Method for purifying and recovering methyl chloride of glyphosate byproduct

Abstract

The invention discloses a method for purifying and recovering a byproduct of glyphosate, namely chloromethane. The method comprises a step of washing with an organic solvent before washing with water, i.e. the step of absorbing methylal, methanol, etc. in a chloromethane mixture gas produced during the process for preparing glyphosate by an alkyl ester method by the organic solvent. The method can solve the problem of environment pollution resulting from glyphosate and water washing as well as alcohol washing for recovering chloromethane, and can reduce the comprehensive cost for recovering chloromethane and glyphosate, improve the recovery rates of chloromethane and glyphosate and achieve large circulation of alcohol washing mixture and water for the water washing until authentically achieve the zero emission of waste water.

Description

technical field [0001] The present invention relates to a method for purifying and recovering methyl chloride, in particular to a method for purifying and recovering hydrolysis tail gas in the process of synthesizing glyphosate acid by alkyl method and producing alkyl ester by-product methyl chloride, especially its pretreatment process . Background technique [0002] Glyphosate is the herbicide with the largest sales volume and the fastest growth rate in the world. At present, the total production of glyphosate technical products in the world has reached 300,000 tons, and with the successful development and popularization of glyphosate-resistant transgenic crops , opened up a new field for the development of glyphosate. There are two main methods for global glyphosate industrial production: one is the IDA method adopted by Monsanto Company of the United States; the other is the alkyl ester method adopted by most domestic enterprises. [0003] The preparation of glyphosate...

AI Technical Summary

Problems solved by technology

However, this process has some shortcomings in recovery rate and environmental protection: ① The quality of recovered methyl chloride is not good

In this process, methylal and methanol are removed by washing with water, but due to the immiscibility of methylal and water, coupled with the influence of mass transfer rate, the methylal content in the obtained methyl chloride product is still high. In the process of methyl chlorosilane, it reacts with the target product to form a polymer or pyrolyzes to coke and carbonize the surface of the catalyst, thus affecting production

②The amount of washing water is large, resulting in a large amount of wastewater treatment and polluting the environment

Since methylal is not miscible with water, a large amount of water needs to be used for washing. Usually, one ton of methyl chloride needs to consume nearly 6 tons of washing water. The large amount of waste water generated will cause high treatment costs and increase the pressure on environmental protection.

③ Low recovery rate

Need to wash with a large amount of water in order to guarantee the product quality of methyl chloride, but methyl chloride also has certain solubility (0.38 g / liter) in water, and the solubility loss of methyl chloride caused by washing water increases greatly, has influenced recovery rate

④Waste of Methanol and Methylal Resources

In this method, due to the large amount of impurity gases such as methanol, methylal, and water in the mixed gas of methyl chloride, the amount of adsorbent required is very large, and the regeneration process of the adsorbent not only needs to consume a large amount of energy, but also As a result, the adsorbate pollutes the atmosphere. In addition, methylal needs to be desorbed from the adsorbent. The obtained desorbed gas has complex components and needs to be obtained by rectification. The recovery is difficult and costly.