Continuous system and method for converting low-value glyphosate byproducts into high-value chemical products

Abstract

The application discloses a continuous system and method for converting low-value glyphosate by-products into high-value chemical products, comprising: pumping low-value glyphosate by-products and alkaline compounds into a constant-temperature conversion kettle for conversion and decomposition, and introducing nitrogen into the top of the constant-temperature conversion kettle to blow off and replace gaseous volatile products generated in the reaction; after gaseous products pass through a buffer tank to capture water vapor, the gaseous products enter a three-stage condenser to recover condensable components into a crude product receiving tank, and the non-condensable components are purified and impurities are removed by an acid absorption system and then utilized; liquid crude product is pumped into a low-temperature vacuum desolventizing kettle to realize separation of condensable components from liquid water, and then enters a two-stage condenser for deep dehydration and separation, and is recovered into a pure product receiving tank. The application realizes a new process for preparing high-purity N,N-diethylmethylamine, and forms a whole-process process system for converting low-value waste materials such as chloromethane, triethylamine and synthetic products thereof into high-value chemical products such as N,N-diethylmethylamine and ethylene.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a continuous system and method for converting low-value glyphosate byproducts into high-value-added chemical products. Background Technology

[0002] Currently, my country's annual glyphosate pesticide production is between 500,000 and 700,000 tons, mainly produced using the "glycine method," accounting for about 70% of the total capacity. The "glycine method" for glyphosate production uses paraformaldehyde, glycine, and dimethyl phosphite as main raw materials, triethylamine as a catalyst, and methanol as a solvent. Glyphosate is produced through depolymerization, addition, condensation, and hydrolysis reactions. One of its key byproducts is chloromethane. Because the continuous production process uses triethylamine as a catalyst, it inevitably reacts with chloromethane under certain temperature and pressure conditions to transform into a high-boiling-point oily product containing quaternary ammonium salts (methyltriethylammonium chloride), water, and other impurities. Calculations show that approximately 0.5% to 1% of the quaternary ammonium salt-containing product can be extracted from about 5 tons of glyphosate mother liquor produced per ton of glyphosate. The annual production of this high-boiling-point, complex-component oily product exceeds 15,000 tons. Meanwhile, the existing stock of these glyphosate byproducts is substantial, and all glyphosate producers face the technical challenge of effectively utilizing them. The existing "direct incineration process" leads to excessively high incineration temperatures, severe equipment corrosion, high operating and maintenance costs, and excessive pollutant emissions, resulting in direct economic losses exceeding one million yuan annually for each company. Therefore, achieving the value-added transformation and engineering of these glyphosate byproducts is crucial for Chinese glyphosate producers to reduce costs, increase efficiency, and achieve green and low-carbon development.

[0003] Chinese patent document application number 201711457366.1 discloses a method for preparing methyltriethylammonium chloride, specifically including evaporating and concentrating glyphosate mother liquor to obtain concentrated glyphosate mother liquor, then performing liquid-liquid separation of the glyphosate mother liquor, collecting the upper floating oil (high-boiling-point oily product), and then decolorizing and drying it to obtain methyltriethylammonium chloride. However, due to the high boiling point and strong hygroscopicity of methyltriethylammonium chloride, its strong polarity, high solubility in water, and poor thermal stability, experiments have shown that it is difficult to completely separate it from water and other solid impurities (salts, sulfur). Therefore, conventional decolorization and drying processes are difficult to purify it and obtain products that meet market purity requirements. These processes are energy-intensive and costly, and the reaction is incomplete, easily generating secondary waste, making industrial-scale application difficult.

[0004] Chinese patent application No. 201510214834.7 discloses a method for preparing methyltriethylammonium tetrafluoroborate (TEMATFB) using methyltriethylammonium chloride. The method involves dissolving methyltriethylammonium chloride and its hydroxide separately in a reaction medium to prepare solutions, then mixing the two solutions and allowing them to react fully to obtain a filtrate of methyltriethylammonium hydroxide. This filtrate is then mixed with an appropriate amount of 40% fluoroboric acid and reacted, followed by filtration to remove the solids, resulting in a filtrate containing methyltriethylammonium tetrafluoroborate. Finally, after recrystallization and drying, methyltriethylammonium tetrafluoroborate salt is obtained. This method requires high-purity methyltriethylammonium chloride as a raw material. If the raw material contains solid impurities that are difficult to separate, the purity of the product will be affected due to the high boiling point and high water solubility of the quaternary ammonium salt, making purification and utilization difficult.

[0005] Chinese patent document with application number 202310413279.5 discloses a method for the continuous synthesis of N,N-diethylmethylamine in a tubular reactor under ionic liquid catalysis, comprising the following steps: (1) setting the temperature of the tubular reactor to the reaction temperature, and then using a plunger feed pump to pump methanol, diethylamine and ionic liquid catalyst into the tubular reactor, where methanol and diethylamine react to obtain a crude product; (2) pumping the crude product into a light-weight removal tower for separation and purification, distilling off excess diethylamine and condensing it for collection, and then feeding the bottom product into a heavy-weight removal tower to obtain pure N,N-diethylmethylamine. The ionic liquid catalyst separated at the bottom of the tower can be reused after being separated from water. This method uses an ionic liquid as a catalyst, which avoids conventional high-temperature and high-pressure reactions, but the catalyst preparation process still requires vacuum and hydrogenation reactions, and the raw materials involved are relatively complicated, which to some extent increases the production cost and operational risks of N,N-diethylmethylamine, making it difficult to achieve a safe and mild chemical reaction process with low purity. Summary of the Invention

[0006] This invention addresses the low-value, difficult-to-utilize byproducts containing complex components of methyltriethylammonium chloride generated during glyphosate pesticide production. It proposes a continuous system and method for converting these low-value glyphosate byproducts into high-value-added chemical products. This is a low-cost, short-process continuous value-added conversion system, achieving a novel process for producing high-purity N,N-diethylmethylamine with mild reaction, single material composition, and low carbon emissions. Simultaneously, it innovates methods for the deep purification and value-added conversion of recalcitrant VOCs from chloromethane and triethylamine in the pesticide chemical industry, forming a complete process system for converting low-value waste such as chloromethane and triethylamine into high-value-added chemical products such as N,N-diethylmethylamine and ethylene.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A continuous system for converting low-value glyphosate byproducts into high-value-added chemical products includes:

[0009] Feed pumps and feed valves are used for feeding glyphosate byproducts and alkaline substances;

[0010] The constant-temperature conversion vessel is connected to the output of the feed valve;

[0011] A buffer tank connected to the nitrogen outlet of the constant-temperature conversion reactor;

[0012] Three or more condensers connected in series to the outlet of the buffer tank;

[0013] An acid absorption device is connected to the outlet of the condenser;

[0014] A crude product receiving tank is connected to the drain port of the condenser;

[0015] A vacuum desolvation vessel connected to the crude product receiving tank via a feed pump and a crude product feed valve;

[0016] The outlet of the vacuum desolventizing vessel is connected to two or more condensers connected in series;

[0017] A pure product receiving tank connected to the liquid outlet of the two or more condensers connected in series;

[0018] The outlets of the two or more condensers connected in series are connected to the acid absorption device via a vacuum pump.

[0019] The constant temperature conversion vessel is equipped with a variable frequency stirrer, and the constant temperature conversion vessel is equipped with a nitrogen inlet and a nitrogen outlet.

[0020] The buffer tank is equipped with an air inlet, an air outlet, and a liquid outlet.

[0021] The three or more condensers connected in series are provided with an air outlet and a liquid drain outlet.

[0022] The vacuum desolventizing vessel is equipped with a frequency converter and has an air outlet and a liquid outlet.

[0023] The two or more condensers connected in series are provided with an air outlet and a liquid outlet.

[0024] The drain ports of the buffer tank and the vacuum desolvation vessel are connected to the constant temperature conversion vessel via a reflux pump and a liquid water recycling feed valve.

[0025] A method for converting low-value glyphosate byproducts into high-value-added chemical products, employing the aforementioned continuous system, includes:

[0026] S1. Isothermal Conversion: Low-value glyphosate byproducts and alkaline compounds are fed into the isothermal conversion reactor via a feed pump and feed valve. The conversion efficiency is controlled by constant temperature heating and variable frequency stirring. Nitrogen gas is introduced into the top of the isothermal conversion reactor to strip and replace the gaseous volatile products generated by the reaction.

[0027] S2. Crude Product Recovery: The gaseous volatile products generated by the isothermal conversion are buffered to collect water vapor, and then enter three or more condensers connected in series to recover the condensable components in the gaseous volatile products, which are then sent to the crude product receiving tank; the non-condensable components in the gaseous volatile products are purified by an acid absorption device to remove impurities and are then recycled.

[0028] S3. Dehydration and purification: The liquid crude product in the crude product receiving tank enters the vacuum desolvation kettle through the feed pump and crude product feed valve, and the desolvation rate is controlled by the frequency converter and vacuum pump. After the condensable component is separated from the liquid water, the condensable component enters two or more condensers connected in series to be recovered to the pure product receiving tank.

[0029] S4. Zero waste discharge: The brine discharged from the bottom of the constant temperature conversion kettle is dried, purified and reused; the liquid water collected in the buffer tank and vacuum desolvation kettle is returned to the constant temperature conversion kettle via the reflux pump and liquid water recycling feed valve for water replenishment in the reaction process; the tail gas condensed by two or more condensers connected in series enters the acid absorption device.

[0030] In step S1, the acquisition of low-value glyphosate byproducts specifically includes:

[0031] Glyphosate and glyphosate production mother liquor are obtained through the glycine method. The liquid oily product extracted from the glyphosate production mother liquor is a low-value glyphosate byproduct.

[0032] In step S1, the alkaline compound is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phenolate, sodium formate, sodium acetate, or ammonia.

[0033] In step S1, the temperature of the constant temperature conversion reactor is controlled at 100-130℃, and the nitrogen pressure is controlled at 0.1-0.3MPa;

[0034] In step S1, the speed of the variable frequency stirring is controlled between 100 and 500 r / min;

[0035] In step S3, the speed of the variable frequency stirrer is controlled between 100 and 500 r / min.

[0036] In step S2, the first condenser in the three or more condensers connected in series (6) condenses to [10℃, 5℃], the second condenser condenses to [0℃, -7℃], and the third condenser condenses to [-10℃, -15℃].

[0037] In step S3, the temperature of the vacuum desolventizing vessel (12) is controlled at 30 to 65°C, and the vacuum degree is controlled at -0.04 to -0.08 MPa.

[0038] In step S3, the first condenser in a series of two or more condensers condenses to [0, -7℃], and the second condenser condenses to [-10℃, -15℃].

[0039] Furthermore, a continuous system for converting low-value glyphosate byproducts into high-value-added chemical products is provided, specifically including the following steps:

[0040] S1. Isothermal Conversion: Low-value glyphosate byproducts and alkaline compounds are fed into the isothermal conversion reactor via a feed pump and feed valve, with the conversion efficiency controlled by isothermal heating and variable frequency stirring. A certain flow rate of nitrogen (N2) is introduced into the top of the isothermal conversion reactor to strip and replace the gaseous volatile products (volatile components and water vapor) generated by the reaction.

[0041] S2. Crude product recovery: The gaseous product generated by the constant temperature conversion is filtered by a buffer tank to capture water vapor, and then enters the (6) three-stage condenser to recover a small amount of water and condensable components (N,N-diethylmethylamine) in the gaseous product, and then to the crude product receiving tank; the non-condensable components (ethylene) in the gaseous product are purified by an acid absorption system to remove impurities and are then recycled.

[0042] S3. Dehydration and purification: The liquid crude product enters the low-temperature vacuum desolvation kettle through the feed pump and feed valve, and the desolvation rate is controlled by the frequency converter and vacuum pump; after the condensable components are separated from the liquid water, they enter the secondary condenser for deep dehydration and separation, and are recovered to the pure product receiving tank.

[0043] S4. Zero waste discharge: The brine discharged from the bottom of the constant temperature conversion kettle is dried, purified and reused; the liquid water collected in the buffer tank and the low temperature vacuum desolvation kettle is returned to the constant temperature conversion kettle through the reflux pump and the feed valve for water replenishment in the reaction process; the vacuum tail gas is condensed and then enters the acid absorption device.

[0044] As a preferred option, the low-value glyphosate byproduct is a high-boiling-point oily product consisting of a quaternary ammonium salt (methyltriethylammonium chloride) and water, along with other impurities. The quaternary ammonium salt content is 40%–45%, with the remainder mainly consisting of water, salt, etc.

[0045] Preferably, the pH of the low-value glyphosate byproduct mixed with an alkaline compound is >12.

[0046] Preferably, the mass fraction of the alkaline compound is 32% to 40%.

[0047] Preferably, the volume ratio of the low-value glyphosate byproduct to the alkaline compound solution is 5:1.

[0048] Preferably, the optimal reaction temperature between the low-value glyphosate byproduct and the basic compound is 120–130°C.

[0049] Preferably, the nitrogen pressure is controlled at 0.1 to 0.3 MPa.

[0050] Preferably, the low-value glyphosate byproducts are reacted with the alkaline compound for 3 to 4 hours.

[0051] As a preferred option, the variable frequency stirring rate is controlled at 500 r / min.

[0052] As a preferred option, the three-stage condensation temperature is set to 5°C for the first stage, -7°C for the second stage, and -15°C for the third stage.

[0053] As a preferred option, the low-temperature vacuum desolvation temperature is controlled at 60-65°C, and the vacuum degree is controlled at -0.08MPa.

[0054] As a priority, the secondary condensation temperature is set to -7°C for the first stage and -15°C for the second stage.

[0055] In step S1, a certain flow rate of nitrogen (N2) is introduced into the top of the constant temperature conversion vessel to strip off the gaseous volatile products (volatile components, water vapor) generated by the replacement reaction. The flow rate of N2 is set in proportion to the volume of the reaction vessel, ensuring high safety and stability.

[0056] In step S2, the non-condensable components in the gaseous product are purified by an acid absorption device to remove impurities and are then recycled. The acid absorption device is based on the principle of acid absorption (sulfuric acid solution or hydrochloric acid solution) to generate diethylmethylamine organic salt, which realizes the efficient separation of N,N-diethylmethylamine and ethylene gas.

[0057] In step S2, the low-temperature vacuum desolvation vessel achieves efficient separation of N,N-diethylmethylamine and trace amounts of moisture through the coordinated control of heating temperature and vacuum degree.

[0058] In step S4, zero waste discharge mainly includes the collection of liquid water from buffer tanks and low-temperature vacuum desolvation kettles, and the direct reuse of diethylmethylamine organic salt aqueous solution from acid absorption devices.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] (1) A continuous system for converting low-value glyphosate production by-products into a variety of high-value-added chemical products (N,N-diethylmethylamine, ethylene) was invented.

[0061] (2) A new low-cost, short-process conversion process for producing high-purity N,N-diethylmethylamine has been established, which is mild, uses a single material, and is low-carbon and waste-free.

[0062] (3) Innovative methods for deep purification and value-added conversion of VOCs from chloromethane, triethylamine and other difficult-to-oxidize materials in the pesticide chemical industry have been developed, and a complete process system for converting low-value wastes such as chloromethane, triethylamine and their synthetic products into high-value-added chemical products such as N,N-diethylmethylamine and ethylene has been developed. Attached Figure Description

[0063] Figure 1 A continuous process for converting low-value glyphosate byproducts into high-value-added chemical products. Figure 2 Complete sets of equipment for converting low-value glyphosate byproducts into high-value-added chemical products;

[0064] Among them, (1) feeding pump, (2) raw material feeding valve, (3) frequency conversion stirring, (4) constant temperature conversion kettle, (5) buffer tank, (6) three-stage condenser, (7) crude product receiving tank, (8) acid absorption device, (9) feeding pump, (10) crude product feeding valve, (11) frequency conversion stirring, (12) low temperature vacuum desolvation kettle, (13) two-stage condenser, (14) pure product receiving tank, (15) vacuum pump, (16) reflux pump, and (17) liquid water recycling feeding valve.

[0065] Figure 3 Qualitative spectra of organic components in glyphosate byproducts;

[0066] Among them, the spectral response values ​​are those of the glyphosate byproduct sample and the methyltriethylammonium chloride standard sample, respectively.

[0067] Figure 4 Qualitative and quantitative chromatograms of samples for the value-added conversion of glyphosate by-products; among which, (1) 10000 mg / m 3 (1) Chromatogram of ethylene standard sample; (2) Chromatogram of N,N-diethylmethylamine commercial reagent; (3) Chromatogram of crude glyphosate by-product value-added conversion; (4) Chromatogram of pure glyphosate by-product value-added conversion. Detailed Implementation

[0068] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0069] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0070] The present invention will now be further illustrated with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation thereof. The test samples and test procedures used in the following embodiments include the following (if the specific experimental conditions are not specified in the embodiments, they are usually performed according to conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments can be obtained commercially unless otherwise specified).

[0071] like Figure 1 , Figure 2 As shown, a continuous system (process flow and complete equipment) for converting low-value glyphosate by-products into high-value-added chemical products includes: a feed pump 1 and a feed valve 2 for feeding glyphosate by-products and alkaline substances; a constant-temperature conversion vessel 4 connected to the output of the feed valve 2; a buffer tank 5 connected to the nitrogen outlet of the constant-temperature conversion vessel 4; three or more condensers 6 connected in series and connected to the outlet of the buffer tank 5; an acid absorption device 8 connected to the outlet of the condensers 6; a crude product receiving tank 7 connected to the drain outlet of the condensers 6; a vacuum desolvation vessel 12 connected to the crude product receiving tank 7 via a feed pump 9 and a crude product feed valve 10; two or more condensers 13 connected in series and connected to the outlet of the vacuum desolvation vessel 12; a pure product receiving tank 14 connected to the liquid outlet of the two or more condensers 13 connected in series; and the outlets of the two or more condensers 13 connected in series and connected to the acid absorption device 8 via a vacuum pump 15. The isothermal conversion vessel 4 is equipped with a variable frequency stirrer 3, and has a nitrogen inlet and a nitrogen outlet. The buffer tank 5 has an air inlet, an air outlet, and a liquid drain. Three or more condensers 6 connected in series have air outlets and liquid drains. The vacuum desolvation vessel 12 is equipped with a variable frequency stirrer 11, and has an air outlet and a liquid drain. Two or more condensers 13 connected in series have air outlets and liquid outlets. The liquid drains of the buffer tank 5 and the vacuum desolvation vessel 12 are connected to the isothermal conversion vessel 4 via a reflux pump 16 and a liquid water recycling feed valve 17.

[0072] The following examples illustrate the sources of low-value glyphosate production byproducts:

[0073] The glycine-based glyphosate production process uses glycine, paraformaldehyde, and dimethyl phosphite as main raw materials, triethylamine as a catalyst, and methanol as a solvent. The process involves four steps: depolymerization, addition, condensation, and hydrolysis to produce glyphosate technical grade. The main reaction equations are as follows:

[0074] (1) Depolymerization:

[0075]

[0076] (2) Bonus:

[0077]

[0078] (3) Condensation:

[0079]

[0080] (4) Hydrolysis:

[0081]

[0082] Chinese patent document application number 201711457366.1 discloses a method for preparing methyltriethylammonium chloride, wherein the formation principle of methyltriethylammonium chloride in glyphosate mother liquor is as follows:

[0083]

[0084] The liquid oily product extracted from the mother liquor of glyphosate production via the "glycine method" was qualitatively analyzed by mass spectrometry, and its main component was found to be 40%–45% methyltriethylammonium chloride (e.g., ...). Figure 3 (As shown), 50%–60% moisture, salt, and solid impurities, etc. Other test indicators are as follows:

[0085] Calorific value: 2739~4207Kcal / kg;

[0086] pH value 7.0–8.0;

[0087] Density 1.08 g / mL;

[0088] Salinity 4.0–5.0 g / L;

[0089] The elemental content is 29.59% C, 9.75% H, 3.39% N, and 1.84% S.

[0090] A method for converting low-value glyphosate byproducts into high-value-added chemical products, employing a continuous system, includes:

[0091] S1. Isothermal Conversion: Low-value glyphosate byproducts and alkaline compounds are fed into isothermal conversion reactor 4 via feed pump 1 and feed valve 2. The conversion efficiency is controlled by constant temperature heating and frequency conversion stirring. Nitrogen gas is introduced into the top of isothermal conversion reactor 4 to strip and replace the gaseous volatile products generated by the reaction.

[0092] Glyphosate and glyphosate production mother liquor are obtained through the glycine method. The liquid oily product extracted from the glyphosate production mother liquor is a low-value glyphosate byproduct, the main component of which is methyltriethylammonium chloride.

[0093] The alkaline compounds are sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phenolate, sodium formate, sodium acetate, or ammonia.

[0094] S2. Crude product recovery: The gaseous volatile products generated by the constant temperature conversion are filtered by the buffer tank 5 to capture water vapor, and then enter three or more sets of condensers 6 connected in series to recover the condensable components in the gaseous volatile products and send them to the crude product receiving tank 7; the non-condensable components in the gaseous volatile products are purified by the acid absorption device (8) to remove impurities and then recycled.

[0095] S3. Dehydration and purification: The liquid crude product in the crude product receiving tank 7 enters the vacuum desolvation kettle 12 through the feed pump 9 and crude product feed valve 10, and the desolvation rate is controlled by the frequency converter 11 and vacuum pump 15. After the condensable component is separated from the liquid water, the condensable component enters two or more condensers 13 connected in series and is recovered to the pure product receiving tank 14.

[0096] S4. Zero waste discharge: The brine discharged from the bottom of the constant temperature conversion kettle 4 is dried, purified and reused; the liquid water collected by the buffer tank 5 and the vacuum desolvation kettle 12 is returned to the constant temperature conversion kettle 4 via the reflux pump 16 and the liquid water recycling feed valve 17 for water replenishment in the reaction process; the tail gas condensed by two or more condensers 13 in series enters the acid absorption device 8.

[0097] In step S1, the speed of the variable frequency stirrer 3 is controlled between 100 and 500 r / min.

[0098] In step S2, the first condenser in the three or more condensers connected in series 6 condenses to [10℃, 5℃], the second condenser condenses to [0℃, -7℃], and the third condenser condenses to [-10℃, -15℃].

[0099] In step S3, the speed of the variable frequency stirrer 11 is controlled between 100 and 500 r / min.

[0100] In step S3, the temperature of the vacuum desolventizing vessel 12 is controlled at 30 to 65°C, and the vacuum degree is controlled at -0.04 to -0.08 MPa.

[0101] In step S3, the first condenser in the two or more condensers connected in series 13 condenses to [0, -7℃], and the second condenser condenses to [-10℃, -15℃].

[0102] Example 1: Small-scale experiment on the value-added conversion of low-value glyphosate byproducts using sodium hydroxide.

[0103] The main reaction equations are as follows:

[0104] (1) Quaternary ammonium salt → Quaternary ammonium base

[0105]

[0106] (2) Quaternary ammonium base thermal decomposition

[0107]

[0108] Experimental steps:

[0109] Step S1: Add 300 mL of glyphosate byproduct solution to a 1 L constant temperature conversion reactor (oil bath heating), along with 50 g NaOH and 50 mL of water. After stirring and mixing evenly, turn on the oil bath heating of the reactor to 120 °C, and control the stirring rate at 500 r / min; control the nitrogen blowing flow rate at 1 L / min.

[0110] Step S2: Set the temperatures of the three sets of serpentine glass condensers to 5℃, -7℃, and -15℃ respectively. Collect the liquid condensate components of the nitrogen-blown tail gas from the constant-temperature conversion reactor and perform qualitative and quantitative detection of liquid N,N-diethylmethylamine. At the same time, collect and detect the gas composition and content of the non-condensable component (ethylene) at the outlet of the condensate tail gas. After 3.5 hours of complete reaction, calculate the recovery amount of N,N-diethylmethylamine and ethylene, and weigh the dried salt.

[0111] Step S3: The collected liquid product is purified by negative pressure rotary evaporation in a 1L glass desolvation vessel. The water bath temperature is controlled at 65℃, the vacuum degree is controlled at -0.08MPa, and the temperatures of the two sets of serpentine glass condensers are -7℃ and -15℃, respectively. The liquid product is collected, and the content and purity of liquid N,N-diethylmethylamine are measured (e.g., Figure 4 As shown), (1) 10000mg / m 3 Chromatogram of ethylene standard sample: ethylene peak time 1.339 min, purity 95.44%; other impurities 4.56%. (2) Chromatogram of N,N-diethylmethylamine commercial reagent: N,N-diethylmethylamine peak time 2.557 min, purity 98.71%; other impurities 1.29%. (3) Chromatogram of crude glyphosate by-product value-added conversion: ethylene peak time 1.335 min, purity 3.70%; N,N-diethylmethylamine peak time 2.521 min, purity 95.95%; other impurities 0.35%. (4) Chromatogram of pure glyphosate by-product value-added conversion: N,N-diethylmethylamine peak time 2.596 min, purity 99.87%; other impurities 0.13%.

[0112] Results: Analysis showed that N,N-diethylmethylamine was recovered in the amount of 120.2 g, ethylene was recovered in the amount of 24.0 g, and the weight of the salt after drying (including impurities) was 66.9 g. The product purity was >99.0%.

[0113] Example 2: Small-scale experiment on the value-added conversion of low-value glyphosate byproducts using potassium hydroxide.

[0114] The main reaction equations are as follows:

[0115] (1) Quaternary ammonium salt → Quaternary ammonium base

[0116]

[0117] (2) Quaternary ammonium base thermal decomposition

[0118]

[0119] Experimental steps:

[0120] Step S1: Add 300 mL of glyphosate byproduct solution to a 1 L constant temperature conversion reactor (oil bath heating), along with 60 g KOH and 50 mL of water. After stirring and mixing evenly, turn on the oil bath heating of the reactor to about 120 °C, and control the stirring rate at 500 r / min; control the nitrogen blowing flow rate at 1 L / min.

[0121] Step S2: Set the temperatures of the three sets of serpentine glass condensers to 5℃, -7℃, and -15℃ respectively. Collect the liquid condensate components of the nitrogen-blown tail gas from the constant-temperature conversion reactor and perform qualitative and quantitative detection of liquid N,N-diethylmethylamine. At the same time, collect and detect the gaseous composition and content of the non-condensable component (ethylene) at the outlet of the condensate tail gas. After about 3.0 hours of complete reaction, calculate the recovery amount of N,N-diethylmethylamine and ethylene, and weigh the dried salt.

[0122] Step S3: The collected liquid product is purified by negative pressure rotary evaporation in a 1L glass desolvation vessel. The water bath temperature is controlled at 65℃, the vacuum degree is controlled at -0.08MPa, and the temperatures of the two sets of serpentine glass condensers are -7℃ and -15℃, respectively. The liquid product is collected, and the content and purity of liquid N,N-diethylmethylamine are measured.

[0123] Results: Analysis showed that N,N-diethylmethylamine was recovered in the amount of 125.0 g, ethylene was recovered in the amount of 25.3 g, and the weight of the salt after drying (including impurities) was 82.5 g. The product purity was >99.0%.

[0124] Example 3: Small-scale experiment on the value-added conversion of low-value glyphosate byproducts using sodium phenolate.

[0125] Experimental steps:

[0126] Step S1: Add 300 mL of glyphosate byproduct solution, 75 g of sodium phenolate and 50 mL of water to a 1 L constant temperature conversion reactor (oil bath heating). After stirring and mixing evenly, turn on the oil bath heating of the reactor to about 130 °C, and control the stirring rate at 500 r / min; control the nitrogen blowing flow rate at 1 L / min.

[0127] Step S2: Set the temperatures of the three sets of serpentine glass condensers to 5℃, -7℃, and -15℃ respectively, collect the liquid condensate components of the nitrogen blowing tail gas from the constant temperature conversion reactor, and perform qualitative and quantitative detection of liquid N,N-diethylmethylamine; after about 6.0 hours, the reaction is nearly complete, and the N,N-diethylmethylamine is calculated.

[0128] Step S3: The collected liquid product is purified by negative pressure rotary evaporation in a 1L glass desolvation vessel. The water bath temperature is controlled at 65℃, the vacuum degree is controlled at -0.08MPa, and the temperatures of the two sets of serpentine glass condensers are -7℃ and -15℃, respectively. The liquid product is collected, and the content and purity of liquid N,N-diethylmethylamine are measured.

[0129] Results: Analysis showed that the recovery of N,N-diethylmethylamine was 48.5g, with a product purity of approximately 95%. Other liquid organic matter was generated in the substrate, making it difficult to separate the solid salts. After separation and purification, approximately 5% triethylamine impurities were still present in the pure liquid N,N-diethylmethylamine.

[0130] Comparative Example: Pilot-scale demonstration of value-added conversion of low-value glyphosate byproducts

[0131] Experimental equipment: 100L electrically heated constant temperature conversion reactor, shell-and-tube 304 stainless steel condenser, 304 stainless steel buffer tank, 304 stainless steel receiving tank, nitrogen generator, and exhaust gas purification device.

[0132] Step S1: Take 30L of liquid byproduct, add 5kg NaOH and 5L of water, mix and stir evenly, turn on the electric heating to about 130℃, and stir at a rate of 500r / min; control the nitrogen blowing flow rate at 100L / min.

[0133] Step S2: The temperatures of the three condensers are 5℃, -7℃, and -15℃, respectively. As the reaction heats up, water is added in a timely manner to maintain a certain liquid level. Liquid condensate products are collected, and the content of non-condensable components (ethylene) at the tail gas outlet is sampled and analyzed.

[0134] Step S3: After running for 3.5 hours, stop heating, collect the liquid product and perform negative pressure rotary evaporation for dehydration and purification. The water bath temperature is controlled at 65℃, the vacuum degree is controlled at -0.08MPa, and the temperatures of the two condensers are -7℃ and -15℃, respectively. Collect the liquid product and measure the content and purity of liquid N,N-diethylmethylamine. Dry and weigh the reaction substrate and perform material balance.

[0135] Results: Analysis showed that the recovery rate of N,N-diethylmethylamine in the pilot test was 11.5 kg, the recovery rate of ethylene was 2.2 kg, and the weight of the salt after drying (including impurities) was 6.7 kg. The product purity was >99.0%. Application Example: Engineering application of converting low-value glyphosate byproducts into high-value-added chemical products.

[0136] Complete sets of equipment (such as) Figure 2 The equipment includes: 5 sets of 500L constant temperature conversion kettles, 1 set of 500L vacuum desolvation kettles, 1 set of metering tanks, nitrogen generation system, 1 set of buffer tanks, 3 sets of shell-and-tube 304 stainless steel condensers, 2 sets of 304 stainless steel receiving tanks (crude product and pure product), 1 set of acid absorption device, vacuum pump, feeding pump and feed valve.

[0137] Step S1: Pump 150L of liquid product into each of the 5 constant temperature conversion reactors, for a total of 750L of glyphosate byproduct. Add 25kg of NaOH and 25L of tap water to each reactor and mix thoroughly. Turn on the electric heating to maintain the material temperature above 130℃, and set the frequency conversion stirring speed to 500r / min. Control the nitrogen stripping flow rate at 500L / min.

[0138] Step S2: The gaseous products generated by the constant temperature conversion reactor are filtered by a buffer tank to capture water vapor, and then enter three sets of 304 stainless steel condensers with condensation temperatures of 5℃, -7℃ and -15℃ respectively. The liquid condensed products enter the crude product receiving tank. The gaseous non-condensable products enter the acid absorption device to purify the condensable components and are then recycled.

[0139] Step S3: The liquid crude product is pumped into a vacuum desolvation vessel. The vessel heating temperature is controlled at 60-65℃. Stirring and vacuuming are started. The vacuum exhaust gas enters two sets of 304 stainless steel condensers for deep separation from water. The condensation temperatures are -7℃ and -15℃, respectively, and the product is recovered to the pure product receiving tank.

[0140] Step S4: After 4.0 hours of reaction, about 100L of brine discharged from the bottom of the constant temperature conversion vessel is dried, purified, and reused; the liquid water collected in the buffer tank and the low temperature vacuum desolvation vessel is pumped into the constant temperature conversion vessel for water replenishment; the vacuum tail gas enters the acid absorption system.

[0141] Results: Analysis showed that the recovery rate of N,N-diethylmethylamine at the industrial scale was 285.6 kg, the recovery rate of ethylene was 55.0 kg, and the weight of the salt after drying (including impurities) was 166.4 kg. The product purity was >99.0%.

[0142] Table 1. Material Balance Comparison of High-Efficiency Conversion of Low-Value Glyphosate Byproducts

[0143]

[0144] Note: Ethylene recovery rate is based on gas phase concentration (mg / m³). 3 ) and gas flow rate (L / min) calculation.

[0145] In summary, this invention proposes a low-cost, short-process continuous system for the value-added conversion of low-value glyphosate byproducts (experimental pilot-scale test → pilot-scale test → industrial verification), and realizes a new process for the production of high-purity N,N-diethylmethylamine. It also forms a complete process system for the conversion of low-value wastes such as chloromethane, triethylamine and their synthesis products into high-value-added chemical products such as N,N-diethylmethylamine and ethylene.

[0146] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0147] The continuous system for converting low-value glyphosate byproducts into high-value-added chemical products, provided by this invention, has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for converting low-value glyphosate byproducts into high-value-added chemical products, characterized in that, The continuous system is adopted, including: The feed pump (1) and feed valve (2) are used for feeding glyphosate byproducts and alkaline substances; The constant temperature conversion vessel (4) is connected to the output of the feed valve (2); A buffer tank (5) is connected to the nitrogen outlet of the constant temperature conversion vessel (4); Three or more condensers (6) connected in series to the outlet of the buffer tank (5); An acid absorption device (8) is connected to the outlet of the condenser (6); A crude product receiving tank (7) is connected to the drain port of the condenser (6); A vacuum desolvation vessel (12) connected to the crude product receiving tank (7) via a feed pump (9) and a crude product feed valve (10); Two or more condensers (13) connected in series to the outlet of the vacuum desolvation vessel (12); A pure product receiving tank (14) is connected to the liquid outlet of the two or more condensers (13) connected in series; The outlet of the two or more condensers (13) connected in series is connected to the acid absorption device (8) via a vacuum pump (15); The method includes: S1. Constant temperature conversion: Low-value glyphosate by-products and alkaline compounds are fed into the constant temperature conversion vessel (4) by the feed pump (1) and feed valve (2) to control the feed rate. The conversion efficiency is controlled by the constant temperature heating of the reaction and the frequency converter (3). Nitrogen gas is introduced into the top of the constant temperature conversion vessel (4) to strip and replace the gaseous volatile products generated by the reaction. The acquisition of low-value glyphosate byproducts specifically includes: Glyphosate and glyphosate production mother liquor are obtained by the glycine method. The liquid oily product extracted from the glyphosate production mother liquor is a low-value glyphosate byproduct. The main component of the liquid oily product is methyltriethylammonium chloride; The alkaline compound is sodium hydroxide or potassium hydroxide; The pH of the low-value glyphosate byproducts mixed with alkaline compounds is >12; The temperature of the constant temperature conversion reactor (4) is controlled at 100~130℃, and the nitrogen pressure is controlled at 0.1~0.3 MPa; S2. Crude product recovery: The gaseous volatile products generated by constant temperature conversion are filtered by a buffer tank (5) to capture water vapor, and then enter three or more condensers (6) connected in series to recover the condensable components in the gaseous volatile products, and then to the crude product receiving tank (7); the non-condensable components in the gaseous volatile products are purified by an acid absorption device (8) to remove impurities and then recycled. S3. Dehydration and purification: The liquid crude product in the crude product receiving tank (7) enters the vacuum desolvation kettle (12) through the feed pump (9) and crude product feed valve (10), and the desolvation rate is controlled by the frequency converter (11) and vacuum pump (15). After the condensable component is separated from the liquid water, the condensable component enters two or more condensers (13) connected in series to be recovered to the pure product receiving tank (14). The condensable component is N,N-diethylmethylamine; S4. Zero waste discharge: The brine discharged from the bottom of the constant temperature conversion kettle (4) is dried, purified and reused; the liquid water collected by the buffer tank (5) and the vacuum desolvation kettle (12) is returned to the constant temperature conversion kettle (4) via the reflux pump (16) and the liquid water recycling feed valve (17) for water replenishment in the reaction process; the tail gas condensed by two or more condensers (13) in series enters the acid absorption device (8).

2. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The constant temperature conversion vessel (4) is equipped with a variable frequency stirrer (3), and the constant temperature conversion vessel (4) is equipped with a nitrogen inlet and a nitrogen outlet.

3. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The buffer tank (5) is provided with an air inlet, an air outlet and a liquid outlet.

4. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The three or more condensers (6) connected in series are provided with an air outlet and a liquid drain.

5. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The vacuum desolventizing vessel (12) is equipped with a variable frequency stirrer (11) and a gas outlet and a liquid outlet.

6. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The two or more condensers (13) connected in series are provided with an air outlet and a liquid outlet.

7. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, The drain ports of the buffer tank (5) and the vacuum desolvation vessel (12) are connected to the constant temperature conversion vessel (4) via a reflux pump (16) and a liquid water recycling feed valve (17).

8. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, In step S1, the speed of the variable frequency stirrer (3) is controlled at 100~500 r / min; In step S3, the speed of the variable frequency stirrer (11) is controlled at 100~500 r / min.

9. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, In step S2, the first condenser in the three or more condensers connected in series (6) condenses to [10℃, 5℃], the second condenser condenses to [0℃, -7℃], and the third condenser condenses to [-10℃, -15℃].

10. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, In step S3, the temperature of the vacuum desolventizing vessel (12) is controlled at 30~65℃ and the vacuum degree is controlled at -0.04~-0.08 MPa.

11. The method for converting low-value glyphosate byproducts into high-value-added chemical products according to claim 1, characterized in that, In step S3, the first condenser in the two or more condensers (13) connected in series condenses to [0, -7℃], and the second condenser condenses to [-10℃, -15℃].

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