Glyphosate preparation process by glycine method and application thereof

Abstract

The invention relates to the technical field of glyphosate preparation, in particular to a glyphosate preparation process by a glycine method and application of the glyphosate preparation process, and the glyphosate preparation process at least comprises the following steps: carrying out dealcoholization, deacidification, crystallization, centrifugation and drying on glyphosate acidified liquid to obtain glyphosate; the crystallization step comprises the following steps: S1, transferring deacidification liquid obtained after the deacidification step to a crystallization kettle, stirring materials in the crystallization kettle, and cooling to 60-70 DEG C; s2, keeping the temperature of the material constant at 60-70 DEG C, and dropwise adding liquid caustic soda into the crystallization kettle; and S3, after the dropwise addition of the liquid caustic soda is completed, continuously stirring and cooling to 25-30 DEG C, and carrying out heat preservation to complete the crystallization step. The novel process for preparing glyphosate by using the glycine method can solve the problem that the yield and quality of a glyphosate product are affected due to incomplete deacidification in a deacidification process in a conventional process, the content of the obtained glyphosate is greater than 96%, and the yield is greater than 76%.

Description

TECHNICAL FIELD

[0001] The present application relates to the glyphosate preparation technical field, specifically to a glycine method glyphosate preparation process and application thereof. BACKGROUND

[0002] There are two main industrial production methods of glyphosate: IDA method (iminodiacetic acid method) and glycine method. The main steps of the glycine method are synthesis, hydrolysis, crystallization and solid-liquid separation. Specifically, methanol, paraformaldehyde and triethylamine are subjected to depolymerization reaction, then glycine is added for addition reaction, then dimethyl phosphite is added for condensation reaction to obtain a synthesis solution, and finally, through hydrolysis, crystallization and solid-liquid separation, glyphosate is obtained. At present, through the exploration of the synthesis reaction mechanism and the continuous optimization of the process parameters, the glyphosate yield is generally more than 78% based on glycine, the technical material yield is more than 82%, and the glyphosate content is more than 95%.

[0003] In the preparation process of glyphosate, the negative pressure rectification in the deacidification process removes hydrochloric acid, chloromethane, methanol, water and a small amount of triethylamine hydrochloride. This process is crucial to improve the yield and purity of glyphosate. If deacidification is not effective, the pH value of the system will be unstable, which will affect the production efficiency and product quality of glyphosate.

[0004] The deacidification effect is related to the vacuum degree and deacidification time. In order to ensure the deacidification effect, an appropriate amount of alkali is added into the deacidification kettle after deacidification to neutralize the residual acidic substances in the system, so as to ensure that the pH value of the system returns to the appropriate range, and then the subsequent crystallization, drying and other processes are carried out. For example, the Chinese invention patent CN101704840B provides a crystallization method for continuous de-solvent production of glyphosate by glycine method. In this method, liquid alkali and water at room temperature are added into the deacidification kettle at one time under high temperature conditions (115-117℃), then the temperature is not lowered, and the material is directly discharged to the crystallization kettle for slow cooling and crystallization. In this patent process, the crystallization liquid which has been cooled is poured into the crystallization kettle and then heated. This process consumes a large amount of energy, and the liquid alkali and water are added at one time, which may cause incomplete acid-base reaction. The alkali and water are added at a high temperature of 115-117℃, and the crystallization kettle is generally made of enamel / glass lining material. The sudden cooling may cause the enamel to crack, which may damage the equipment and increase the workload of replacing and repairing the kettle body. SUMMARY

[0005] In order to solve the problems in the prior art, the first aspect of the present application provides a glycine method glyphosate preparation process, which at least comprises the following steps: glyphosate acidification liquid is subjected to de-alcoholization, de-acidification, crystallization, centrifugation and drying to obtain glyphosate. The crystallization step comprises: S1, the deacidification step after the end of the deacidification liquid to the crystallization kettle, and the material in the crystallization kettle is stirred and cooled to 60-70℃; S2, the material temperature is kept at 60-70℃ unchanged, and liquid alkali is added into the crystallization kettle; S3, after the completion of liquid alkali drop, continue to stir and cool to 25-30℃, and keep the crystallization step.

[0006] In an embodiment, the preparation method of glyphosate acidification liquid comprises depolymerization, synthesis, acidification steps.

[0007] In an embodiment, the depolymerization step comprises: adding methanol, paraformaldehyde and triethylamine into the depolymerization kettle in turn, and keeping the temperature at 50-60℃ for 60-80min to obtain depolymerization liquid.

[0008] In an embodiment, the mass ratio of methanol, paraformaldehyde and triethylamine is (8.5-9):10:1.

[0009] In an embodiment, the synthesis step comprises: adding methanol, triethylamine, depolymerization liquid into the synthesis kettle, mixing, then dropping glycine for addition reaction at 40-50℃, keeping for 50-60min, then dropping dimethyl phosphite for condensation reaction, cooling to 30-40℃ after the completion of condensation reaction to obtain synthesis liquid.

[0010] In an embodiment, the mass ratio of methanol, triethylamine, depolymerization liquid, glycine and dimethyl phosphite in the synthesis step is (3.5-5):(1.1-1.2):(1.5-1.6):1:(1.6-1.7).

[0011] In an embodiment, the acidification step comprises: continuously adding the synthesis liquid and hydrochloric acid into the acidification kettle, and controlling the temperature at 40-50℃ to obtain acidification liquid.

[0012] In an embodiment, the mass ratio of synthesis liquid and hydrochloric acid is (1.6-1.7):1.

[0013] In an embodiment, the de-alcoholization step comprises: gradually heating the acidification liquid to 95-105℃ through preheating to remove methanol, methylal and chloromethane, and finally heating to 115-120℃ to complete the de-alcoholization.

[0014] In an embodiment, the de-alcoholization step comprises: preheating the acidification liquid to 40-50℃, then adding into the de-alcoholization kettle to complete the de-alcoholization step through four-stage heating.

[0015] In an embodiment, the four-stage heating is specifically: The first stage: after the feeding is completed, the temperature is uniformly increased to 65-70℃ at a rate of 1-1.5℃ / min, and then the temperature is kept for 20-30min; The second stage: the temperature is uniformly increased to 80-85℃ at a rate of 0.5-1℃ / min, and then the temperature is kept for 30-40min; The third stage: the temperature is uniformly increased to 95-105℃ at a rate of 0.5-1℃ / min, and then the temperature is kept for 20-30min; The fourth stage: after the temperature keeping is completed, the temperature is concentratedly increased to 115-120℃ at a rate of 0.5-1℃, which is the temperature end point of dealcoholization, and then the material is discharged to the deacidification kettle.

[0016] In an embodiment, the dealcoholization feeding amount is 8-9m 3 , and the total temperature increasing time is 2-3h.

[0017] In an embodiment, the deacidification step comprises: after the dealcoholization, the material enters the deacidification kettle, 0.1-0.2m 3 of washing water is added to flush the dealcoholization kettle, the flushing water is directly discharged into the deacidification kettle, and the temperature is increased to 115-125℃ under vacuum to complete the deacidification.

[0018] In an embodiment, the temperature decreasing in the S1 step is uniformly decreasing the material from 115-125℃ to 60-70℃, and the temperature decreasing time is 1.5-3h.

[0019] In an embodiment, the temperature decreasing in the S1 step is uniformly decreasing the material from 120℃ to 60℃, and the temperature decreasing time is 124min.

[0020] In an embodiment, the dropwise adding amount of the liquid alkali is 0.8-1.2m 3 . For example, the dropwise adding amount of the liquid alkali is 0.8m 3 , 1m 3 , or 1.2m 3 .

[0021] In an embodiment, the dropwise adding time of the liquid alkali in the S2 step is 1-3h. For example, the dropwise adding time of the liquid alkali is 58min, 60min, 62min, 120min, or 125min.

[0022] In an embodiment, the liquid alkali is sodium hydroxide aqueous solution.

[0023] In an embodiment, the mass percentage concentration of the liquid alkali is 30-35%. For example, the mass percentage concentration of the liquid alkali is 30%, 32%, or 35%.

[0024] In an embodiment, the temperature decreasing time in the S3 step is 3-4.5h. For example, the temperature decreasing time is 219min, 228min, or 234min.

[0025] In one embodiment, the heat preservation time in step S3 is 120-150 minutes. Examples include 120 minutes, 123 minutes, and 149 minutes.

[0026] In one embodiment, step S1 includes: transferring the deacidified liquid obtained after the deacidification step to a crystallization vessel, while adding washing water to rinse the deacidification vessel, and directly discharging the rinsing water into the crystallization vessel; and stirring the material in the crystallization vessel and cooling it to 60-70°C.

[0027] In one embodiment, the amount of washing water added in step S1 is 0.1-0.2 mg / L. 3 .

[0028] In one embodiment, the temperature of the washing water is 50-70°C.

[0029] In one embodiment, the crystallizer is rinsed with washing water after discharge, and the amount of water added is 0.2 m³. 3 After the crystallizer discharges material, wash water is added to rinse the crystallizer and pipelines to prevent material from accumulating and clogging the pipelines.

[0030] In this invention, after the crystallization step is completed, the material is centrifuged. The upper liquid is the mother liquor, and the lower layer is wet glyphosate solid material. The wet glyphosate solid material is dried to obtain the glyphosate product.

[0031] The second aspect of this invention provides the application of a glycine-based glyphosate preparation process in the preparation of pesticide formulations.

[0032] Beneficial effects 1. This invention provides a novel process for preparing glyphosate using the glycine method, which solves the problem of incomplete deacidification in conventional processes, affecting the yield and quality of glyphosate products. This process adjusts the alkali addition step after deacidification. After deacidification, the deacidified material is discharged into a crystallization kettle, where liquid alkali is added dropwise under stirring, controlling the reaction temperature and dropping rate. The resulting glyphosate has a content >96% and a yield >76%.

[0033] 2. This invention eliminates the need for one-time alkali addition in the deacidification kettle, reduces the damage to the equipment caused by high-temperature alkali addition, completely solves the problem of high-temperature corrosion in the deacidification kettle, extends the equipment life, and reduces maintenance workload.

[0034] 3. The glycine-based glyphosate preparation process provided by this invention reduces the total processing time in the crystallization vessel from 11 hours in the conventional process to about 9 hours, significantly improving production efficiency.

[0035] 4. In this invention, the material in the crystallization vessel is cooled to 60-70℃ and alkali is added dropwise. The acid-base neutralization system has a mild reaction, which reduces the risk of a one-time alkali addition reaction at high temperature and avoids the production of by-products. Attached Figure Description

[0036] Figure 1 This is a flow chart of the glycine-based glyphosate preparation process.

[0037] Figures 2-9 The images show the appearance of the materials after samples were taken and left to stand following the crystallization endpoint in Examples 1-3 and Comparative Examples 1-5, respectively. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0039] The methanol (99.5%), paraformaldehyde (96%), triethylamine (99.7%), glycine (98%), and dimethyl phosphite (98%) used in the following examples and comparative examples are all industrial-grade finished products.

[0040] Example 1 The first aspect of this example provides a glycine-based glyphosate preparation process, which includes the following steps: glyphosate acidification solution is subjected to de-alcoholization, deacidification, crystallization, centrifugation, and drying to obtain glyphosate.

[0041] The preparation method of the glyphosate acidified solution includes depolymerization, synthesis, and acidification steps.

[0042] The depolymerization step includes: adding methanol, paraformaldehyde and triethylamine in a mass ratio of 8.8:10:1 to the depolymerization vessel in sequence, and heating to 50°C and holding at that temperature for 60 minutes to obtain a depolymerization solution.

[0043] The synthesis steps include: adding methanol, triethylamine, and depolymerization solution to a synthesis reactor, mixing, cooling to 40°C, adding glycine for an addition reaction, maintaining the temperature for 50 minutes, adding dimethyl phosphite dropwise for a condensation reaction, and cooling to 30°C after the condensation reaction is completed to obtain the synthesis solution.

[0044] In the synthesis step, the mass ratio of methanol, triethylamine, depolymerization solution, glycine, and dimethyl phosphite is 4:1.1:1.5:1:1.6.

[0045] The acidification step includes: continuously feeding the synthesis solution and hydrochloric acid into an acidification reactor, controlling the temperature at 40-50℃, to obtain an acidified solution.

[0046] The mass ratio of the synthesis solution to hydrochloric acid is 1.6:1.

[0047] The de-alcoholization step includes: preheating the acidified liquid to 50°C and then adding it to the de-alcoholization kettle, and completing the de-alcoholization step through four stages of heating.

[0048] The four stages of temperature increase are as follows: First stage: After feeding is completed, heat the material at a rate of 1.5℃ / min to 70℃, and then keep it at that temperature for 25 minutes. Second stage: Heat to 82℃ at a constant rate of 1℃ / min, and then hold for 35 minutes; Third stage: Continue to heat to 100℃ at a constant rate of 1℃ / min, and then hold for 25min; In the fourth stage, after the heat preservation is completed, the temperature is concentrated at a rate of 0.7℃ to 117℃, which is the temperature endpoint for de-alcoholization, and then the material is discharged to the deacidification kettle.

[0049] The de-alcoholization feed rate is 8.4 m³. 3 The total heating time is 2.5 hours.

[0050] The deacidification step includes: the de-alcoholized material enters the deacidification kettle, and 0.2m is added simultaneously. 3 The washing water is used to rinse the alcohol removal vessel, and the rinsing water is directly discharged into the deacidification vessel. The deacidification is completed by heating to 120°C under vacuum conditions.

[0051] The crystallization step includes: S1. Transfer the deacidified solution obtained after the deacidification step to the crystallization vessel, and add 0.2m... 3 The washing water is used to rinse the deacidification vessel, and the rinsing water is directly discharged into the crystallization vessel; the material in the crystallization vessel is stirred and cooled to 60°C; S2. Maintaining the material temperature at 60℃, add 1m of solution dropwise into the crystallization vessel. 3 A 32% (w / w) liquid alkali was added over a time of 62 minutes. S3. After the liquid alkali is added dropwise, continue stirring and cool down to 30°C. Keep warm for 120 minutes to complete the crystallization step.

[0052] The cooling process in step S1 involves uniformly cooling the material from 120°C to 60°C over a period of 166 minutes.

[0053] The cooling time in step S3 is 234 minutes.

[0054] The temperature of the washing water is 60°C.

[0055] The liquid alkali is an aqueous solution of sodium hydroxide with a mass percentage concentration of 32%.

[0056] After the material is discharged from the crystallization vessel, it is rinsed with washing water at a volume of 0.2 m³. 3 .

[0057] The second aspect of this example provides an application of the glycine-based glyphosate preparation process in the preparation of pesticide formulations.

[0058] Figure 2 This is a picture of the material after the crystallization endpoint was reached and the sample was allowed to stand. As can be seen from the picture, there are a small amount of glyphosate particles in the upper mother liquor. Most of the glyphosate has formed into sedimentable solid crystals. Only a very small amount of fine crystals are temporarily suspended in the upper mother liquor due to the slow settling rate. This is a normal residual state after crystallization.

[0059] Example 2 The specific implementation method in this example is the same as in Example 1, except that the crystallization step includes: S1. Transfer the deacidified solution obtained after the deacidification step to the crystallization vessel, and add 0.2m... 3 The washing water is used to rinse the deacidification vessel, and the rinsing water is directly discharged into the crystallization vessel; the material in the crystallization vessel is stirred and cooled to 70°C; S2. Maintaining the material temperature at 70℃, add 1m dropwise into the crystallization vessel. 3 A 32% (w / w) liquid alkali was added over a time of 125 minutes. S3. After the liquid alkali is added dropwise, continue stirring and cool down to 30°C. Keep warm for 123 minutes to complete the crystallization step.

[0060] The cooling process in step S1 involves uniformly cooling the material from 120°C to 70°C over a period of 132 minutes.

[0061] The cooling time in step S3 is 219 minutes.

[0062] Figure 3 This is a picture of the appearance of the material after the crystallization endpoint was reached and the sample was left to stand. It can be seen from the picture that the upper mother liquor is slightly turbid and contains a small amount of flocculent matter.

[0063] Example 3 The specific implementation method in this example is the same as in Example 1, except that the crystallization step includes: S1. Transfer the deacidified solution obtained after the deacidification step to the crystallization vessel, and add 0.2m... 3 The washing water is used to rinse the deacidification vessel, and the rinsing water is directly discharged into the crystallization vessel; the material in the crystallization vessel is stirred and cooled to 70°C; S2. Maintaining the material temperature at 70℃, add 1m dropwise into the crystallization vessel.3 A 32% (w / w) liquid alkali was added over a time of 58 minutes. S3. After the liquid alkali is added dropwise, continue stirring and cool down to 30°C. Keep warm for 149 minutes to complete the crystallization step.

[0064] The cooling process in step S1 involves uniformly cooling the material from 120°C to 70°C over a period of 124 minutes.

[0065] The cooling time in step S3 is 228 minutes.

[0066] Figure 1 This is a flow chart of the glycine-based glyphosate preparation process.

[0067] Figure 4 This is a picture of the material after it has been sampled and left to stand after the crystallization endpoint. As can be seen from the picture, the stratification is normal and the upper layer of mother liquor is clear.

[0068] Comparative Example 1 This example uses a conventional process to prepare glyphosate. The glyphosate acidification solution is de-alcoholized and then sent to a deacidification reactor for deacidification. After the deacidification temperature reaches 120℃, 0.5 mg of glyphosate solution is added at once. 3 A 32% (w / w) liquid alkali solution was stirred and then poured into a crystallization vessel, with 0.2 mg / L added. 3 The material is rinsed with water, cooled to 35°C, and then naturally kept warm before being discharged for centrifugation and drying to obtain glyphosate. The entire crystallization process takes 11 hours.

[0069] In this example, the preparation method and de-alcoholization steps of the glyphosate acidified solution are the same as in Example 1.

[0070] Figure 5 This is a picture of the material after the crystallization endpoint was reached and the sample was left to stand. It can be seen from the picture that there is obvious stratification, and the glyphosate particles precipitated in the lower layer are slightly coarser than those in the example.

[0071] Comparative Example 2 The specific implementation method in this example is the same as that in Comparative Example 1, except that liquid alkali is not added in this example.

[0072] Figure 6 The image shows the appearance of the material sampled and left to stand after the crystallization endpoint in this case. It can be seen from the image that there is no obvious stratification, little crystal precipitation, or no crystal formation. After centrifugation for several hours, it is in a viscous / paste-like suspension state, and the washing mother liquor is turbid. It is inferred that a large amount of glyphosate remains in the mother liquor, and clumping occurs during drying.

[0073] Comparative Example 3 The specific implementation method in this example is the same as in Example 2, except that after S1 in the crystallization step, 1m 3 A 32% (w / w) liquid alkali solution was added to the crystallization vessel in one go.

[0074] Figure 7 This is a picture of the material after the crystallization endpoint was reached and the sample was left to stand. As can be seen from the picture, the upper mother liquor is turbid and the stratification is not obvious, making the subsequent centrifugation process difficult.

[0075] Comparative Example 4 The specific implementation method in this example is the same as in Example 3, except that... S1. Transfer the deacidified solution obtained after the deacidification step to the crystallization vessel, and add 0.2m... 3 The washing water is used to rinse the deacidification vessel, and the rinsing water is directly discharged into the crystallization vessel; the material in the crystallization vessel is stirred and cooled to 40°C; S2. Maintaining the material temperature at 40℃, add 1m dropwise into the crystallization vessel. 3 A 32% (w / w) liquid alkali is added over a time of 60 minutes. Figure 8 This is an image of the material after it was sampled and left to stand after the crystallization endpoint in this example. As can be seen from the image, the stratification is not obvious when the sample is still, and the crystals precipitated at the bottom are suspended. The crystals are few and appear milky white.

[0076] Comparative Example 5 The specific implementation method in this example is the same as in Example 3, except that... S1. Transfer the deacidified solution obtained after the deacidification step to the crystallization vessel, and add 0.2m... 3 The washing water is used to rinse the deacidification vessel, and the rinsing water is directly discharged into the crystallization vessel; the material in the crystallization vessel is stirred and cooled to 80°C; S2. Maintaining the material temperature at 80℃, add 1m dropwise into the crystallization vessel. 3 A 32% (w / w) liquid alkali was added over a period of 60 minutes. Figure 9 This is a picture of the material after it was sampled and left to stand after the crystallization endpoint in this example. It can be seen from the picture that the stratification is obvious when it is still, but the cooling time in the later stage is long, the overall production cycle is long, and the energy consumption is high.

[0077] Performance testing Samples from each embodiment and comparative example were taken and analyzed to determine the glyphosate product content (dry solids content) and the glyphosate content (wet solids content) and chloride ion content in the mother liquor and wet glyphosate solids, respectively. The test results are shown in Table 1.

[0078] Table 1

[0079] As shown in Table 1, the glyphosate content (dry solid content) of Examples 1-3 of this application is all >96%, and the yield is >76%. Furthermore, the total processing time in the crystallization vessel is significantly shorter than that of the conventional process in Comparative Example 1, thus improving production efficiency. In Comparative Example 2, the glyphosate content in the mother liquor is still very high, indicating a large loss of product. After drying, the solid material forms hard lumps with a yellowish color and many impurities, resulting in an extremely low overall yield. Although Comparative Example 5 has a higher glyphosate content and yield, its later cooling time is long, resulting in a long overall production cycle and high energy consumption.

Claims

1. A glycine-based process for preparing glyphosate, characterized in that, The process includes at least the following steps: glyphosate is obtained by de-alcoholizing, deacidifying, crystallizing, centrifuging, and drying the glyphosate acidified solution; The crystallization step includes: S1. Transfer the deacidified liquid obtained after the deacidification step to the crystallization kettle, stir the material in the crystallization kettle and cool it to 60-70℃; S2. Keep the material temperature constant at 60-70℃ and add liquid alkali dropwise into the crystallization kettle; S3. After the liquid alkali is added dropwise, continue stirring and cool down to 25-30℃, then keep warm to complete the crystallization step.

2. The glyphosate preparation process using the glycine method according to claim 1, characterized in that, The cooling process in step S1 involves uniformly cooling the material from 115-125℃ to 60-70℃ over a period of 1.5-3 hours.

3. The glycine-based glyphosate preparation process according to claim 1, characterized in that, The liquid alkali is added in step S2 over a period of 1-3 hours.

4. The glycine-based glyphosate preparation process according to claim 3, characterized in that, The amount of liquid alkali added is 0.8-1.2 ml. 3 .

5. The glycine-based glyphosate preparation process according to claim 3, characterized in that, The mass percentage concentration of the liquid alkali is 30-35%.

6. The glycine-based glyphosate preparation process according to claim 1, characterized in that, The cooling time in step S3 is 3-4.5 hours.

7. The glyphosate preparation process using the glycine method according to claim 1, characterized in that, The heat preservation time in step S3 is 120-150 minutes.

8. The glycine-based glyphosate preparation process according to claim 1, characterized in that, Step S1 includes: transferring the deacidified liquid obtained after the deacidification step to the crystallization vessel, adding washing water to rinse the deacidification vessel, and directly discharging the rinsing water into the crystallization vessel; and stirring the material in the crystallization vessel and cooling it to 60-70℃.

9. The glycine-based glyphosate preparation process according to claim 8, characterized in that, The amount of washing water added in step S1 is 0.1-0.2 mg / L. 3 .

10. The application of the glycine-based glyphosate preparation process according to any one of claims 1-9 in the preparation of pesticide formulations.

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