阅读说明：本技术 清洗甲基二氯化膦合成捕集系统焦化物的方法 (Method for cleaning coking substance of methyl phosphine dichloride synthesis trapping system ) 是由 张飞 辛杨杨 王志豪 程柯 尹英遂 于 2019-09-11 设计创作，主要内容包括：本发明涉及清洗甲基二氯化膦合成捕集系统焦化物的方法,属于除草剂草铵膦生产技术领域。本发明解决的技术问题是现有甲基二氯化膦法捕集系统焦化物累积后将严重影响甲基二氯化膦的连续合成,目前还没有有效的解决措施。本发明的清洗方法是在含有焦化物的捕集系统中加入乙腈或二恶烷进行溶解分散,将分散后的固液混合物通过沉降的方式进行分离,从而实现捕集系统焦化物的清洗。本发明溶解分散效果好,不溶物易沉降,不会剧烈反应放热,安全系数高,产生少量有机废液。(The invention relates to a method for cleaning a coking substance of a synthesis and trapping system of methyl phosphine dichloride, belonging to the technical field of production of herbicide glufosinate-ammonium. The invention solves the technical problem that the continuous synthesis of the methyl phosphine dichloride is seriously influenced after the accumulation of coked substances of the existing methyl phosphine dichloride capturing system, and no effective solution is provided at present. The cleaning method of the invention is to add acetonitrile or dioxane into a trapping system containing the coking substances for dissolving and dispersing, and separate a dispersed solid-liquid mixture in a sedimentation mode, thereby realizing the cleaning of the coking substances in the trapping system. The invention has good dissolving and dispersing effects, high safety factor and generates a small amount of organic waste liquid, and insoluble substances are easy to settle, do not react violently and release heat.)

1. The method for cleaning the coking substance of the synthesis and trapping system of the methyl phosphine dichloride is characterized by comprising the following steps:

(1) Adding a cleaning solvent into a trapping system containing a coking substance for dissolving and dispersing to form a solid-liquid mixture;

(2) And carrying out solid-liquid separation on the solid-liquid mixture in a sedimentation mode to obtain supernatant and solid residues.

2. The method of cleaning phosphine methyldichloride synthesis capture system char of claim 1, wherein: the trapping system is a system for cooling and collecting high-temperature materials after reaction in the method for preparing the methyl phosphine dichloride by taking the phosphorus trichloride and the methane as raw materials.

3. the method of cleaning phosphine methyldichloride synthesis capture system char according to claim 1 or 2, wherein: the cleaning solvent is selected from acetonitrile or dioxane.

4. The method of cleaning phosphine methyldichloride synthesis capture system char according to claim 3, wherein: when the cleaning solvent is acetonitrile, the mass ratio of the acetonitrile to the charred substance is 2-20: 1, preferably 2-5: 1, and more preferably 3: 1.

5. The method of cleaning phosphine methyldichloride synthesis capture system char according to claim 3, wherein: when the cleaning solvent is dioxane, the mass ratio of the dioxane to the scorched substance is 3-20: 1, preferably 3-5: 1, and more preferably 3: 1.

6. The method for cleaning the scorch generated by the methyl phosphine dichloride synthesis capture system according to any one of claims 1 to 5, wherein: the temperature of the dissolution and dispersion is controlled to be 0-50 ℃, and preferably 20-40 ℃.

7. The method of cleaning phosphine methyldichloride synthesis capture system char of claim 1, wherein: the solid-liquid mixture is subjected to solid-liquid separation through a settling device, and the settling device comprises a circulating pump and a settling tank.

8. The method of cleaning phosphine methyldichloride synthesis capture system char of claim 1, wherein: the method also comprises the step of recycling the supernatant as a part or all of the cleaning solvent.

Technical Field

The invention belongs to the technical field of herbicide glufosinate-ammonium production, and particularly relates to a method for cleaning a coking substance of a synthesis and trapping system of methyl phosphine dichloride.

Background

The research and edification of the foreign industrial route of glufosinate-ammonium for Zhuang Jianyuan and Hulaugh review the industrial synthesis method of glufosinate-ammonium, which comprises the following steps: the Strecker process route using diethyl methylphosphonite as a key intermediate, and the Michael addition process route using Methylphosphonite (MPE) and Acrolein Cyanohydrin Acetate (ACA) as key intermediates. Most domestic enterprises adopt a Strecker method, wherein a key intermediate diethyl methylphosphonite can be obtained by a Grignard method and a methyl phosphine dichloride method. The Grignard method has low atom economy, low yield, large amount of three wastes (magnesium chloride) and high production cost. In contrast, the methyl phosphine dichloride process requires cheap and easily available raw materials, high atom economy and small amount of three wastes.

The process of the methyl phosphine dichloride process generally involves a high temperature cracking reaction above 500 ℃, deep cooling of the material at low temperature, and separation of the methyl phosphine dichloride and phosphorus trichloride. For example, US4101573 uses carbon tetrachloride as an initiator, methane and phosphorus trichloride as raw materials, synthesizes phosphine methyl dichloride in a tubular reactor by controlling the residence time, the reaction temperature and the concentration of carbon tetrachloride, and then cools and collects the high-temperature materials through a capturing system connected to the rear end of the tubular reactor. However, the accumulation of the char produced by the capture system will seriously affect the continuous synthesis of methyl phosphine dichloride.

Therefore, in order to better realize the continuous synthesis of methyl phosphine dichloride, a method for cleaning a capture system of the coking object needs to be developed.

Disclosure of Invention

The invention solves the technical problem that the continuous synthesis of the methyl phosphine dichloride is seriously influenced after the accumulation of the coke compounds of the existing synthesis and trapping system of the methyl phosphine dichloride method, and no effective solution is provided at present.

The technical scheme for solving the problems is to provide a method for cleaning a coking substance of a methyl phosphine dichloride synthesis and capture system, which comprises the following steps: and adding a cleaning solvent into the trapping system containing the coking substances for dissolving and dispersing to form a solid-liquid mixture, and separating the dispersed solid-liquid mixture in a settling manner to obtain a supernatant and solid residues, thereby realizing the cleaning of the coking substances of the trapping system. The trapping system is a system for cooling and collecting high-temperature materials after reaction in the method for preparing the methyl phosphine dichloride by taking the phosphorus trichloride and the methane as raw materials.

Wherein, the residual coking substance in the trapping system is a mixed substance with complex components, mainly contains elements such as carbon, phosphorus, chlorine and the like, and comprises solid by-products generated in the high-temperature reaction process of phosphorus trichloride and methane, methyl phosphine dichloride generated by the reaction and unreacted phosphorus trichloride. The inventor has adopted a method of removing the pipeline of the trapping system and cleaning the pipeline one by one with water, but the following problems exist: when water is adopted for cleaning, the water enters a trapping system, reacts with the coking substances and releases heat violently, although the dissolving effect is good, insoluble substances are few, the reaction is violent, the heat release is large, the safety risk is high, and phosphoric acid-containing water with the quality 5-10 times that of the coking substances is also generated; in addition, the dismantling and cleaning operations are cumbersome.

The invention screens out two cleaning solvents, acetonitrile and dioxane, which do not react with main components, namely phosphorus trichloride, methyl phosphine dichloride and the like in a char under the condition of anhydrous and anaerobic environment in a trapping system, can dissolve and disperse the char with certain fluidity, and can carry out circulating cleaning through a pump, thereby avoiding the trouble of dismantling pipelines of the trapping system and cleaning the pipelines one by one independently.

In the dissolving and dispersing process of the coking substance, part of substances in the coking substance can be dissolved by the cleaning solvent, the insoluble part is dispersed into small particles, and then the insoluble substances are separated in a settling mode and are easy to transfer, so that the coking substance in the trapping system is cleaned.

Wherein, when the cleaning solvent is acetonitrile, the adding amount of the acetonitrile is 2-20 times, preferably 2-5 times and more preferably 3 times of the mass of the coked material.

Wherein, when the cleaning solvent is dioxane, the addition amount of the dioxane is 3-20 times, 3-5 times and more preferably 3 times of the mass of the coking substance.

Wherein the dissolving and dispersing temperature is controlled at 0-50 ℃, preferably 20-40 ℃.

The coking substance is dissolved and dispersed by the cleaning solvent to obtain a solid-liquid mixture, then the solid-liquid mixture is separated by a sedimentation mode, and in order to improve the separation efficiency, a sedimentation device comprising a circulating pump and a sedimentation tank can be introduced for solid-liquid separation. Preferably, the circulating pump adopts an electric diaphragm pump, and the settling tank adopts a horizontal settling tank with the length of 2-4 m and the diameter of DN300 mm-DN 500 mm.

Specifically, a solid-liquid mixture is obtained after the dissolution and dispersion of the coked substance, and enters a settling tank for settling under the action of a circulating pump, so that supernatant and solid residues are obtained. Furthermore, supernatant liquor can enter a trapping system for recycling, and the flow rate of the circulating liquor is controlled to be 10m³/h～20m³And h, recycling supernatant liquor for a certain batch, distilling and recovering, and treating solid residues as solid wastes. The invention adopts a circular cleaning mode, and only generates organic waste liquid with the mass of 0.5-1 time of that of the coking substances.

The invention has the beneficial effects that:

According to the invention, the coked substance in the methyl phosphine dichloride synthesis and trapping system is cleaned by acetonitrile or dioxane, the solvent dosage and the temperature are controlled, the dissolving and dispersing effects are good, insoluble substances are easy to settle, the violent reaction and heating are avoided, and the safety coefficient is high; the invention introduces the settling device comprising the circulating pump and the settling tank to carry out solid-liquid separation, improves the cleaning efficiency, generates a small amount of organic waste liquid, and avoids the trouble of dismantling the pipeline of the trapping system and cleaning the pipelines one by one independently.

Detailed Description

The invention is further explained and illustrated by the process screening examples below.