Method for continuously producing 2, 4-D ammonium salt without solvent

Abstract

The invention relates to a solvent-free environment-friendly continuous production method of 2, 4-D ammonium salt, which comprises the following steps: introducing 2, 4-D acid, ammonia gas and a catalyst into a first-stage tubular reactor for reaction, grinding by a pipeline mill, introducing into a second-stage tubular reactor, adding ammonia gas for reaction at the same time, and grinding through a pipeline mill, feeding into a three-stage tubular reactor, supplementing ammonia gas for reaction, and finally collecting materials at an outlet to obtain the 2, 4-D ammonium salt. According to the method, 2, 4-D acid can be continuously ammoniated to produce the 2, 4-D ammonium salt, no organic solvent needs to be added in the production process, scaling is not prone to occurring, and the method is easy to operate and suitable for automatic and even intelligent large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides, and particularly relates to a method for continuously producing 2,4-D ammonium salt without solvent. Background Art

[0002] 2,4-D, the full name of which is 2,4-dichlorophenoxyacetic acid, is a hormone-type herbicide. It is not only a flower and fruit protectant, but also a highly active herbicide. It has excellent systemic conductivity and can enter the plant body from the roots, stems, and leaves. It promotes or inhibits the excessive growth of the weed conductive tissue, causing the weed stems and leaves to twist, the stem base to become thicker, and the weeds to swell and crack, ultimately killing the weeds. It has the advantages of a wide weed control range, thorough weed control, easy mixing, not easy to produce resistance, and low price. Although it is an old variety of herbicide, it is still a very excellent herbicide and is still widely used in agricultural production.

[0003] Since 2,4-D is not very soluble in water, it is usually made into 2,4-D ammonium salt, 2,4-D dimethylamine salt or 2,4-D isopropylamine salt during use. One is to increase the solubility in water, and the other is to better penetrate the wax layer of plant leaves. Not only the dosage is reduced, but also the efficacy is improved. The information of 2,4-D ammonium salt compound is as follows:

[0004] Chinese name: 2,4-D ammonium salt

[0005] Chinese alias: 2,4-dichlorophenoxy ammonium acetate

[0006] CAS No.: 2307-55-3

[0007] The chemical structure is as follows:

[0008]

[0009] At present, the dosage forms of 2,4-D ammonium (amine) salt include aqueous solution, wettable powder, soluble powder, soluble granule and other dosage forms. Solid preparations are easy to package and transport, and can be made into high-content preparations to reduce production costs, such as 80% 2,4-D ammonium (amine) salt soluble granules. The production method of 2,4-D ammonium (amine) salt is to add water to 2,4-D acid, and drip ammonia water, dimethylamine aqueous solution, and isopropylamine aqueous solution in a reactor under stirring. After the reaction is completed, cool and recrystallize, centrifuge, and dry. The mother liquor water is recycled. This method has a long production process, high energy consumption, high labor intensity, and during the salt-forming reaction process, the side reactions increase due to the reaction in the water base, and the yield decreases. It is impossible to achieve continuity and is not suitable for future automation and even intelligent needs. The existing gas-solid reaction method cannot solve the problem of incomplete reaction caused by the encapsulation of the product crystals.

[0010] Therefore, it is urgent to develop a continuous, automated and intelligent industrial production method for 2,4-D ammonium salt. Summary of the invention

[0011] The invention provides a solvent-free, green and environmentally friendly method for continuously producing 2,4-D ammonium salt. Through multi-stage serially connected tubular reactors, the reaction is more complete and thorough, the yield is higher, and the continuous, automated and intelligent industrial production of 2,4-D ammonium salt is easily realized.

[0012] The technical solution adopted to achieve the above invention object is:

[0013] The first aspect of the present invention relates to a method for solvent-free continuous production of 2,4-D ammonium salt, comprising the following steps:

[0014] (1) introducing 2,4-D acid, ammonia and a catalyst into a primary tubular reactor for reaction to obtain a primary reaction material;

[0015] (2) grinding the primary reaction material in step (1) through a pipeline mill and feeding it into a secondary tubular reactor while adding ammonia gas for reaction to obtain a secondary reaction material;

[0016] (3) grinding the secondary reaction material in step (2) through a pipeline mill and feeding it into a tertiary tubular reactor while adding ammonia gas for reaction to obtain a tertiary reaction material;

[0017] (4) Collect the tertiary reaction material of step (3) through the outlet material to obtain 2,4-D ammonium salt.

[0018] Wherein, the catalyst in step (1) is an aqueous solution of an aminating agent with a mass concentration of 5% to 15%, and the catalyst is preferably a 10% ammonia aqueous solution.

[0019] Wherein, the amount of ammonia introduced in step (1) is 100-150 g / min, the amount of 2,4-D acid introduced is 1300-2000 g / min, and the amount of catalyst introduced is 65-100 mL / min.

[0020] Wherein, the reaction temperature of the tubular reactor in steps (1) to (3) is 30 to 50° C., the reaction pressure is 0.1 to 0.2 MPa, and the reaction time is 20 to 40 min.

[0021] The distribution ratio of ammonia in the three reactors is 20:4:1.

[0022] Wherein, the ammonia gas in step (1) may also be isopropylamine.

[0023] Wherein, the grinding fineness of the pipeline mill is 200-400 meshes.

[0024] Another aspect of the present invention relates to a multi-stage series tubular reactor for a solvent-free continuous production method of 2,4-D ammonium salt, comprising:

[0025] A stirring shaft, wherein a first cooling cavity is provided in the stirring shaft, wherein the first cooling cavity is used to pass a cooling medium, and the stirring shaft is spirally provided with propeller blades;

[0026] A cylinder, wherein the cylinder is sleeved outside the stirring shaft, and a reaction chamber is formed between the cylinder and the stirring shaft;

[0027] A cylinder head converter, which is arranged at the left and right ends of the stirring shaft;

[0028] A jacket, wherein the jacket is sleeved outside the cylinder, and a second cooling cavity is formed between the jacket and the cylinder, and the second cooling cavity is also used for passing the cooling medium;

[0029] A pipeline mill, which is arranged between the inlet and outlet of the series-connected tubular reactor;

[0030] A motor and a reducer, wherein the motor and the reducer are drivingly connected to the cylinder head converter;

[0031] Wherein, the multi-stage tubular reactor is a three-stage series reactor.

[0032] Wherein, the stirring shaft is provided with one or more propeller blades.

[0033] Among them, the jacket is provided with a solid raw material inlet, a liquid or gas raw material inlet, and a catalyst addition port, and one end thereof penetrates the jacket and the cylinder respectively, and is connected with the reaction chamber; the solid raw material inlet and the catalyst addition port are provided with a star-shaped discharge valve, and the liquid or gas raw material inlet is provided with a flow meter.

[0034] Wherein, a tubular reactor discharge port is also provided at the lower end of the jacket and is communicated with the reaction chamber; a sampling port and a star-shaped discharge valve are provided on the pipeline at the lower end of the tubular reactor discharge port.

[0035] Wherein, a stirring shaft cooling water inlet and a stirring shaft cooling water outlet are respectively arranged at the left and right ends of the first cooling cavity formed by the stirring shaft.

[0036] Wherein, a second cooling cavity is formed between the jacket and the cylinder, and a tubular reactor cooling water inlet and a tubular reactor cooling water outlet are respectively arranged at the upper and lower ends thereof.

[0037] Among them, the cylinder head converter is composed of bearing seals at both ends, an intermediate transmission wheel and a head; the bearing seal is a swivel joint, the head is connected to the converter by fasteners, and the intermediate transmission wheel is a welded forging or an integral casting; and the cylinder head converter is connected to the stirring shaft by a keyway.

[0038] Wherein, the pipeline mill has a grinding fineness of 200 to 400 meshes, preferably 300 meshes.

[0039] A continuous multi-stage serial tubular reactor also includes two groups of temperature sensors and pressure sensors arranged on the jacket, and the temperature sensors and pressure sensors are connected to the tubular reactor through a thermometer interface and a pressure gauge interface.

[0040] The multi-stage series channel reactor works as follows:

[0041] Open the jacket and the cooling medium of the stirring shaft, start stirring, and add solid materials and liquid materials or gas materials to the first-stage tubular reactor at the same time. As the stirring is running, the materials move to the other end of the tubular reactor. Monitor the temperature and pressure changes in the tubular reactor at any time to adjust the feeding speed and the flow rate of the cooling medium. The reaction materials enter the pipeline mill from the outlet of the first-stage tubular reactor to destroy the crystal layer of the outer layer of the particles and then enter the second-stage tubular reactor. A certain amount of liquid or gas raw materials can be added to the second-stage tubular reactor to make the reaction sufficient. Similarly, a certain amount of liquid or gas raw materials can be added after entering the third-stage tubular reactor to make the reaction more complete. It is necessary to ensure that the materials from the outlet of the third-stage tubular reactor fully meet the technical indicators of the product. During the trial production process, samples can be taken from the sampling ports of the tubular reactor for analysis so as to adjust the production process parameters at any time. After optimizing all the process parameters, qualified products can be produced according to the process parameters. The reaction of the materials coming out of the third-stage outlet has been completed, the process risk has been greatly reduced, and it can enter the next process or post-processing process.

[0042] The technical solution of the present invention has at least the following beneficial technical effects:

[0043] 1. The multi-stage continuous reactor used in the method of the present invention can realize stable control of the reaction temperature by arranging a jacket and a hollow stirring shaft; by arranging a stirring shaft, it can realize forward propulsion of materials, so that gas-solid heterogeneous continuous reaction can be achieved; by arranging a pipeline mill, the outer wall of the crystal can be broken, so that the reaction is more complete, more thorough, and the yield is higher.

[0044] 2. The method of the present invention can not only produce 2,4-D ammonium salt by continuous ammoniation of 2,4-D acid, but also does not require the addition of organic solvents during the production process, is not prone to scaling, is simple to operate, and is suitable for automated and intelligent large-scale industrial production.

[0045] 3. The multi-stage continuous reaction device of the present invention realizes stable control of reaction temperature by setting a jacket and a hollow stirring shaft; by setting a stirrer, it can realize forward conveying of materials, so that the heterogeneous phase participating in the solid can react smoothly and continuously; by setting a pipeline mill, it can realize the crushing of the outer wall of the crystal, so that the reaction is more complete and thorough, and the yield is higher. Automatic control can be realized by setting a star-shaped discharge valve, a flow meter, a temperature sensor and a pressure sensor.

[0046] 4. The present invention can be used not only for gas-solid phase reactions, but also for liquid-solid phase reactions. It can reduce the danger of dangerous chemical reaction units such as alkylation, nitration, hydrogenation, reduction and other dangerous chemical reactions, has large production capacity, low equipment investment, and is more suitable for remote automated intelligent control, which will play an immeasurable value for future chemical industry production. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the tubular reactor structure for this application

[0048] Figure 2 Schematic diagram of the multi-stage series tubular reactor structure of this application

[0049] Figure numerals: primary tubular reactor a, secondary tubular reactor b, tertiary tubular reactor c, stirring shaft 1, propeller blade 101, cylinder 2, cylinder head converter 3, jacket 4, pipeline mill 5, motor 6, reducer 7, temperature sensor 8, pressure sensor 9, solid raw material inlet 10, liquid or gas raw material inlet 11, catalyst addition port 12, star-shaped discharge valve 13, flow meter 14, tubular reactor discharge port 15, sampling port 16, stirring shaft cooling water inlet 17, stirring shaft cooling water outlet 18, tubular reactor cooling water inlet 19, tubular reactor cooling water outlet 20, pressure gauge interface 21, thermometer interface 22. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0051] Example 1

[0052] Open the jacket and the cooling water of the stirring shaft, add ammonia, 2,4-D acid (98%) and 10% ammonia solution into the tubular reactor at the same time, the addition rate of 2,4-D acid is 1105g / min, the ammonia rate of the first-stage tubular reactor is 68g / min, the ammonia rate of the second-stage tubular reactor is 13.6g / min, and the ammonia rate of the third-stage tubular reactor is 3.4g / min; the addition rate of 10% ammonia solution solvent is 55g / min, and it is added from the catalyst port of the first-stage pipeline reactor. The mixed material is continuously transported to the tubular reactor through the agitator, and the temperature is controlled at 40-50℃ and the pressure is 0.1-0.2MPa. It stays in each tubular reactor for 30min, and the material from the outlet of the third-stage reactor enters the receiving mixer to extract the remaining ammonia under negative pressure and enters the tail gas absorption tower for absorption. The absorption liquid can be used as a catalyst. Sample drying analysis shows that the content of 2,4-D ammonium salt is 95.6%, and the yield of 2,4-D acid is 94.8%.

[0053] Example 2

[0054] Open the jacket and the cooling water of the stirring shaft, add ammonia, 2,4-D acid (98%) and 10% ammonia solution into the tubular reactor at the same time, the addition rate of 2,4-D acid is 1105g / min, the ammonia rate of the first-stage tubular reactor is 74.8g / min, the ammonia rate of the second-stage tubular reactor is 14.96g / min, and the ammonia rate of the third-stage tubular reactor is 3.74g / min; the addition rate of 10% ammonia solution solvent is 55g / min, and it is added from the catalyst port of the first-stage pipeline reactor. The mixed material is continuously transported to the tubular reactor through the agitator, and the temperature is controlled at 40-50℃ and the pressure is 0.1-0.2MPa. It stays in each tubular reactor for 30min, and the material from the outlet of the third-stage reactor enters the receiving mixer to extract the remaining ammonia under negative pressure and enters the tail gas absorption tower for absorption. The absorption liquid can be used as a catalyst. Sample drying analysis shows that the content of 2,4-D ammonium salt is 98.6%, and the yield of 2,4-D acid is 98.3%.

[0055] Example 3

[0056] Open the jacket and the cooling water of the stirring shaft, add ammonia, 2,4-D acid (98%) and 10% ammonia solution into the tubular reactor at the same time, the addition rate of 2,4-D acid is 1105g / min, the ammonia rate of the first-stage tubular reactor is 71.4g / min, the ammonia rate of the second-stage tubular reactor is 14.28g / min, and the ammonia rate of the third-stage tubular reactor is 3.57g / min; the addition rate of 10% ammonia solution solvent is 55g / min, and it is added from the catalyst port of the first-stage pipeline reactor. The mixed material is continuously transported to the tubular reactor through the agitator, and the temperature is controlled at 40-50℃ and the pressure is 0.1-0.2MPa. It stays in each tubular reactor for 30min, and the material from the outlet of the third-stage reactor enters the receiving mixer to extract the remaining ammonia under negative pressure and enters the tail gas absorption tower for absorption. The absorption liquid can be used as a catalyst. Sample drying analysis shows that the content of 2,4-D ammonium salt is 97.5%, and the yield of 2,4-D acid is 97.3%.

[0057] Example 4

[0058] Open the jacket and the cooling water of the stirring shaft, add ammonia, 2,4-D acid (98%) and 10% ammonia solution into the tubular reactor at the same time, the addition rate of 2,4-D acid is 1105g / min, the ammonia rate of the first-stage tubular reactor is 81.6g / min, the ammonia rate of the second-stage tubular reactor is 16.32g / min, and the ammonia rate of the third-stage tubular reactor is 4.08g / min; the addition rate of 10% ammonia solution solvent is 55g / min, and it is added from the catalyst port of the first-stage pipeline reactor. The mixed material is continuously transported to the tubular reactor through the agitator, and the temperature is controlled at 40-50℃ and the pressure is 0.1-0.2MPa. It stays in each tubular reactor for 30min, and the material from the outlet of the third-stage reactor enters the receiving mixer to extract the remaining ammonia under negative pressure and enters the tail gas absorption tower for absorption. The absorption liquid can be used as a catalyst. Sample drying analysis shows that the content of 2,4-D ammonium salt is 98.7%, and the yield of 2,4-D acid is 98.5%.

[0059] Comparative Example 1

[0060] The pipeline mill was dismantled and the feed reaction was carried out according to Example 2. The sample was taken from the third-level sampling port and dried for analysis. The 2,4-D ammonium salt content was 89.2%, and the recovery rate of 2,4-D acid was 90.5%. It can be seen that the pipeline mill has a very good effect on the destruction of the crystal wall.

[0061] Comparative Example 2

[0062] A 1000mL four-necked flask was fixed on a stirrer, 242.8g of 2,4-D acid (98%) and 650g of water were added, 17.85g of ammonia gas was introduced under the condition of cooling water while controlling the temperature below 40 degrees, stirring was continued for 30min after the ammonia gas was introduced, cooled to -5°C for crystallization, filtered and dried to obtain 165.01g of product with a content of 98.8% and a yield of 68.5% based on 2,4-D acid.

[0063] Comparative Example 3

[0064] A 500mL four-necked flask was fixed on a stirrer, and 350g of the centrifuged mother liquor after the reaction of Comparative Example 2 was added, and 121.4g of 2,4-D acid (98%) was added. In the presence of cooling water, 8.93g of ammonia gas was introduced at a temperature below 40 degrees. After the ammonia gas was introduced, stirring was continued for 30min. The mixture was cooled to -5°C for crystallization, filtered and dried to obtain 116.94g of the product with a content of 98.4% and a yield of 96.7% based on 2,4-D acid.

Claims

1. A method for solvent-free continuous production of 2,4-D ammonium salt, comprising the following steps: (1) introducing 2,4-D acid, ammonia and a catalyst into a primary tubular reactor for reaction to obtain a primary reaction material; (2) grinding the primary reaction material in step (1) through a pipeline mill and feeding it into a secondary tubular reactor while adding ammonia gas for reaction to obtain a secondary reaction material; (3) grinding the secondary reaction material in step (2) through a pipeline mill and feeding it into a tertiary tubular reactor while adding ammonia gas for reaction to obtain a tertiary reaction material; (4) Collect the tertiary reaction material of step (3) through the outlet material to obtain 2,4-D ammonium salt.

2. The method according to claim 1, characterized in that The catalyst in step (1) is an aqueous solution of an aminating agent with a mass concentration of 5% to 15%.

3. The method according to claim 1, characterized in that The amount of ammonia introduced in step (1) is 100-150 g / min, the amount of 2,4-D acid introduced is 1300-2000 g / min, and the amount of catalyst introduced is 65-100 mL / min.

4. The method according to claim 1, characterized in that The reaction temperature in steps (1)-(3) is 30-50° C., the reaction pressure is 0.1-0.2 MPa, and the reaction time is 20-40 min.

5. The method according to claim 1, characterized in that The distribution ratio of the ammonia in the three reactors is 20:4:

1.

6. The method according to any one of claims 1 to 5, characterized in that The ammonia in step (1) may also be isopropylamine.

7. The method according to any one of claims 1 to 5, characterized in that The grinding fineness of the pipeline mill is 200-400 mesh.

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