Preparation method for glyphosate

Abstract

A preparation method for glyphosate comprises the steps as follows: oxydol is adopted for catalytic oxidation of a pmida raw material to obtain oxidation liquid, sulfide reductant with weaker reducibility is added into the oxidation liquid to consume excess oxydol in the oxidation reaction, then ferrous sulfate is added for reduction, and finally separation and drying are conducted so as to prepare the glyphosate; and the sulfide reductant with the weaker reducibility is any one or any combination of sodium sulfite, ammonium sulfite, potassium sulfite, ammonium bisulfite, sodium thiosulfate and sodium bisulfite. According to the method provided by the invention, the amount of the ferrous sulfate reductant is low, so as to save the raw material cost; the technical problem that the glyphosate prepared by the process in the prior art is yellowish is solved due to oxidation, reduction and other treatments in the method; meanwhile, the purity of the glyphosate prepared by using the method is high, the content of the glyphosate in solid powder is more than 96 percent, and the yield is more than 82 percent; and through the adoption of the method, the consumption of raw and auxiliary materials is lower, ammonia water, sulfuric acid and other raw materials are not used in the process.

Description

technical field [0001] The invention relates to a preparation method of glyphosate, in particular to a preparation method of glyphosate with high yield, and belongs to the field of chemical synthesis. Background technique [0002] Glyphosate is a high-efficiency, low-toxicity, post-emergent herbicide, and its sales volume occupies an important position in pesticide products. Glyphosate was originally synthesized by Monsanto Chemical Company of the United States; the current production process of glyphosate mainly includes glycine Method and IDA method two process routes. [0003] Glycine method is a traditional production process in my country that started earlier. After years of development, the process technology has matured, but the process has the following disadvantages: long process route, complicated process, many by-products, a large amount of organic recovery solvents are used in the process, and environmental pollution. The impact is large and the energy consumptio...

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Problems solved by technology

[0003] Glycine method is a traditional production process in my country that started earlier. After years of development, the process technology has matured, but the process has the following disadvantages: long process route, complicated process, many by-products, a large amount of organic recovery solvents are used in the process, and environmental pollution. The impact is large and the energy consumption is also large, which is not conducive to industrial production. The glyphosate powder is directly obtained by the glycine method. In this method, the solid-liquid separation mother liquor is used to produce the water preparation, and the NaCl content in the produced water preparation is high. If the dosage is large Cause negative effects such as land compaction, which is not good for the environment

Among them, the air oxidation method using precious metals as catalysts is the method adopted by Monsanto, the leader in glyphosate production. The glyphosate obtained by this method has a high content and a purity of up to 97%, and the selectivity and conversion rate of the reaction are also very good. Good, the yield is as high as 96%, but precious metals are expensive in this method, difficult to recycle, and the catalyst is easily deactivated. The most important thing is that this method is a patent of Monsanto, and it is urgent to develop a new process due to its patent restrictions; patent documents CN1183100A, CN1480460A, CN1066152C have reported to take active carbon as catalyst, the method for preparing glyphosate by hydrogen peroxide oxidation, the catalyst used in this method is cheap and easy to get, but its active carbon used is an amorphous state, and different preparation methods and raw material sources lead to its performance The difference is large, and the effect of activated carbon is poor, which will easily lead to fluctuations and instability in production, and is not suitable for industrial production; the patent document CN1563021A discloses a redox system using sodium tungstate as a catalyst and hydrogen peroxide-ferrous sulfate, but the method The existing defects are: 1. Improper control of the oxidation reaction, no treatment of the excess oxidant after the completion of the oxidation reaction, and excessive temperature control of the reduction reaction, causing a large number of subsequent side reactions to occur, affecting product quality and yield; 2. The iron ion introduced in the reduction process makes the color of the product turn yellow, which seriously affects the quality of the glyphosate produced; 3, the yield of the raw glyphosate powder produced by this method is low, only about 68%, and the amount of waste water is large , complex ingredients, difficult to handle, etc.

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