Post-treatment system of dimethyl phosphite reaction liquid

Abstract

The utility model discloses a post-treatment system for dimethyl phosphite reaction liquid, and belongs to the technical field of purification of dimethyl phosphite which is an intermediate of glyphosate. The post-treatment system comprises a deacidification kettle and a packed tower, the deacidification kettle is arranged on the rear side of a gas-liquid separator station in the dimethyl phosphite preparation system, and the gas-liquid separator is connected with the deacidification kettle; a distributor is arranged in the deacidification kettle and is communicated with the gas-liquid separator; the deacidification kettle is connected with the packed tower through an exhaust pipe, and the packed tower is connected with the deacidification kettle; a dimethyl phosphite storage tank is arranged on the rear side of the station of the deacidification kettle, and a liquid discharging pipe of the deacidification kettle extends to the middle or the bottom of the dimethyl phosphite storage tank to ensure that liquid seal is formed. The post-treatment system can be well matched with the preparation process of the dimethyl phosphite, continuous deacidification is achieved, and the yield and quality of the dimethyl phosphite are improved; meanwhile, the method is environment-friendly.

Description

Technical Field

[0001] This utility model specifically relates to a post-processing system for dimethyl phosphite reaction solution, belonging to the field of purification technology of dimethyl phosphite, an intermediate of glyphosate. Background Technology

[0002] Dimethyl phosphite, as an intermediate, is mainly used in the synthesis of the pesticide glyphosate. Currently, the industrial synthesis method for dimethyl phosphite generally involves: continuously and quantitatively adding phosphorus trichloride and methanol, reacting under negative pressure while simultaneously removing the generated hydrogen chloride; finally, after deep deacidification and distillation, dimethyl phosphite is obtained. The reaction mechanism involved includes: the reaction of methanol with phosphorus trichloride to produce trimethyl phosphite and hydrogen chloride; the trimethyl phosphite then rapidly reacts with one molecule of hydrogen chloride to produce dimethyl phosphite and one molecule of chloromethane. The overall reaction equation is as follows:

[0003] PCl3+3CH3OH =H(O)P(OCH3)2+2 HCl↑+CH3Cl↑

[0004] One molecule of phosphorus trichloride requires three molecules of methanol to produce one molecule of dimethyl phosphite, two molecules of hydrogen chloride, and one molecule of chloromethane. The hydrogen chloride is absorbed by water to form hydrochloric acid, which can be used in the subsequent hydrolysis process of glyphosate synthesis. The chloromethane, however, needs to be purified before being sold as a byproduct.

[0005] Although existing technologies such as CN110746453A disclose "a production process and production apparatus for dimethyl phosphite", CN218945019U disclose "a continuous production system for dimethyl phosphite", and CN219681722U disclose "a continuous distillation apparatus for dimethyl phosphite", the post-processing processes involved are mainly applicable to the dimethyl phosphite reaction liquid formed from phosphorus trichloride and methanol as raw materials. In this case, the product dimethyl phosphite contains only 2 methoxy groups. Of the 3 molecules of methanol consumed, 1 molecule of methanol is ultimately converted into chloromethane, resulting in low methanol molecule utilization and the by-product chloromethane. This requires additional purification and storage of by-products, thereby increasing the risk sources and environmental pressure. In addition, the reaction solution for synthesized dimethyl phosphite needs to be cleaned of unreacted methanol, phosphorous acid generated from excessive reaction, hydrogen chloride and a small amount of chloromethane dissolved in it. In particular, if hydrogen chloride is not removed in time, it can continue to react with dimethyl phosphite to generate monomethyl phosphite or even phosphorous acid, which seriously affects product quality and the sustainability of the preparation process.

[0006] Therefore, a post-treatment system for dimethyl phosphite reaction solution that meets practical requirements is needed. Summary of the Invention

[0007] To complement the continuous production process of dimethyl phosphite from water, methanol, and phosphorus trichloride, this invention provides a post-treatment system for the dimethyl phosphite reaction solution. The system, through the installation of a deacidification reactor and a packed tower, not only achieves continuous deacidification, improving the yield and quality of dimethyl phosphite, but also effectively treats and recovers the exhaust gas during the post-treatment process, enhancing environmental friendliness and reducing environmental pressure.

[0008] To achieve the above technical objectives, the following technical solution is proposed:

[0009] A post-treatment system for dimethyl phosphite reaction solution includes a deacidification vessel and a packed tower;

[0010] Deacidification kettle: Located behind the gas-liquid separator station in the dimethyl phosphite preparation system, with the reaction liquid outlet of the gas-liquid separator connected to the deacidification kettle;

[0011] The deacidification vessel is equipped with a distributor, which is connected to the reaction liquid outlet of the gas-liquid separator through a liquid inlet pipe; the gas outlet of the deacidification vessel is connected to the middle or lower part of the packed tower through an exhaust pipe, and the bottom of the packed tower is connected to the deacidification vessel through a reflux pipe. A continuous passage for the condensation and reflux of heavy components in the gas is formed between the gas outlet of the deacidification vessel, the exhaust pipe, the packed tower and the reflux pipe.

[0012] A dimethyl phosphite storage tank is located at the rear of the deacidification reactor. The lower liquid pipe of the deacidification reactor extends to the middle or bottom of the dimethyl phosphite storage tank to ensure the formation of a liquid seal. Preferably, the positional difference between the bottom of the deacidification reactor and the bottom of the dimethyl phosphite storage tank is controlled at 10-15m to ensure that the deacidification reactor can operate continuously under negative pressure, thereby achieving continuous operation of the entire system.

[0013] A continuous pathway for the post-treatment of dimethyl phosphite reaction liquid is formed between the reaction liquid outlet, liquid phase inlet pipe, deacidification vessel, liquid outlet pipe, and dimethyl phosphite storage tank on the gas-liquid separator.

[0014] Furthermore, the dimethyl phosphite preparation system includes a continuous flow reactor I, a continuous flow reactor II, and a gas-liquid separator; the phosphorus trichloride inlet of the continuous flow reactor I is connected to a phosphorus trichloride storage tank via a phosphorus trichloride inlet pipe, and the water inlet of the continuous flow reactor I is connected to a water storage tank via a water inlet pipe; the continuous flow reactor II is located behind the station of the continuous flow reactor I, the outlet of the continuous flow reactor I is connected to the reaction intermediate liquid inlet of the continuous flow reactor II, and the methanol inlet of the continuous flow reactor II is connected to a methanol storage tank via a methanol inlet pipe; the gas-liquid separator is located behind the station of the continuous flow reactor II, and the outlet of the continuous flow reactor II is connected to the inlet of the gas-liquid separator;

[0015] A continuous flow path for the preparation and post-treatment of dimethyl phosphite is formed between continuous flow reactor I, continuous flow reactor II, gas-liquid separator, deacidification vessel and dimethyl phosphite storage tank.

[0016] Furthermore, the phosphorus trichloride feed pipe is equipped with a phosphorus trichloride flow meter and a phosphorus trichloride regulating valve, the water feed pipe is equipped with a water flow meter and a water regulating valve, and the methanol feed pipe is equipped with a methanol flow meter and a methanol regulating valve.

[0017] Furthermore, the gas-liquid separator is equipped with a pressure transmitter and a level gauge, and a liquid phase feed regulating valve is provided on the liquid phase inlet pipe. The level gauge and the liquid phase feed regulating valve are connected by an electrical signal.

[0018] Furthermore, the distributor includes a disc-shaped distribution tank, which is connected to a motor via a rotating shaft. The motor drives the distribution tank in a centrifugal motion. The dimethyl phosphite reaction solution is introduced into the distribution tank. Under centrifugal force, the dimethyl phosphite reaction solution moves outward along the surface of the distribution tank, then flows back into the tank, uniformly adhering to the inner wall of the deacidification vessel, and flowing downward. During this flow, it is heated, and low-boiling-point substances vaporize, ultimately achieving efficient and high-quality material separation.

[0019] Furthermore, a heat exchanger is connected to the top of the packed tower, and a receiving tank is connected to the heat exchanger. The gas outlet of the receiving tank is connected to the tail gas treatment device. The tail gas treatment device is connected to a vacuum unit to ensure that the deacidification reactor operates under negative pressure. The liquid outlet of the receiving tank is connected to the packed tower, and the liquid outlet of the receiving tank is connected to the methanol storage tank.

[0020] Furthermore, the exhaust gas treatment device includes a scrubbing tower connected to a chloromethane recovery system.

[0021] The positional relationships involved in this technical solution, such as "between", "upper", "rear side of the workstation", "inner", "middle", "lower", "bottom", and "top", are defined according to the actual usage conditions and are common terms in this technical field, as well as common terms used by those skilled in the art in actual use.

[0022] In the description of this technical solution, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "equipped with," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this technical solution based on the specific circumstances.

[0023] The beneficial technical effects of adopting this technical solution are as follows:

[0024] This invention, through the combined arrangement of a deacidification kettle and a packed tower, can be well integrated with the preparation process of dimethyl phosphite, enabling continuous deacidification and improving the yield and quality of dimethyl phosphite.

[0025] In addition, by using heat exchangers, receiving tanks, and tail gas treatment devices, the effective components in the gas phase formed after deacidification of the dimethyl phosphite reaction solution are separated and recovered, thereby improving the yield of the target product and the purity of raw materials and by-products, facilitating subsequent reuse. Furthermore, the environmental friendliness of this preparation system is also improved. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the working principle of this utility model;

[0027] Figure 2 This is a diagram showing the arrangement of the present invention with the dimethyl phosphite preparation system;

[0028] In the diagram: 1. Continuous flow reactor I; 2. Continuous flow reactor II; 3. Gas-liquid separator; 4. Deacidification vessel; 5. Packed tower; 6. Tail gas treatment device; 7. Phosphorus trichloride inlet pipe; 8. Phosphorus trichloride storage tank; 9. Phosphorus trichloride flow meter; 10. Phosphorus trichloride regulating valve; 11. Water inlet pipe; 12. Water storage tank; 13. Water flow meter; 14. Water regulating valve; 15. Methanol inlet pipe; 16. Methanol storage tank; 17. Methanol flow meter; 18. Methanol regulating valve; 19. Level gauge; 20. Pressure transmitter; 21. Liquid phase inlet pipe; 22. Liquid phase feed regulating valve; 23. Heat exchanger; 24. Condensate pipeline; 25. Distributor; 26. Exhaust pipe; 27. Return pipe; 28. Receiving tank; 29. ​​Vacuum unit; 30. Dimethyl phosphite storage tank; 31. Downflow pipe; 32. Motor. Detailed Implementation

[0029] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0030] Example 1

[0031] This embodiment provides: a post-treatment system for dimethyl phosphite reaction solution, such as... Figure 1 As shown, it includes a deacidification reactor 4 and a packed tower 5;

[0032] Deacidification kettle 4: Located behind the gas-liquid separator 3 in the dimethyl phosphite preparation system, with the reaction liquid outlet of the gas-liquid separator 3 connected to the deacidification kettle 4;

[0033] The deacidification vessel 4 is equipped with a distributor 25, which is connected to the reaction liquid outlet of the gas-liquid separator 3 through a liquid inlet pipe 21; the gas outlet of the deacidification vessel 4 is connected to the middle or lower part of the packed tower 5 through an exhaust pipe 26, and the bottom of the packed tower 5 is connected to the deacidification vessel 4 through a reflux pipe 27. A continuous passage for the condensation and reflux of heavy components in the gas is formed between the gas outlet of the deacidification vessel 4, the exhaust pipe 26, the packed tower 5, and the reflux pipe 27.

[0034] A dimethyl phosphite storage tank 30 is provided at the rear of the deacidification reactor 4. The liquid outlet pipe 31 of the deacidification reactor 4 extends to the middle or bottom of the dimethyl phosphite storage tank 30 to ensure the formation of a liquid seal. Preferably, the positional difference between the bottom of the deacidification reactor 4 and the bottom of the dimethyl phosphite storage tank 30 is controlled at 10-15m to ensure that the deacidification reactor 4 can operate continuously under negative pressure, thereby realizing continuous operation of the entire system.

[0035] A continuous pathway for the post-treatment of dimethyl phosphite reaction liquid is formed between the gas-liquid separator 3, the reaction liquid outlet, the liquid inlet pipe 21, the deacidification vessel 4, the liquid outlet pipe 31, and the dimethyl phosphite storage tank 30.

[0036] Example 2

[0037] This embodiment provides: a dimethyl phosphite preparation system, such as... Figure 2 As shown, the reactor specifically includes a continuous flow reactor I1, a continuous flow reactor II2, and a gas-liquid separator 3. The phosphorus trichloride inlet of the continuous flow reactor I1 is connected to a phosphorus trichloride storage tank via a phosphorus trichloride inlet pipe, and the water inlet of the continuous flow reactor I1 is connected to a water storage tank via a water inlet pipe. The continuous flow reactor II2 is located behind the station of the continuous flow reactor I1, and the outlet of the continuous flow reactor I1 is connected to the intermediate reaction liquid inlet of the continuous flow reactor II2. The methanol inlet of the continuous flow reactor II2 is connected to a methanol storage tank via a methanol inlet pipe. The gas-liquid separator 3 is located behind the station of the continuous flow reactor II2, and the outlet of the continuous flow reactor II2 is connected to the inlet of the gas-liquid separator 3.

[0038] A continuous flow path for the preparation and post-treatment of dimethyl phosphite is formed between continuous flow reactor I1, continuous flow reactor II2, gas-liquid separator 3, deacidification vessel 4, and dimethyl phosphite storage tank 30.

[0039] The phosphorus trichloride feed pipe is equipped with a phosphorus trichloride flow meter 9 and a phosphorus trichloride regulating valve 10, which are interlocked by an electrical signal. This is used to precisely control the feed of phosphorus trichloride, thereby better coordinating with the feed of methanol and water, i.e., precisely controlling the reaction.

[0040] A water flow meter 13 and a water regulating valve 14 are installed on the water inlet pipe. The water flow meter 13 and the water regulating valve 14 are interlocked by an electrical signal. This is used to precisely control the water feed, thereby better coordinating with the feed of phosphorus trichloride and methanol, i.e., precisely controlling the reaction.

[0041] A methanol flow meter 17 and a methanol regulating valve 18 are installed on the methanol feed pipe. The methanol flow meter 17 and the methanol regulating valve 18 are interlocked by an electrical signal. This is used to precisely control the methanol feed, thereby better coordinating with the feed of phosphorus trichloride and water, i.e., precisely controlling the reaction.

[0042] In addition, pressure and temperature sensors are installed on the phosphorus trichloride feed pipe, water feed pipe, and methanol feed pipe to detect the pressure and material temperature in the corresponding feed pipe, thereby improving the orderliness and controllability of the reaction process.

[0043] Example 3

[0044] Based on Examples 1-2, this example further defines the gas-liquid separator 3 to further illustrate the technical solution.

[0045] The gas-liquid separator 3 is equipped with a pressure transmitter 20 and a level gauge 19. The liquid phase inlet pipe 21 is equipped with a liquid phase feed regulating valve 22. The level gauge 19 and the liquid phase feed regulating valve 22 are connected by an electrical signal. The feed of the deacidification kettle 4 is adjusted according to the changes in the liquid level in the gas-liquid separator 3.

[0046] Example 4

[0047] Based on embodiments 1-3, this embodiment further defines the distributor 25 to further illustrate the technical solution.

[0048] The distributor 25 includes a disc-shaped distribution tank. The distributor 25 is connected to the motor 32 via a rotating shaft, meaning the motor 32 drives the distribution tank to perform centrifugal motion. The dimethyl phosphite reaction solution is introduced into the distribution tank. Under centrifugal force, the dimethyl phosphite reaction solution moves outward along the surface of the distribution tank, then flows back into the tank, uniformly adhering to the inner wall of the deacidification vessel 4, and flowing downward. During this flow, it is heated, and low-boiling-point substances vaporize, ultimately achieving efficient and high-quality material separation.

[0049] Example 5

[0050] Based on Examples 1-4, this example further defines the packed tower 5 to further illustrate the technical solution.

[0051] A heat exchanger 23 is connected to the top of the packed tower 5, and a receiving tank 28 is connected to the heat exchanger 23. The gas outlet of the receiving tank 28 is connected to the tail gas treatment device 6. The tail gas treatment device 6 is connected to a vacuum unit 29 to ensure that the deacidification kettle 4 operates under negative pressure. The liquid outlet of the receiving tank 28 is connected to the packed tower 5, and the liquid outlet of the receiving tank 28 is connected to the methanol storage tank 16.

[0052] The exhaust gas treatment device 6 includes a scrubbing tower, which is connected to a chloromethane recovery system.

[0053] Example 6

[0054] Based on Examples 1-5, this example provides a preparation process for dimethyl phosphite, comprising the following steps:

[0055] 1) First reaction: Assuming a molar ratio of phosphorus trichloride to water of 1:0 to 1, phosphorus trichloride and water are introduced into continuous flow reactor I. The temperature inside continuous flow reactor I is controlled at 30 to 80°C and the pressure is -0.1 to 0.1 MPa to obtain intermediate product;

[0056] 2) Second reaction: With a molar ratio of phosphorus trichloride to methanol of 1:2 to 4, methanol and the intermediate product obtained in step S1 are fed into continuous flow reactor II. The temperature in continuous flow reactor II is controlled at 20 to 70°C and the pressure is -0.1 to 0.1 MPa to obtain the reaction solution.

[0057] In the entire reaction process of steps 1) and 2), the molar ratio of the total amount of water and methanol introduced to the amount of phosphorus trichloride introduced is controlled to be 3.1 to 4:1; for the raw material-water, it can specifically be "deionized water";

[0058] 3) Gas-liquid separation: The reaction liquid obtained in step 2) is passed into a gas-liquid separator. The temperature inside the gas-liquid separator is controlled at 20-70℃ and the pressure is -0.1-0.1 MPa to perform gas-liquid separation, yielding gas I (a large amount of gas, which is hydrogen chloride gas containing small amounts of chloromethane, methanol and vaporized dimethyl phosphite) and the separated liquid;

[0059] Gas I is condensed and then passed into a tail gas treatment device for water washing, yielding a large amount of by-product hydrochloric acid and a small amount of water-non-absorbable gas (mainly chloromethane). This small amount of water-non-absorbable gas is discharged to the chloromethane recovery system. The condensation of gas I first reduces the amount of phosphorus-containing substances entering the tail gas treatment system, effectively lowering the phosphorus content of the by-product hydrochloric acid and improving its quality.

[0060] 4) Deacidification and separation: The separation liquid obtained in step 3) is passed into the deacidification reactor. The distributor speed in the deacidification reactor is controlled at 30-120 r / min, the temperature at 30-80℃, and the pressure at -0.1--0.5 MPa for separation, yielding gas II (a small amount of gas, mainly including vaporized dimethyl phosphite, methanol, hydrogen chloride gas, and a very small amount of chloromethane) and crude dimethyl phosphite.

[0061] Gas II is introduced into a packed tower, where it is separated to obtain heavy components (mainly dimethyl phosphite) and light components (methanol containing trace amounts of hydrogen chloride and chloromethane). The heavy components are refluxed into the deacidification reactor, while the light components are recovered (condensed) and reused in the synthesis of dimethyl phosphite. A small amount of non-condensable gas (mainly hydrogen chloride and chloromethane) is introduced into the tail gas treatment system for water washing, yielding a small amount of by-product hydrochloric acid and a very small amount of water-non-absorbable gas (mainly chloromethane). This very small amount of water-non-absorbable gas is discharged into the chloromethane recovery system. The introduction of gas II into the packed tower, with condensation and reflux at the top, avoids the entrainment of heavy components in the gas phase, effectively reducing the phosphorus content of the by-product hydrochloric acid in the subsequent tail gas treatment unit, thus improving the quality of the hydrochloric acid. Simultaneously, the recovered hydrochloric acid yields a high-content anhydrous methanol, which can be directly reused in the dimethyl phosphite synthesis process, achieving the goal of reducing methanol consumption. In other words, without increasing energy consumption, methanol consumption is reduced and the quality of the by-product hydrochloric acid is improved.

[0062] 5) Distillation treatment: The crude dimethyl phosphite obtained in step 4) is subjected to distillation treatment to obtain dimethyl phosphite, which is a transparent liquid.

Claims

1. A post-treatment system for dimethyl phosphite reaction solution, characterized in that: It includes a deacidification vessel (4) and a packed tower (5). The deacidification vessel (4) is located behind the gas-liquid separator (3) in the dimethyl phosphite preparation system. The reaction liquid outlet of the gas-liquid separator (3) is connected to the deacidification vessel (4). The deacidification vessel (4) is equipped with a distributor (25), which is connected to the reaction liquid outlet of the gas-liquid separator (3) through a liquid inlet pipe (21); the gas outlet of the deacidification vessel (4) is connected to the middle or lower part of the packed tower (5) through an exhaust pipe (26), and the bottom of the packed tower (5) is connected to the deacidification vessel (4) through a reflux pipe (27). A continuous passage for the condensation and reflux of heavy components in the gas is formed between the gas outlet of the deacidification vessel (4), the exhaust pipe (26), the packed tower (5) and the reflux pipe (27). A dimethyl phosphite storage tank (30) is provided on the rear side of the deacidification kettle (4). The liquid outlet pipe (31) of the deacidification kettle (4) extends to the middle or bottom of the dimethyl phosphite storage tank (30) to ensure the formation of a liquid seal. A continuous pathway for the post-treatment of dimethyl phosphite reaction liquid is formed between the upper reaction liquid outlet, liquid phase inlet pipe (21), deacidification vessel (4), lower liquid pipe (31), and dimethyl phosphite storage tank (30) of the gas-liquid separator (3).

2. The post-treatment system for the dimethyl phosphite reaction solution according to claim 1, characterized in that: The dimethyl phosphite preparation system includes a continuous flow reactor I (1), a continuous flow reactor II (2), and a gas-liquid separator (3); the phosphorus trichloride inlet of the continuous flow reactor I (1) is connected to the phosphorus trichloride storage tank through a phosphorus trichloride inlet pipe, and the water inlet of the continuous flow reactor I (1) is connected to the water storage tank through a water inlet pipe; the continuous flow reactor II (2) is located behind the station of the continuous flow reactor I (1), the outlet of the continuous flow reactor I (1) is connected to the reaction intermediate liquid inlet of the continuous flow reactor II (2), and the methanol inlet of the continuous flow reactor II (2) is connected to the methanol storage tank through a methanol inlet pipe; the gas-liquid separator (3) is located behind the station of the continuous flow reactor II (2), and the outlet of the continuous flow reactor II (2) is connected to the inlet of the gas-liquid separator (3); A continuous flow path for the preparation and post-treatment of dimethyl phosphite is formed between continuous flow reactor I (1), continuous flow reactor II (2), gas-liquid separator (3), deacidification vessel (4) and dimethyl phosphite storage tank (30).

3. The post-treatment system for the dimethyl phosphite reaction solution according to claim 2, characterized in that: The phosphorus trichloride feed pipe is equipped with a phosphorus trichloride flow meter (9) and a phosphorus trichloride regulating valve (10), the water feed pipe is equipped with a water flow meter (13) and a water regulating valve (14), and the methanol feed pipe is equipped with a methanol flow meter (17) and a methanol regulating valve (18).

4. The post-treatment system for the dimethyl phosphite reaction solution according to claim 3, characterized in that: The gas-liquid separator (3) is equipped with a pressure transmitter (20) and a level gauge (19). The liquid phase inlet pipe (21) is equipped with a liquid phase feed regulating valve (22). The level gauge (19) and the liquid phase feed regulating valve (22) are connected by an electrical signal.

5. The post-treatment system for the dimethyl phosphite reaction solution according to any one of claims 1-4, characterized in that: The distributor (25) includes a disc-shaped distribution slot and is connected to the motor (32) via a rotating shaft.

6. The post-treatment system for the dimethyl phosphite reaction solution according to claim 1, characterized in that: The bottom of the deacidification vessel (4) is 10-15m above the bottom of the dimethyl phosphite storage tank (30).

7. The post-treatment system for the dimethyl phosphite reaction solution according to claim 1, characterized in that: The top of the packed tower (5) is connected to a heat exchanger (23), the heat exchanger (23) is connected to a receiving tank (28), the gas outlet of the receiving tank (28) is connected to the tail gas treatment device (6); the tail gas treatment device (6) is connected to a vacuum unit (29); the liquid outlet of the receiving tank (28) is connected to the packed tower (5), and the liquid outlet of the receiving tank (28) is connected to the methanol storage tank (16).

8. The post-treatment system for the dimethyl phosphite reaction solution according to claim 7, characterized in that: The exhaust gas treatment device (6) includes a scrubbing tower connected to a chloromethane recovery system.

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