Fully-continuous synthesis method of glyphosate

Abstract

To provide a fully-continuous synthesis method of glyphosate.SOLUTION: In the present invention, high-purity glyphosate is prepared by using a fully-continuous system in which a feed pump, a plurality of micromixers, a plurality of microchannel reactors, a dynamic rotary reactor, a buffer tank, a back pressure valve, a continuous reaction-kettle-type reactor, and a continuous crystallizer are sequentially connected, in which glycine is used as a raw material.EFFECT: According to the present invention, stable fully-continuous industrial production is achieved, no external intervention is required during the process, the efficiency of time and space is high, the number of operators and the labor intensity are greatly reduced, the production cost is greatly reduced, complicated operations in the conventional reaction-vessel process, a rapid rise of temperature in the kettle and the risk of material ejection are avoided, production safety is improved, the quality of glyphosate products is ensured, the operation of the apparatus is stable, the reaction time is short, the reaction yield is high, and the quality of the product is stable.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention belongs to the technical field of organic chemical synthesis, and specifically relates to a completely continuous method for the synthesis of glyphosate. [Background technology]

[0002] Glyphosate is a highly effective, low-toxicity, broad-spectrum, non-selective herbicide, making it one of the most valuable organophosphate pesticides ever discovered. Its broad spectrum, low toxicity, non-residue absorption, translocation, and excellent inertness allow it to rapidly enter the plant's transport system by dissolving the waxy layer on the surface of weed leaves, killing them. Glyphosate is the pesticide variety with the fastest growing demand and the world's largest pesticide active ingredient, accounting for 60% of the total herbicide market. Currently, glyphosate is synthesized primarily through the glycine method and the iminodiacetic acid method. The glycine method is the primary process used in China, using glycine, paraformaldehyde, and dimethyl phosphite as raw materials, reacting them under triethylamine conditions to obtain glyphosate. However, this method does not have a high yield (generally 75%-85%), produces many by-products, and is not highly pure. Because the entire production process uses reactor technology, the degree of continuity is not high and the efficiency is low. Furthermore, the production process requires complicated operations, and many steps require temperature and speed control, which imposes strict conditions and seriously affects the quality of glyphosate in each pitch, resulting in variations in the quality of the produced products, making it unsuitable for industrial production.

[0003] Previously reported documents and patents CN115232167A, CN116102592A, and CN116041388A reported the development of continuous hydrolysis processes for glyphosate, but were limited to the continuous hydrolysis of glyphosate-methyl. Patent CN104163832B reported a continuous reactor-type production process for glyphosate, but the degree of continuity was not high enough to meet large-scale industrial production, and no report was made on the continuous synthesis of paraformaldehyde to glyphosate-methyl. As a result, the shortcomings of the existing reactor-type process could not be avoided, which seriously affected the quality of glyphosate for each pitch, resulting in variations in the quality of the produced products and being disadvantageous for industrial production. Summary of the Invention

[0004] The objective of the present invention is to provide a fully continuous method for synthesizing glyphosate with high production efficiency, excellent product quality, and high consistency, in order to solve the problems of the conventional glyphosate reactor process, such as variable product quality, large amount of by-products, low purity, and complicated production operation.

[0005] The present invention provides a completely continuous method for synthesizing glyphosate using a completely continuous system consisting of a feed pump, multiple micromixers, a microchannel reactor, a dynamic rotating reactor, a buffer tank, a backpressure valve, a continuous kettle reactor, and a continuous crystallizer, all of which are connected in series. Specifically, the method comprises the following steps (1) to (3): Step (1): Paraformaldehyde and an alkali are dissolved or dispersed in a solvent to prepare a raw material solution. The two raw material solutions are thoroughly mixed in a micromixer 1 and then sent to a microchannel reactor 1 where they are depolymerized to obtain a depolymerized solution. Glycine is dissolved or dispersed in a solvent to prepare a feed solution. This feed solution and the depolymerized solution flowing out of the microchannel reactor 1 are thoroughly mixed in a micromixer 2 and then sent to the microchannel reactor 2 to undergo an addition reaction to produce N,N-dihydroxymethylglycine. The reaction solution is then sent to a small buffer tank and quantitatively discharged using a plunger pump. (2) The reaction liquid sent from the small buffer tank and dimethyl phosphite are thoroughly mixed in a micromixer 3, then sent to a microchannel reactor 4 where an esterification reaction occurs to produce glyphosate methyl ester. The temperature of the microchannel reactor 4 is raised to allow the reaction to proceed sufficiently, and the reaction liquid flows out and enters a backpressure valve 1, which adjusts the reaction pressure in the microchannel reactors 3 and 4. (3) The reaction liquid and acid flowing out of back-pressure valve 1 are sent to micromixer 4 and thoroughly mixed before being sent to microchannel reactor 5 for neutralization. The pH of the reaction liquid is adjusted from alkaline to acidic. The acidic reaction liquid is then sent directly to microchannel reactor 6 and heated to rapidly increase the temperature. After the temperature is increased, the reaction liquid is sent to back-pressure valve 2. Back-pressure valve 2 adjusts the pressure in microchannel reactors 5 and 6. The reaction liquid flowing out of back-pressure valve 2 is sent to reactor 1 for desolvation to remove solvent and low-boiling compounds. It is then continuously sent to reactor 2 for hydrolysis and subsequently sent to reactor 3 for complete hydrolysis. During the hydrolysis reaction, water in the reaction system continuously evaporates, increasing the internal temperature of the reaction liquid and accelerating the hydrolysis reaction. The reaction liquid in reactor 3 is then sent directly to a continuous crystallizer, where it is cooled and crystallized to obtain glyphosate solids. The glyphosate product is then filtered and dried to obtain a glyphosate product with a purity of more than 98% and a total yield of more than 85% in terms of glycine.

[0006] Preferably, in steps (1) and (3), the alkali is one or a combination of more of triethylamine, trimethylamine, tributylamine, and diethylamine, and the acid is one or a combination of more selected from 20% aqueous hydrogen chloride solution, 30% aqueous hydrogen chloride solution, 37% aqueous hydrogen chloride solution, hydrogen chloride methanol solution, 30% aqueous phosphoric acid solution, and 37% aqueous phosphoric acid solution.

[0007] Preferably, in step (1), in the process of preparing the raw material solution by dissolving or dispersing the paraformaldehyde and glycine in a solvent, the solvent is one or a combination of solvents selected from butanol, isobutanol, propanol, isopropanol, ethanol, methanol, acetone, butanone, and methyl isobutyl ketone.

[0008] Preferably, in steps (1), (2), and (3), the alkali, dimethyl phosphite, and acid are added without a solvent or a solution thereof is prepared in advance with a solvent, and the solvent is one or a combination of one or more selected from pentanol, butanol, isobutanol, propanol, isopropanol, ethanol, methanol, and acetone.

[0009] Preferably, in step (1), the amount of alkali used is 0.65-0.90 equivalents of glycine, the amount of paraformaldehyde used is 1.5-3.0 equivalents of glycine, and in step (2), the amount of dimethyl phosphite used is 1.0-1.2 equivalents of glycine, the amount of alkali used is 0.1-0.30 equivalents of glycine, and the amount of acid used is 1.0-8 equivalents of glycine.

[0010] Preferably, in steps (1), (2), and (3), the temperature of microchannel reactor 1 is 35-60°C, the reaction time is 3-9 min, the temperature of microchannel reactor 2 is 45-75°C, the reaction time is 8-12 min, the temperature of microchannel reactor 3 is 60-80°C, the reaction time is 3-8 min, the temperature of microchannel reactor 4 is 65-85°C, the reaction time is 7-15 min, and the temperature of microchannel reactor 5 is 5- The temperature of the microchannel reactor 6 is 95-180°C, the reaction time is 0.5-2.8 min, the temperature of the reactor 1 is 85-140°C, the reaction time is 6-40 min, the temperature of the reactor 2 is 90-150°C, the reaction time is 9-40 min, the temperature of the reactor 3 is 100-160°C, the reaction time is 12-40 min, and the temperature of the continuous crystallizer is 20-80°C, the residence time is 5-30 min.

[0011] Preferably, in steps (1), (2) and (3), the micro-mixer 1 and micro-mixer 2 are dynamic rotary mixers, with inlet and outlet sizes of 2.5mm-50mm, mixing chamber diameters of 5.0mm-400mm and heights of 5.0mm-80mm, the micro-mixer 3 and micro-mixer 4 are Z-shaped micro-mixers with plate-type structures, with inner diameters of 1.0-50mm and lengths of 2-100m, and the reactor is a plate-type or tubular microchannel structure, with inner diameters of 1.0-85mm and lengths of 20-10000m.

[0012] Preferably, in step (1), the dynamic continuous reactor is a horizontal or vertical multi-stage rotary stirring reactor with a heat exchange jacket, has a circular interior, an inner diameter of 20-500 mm, and a length of 1-50 m; in step (3), the reactors 1, 2, and 3 have diameters of 10-1000 mm and aspect ratios of 5:1-50:1; and in step (3), the continuous crystallizer has an inlet size of 1.0 mm-50 mm, an outlet size of 20-200 mm, an inner diameter of 1.0 mm-50 mm, and a length of 5-200 m.

[0013] Preferably, in step (2), the pressure of the back pressure valve is 2-10 bar, and in step (3), the pressure of the back pressure valve is 2-20 bar.

[0014] Preferably, in step (3), the solvent used during the crystallization is one or a combination of two or more selected from the group consisting of water, methanol, ethanol, and propanol.

[0015] Compared with the prior art, the present invention has the following advantages: (1) The micro-mixer significantly improves the mass transfer effect of multi-phase systems, accelerating the reaction rate while reducing the reactor volume. The microchannel reactor has excellent mass transfer, heat transfer, and continuous material mixing enhancement performance, effectively shortening the reaction time, improving reaction efficiency and the flow rate per unit volume of the reactor, improving reaction safety, and significantly reducing the three waste emissions (exhaust gas, wastewater, and solid waste) and energy consumption. The time required for glyphosate preparation is reduced from 5-10 hours in traditional batch reactors to 1-2 hours. (2) According to the present invention, stable and fully continuous industrial production of glyphosate from raw materials is realized, the process is continuous and highly automated, no external intervention is required during the process, and the efficiency of time and space is high, the number of workers and labor intensity are greatly reduced, and production costs are significantly reduced. (3) The present invention avoids the complicated operations, sudden rise in temperature inside the reactor, and the risk of material ejection that occur in the conventional reactor process, thereby improving production safety and ensuring the quality of glyphosate products. (4) The purity of the product was 98%, and the total yield was higher than 85% in terms of glycine. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a flow chart of the reaction process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be further described below with reference to examples and drawings, but the scope of protection of the present invention is not limited to the following examples.

[0018] Example 1 Paraformaldehyde (0.4 kg / L, 2.2 eq) was dispersed in methanol, and tributylamine (0.8 eq) was dispersed in methanol. The two feedstocks were pumped through micromixer 1 and thoroughly mixed. Then, in microchannel reactor 1, they were subjected to esterification and depolymerization at 50 °C for 5 min. The depolymerized solution was obtained. Glycine (0.5 kg / L, 1.1 eq) was dispersed in methanol to prepare a feed solution. This feed solution was pumped through micromixer 2 and thoroughly mixed with the depolymerized solution flowing out of microchannel reactor 1. The mixture was then sent to reactor 2, where it underwent an addition reaction at 60 °C for 8 min to produce N,N-dihydroxymethylglycine. The reaction solution was then pumped into a small buffer tank and quantitatively delivered by a plunger pump. The reaction liquid delivered from the small buffer tank and a methanol solution of dimethyl phosphite (0.2 kg / L, 1.1 eq) were pumped into micromixer 3 and mixed thoroughly, and then sent to microchannel reactor 3, where an esterification reaction was carried out at 65°C with a retention time of 5 minutes to produce glyphosate methyl ester. To allow the reaction to proceed sufficiently, the temperature of microchannel reactor 4 was raised to 70°C, and the reaction was completed with a retention time of 3 minutes to produce glyphosate methyl ester. After the reaction liquid flowed out, it entered backpressure valve 1 (7 bar), and the reaction pressure in microchannel reactors 3 and 4 was adjusted by backpressure valve 1. The reaction liquid flowing out from the back pressure valve 1 and the 30% hydrochloric acid solution are pumped into the micro mixer 4 and mixed thoroughly, then sent to the micro channel reactor 5, where a neutralization reaction is carried out at 10°C and a retention time of 1 minute. After that, the acidic reaction liquid is sent directly to the micro channel reactor 6, where it is rapidly heated. After the reaction liquid is heated to 85°C, it is sent to the back pressure valve 2 (4 bar). The pressure of the micro channel reactors 5 and 6 is controlled and adjusted by the back pressure valve 2, and the reaction liquid flowing out from the back pressure valve 2 is sent to the reaction vessel 1 to carry out desolvation. The resulting mixture was then heated at 90°C for 20 minutes to remove the solvent, low-boiling methanol, and by-product methyl chloride. The mixture was then continuously sent to reactor 2, where it was hydrolyzed at 105°C for 25 minutes, and then sent to reactor 3, where it was fully hydrolyzed at 120°C for 30 minutes. During the hydrolysis, water in the reaction system continuously evaporated, increasing the internal temperature of the reaction solution and accelerating the hydrolysis reaction rate. The reaction solution in reactor 3 was then directly transported to a continuous crystallizer, where it was cooled and crystallized to yield solid glyphosate. The glyphosate product was filtered and dried. The purity of the product was 97%, and the total yield, calculated as glycine, was 86%. The total reaction time was 59 minutes.

[0019] Example 2 Paraformaldehyde (0.5 kg / L, 2.5 eq) was dispersed in methanol, and tributylamine (0.9 eq) was dispersed in methanol. The two feedstocks were pumped through micromixer 1 and thoroughly mixed. Then, in microchannel reactor 1, they were subjected to esterification and depolymerization at 55°C for 6 min. The depolymerized solution was obtained. Glycine (0.6 kg / L, 1.0 eq) was dispersed in methanol to prepare a feed solution. This feed solution was pumped through micromixer 2 and thoroughly mixed with the depolymerized solution flowing out of microchannel reactor 1. The mixture was then sent to reactor 2, where it underwent an addition reaction at 55°C for 7 min to produce N,N-dihydroxymethylglycine. The reaction solution was then pumped into a small buffer tank and quantitatively delivered by a plunger pump. The reaction liquid delivered from the small buffer tank and a methanol solution of dimethyl phosphite (0.3 kg / L, 1.2 eq) were pumped into micromixer 3 and mixed thoroughly, and then sent to microchannel reactor 3, where an esterification reaction was carried out at 60°C with a retention time of 7 minutes to produce glyphosate methyl ester. To allow the reaction to proceed sufficiently, the temperature of microchannel reactor 4 was raised to 70°C, and the reaction was completed with a retention time of 4 minutes to produce glyphosate methyl ester. After the reaction liquid flowed out, it entered backpressure valve 1 (8 bar), and the reaction pressure in microchannel reactors 3 and 4 was adjusted by backpressure valve 1. The reaction liquid flowing out from the back pressure valve 1 and the 31.5% hydrochloric acid solution are pumped into the micro mixer 4 and mixed thoroughly, then sent to the micro channel reactor 5, where a neutralization reaction is carried out at 5°C and a retention time of 1.5 minutes. The acidic reaction liquid is then sent directly to the micro channel reactor 6, where it is rapidly heated. After the reaction liquid is heated to 90°C, it is sent to the back pressure valve 2 (5 bar). The pressure of the micro channel reactors 5 and 6 is controlled and adjusted by the back pressure valve 2, and the reaction liquid flowing out from the back pressure valve 2 is sent to the reactor 1 to carry out desolvation. The resulting mixture was then heated at 100°C for 22 minutes to remove the solvent, low-boiling methanol, and by-product methyl chloride. The mixture was then continuously sent to reactor 2, where it was hydrolyzed at 110°C for 27 minutes, and then sent to reactor 3, where it was fully hydrolyzed at 125°C for 33 minutes. During the hydrolysis, water in the reaction system continuously evaporated, increasing the internal temperature of the reaction solution and accelerating the hydrolysis reaction rate. The reaction solution in reactor 3 was then directly transported to a continuous crystallizer, where it was cooled and crystallized to obtain solid glyphosate. The glyphosate product was filtered and dried. The purity of the product was 98%, and the total yield, calculated as glycine, was 85.5%. The total reaction time was 74.5 minutes.

[0020] Example 3 Paraformaldehyde (0.1 kg / L, 2.0 eq) was dispersed in methanol, and triethylamine (0.8 eq) was dispersed in methanol. The two feedstocks were pumped through micromixer 1 and thoroughly mixed. Then, in microchannel reactor 1, they were subjected to esterification and depolymerization at 50 °C for 5 min. The depolymerized solution was obtained. Glycine (0.7 kg / L, 1.0 eq) was dispersed in methanol to prepare a feed solution. This feed solution was pumped through micromixer 2 and thoroughly mixed with the depolymerized solution flowing out of microchannel reactor 1. The mixture was then sent to reactor 2, where it underwent an addition reaction at 50 °C for 5 min to produce N,N-dihydroxymethylglycine. The reaction solution was then pumped into a small buffer tank and quantitatively delivered by a plunger pump. The reaction liquid delivered from the small buffer tank and a methanol solution of dimethyl phosphite (0.3 kg / L, 1.4 eq) were pumped into micromixer 3 and mixed thoroughly, and then sent to microchannel reactor 3, where an esterification reaction was carried out at 70°C with a retention time of 4 minutes to produce glyphosate methyl ester. To allow the reaction to proceed sufficiently, the temperature of microchannel reactor 4 was raised to 75°C, and the reaction was completed with a retention time of 2.5 minutes to produce glyphosate methyl ester. After the reaction liquid flowed out, it entered backpressure valve 1 (4 bar), and the reaction pressure in microchannel reactors 3 and 4 was adjusted by backpressure valve 1. The reaction liquid flowing out from the back pressure valve 1 and the 20% hydrochloric acid solution are pumped into the micro mixer 4 and mixed thoroughly, then sent to the micro channel reactor 5, where a neutralization reaction is carried out at 0°C for a retention time of 3 minutes. The acidic reaction liquid is then sent directly to the micro channel reactor 6, where it is rapidly heated. After the reaction liquid is heated to 100°C, it is sent to the back pressure valve 2 (6 bar). The pressure of the micro channel reactors 5 and 6 is controlled and adjusted by the back pressure valve 2, and the reaction liquid flowing out from the back pressure valve 2 is sent to the reaction vessel 1 to carry out desolvation. The resulting mixture was then heated at 110°C for 28 minutes to remove the solvent, low-boiling methanol, and by-product methyl chloride. The mixture was then continuously sent to reactor 2, where it was hydrolyzed at 115°C for 35 minutes, and then sent to reactor 3, where it was fully hydrolyzed at 125°C for 35 minutes. During the hydrolysis, water in the reaction system continuously evaporated, increasing the internal temperature of the reaction solution and accelerating the hydrolysis reaction rate. The reaction solution in reactor 3 was then directly transported to a continuous crystallizer, where it was cooled and crystallized to yield solid glyphosate. The glyphosate product was filtered and dried. The purity of the product was 97%, and the total yield, calculated as glycine, was 85%. The total reaction time was 82.5 minutes.

[0021] Example 4 Paraformaldehyde (0.7 kg / L, 2.5 eq) was dispersed in ethanol, and tributylamine (0.8 eq) was dispersed in ethanol. The two raw materials were pumped through micromixer 1 and thoroughly mixed. Then, in microchannel reactor 1, esterification reaction was carried out at 50 °C for 6 min, followed by depolymerization to obtain a depolymerized solution. Glycine (0.7 kg / L, 1.2 eq) was dispersed in ethanol to prepare a feed solution. This feed solution was pumped through micromixer 2 and thoroughly mixed with the depolymerized solution flowing out of microchannel reactor 1. Then, it was sent to reactor 2, where it underwent an addition reaction at 65 °C for 10 min to produce N,N-dihydroxymethylglycine. The reaction solution was then pumped into a small buffer tank and quantitatively delivered by a plunger pump. The reaction liquid delivered from the small buffer tank and an ethanol solution of dimethyl phosphite (0.5 kg / L, 1.4 eq) were pumped into micromixer 3 and mixed thoroughly, and then sent to microchannel reactor 3, where an esterification reaction was carried out at 65°C with a retention time of 5 minutes to produce glyphosate methyl ester. To allow the reaction to proceed sufficiently, the temperature of microchannel reactor 4 was raised to 70°C, and the reaction was completed with a retention time of 1 minute to produce glyphosate methyl ester. After the reaction liquid flowed out, it entered backpressure valve 1 (9 bar), and the reaction pressure in microchannel reactors 3 and 4 was adjusted by backpressure valve 1. The reaction liquid flowing out from the back pressure valve 1 and the 37% hydrochloric acid solution are pumped into the micro mixer 4 and mixed thoroughly, then sent to the micro channel reactor 5, where a neutralization reaction is carried out at 15°C and a retention time of 2 minutes. After that, the acidic reaction liquid is sent directly to the micro channel reactor 6, where it is rapidly heated. After the reaction liquid is heated to 80°C, it is sent to the back pressure valve 2 (7 bar). The pressure of the micro channel reactors 5 and 6 is controlled and adjusted by the back pressure valve 2, and the reaction liquid flowing out from the back pressure valve 2 is sent to the reaction vessel 1 to carry out desolvation. The resulting mixture was then heated at 90°C for 15 minutes to remove the solvent, low-boiling methanol, and by-product methyl chloride. The mixture was then continuously sent to reactor 2, where it was hydrolyzed at 100°C for 30 minutes, and then sent to reactor 3, where it was fully hydrolyzed at 115°C for 35 minutes. During the hydrolysis, water in the reaction system continuously evaporated, increasing the internal temperature of the reaction solution and accelerating the hydrolysis reaction rate. The reaction solution in reactor 3 was then directly transported to a continuous crystallizer, where it was cooled and crystallized to yield solid glyphosate. The glyphosate product was filtered and dried. The purity of the product was 98%, and the total yield, calculated as glycine, was 85%. The total reaction time was 69 minutes.

[0022] Although the above embodiments have been described in this specification, they are not intended to limit the scope of protection of the present invention. Therefore, any changes and modifications to the embodiments described in this specification based on the concept of the present invention, or equivalent structure or process conversions made in accordance with the contents of this specification and drawings, or direct or indirect application of the above technical means to other related technologies, are all included in the scope of protection of the present invention.

Claims

1. A completely continuous method for synthesizing glyphosate, which uses a completely continuous system consisting of a feed pump, a plurality of micromixers, a microchannel reactor, a dynamic rotating reactor, a buffer tank, a back pressure valve, a continuous reaction kettle reactor, and a continuous crystallizer, all of which are connected in series, The method includes the following steps (1) to (3): Step (1): preparing raw material solutions by dissolving or dispersing paraformaldehyde and an alkali in a solvent, respectively; thoroughly mixing the two raw material solutions in a first micromixer and then feeding them into a first microchannel reactor, where they are depolymerized to obtain a depolymerized solution; dissolving or dispersing glycine in a solvent to prepare a feed solution; thoroughly mixing the feed solution and the depolymerized solution flowing out of the first microchannel reactor in a second micromixer; then feeding them into a second microchannel reactor, where they are subjected to an addition reaction to produce N,N-dihydroxymethylglycine; feeding the reaction solution into a small buffer tank, and then quantitatively delivering it using a plunger pump; Step (2): The reaction liquid sent from the small buffer tank is thoroughly mixed with dimethyl phosphite in the third micromixer, and then sent to the third microchannel reactor for esterification reaction to produce glyphosate methyl ester. In order to ensure the reaction proceeds sufficiently, a fourth microchannel reactor is provided with a temperature slightly higher than that of the third microchannel reactor, and the reaction liquid flows out and enters the first backpressure valve, and the reaction pressure in the third and fourth microchannel reactors is adjusted by the first backpressure valve 1; Step (3): The reaction liquid and the acid flowing out of the first back pressure valve are sent to the fourth micro-mixer and thoroughly mixed, and then sent to the fifth micro-channel reactor for neutralization. The pH value of the reaction liquid is adjusted from alkaline to acidic. The acidic reaction liquid is directly sent to the sixth micro-channel reactor and heated to quickly increase its temperature. After the temperature is increased, the reaction liquid is sent to the second back pressure valve. The pressure of the fifth and sixth micro-channel reactors is controlled and adjusted by the second back pressure valve. The reaction liquid flowing out of the second back pressure valve is sent to the first reactor for desolvation, removing the solvent and low boiling point compounds. The reaction mixture is then continuously fed into a second reactor for hydrolysis, and then fed into a third reactor for complete hydrolysis. During the hydrolysis reaction, water in the reaction system is continuously evaporated, increasing the internal temperature of the reaction mixture and accelerating the hydrolysis reaction rate. The reaction mixture in the third reactor is directly transported to a continuous crystallizer, where the temperature is reduced to crystallize the mixture. The glyphosate solid is obtained, filtered, and dried to obtain a glyphosate product, which has a purity of more than 98% and a total yield of more than 85% in terms of glycine.

2. 2. The method for completely continuously synthesizing glyphosate according to claim 1, wherein in step (1) and step (3), the alkali is selected from liquid ammonia, triethylamine, trimethylamine, tributylamine, diethylamine, N,N-diisopropylethylamine, and sodium methoxide, and the acid is selected from 10% aqueous hydrogen chloride solution, 20% aqueous hydrogen chloride solution, 30% aqueous hydrogen chloride solution, 37% aqueous hydrogen chloride solution, methanolic hydrogen chloride solution, formic acid, acetic acid, 10% aqueous phosphoric acid solution, 20% aqueous phosphoric acid solution, 30% aqueous phosphoric acid solution, and 37% aqueous phosphoric acid solution.

3. 2. The method for completely continuously synthesizing glyphosate according to claim 1, characterized in that in step (1), the paraformaldehyde and glycine are dissolved or dispersed in a solvent to prepare a raw material solution, and the solvent is selected from pentanol, butanol, isobutanol, tert-butanol, propanol, isopropanol, ethanol, methanol, diethyl ether, acetone, butanone, and methyl isobutyl ketone.

4. 2. The method for completely continuously synthesizing glyphosate according to claim 1, characterized in that in step (1), step (2), and step (3), the alkali, dimethyl phosphite, and acid are added without solvent or a solution thereof is prepared in advance with a solvent, and the solvent is selected from the group consisting of water, pentanol, butanol, isobutanol, tert-butanol, propanol, isopropanol, ethanol, methanol, acetone, and methyl isobutyl ketone.

5. 2. The method for completely continuous synthesis of glyphosate according to claim 1, characterized in that in step (1), the amount of alkali used is 0.6-0.95 equivalents of glycine, the amount of paraformaldehyde used is 1.0-3.0 equivalents of glycine, and in step (2), the amount of dimethyl phosphite used is 1.0-1.4 equivalents of glycine, the amount of alkali used is 0.1-0.35 equivalents of glycine, and the amount of acid used is 1.0-10 equivalents of glycine.

6. In steps (1), (2), and (3), the temperature of the first microchannel reactor is 30-60°C, and the reaction time is 1-9 min; the temperature of the second microchannel reactor is 45-80°C, and the reaction time is 6-12 min; the temperature of the third microchannel reactor is 50-80°C, and the reaction time is 1-8 min; the temperature of the fourth microchannel reactor is 60-90°C, and the reaction time is 5-15 min; and the temperature of the fifth microchannel reactor is 0-30°C, and the reaction time is the temperature of the third reactor is 90-160°C, the reaction time is 5-40 min; the temperature of the continuous crystallizer is 0-80°C, and the residence time is 1-30 min.

7. In step (1), step (2), and step (3), the first micro-mixer and the second micro-mixer are dynamic rotary mixers, with inlet and outlet sizes of 1.0 mm-50 mm, a mixing chamber diameter of 5.0 mm-500 mm, and a height of 5.0 mm-100 mm; 2. The method for fully continuously synthesizing glyphosate according to claim 1, wherein the third micro-mixer and the fourth micro-mixer are Z-shaped micro-mixers with a plate-type structure, with an inner diameter of 0.5-50 mm and a length of 0.1-100 m; and the micro-channel reactor has a plate-type or tubular micro-channel structure, with an inner diameter of 1.0-100 mm and a length of 10-10,000 m.

8. 2. The method for completely continuously synthesizing glyphosate according to claim 1, wherein in step (1), the dynamic continuous reactor is a horizontal or vertical multi-stage rotary stirring reactor with a heat exchange jacket, has a circular interior, an inner diameter of 10-500 mm, and a length of 0.1-50 m; in step (3), the first, second, and third reactors each have a diameter of 5-1000 mm and an aspect ratio of 5:1-50:1; and in step (3), the continuous crystallizer has an inlet size of 1.0 mm-50 mm, an outlet size of 10-200 mm, an inner diameter of 1.0 mm-50 mm, and a length of 1-200 m.

9. 2. The method for fully continuously synthesizing glyphosate according to claim 1, wherein in step (2), the pressure of the first backpressure valve is 1-10 bar, and in step (3), the pressure of the second backpressure valve is 1-20 bar.

10. 2. The method for the complete continuous synthesis of glyphosate according to claim 1, characterized in that in step (3), the solvent used in the crystallization is selected from the group consisting of water, methanol, ethanol, propanol, and isopropanol.

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