Carbon Dioxide → (+-)-Methionine

Participants

Reaction Steps

686 l per hour of an aqueous solution with 83.6 kg of potassium D,L-methioninate (hydrolysis solution of 5-(2-methylmercaptoethyl)-hydantoin) with additionally 39.77 kg of recycled methionine and potassium compounds are fed in continuously at the top of a stirred reactor 10 with a capacity of 340 l. At the same time, carbon dioxide is fed in at the bottom of the reactor so that a pressure of 2-3 bar is carried in the reactor. Similarly, 0.38 kg per hour of defoaming agent are fed into the reactor in the form of an aqueous emulsion; this quantity corresponds to approximately 3940 ppm of defoaming agent per kilogram of total methionine. The reaction temperature is kept at 25° C. In order to keep a constant level in the reactor, quantities of reaction solution corresponding to the inflow are removed from the lower part of the reactor. The suspension removed is filtered, 66.5 kg per hour of solid D,L-methionine (calculated as dry substance) being obtained, and the mother liquor with a residual content of 39.77 kg of D,L-methionine can be recycled to the hydantoin hydrolysis stage as saponification agent. The yield is quantitative.

Provenance & Evidence