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CN-118930439-B - Continuous system and method for preparing high-added-value chemical products by converting low-value glyphosate byproducts

CN118930439BCN 118930439 BCN118930439 BCN 118930439BCN-118930439-B

Abstract

The invention discloses a continuous system and a continuous method for preparing high-added-value chemical products by converting low-value glyphosate byproducts, wherein the continuous system comprises the steps of pumping the low-value glyphosate byproducts and alkaline compounds into a constant-temperature converting kettle for converting and decomposing, introducing nitrogen into the top of the constant-temperature converting kettle for stripping gaseous volatile products generated by displacement reaction, collecting water vapor of the gaseous products through a buffer tank, then, feeding the water vapor into a three-stage condenser for recycling condensable components to a crude product receiving tank, purifying and removing impurities from non-condensable components through an acid absorption system, and feeding the liquid crude product into a low-temperature vacuum desolventizing kettle for separating the condensable components from liquid water, feeding the liquid product into a secondary condenser for deep dehydration and separation, and recycling the liquid product to a pure product receiving tank. The invention realizes a new process for preparing high-purity N, N-diethyl methylamine, and forms a full-flow process system for preparing high-added-value chemical products such as N, N-diethyl methylamine, ethylene and the like based on the conversion of low-value waste materials such as chloromethane, triethylamine, synthetic products thereof and the like.

Inventors

  • ZHANG BAIQING
  • FENG WEI
  • ZHANG YE
  • Yao Eryan
  • LAI YAN
  • ZHOU SHUGUANG
  • WANG XIANGQIAN
  • QIN LONG
  • MAO CHENGBIN
  • WANG YUGANG
  • Yu meidong
  • YOU SICHUN
  • WANG XIAOTAO

Assignees

  • 浙江大学
  • 浙江新安化工集团股份有限公司

Dates

Publication Date
20260512
Application Date
20240725

Claims (11)

  1. 1. A method for preparing high value chemical products by converting low value glyphosate byproducts, which is characterized by adopting a continuous system and comprising the following steps: The feeding pump (1) and the feeding valve (2) are used for feeding glyphosate byproducts and alkaline substances; a constant temperature conversion kettle (4) connected with the output of the feed valve (2); a buffer tank (5) connected with the nitrogen outlet of the constant temperature conversion kettle (4); Three or more condensers (6) connected in series with the air outlet of the buffer tank (5); an acid absorption device (8) connected with the air outlet of the condenser (6); a crude product receiving tank (7) connected with the liquid outlet of the condenser (6); a vacuum desolventizing kettle (12) communicated with the crude product receiving tank (7) through a feeding pump (9) and a crude product feeding valve (10); Two or more condensers (13) connected in series with the air outlet of the vacuum desolventizing kettle (12); a pure product receiving tank (14) connected to the liquid outlets of the two or more condensers (13) connected in series; The air outlets of the two or more condensers (13) connected in series are connected with the acid absorption device (8) through a vacuum pump (15); The method comprises the following steps: S1, constant temperature conversion, namely controlling the feeding quantity of low-value glyphosate byproducts and alkaline compounds through a feeding pump (1) and a feeding valve (2), entering a constant temperature conversion kettle (4), controlling the conversion efficiency through a reaction constant temperature heating and variable frequency stirrer (3), and introducing flow nitrogen at the top of the constant temperature conversion kettle (4) to blow off gaseous volatile products generated by displacement reaction; The obtaining of the low-value glyphosate byproduct specifically comprises: The method comprises the steps of obtaining glyphosate and a glyphosate production mother solution by a glycine method, and extracting a liquid oily product from the glyphosate production mother solution, namely 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 byproduct after mixing with an alkaline compound is >12; the temperature of the constant temperature conversion kettle (4) is controlled to be 100-130 ℃, and the pressure of nitrogen is controlled to be 0.1-0.3 MPa; S2, recovering a crude product, namely collecting vapor from a gaseous volatile product generated by constant temperature conversion through a buffer tank (5), and then, feeding the vapor into three or more condensers (6) connected in series to recover condensable components in the gaseous volatile product to a crude product receiving tank (7), wherein non-condensable components in the gaseous volatile product are purified through an acid absorption device (8) to remove impurities and then are recycled; S3, dehydration and purification, namely, the liquid crude product in the crude product receiving tank (7) enters a vacuum desolventizing kettle (12) through a feeding pump (9) and a crude product feeding valve (10), the desolventizing rate is controlled by a variable frequency stirrer (11) and a vacuum pump (15), after the condensable component is separated from the liquid water, the condensable component enters two or more condensers (13) which are connected in series and is recycled to a pure product receiving tank (14); the condensable component is N, N-diethyl methylamine; S4, zero waste discharge, namely, drying and purifying brine discharged from the bottom of the constant temperature conversion kettle (4) for secondary use, and returning liquid water collected by the buffer tank (5) and the vacuum desolventizing kettle (12) to the constant temperature conversion kettle (4) for water supplementing in the reaction process through a reflux pump (16) and a liquid water recycling feed valve (17), wherein tail gas obtained after condensation of two or more groups of condensers (13) connected in series enters an acid absorption device (8).
  2. 2. The method for preparing high-added-value chemical products by converting low-value glyphosate byproducts according to claim 1, wherein a variable-frequency stirrer (3) is arranged in the constant-temperature converting kettle (4), and a nitrogen inlet and a nitrogen outlet are arranged on the constant-temperature converting kettle (4).
  3. 3. The method for preparing high added value chemical products by converting low value glyphosate byproducts 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. 4. The method for preparing high value chemical products by converting low value glyphosate byproducts according to claim 1, characterized in that said three or more series-connected condensers (6) are provided with an air outlet and a liquid outlet.
  5. 5. The method for preparing high-added-value chemical products by converting low-value glyphosate byproducts according to claim 1, wherein a variable-frequency stirrer (11) is arranged in the vacuum desolventizing kettle (12), and the vacuum desolventizing kettle (12) is provided with an air outlet and a liquid outlet.
  6. 6. The method for preparing high value chemical products by converting low value glyphosate by-products according to claim 1, characterized in that said two or more series-connected condensers (13) are provided with an air outlet and a liquid outlet.
  7. 7. The method for preparing high-added-value chemical products by converting low-value glyphosate byproducts according to claim 1, wherein the liquid outlet of the buffer tank (5) and the liquid outlet of the vacuum desolventizing kettle (12) are connected with the constant-temperature converting kettle (4) through a reflux pump (16) and a liquid water recycling feed valve (17).
  8. 8. The method for preparing high-added-value chemical products by converting low-value glyphosate byproducts according to claim 1, wherein in step S1, the speed of a variable-frequency stirrer (3) is controlled to be 100-500 r/min; In the step S3, the speed of the variable frequency stirrer (11) is controlled to be 100-500 r/min.
  9. 9. The method for producing high value chemical products by conversion of low value glyphosate by-products according to claim 1, wherein in step S2, three or more condensers (6) are connected in series, the first condenser is condensed to [10 ℃,5 ℃, the second condenser is condensed to [0 ℃ -7 ℃, and the third condenser is condensed to [ -10 ℃ -15 ].
  10. 10. The method for preparing high-added-value chemical products by converting low-value glyphosate byproducts according to claim 1, wherein in the step S3, the temperature of the vacuum desolventizing kettle (12) is controlled to be 30-65 ℃, and the vacuum degree is controlled to be-0.04 to-0.08 MPa.
  11. 11. The method for the conversion of low value glyphosate by-products to produce high value added chemical products according to claim 1, characterized in that in step S3, the first set of condensers in two or more sets of condensers (13) in series is condensed to [0, -7 ], and the second set of condensers is condensed to [ -10, -15 ].

Description

Continuous system and method for preparing high-added-value chemical products by converting low-value glyphosate byproducts Technical Field The invention relates to the technical field of chemical industry, in particular to a continuous system and a method for preparing high-added-value chemical products by converting low-value glyphosate byproducts. Background Currently, the annual yield of glyphosate pesticides in China is 50-70 ten thousand tons, and the annual yield is mainly a glycine method production process, and is about 70% of the total yield. The process for preparing glyphosate by glycine method uses paraformaldehyde, glycine and dimethyl phosphite as main raw materials, triethylamine as catalyst and methanol as solvent, and includes such steps as depolymerization, addition, condensation and hydrolysis. Because triethylamine is used as a catalyst in the continuous production process, the triethylamine and methyl chloride are inevitably converted into high-boiling-point oily products of quaternary ammonium salt (methyl triethyl ammonium chloride), water and other impurities under certain temperature and pressure conditions. According to measurement and calculation, about 5 tons of glyphosate mother liquor can be extracted from each 1 ton of glyphosate production, and the annual output of the quaternary ammonium salt-containing product with 0.5% -1% is more than 1.5 ten thousand tons. Meanwhile, the existing quantity of the by-product of the glyphosate is large, each glyphosate production enterprise faces the technical problem that the effective utilization is difficult, and the original 'direct incineration process' causes the problems of overhigh temperature of incineration facilities, serious equipment corrosion, high operation and maintenance cost and excessive pollutant emission, so that each enterprise directly has economic loss exceeding millions of yuan each year. Therefore, the realization of the value-added conversion and engineering of the glyphosate byproducts is the key for reducing the cost and enhancing the efficiency of glyphosate production enterprises in China and realizing the development of green low carbon. The Chinese patent document with the application number 201711457366.1 discloses a preparation method of methyl triethyl ammonium chloride, which specifically comprises the steps of evaporating and concentrating glyphosate mother liquor to obtain glyphosate concentrated mother liquor, then carrying out liquid-liquid separation on the glyphosate mother liquor, collecting upper layer floating oil (high boiling point oily product), decoloring and drying to obtain methyl triethyl ammonium chloride. However, because of its high boiling point and strong hygroscopicity, methyltriethylammonium chloride is highly polar, very soluble in water, and has poor thermal stability, experiments have found that it is difficult to thoroughly separate it from water and other solid impurities (salts, elemental sulfur). Therefore, the conventional decoloring and drying process is difficult to purify and obtain a product meeting the market purity requirement, has higher running energy consumption and cost, is not thorough in reaction, is easy to produce secondary waste, and is difficult to realize industrial amplification application. The chinese patent document with the application number 201510214834.7 discloses a method for preparing methyltriethylammonium tetrafluoroborate (TEMATFB) by using methyltriethylammonium chloride, which comprises the steps of respectively dissolving methyltriethylammonium chloride and hydroxide in a reaction medium to prepare solutions, mixing the solutions, fully reacting to obtain a filtrate of methyltriethylammonium hydroxide, mixing the filtrate of methyltriethylammonium hydroxide with a proper amount of 40% fluoboric acid for reaction, filtering to remove solids, obtaining a filtrate containing methyltriethylammonium tetrafluoroborate, and finally recrystallizing and drying to obtain methyltriethylammonium tetrafluoroborate. The method needs to use high-purity methyltriethyl ammonium chloride as a raw material, and if the raw material contains solid impurities which are difficult to separate, the purity of the product is also affected to a certain extent due to the high boiling point and extremely water-soluble characteristic of the quaternary ammonium salt product, so that the product is difficult to purify and utilize. The Chinese patent document with the application number 202310413279.5 discloses a method for continuously synthesizing and preparing N, N-diethyl methylamine by a tubular reactor under the catalysis of ionic liquid, which comprises the following steps of (1) setting the temperature of the tubular reactor to reach the reaction temperature, pumping methanol, diethylamine and an ionic liquid catalyst into the tubular reactor by a plunger feeding pump, reacting the methanol and the diethylamine to obtain a crude product, and (2) pumping the crude pr