Dimethyl phosphite preparation system based on continuous flow reactor

Abstract

The utility model discloses a dimethyl phosphite preparation system based on a continuous flow reactor, and belongs to the technical field of glyphosate production. The preparation system comprises a continuous flow reactor I, a continuous flow reactor II and a gas-liquid separator, the continuous flow reactor I is connected with a phosphorus trichloride storage tank, and the continuous flow reactor I is connected with a water storage tank; the continuous flow reactor I is connected with a continuous flow reactor II, and the continuous flow reactor II is connected with a methanol storage tank; the continuous flow reactor II is connected with the gas-liquid separator; the gas-liquid separator is connected with a vacuum deacidification system, and the vacuum deacidification system is connected with the product tank; the gas-liquid separator is connected with a washing system; and the washing system is connected with the tail gas recovery system. The method not only ensures efficient and continuous preparation of dimethyl phosphite, but also realizes cost saving, byproduct reduction, environmental protection pressure reduction and the like.

Description

Technical Field

[0001] The utility model specifically relates to a dimethyl phosphite preparation system based on a continuous flow reactor, and belongs to the technical field of glyphosate production. Background Art

[0002] Dimethyl phosphite is primarily used as an intermediate in the synthesis of the pesticide glyphosate. Currently, the industrial synthesis method for dimethyl phosphite generally involves the continuous quantitative addition of phosphorus trichloride and methanol as raw materials, followed by reaction under negative pressure while simultaneously removing the generated hydrogen chloride. Finally, dimethyl phosphite undergoes deep deacidification and distillation. The reaction mechanism involves the reaction of methanol with phosphorus trichloride to form trimethyl phosphite and hydrogen chloride; trimethyl phosphite then rapidly reacts with a molecule of hydrogen chloride to form dimethyl phosphite and a molecule of methyl chloride. The overall reaction equation is as follows:

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

[0004] Among them, one molecule of phosphorus trichloride consumes three molecules of methanol to produce one molecule of dimethyl phosphite, two molecules of hydrogen chloride and one molecule of methyl chloride. After the hydrogen chloride is absorbed into hydrochloric acid with water, it can be used in the subsequent hydrolysis process of glyphosate synthesis; while the methyl chloride needs to be purified and then sold as a by-product.

[0005] Although the prior art CN110746453A discloses a "production process and production device for dimethyl phosphite", CN218945019U discloses a "continuous production system for dimethyl phosphite", and CN219681722U discloses a "continuous dimethyl phosphite distillation device", the preparation systems involved all use phosphorus trichloride and methanol as raw materials. The product dimethyl phosphite has only two methoxy groups, and one molecule of methanol is consumed for every three molecules of methanol, ultimately generating chloromethane. This results in a low utilization rate of the methanol molecules, and the by-product chloromethane requires additional purification, storage, and other treatments of the by-products, thereby increasing risk sources and environmental pressures.

[0006] Therefore, a preparation system is needed that can reduce the amount of raw material methanol, improve the atomic utilization rate, and reduce the by-product of chloromethane. Summary of the Invention

[0007] Aiming to address existing issues such as low atomic utilization of methanol as a raw material and high byproduct production of chloromethane, this system provides a dimethyl phosphite production system based on a continuous flow reactor. This system is ideally suited for dimethyl phosphite production processes using both water and methanol as raw materials (replacing one methanol molecule with one water molecule). The system utilizes a common phosphorus trichloride storage tank, water storage tank, methanol storage tank, continuous flow reactor I, and continuous flow reactor II, ensuring efficient and continuous production of dimethyl phosphite while also achieving cost savings, reducing byproducts, and alleviating environmental pressures.

[0008] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0009] A dimethyl phosphite preparation system based on a continuous flow reactor includes a continuous flow reactor I, a continuous flow reactor II and a gas-liquid separator;

[0010] Continuous flow reactor I: connected to a phosphorus trichloride storage tank via a phosphorus trichloride feed pipe, the phosphorus trichloride feed pipe is provided with a phosphorus trichloride flowmeter and a phosphorus trichloride regulating valve, and the upper discharge port of continuous flow reactor I is connected to continuous flow reactor II;

[0011] It is also connected to a water storage tank through a water feed pipe, and a water flow meter and a water regulating valve are provided on the water feed pipe;

[0012] Continuous flow reactor II: located at the rear of the station of continuous flow reactor I, continuous flow reactor II is connected to a methanol storage tank via a methanol feed pipe, the methanol feed pipe is equipped with a methanol flow meter and a methanol regulating valve, and the upper discharge port of continuous flow reactor II is connected to a gas-liquid separator;

[0013] The phosphorus trichloride feed pipe, water feed pipe and methanol feed pipe are all equipped with pressure sensors and temperature sensors;

[0014] Gas-liquid separator: located at the rear of the continuous flow reactor II, the gas-liquid separator is equipped with a level gauge and a pressure transmitter. The liquid phase outlet of the gas-liquid separator is connected to the vacuum deacidification system through a liquid phase outlet pipe, and a liquid phase regulating valve is provided on the liquid phase outlet pipe;

[0015] The gas phase outlet on the gas-liquid separator is connected to a washing system through a gas phase outlet pipe, and a pressure regulating valve is provided on the gas phase outlet pipe.

[0016] The positional relationships involved in this technical solution, such as "between", "above", and "behind the workstation", are defined based on the actual usage conditions. They are conventional terms in this technical field and are also conventional terms used by technical personnel in this field in actual use.

[0017] In the description of this technical solution, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "provided with," and "connected" should be interpreted broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this technical solution on a case-by-case basis.

[0018] The beneficial technical effects brought about by adopting this technical solution are:

[0019] The utility model is provided with a phosphorus trichloride storage tank, a water storage tank, a methanol storage tank, a continuous flow reactor I, a continuous flow reactor II, etc., which can be well coordinated with the preparation process of dimethyl phosphite, thereby ensuring efficient and continuous preparation of dimethyl phosphite. At the same time, by replacing part of the raw material methanol with water, the amount of raw material methanol is reduced, the atomic utilization rate of methanol is improved, and the by-product of chloromethane is also reduced.

[0020] In addition, by setting up corresponding delivery pumps, flow meters, regulating valves, pressure sensors, temperature sensors, etc., the flow, temperature, pressure, etc. in the preparation system are controlled to improve the controllability and stability of the preparation process of dimethyl phosphite. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a working principle diagram of the utility model;

[0022] Among them, in the figure: 1. continuous flow reactor I, 2. continuous flow reactor II, 3. gas-liquid separator, 4. phosphorus trichloride feed pipe, 5. phosphorus trichloride storage tank, 6. phosphorus trichloride flow meter, 7. phosphorus trichloride regulating valve, 8. water feed pipe, 9. water storage tank, 10. water flow meter, 11. water regulating valve, 12. methanol feed pipe, 13. methanol storage tank, 14. methanol flow meter, 15. methanol regulating valve, 16. liquid level gauge, 17. pressure transmitter, 18. gas phase outlet pipe, 19. pressure regulating valve, 20. liquid phase outlet pipe, 21. liquid phase regulating valve. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. It is obvious that the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1

[0025] This embodiment provides: a dimethyl phosphite preparation system based on a continuous flow reactor, comprising a continuous flow reactor I 1, a continuous flow reactor II 2 and a gas-liquid separator 3;

[0026] Continuous flow reactor I1: the phosphorus trichloride feed port of the continuous flow reactor I1 is connected to the phosphorus trichloride storage tank 5 through the phosphorus trichloride feed pipe 4, and the water feed port of the continuous flow reactor I1 is connected to the water storage tank 9 through the water feed pipe 8;

[0027] Continuous flow reactor II 2: located at the rear side of the station of continuous flow reactor I 1, the upper discharge port of continuous flow reactor I 1 is connected to the reaction intermediate liquid feed port of continuous flow reactor II 2, and the methanol feed port of continuous flow reactor II 2 is connected to the methanol storage tank 13 through the methanol feed pipe 12;

[0028] Gas-liquid separator 3: Located at the rear side of the station of continuous flow reactor II 2, the upper discharge port of continuous flow reactor II 2 is connected to the upper feed port of gas-liquid separator 3; the liquid phase discharge port of gas-liquid separator 3 is connected to a vacuum deacidification system via a liquid phase discharge pipe 20, and the vacuum deacidification system is connected to the product tank; the gas phase discharge port of gas-liquid separator 3 is connected to a washing system via a gas phase discharge pipe 18, and the washing system is connected to the tail gas recovery system;

[0029] A continuous passage for preparing dimethyl phosphite is formed among the continuous flow reactor I1, the continuous flow reactor II2, the gas-liquid separator 3, the liquid phase outlet pipe 20, the vacuum deacidification system and the product tank.

[0030] Among them, the coordinated arrangement of the phosphorus trichloride storage tank 5, the water storage tank 9, the methanol storage tank 13, the continuous flow reactor I1, the continuous flow reactor II2, etc., not only ensures the efficient and continuous preparation of dimethyl phosphite, but also achieves cost savings, reduces by-products (chloromethane), and at the same time, reduces environmental pressure.

[0031] Example 2

[0032] The reaction of phosphorus trichloride with water and methanol is an exothermic reaction, and the reaction is violent. If it is not precisely controlled, side reactions are very likely to occur. Therefore, based on Example 1, this example controls the flow rate, temperature, pressure, etc. in the preparation system to ensure the continuity and controllability of the esterification reaction, thereby improving the controllability and stability of the preparation process of dimethyl phosphite, and further defines:

[0033] The phosphorus trichloride feed pipe is equipped with a phosphorus trichloride flowmeter 6 and a phosphorus trichloride regulating valve 7. The phosphorus trichloride flowmeter 6 and the phosphorus trichloride regulating valve 7 are interlocked by electrical signals. They are used to accurately control the feed of phosphorus trichloride, thereby better coordinating with the methanol and water feeds, that is, accurately controlling the reaction.

[0034] The water feed pipe 8 is provided with a water flow meter 10 and a water regulating valve 11, which are interlocked by electrical signals. This is used to precisely control the water feed, thereby better coordinating with the phosphorus trichloride and methanol feeds, i.e., precisely controlling the reaction.

[0035] The methanol feed pipe 12 is equipped with a methanol flowmeter 14 and a methanol regulating valve 15. The methanol flowmeter 14 and the methanol regulating valve 15 are interlocked by electrical signals. They are used to accurately control the methanol feed, thereby better coordinating with the phosphorus trichloride and water feeds, that is, accurately controlling the reaction.

[0036] In addition, the phosphorus trichloride feed pipe 4, the water feed pipe 8 and the methanol feed pipe 12 are all provided with pressure sensors and temperature sensors for detecting the pressure and material temperature in the corresponding feed pipes, thereby improving the orderliness and controllability of the reaction process.

[0037] Example 3

[0038] On the basis of Examples 1-2, this example further defines the gas-liquid separator 3 to further illustrate this technical solution.

[0039] The gas-liquid separator 3 is provided with a pressure transmitter 17 and a liquid level meter 16 , the gas phase outlet pipe 18 is provided with a pressure regulating valve 19 , and the liquid phase outlet pipe 20 is provided with a liquid phase regulating valve 21 .

[0040] The pressure transmitter 17 and the pressure regulating valve 19 are interlocked by electrical signals. The pressure change of the reaction tail gas is used to monitor the pressure in the gas-liquid separation device, which indirectly reflects the reaction situation in the microchannel reactor.

[0041] The liquid level gauge 16 is electrically interlocked with the liquid outlet regulating valve to regulate the feed level of the vacuum deacidification system based on the liquid level changes within the gas-liquid separator. This ensures a constant amount of liquid in the gas-liquid separator 3, preventing non-condensable gas from entering the vacuum deacidification system. This ensures stable operation of the vacuum deacidification system and significantly reduces the load on the vacuum unit, thereby lowering investment and operating costs.

[0042] Example 4

[0043] Based on Examples 1-3, this embodiment provides a process for preparing dimethyl phosphite, comprising the following steps:

[0044] 1) First reaction: Phosphorus trichloride and water are introduced into a continuous flow reactor I at a molar ratio of phosphorus trichloride to water of 1:0-1, and the temperature and pressure in the continuous flow reactor I are controlled at 30-80°C and -0.1-0.1 MPa to obtain an intermediate product;

[0045] 2) Second Reaction: With a molar ratio of phosphorus trichloride to methanol of 1:2-4, methanol and the intermediate product obtained in step S1 are introduced into a continuous flow reactor II, and the temperature and pressure in the continuous flow reactor II are controlled to be 20-70° C. and -0.1-0.1 MPa, to obtain a reaction solution;

[0046] During the entire reaction process of step 1) and step 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; the raw material - water can specifically be "deionized water";

[0047] 3) Gas-liquid separation: The reaction liquid obtained in step 2) is passed into a gas-liquid separator, and the temperature and pressure in the gas-liquid separator are controlled at 20-70° C. and -0.1-0.1 MPa to perform gas-liquid separation to obtain a gas (a large amount of gas, which is hydrogen chloride gas containing a small amount of methyl chloride, methanol, and vaporized dimethyl phosphite) and a separated liquid;

[0048] After the gas passes through the scrubbing system for scrubbing, it is passed into the tail gas recovery system;

[0049] The separated liquid is deacidified by a vacuum deacidification system and then stored in a product tank.

[0050] In this preparation process, on the one hand, by using water and methanol as raw materials, the amount of methanol used is reduced, and at the same time, the by-product of chloromethane is greatly reduced; on the other hand, by adopting a continuous flow reactor and a gas-liquid separator, and correspondingly treating and recycling the generated tail gas, it is ultimately ensured that this preparation process is no longer like the traditional process - a large amount of non-condensable gas needs to be treated by a vacuum unit before being discharged to the chloromethane recovery system. The load of the vacuum unit in this preparation process is reduced by several times, which can greatly reduce equipment investment and energy consumption.

Claims

1. A dimethyl phosphite preparation system based on a continuous flow reactor, characterized in that: It includes a continuous flow reactor I (1), a continuous flow reactor II (2) and a gas-liquid separator (3); The phosphorus trichloride feed port of the continuous flow reactor I (1) is connected to the phosphorus trichloride storage tank (5) through a phosphorus trichloride feed pipe (4), and the water feed port of the continuous flow reactor I (1) is connected to the water storage tank (9) through a water feed pipe (8); The continuous flow reactor II (2) is arranged at the rear side of the station of the continuous flow reactor I (1), the upper discharge port of the continuous flow reactor I (1) is connected to the upper reaction intermediate liquid feed port of the continuous flow reactor II (2), and the upper methanol feed port of the continuous flow reactor II (2) is connected to the methanol storage tank (13) through the methanol feed pipe (12); The gas-liquid separator (3) is arranged at the rear side of the station of the continuous flow reactor II (2), and the upper discharge port of the continuous flow reactor II (2) is connected to the upper feed port of the gas-liquid separator (3); The upper liquid phase outlet of the gas-liquid separator (3) is connected to a vacuum deacidification system via a liquid phase outlet pipe (20), and the vacuum deacidification system is connected to the product tank; the upper gas phase outlet of the gas-liquid separator (3) is connected to a washing system via a gas phase outlet pipe (18), and the washing system is connected to the tail gas recovery system; A continuous passage for preparing dimethyl phosphite is formed between the continuous flow reactor I (1), the continuous flow reactor II (2), the gas-liquid separator (3), the liquid phase outlet pipe (20), the vacuum deacidification system and the product tank.

2. The dimethyl phosphite preparation system based on a continuous flow reactor according to claim 1, wherein The phosphorus trichloride material pipe is provided with a phosphorus trichloride flow meter (6) and a phosphorus trichloride regulating valve (7).

3. The dimethyl phosphite preparation system based on a continuous flow reactor according to claim 2, characterized in that, The water feed pipe (8) is provided with a water flow meter (10) and a water regulating valve (11).

4. The dimethyl phosphite preparation system based on a continuous flow reactor according to claim 3, characterized in that, The methanol feed pipe (12) is provided with a methanol flow meter (14) and a methanol regulating valve (15).

5. The dimethyl phosphite preparation system based on a continuous flow reactor according to any one of claims 1 to 4, characterized in that: The phosphorus trichloride feed pipe, the water feed pipe (8) and the methanol feed pipe (12) are all provided with a pressure sensor and a temperature sensor.

6. The dimethyl phosphite preparation system based on a continuous flow reactor according to any one of claims 1 to 4, characterized in that: The gas-liquid separator (3) is provided with a pressure transmitter (17), and the gas phase outlet pipe (18) is provided with a pressure regulating valve (19).

7. The dimethyl phosphite preparation system based on a continuous flow reactor according to claim 6, characterized in that, The gas-liquid separator (3) is provided with a liquid level meter (16), and the liquid phase outlet pipe (20) is provided with a liquid phase regulating valve (21).

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