Method for environment-friendly clean production of D,L-methionine

A method for environment-friendly clean production of D,L-methionine includes: performing alkaline hydrolysis of 5-(2-methylmercaptoethyl)-hydantoin to obtain carbonate-containing methionine alkali metal saponified solution; then feeding carbon dioxide, crystallizing, and separating to respectively obtain methionine and hydrocarbonate water solution of methionine; subjecting the hydrocarbonate water solution of methionine to chromatographic separation. The method has advantages that loss of D,L-methionine due to pyrolysis can be reduced, simplicity in operation, low cost and high utilization rate of raw materials are realized, high efficiency in acquisition of high-purity methionine crystals is achieved, the purity of the obtained methionine is up to 99.4%, the methionine recovery rate reaches 97%, and the desalinization rate reaches 98% or above. In addition, accumulation of a great quantity of impurities of methionine-containing potassium bicarbonate mother liquor and emission of the potassium bicarbonate mother liquor are avoided, discharge of saline wastewater is avoided, and accordingly environment friendliness and clean production are realized. In a whole process, potassium carbonate serving as a hydrolysis agent is recycled without loss, and replenishment of alkaline potassium compounds is avoided.