Method and device for preparing methionine and recovering by-product-carbon dioxide

Abstract

The invention discloses a method for preparing methionine and recovering a by-product-carbon dioxide. The method comprises the steps that a methionine salt and carbonate mixed solution obtained by hydrolyzing methylmercapto-ethyl hydantoin with alkali is filtered through a microporous membrane, and then filtrate is delivered to a bipolar membrane electrodialysis system to be subjected to electrodialysis treatment, so that acid liquor A and alkali liquor A are obtained; the alkali liquor A is treated continuously and cyclically, and the acid liquor A is subjected to gas-liquid separation, so that gaseous carbon dioxide and acid liquor B are obtained; the acid liquor B is delivered back into the bipolar membrane electrodialysis system to be subjected to cyclic treatment till the pH value of the acid liquor B is 3.8-4.5, the reaction is completed, a methionine solution is prepared, and the methionine is prepared through concentration and crystallization of the methionine solution; the gaseous carbon dioxide is introduced into an absorption cell, and carbon dioxide on the upper portion of the absorption cell absorbs mother liquor, is subjected to membrane distillation and concentration and then is circulated back to the absorption cell; carbonate crystals are grown at the bottom of the absorption cell and guided out from the bottom of the absorption cell; and carbonate is recovered through solid-liquid separation. According to the method for preparing the methionine and recovering the by-product-carbon dioxide, the gaseous carbon dioxide is recycled, so that carbon emission is reduced, and energy resources are saved through the membrane distillation technique.

Description

Technical field [0001] The invention relates to the application of an integrated membrane technology in the chemical industry, in particular to a method for preparing methionine by bipolar membrane electrodialysis and treating by-product carbon dioxide by membrane distillation. Background technique [0002] Methionine is an essential amino acid for the human body and is widely involved in various metabolic activities in the body. Methionine cannot be synthesized by itself in animals and needs to be ingested from food. Adding it to feed can promote the growth of poultry and livestock, increase the amount of meat, and shorten the feeding cycle. In addition, it is also widely used in medical nutrition, food additives, etc. The current global annual production capacity is about 1 million tons. In recent years, the demand for methionine has increased by 4%, while the demand for methionine in my country has increased by 7%. [0003] The existing process flow for synthesizing methionin...

AI Technical Summary

Problems solved by technology

However, according to these methods, the production process is still not completely zero emission

Usually the content of carbonate by-products in the hydrolyzate is 10% to 15%, so it is estimated that the lost carbon dioxide accounts for about 4.2% to 6.2% of the total material. In addition, the concentration of alkali produced in the process is about 6%. The hydrolysis process of meth

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