers to precipitate crystals, which are then sent to filter II5. The chloroacetic acid product is discharged from the solid phase outlet II5.2 of filter II5, and the filtrate is discharged from the filtrate outlet II5.1 of filter II5 and transported to storage tank 3 via return pipeline 6. In this way, the mother liquor undergoes multiple cycles, converting dichloroacetic acid into chloroacetic acid as much as possible and reducing waste liquid generation.

[0037] In this embodiment, the multi-stage condenser receives insulation media of different temperatures through the cooling medium inlet 31 and outputs the heat-exchanged medium from the cooling medium outlet 32. The heat-exchanged medium is beneficial for heat recovery and utilization.

[0038] Example 2

[0039] This embodiment is a further optimization of embodiment 1, the difference being that the last stage of the multi-stage condenser is a condenser that carries a medium at 20°C.

[0040] Example 3

[0041] This embodiment is a further optimization of embodiment 2, the difference being that the several-stage condensers are condensers that sequentially pass through media at 60°C, 50°C, 40°C, 30°C and 20°C.

[0042] refer to Figure 2 The material output from collection tank I1 is sequentially cooled through a series of condensers: condenser 21 with a medium of 60℃, condenser 22 with a medium of 50℃, condenser 23 with a medium of 40℃, condenser 24 with a medium of 30℃, and condenser 25 with a medium of 20℃. The precipitated chloroacetic acid product has high crystal purity and yield.

[0043] Example 4

[0044] Compared with Examples 1 to 3, the difference in this embodiment is that both the collection tank I1 and the photocatalytic reactor 4 are provided with jackets 14 through which heat-insulating medium is circulated.

[0045] refer to Figure 1 The outer periphery of the collection tank I1 is provided with a jacket 14 through which a heat-insulating medium is circulated. Cooling water is introduced into the jacket 14 to preliminarily cool the material in the collection tank I1. A constant temperature medium at a preset temperature (generally 70~90℃) is introduced into the jacket 14 on the outer periphery of the photocatalytic reactor 4 to ensure that the material in the photocatalytic reactor 4 is in a better reaction condition and to improve the reaction rate.

[0046] Example 5

[0047] Compared with Examples 1 to 4, the difference in this embodiment is that the collection tank I1, filter I2 and filter II5 are all integrated cooling / filtration mixing tanks 15. The integrated cooling / filtration mixing tank 15 is provided with a jacket 14 for passing heat insulation medium, has an internal stirring mechanism 7, and has a solid discharge port 15.1 at the bottom.

[0048] refer to Figure 3 , Figure 3 This is a schematic diagram of one embodiment of the integrated cooling / filtration mixing tank 15. The integrated cooling / filtration mixing tank 15 includes a filtration mechanism 15.3 and a liquid phase outlet 15.2 at the bottom. The built-in stirring mechanism 7 is preferably designed as a vertically movable stirring structure, and its height can be adjusted according to the amount of material. Cooling water can be introduced into the jacket 14 of the tank, achieving both cooling and filtration functions.

[0049] Example 6

[0050] This embodiment is a further optimization of embodiment 5, the difference being that, as referenced... Figure 4 The integrated cooling / filtration mixing tank 15 is connected to a vacuum line 16, and a pressure sensor 17 is installed on the integrated cooling / filtration mixing tank 15.

[0051] Example 7

[0052] The difference between this embodiment and embodiments 1-6 is that, in reference to... Figure 5 The photocatalytic reactor 4 is equipped with a pressure sensor 17 and a temperature sensor 18.

[0053] More preferably, the storage tank 3 is connected to a vacuum line 16.

[0054] A more preferred embodiment is that a booster pump I19 is installed on the pipeline connecting the storage tank 3 and the photocatalytic reactor 4.

[0055] A more preferred embodiment is that a booster pump II20 is provided between the photocatalytic reactor 4 and the first-stage condenser at the rear end.

[0056] Example 8

[0057] This embodiment uses the photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system that our company is piloting as an example to further illustrate this solution. One difference compared to the embodiment is that the collection tank I1, filter I2, and filter II5 all adopt the integrated cooling / filtration stirring tank 15 structure as described in the embodiment.

[0058] refer to Figure 5 This includes a cooling / filtration integrated stirred tank I 26 for collecting the mother liquor containing dichloroacetic acid during the preparation of chloroacetic acid. The mother liquor collected via chlorination replenishment pipeline 30 is temporarily stored in the cooling / filtration integrated stirred tank I 26. The cooling / filtration integrated stirred tank I 26 is connected in sequence to several stages of condensers and a cooling / filtration integrated stirred tank II 27 via pipelines. The filtrate outlet of the cooling / filtration integrated stirred tank II 27 is connected in sequence to a storage tank 3, a photocatalytic reactor 4, a condenser 21 with a 60°C medium (here the condenser provides preliminary cooling of the material), and a cooling / filtration integrated stirred tank III 28 via pipelines. The filtrate outlet of the cooling / filtration integrated stirred tank III 28 then passes in sequence through a condenser 21 with a 60°C medium, a condenser 22 with a 50°C medium, a condenser 23 with a 40°C medium, a condenser 24 with a 30°C medium, and a condenser 25 with a 20°C medium. See [link to relevant documentation]. Figure 6 The final stage condenser is then connected to the integrated cooling / filtration stirred tank IV29 via a pipeline. The filtrate from the integrated cooling / filtration stirred tank IV29 is then connected to the storage tank 3 via the return pipeline 6.

[0059] All integrated cooling / filtration mixing tanks I 26, II 27, III 28, IV 29, and the photocatalytic reactor 4 are equipped with a stirring mechanism 7. The photocatalytic reactor 4 is equipped with an ultraviolet-visible lamp 8. The photocatalytic reactor 4 is connected to a mother liquor supply line 9, a water supply line 10, a catalyst supply line 11, and a hydrogen supply line 12. All integrated mixing tanks are connected to a nitrogen line 13. When filtration is required, pressure filtration is achieved by adding nitrogen.

[0060] In this embodiment, the plurality of condensers are condensers through which media at temperatures of 60°C, 50°C, 40°C, 30°C, and 20°C are sequentially passed. (Reference) Figure 6 , Figure 6 Only the following are shown: a condenser 21 for a medium flowing at 60°C, a condenser 22 for a medium flowing at 50°C, a condenser 23 for a medium flowing at 40°C, a condenser 24 for a medium flowing at 30°C, and a condenser 25 for a medium flowing at 20°C, arranged sequentially between the integrated cooling / filtration mixing tank I 26 and the integrated cooling / filtration mixing tank II 27. Similarly, a condenser 21 for a medium flowing at 60°C, a condenser 22 for a medium flowing at 50°C, a condenser 23 for a medium flowing at 40°C, a condenser 24 for a medium flowing at 30°C, and a condenser 25 for a medium flowing at 20°C, are also arranged sequentially between the integrated cooling / filtration mixing tank III 28 and the integrated cooling / filtration mixing tank IV 29.

[0061] In this embodiment, all integrated stirred tanks and photocatalytic reactors 4 are equipped with jackets 14 for circulating insulation medium around their outer periphery. All integrated stirred tanks adopt the design of Example 6 (see reference). Figure 4 The integrated cooling / filtration mixing tank 15 in the ) has an external jacket 14 for passing heat insulation medium, an internal stirring mechanism 7, and a solid discharge port 15.1 at the bottom; the entire integrated cooling / filtration mixing tank 15 is connected to a vacuum pipeline 16, and a pressure sensor 17 is installed on the integrated cooling / filtration mixing tank 15.

[0062] In this embodiment, the photocatalytic reactor 4 is equipped with a pressure sensor 17 and a temperature sensor 18.

[0063] In this embodiment, the storage tank 3 is connected to the vacuum line 16.

[0064] In this embodiment, a booster pump I19 is provided on the pipeline connecting the storage tank 3 and the photocatalytic reactor 4; a booster pump II20 is provided between the photocatalytic reactor 4 and the first-stage condenser at the rear end.

[0065] In this embodiment, during actual production, an integrated cooling / filtration mixing tank 15 can be added between the multi-stage condensers as needed to prevent excessive product crystal precipitation from clogging the delivery pipeline.

[0066] The photocatalytic dichloroacetic acid dechlorination and chloroacetic acid recovery system in this embodiment treats the mother liquor containing dichloroacetic acid collected during the preparation of chloroacetic acid (acetic anhydride catalytic chlorination method). After cooling the chlorination liquid to 20°C, chloroacetic acid crystals precipitate. After filtering to remove the crystals, mother liquor A, accounting for approximately 13% of the total weight of the reaction solution, is obtained. After photocatalytic treatment of mother liquor A, the final solid chloroacetic acid yield can reach over 96% (the total amount of mother liquor is reduced to 4%). By continuing the catalytic reaction and repeating the process, the final solid chloroacetic acid yield can reach 98-99%, which is significantly higher than the solid yield of chloroacetic acid prepared by traditional techniques (generally 87%).

Claims

1. A system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid, characterized in that: It includes a collection tank I (1) for collecting mother liquor containing dichloroacetic acid in preparing chloroacetic acid, the collection tank I (1) is connected with several stages of condensers and a filter I (2) in sequence, the filtrate outlet I (2.1) of the filter I (2) is connected with a storage tank (3), a photocatalytic reactor (4), several stages of condensers and a filter II (5) in sequence, the filtrate outlet II (5.1) of the filter II (5) is connected with the storage tank (3) through a reflux pipeline (6); The collection tank I (1) and the photocatalytic reactor (4) are both provided with a stirring mechanism (7), the photocatalytic reactor (4) is provided with a UV-Vis light (8), the material inlet (4.1) of the photocatalytic reactor (4) is connected with a mother liquor supplement pipeline (9), a water supplement pipeline (10), a catalyst supplement pipeline (11) and a hydrogen supplement pipeline (12), and the collection tank I (1) is connected with a nitrogen pipeline (13).

2. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: The last stage of the several stages of condensers is a condenser through which a 20℃ medium passes.

3. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 2, characterized in that: The several stages of condensers are condensers through which 60℃, 50℃, 40℃, 30℃ and 20℃ media pass in sequence.

4. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: The collection tank I (1) and the photocatalytic reactor (4) are both provided with a jacket (14) through which a heat preservation medium passes.

5. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: The collection tank I (1), the filter I (2) and the filter II (5) are all cooling / filter integrated stirring tanks (15), the cooling / filter integrated stirring tanks (15) are provided with a jacket (14) through which a heat preservation medium passes, are provided with a stirring mechanism (7) inside and are provided with a solid discharge port (15.1) at the lower part.

6. The system according to claim 5, wherein the system is characterized by: The cooling / filter integrated stirring tanks (15) are connected with a vacuum pumping pipeline (16), and are provided with a pressure sensor (17) on the cooling / filter integrated stirring tanks (15).

7. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: The photocatalytic reactor (4) is provided with a pressure sensor (17) and a temperature sensor (18).

8. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: The storage tank (3) is connected with a vacuum pumping pipeline (16). 9.The system according to claim 1, wherein: A booster pump I (19) is arranged on the pipeline connected between the storage tank (3) and the photocatalytic reactor (4).

10. The system for photocatalytic dechlorination of dichloroacetic acid to recover chloroacetic acid according to claim 1, characterized in that: A booster pump II (20) is arranged between the photocatalytic reactor (4) and the first stage condenser at the rear end.

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