Evonik Degussa Gmbh

Evonik Operations Gmbh

Evonik Industries Ag

Stefan Reichert

Harald Jakob

Hans Joachim Hasselbach

Martin Koerfer

Bernd Drapal

Rainer Peter

Klaus Huthmacher

Christoph Weckbecker

Horst Krull

Hans-Joachim Hasselbach

Martin Körfer

Christian Kaiser

Sebastian Bernhardt

Benny Hartono

A process for preparing methionine includes the alkaline hydrolysis of 5-(2-methylmercaptoethyl)-hydantoin (methionine hydantoin) in an aqueous process solution containing alkali metal hydroxide and/or alkali metal carbonate and/or alkali metal hydrogencarbonate. The alkali metal cations in the process solution are potassium and sodium having a K/Na molar ratio range from 99/1 to 20/80.

Process for preparing methionine

The invention relates to a method for crystallizing D,L-methionine from aqueous solutions and/or suspensions containing D,L-methionine and D,L-methionine ammonium salts, having a Met content of 70-180 g/kg, an NHcontent of 1-5 g/kg, in the presence of a crystallization additive, which comprises a nonionic or anionic surfactant or a mixture of various nonionic or anionic surfactants, in which the temperature of the solution and/or suspension is lowered directly or stepwise from T=85-110&#xb0; C. to T=30-50&#xb0; C., so that D,L-methionine precipitates as a solid.

Process for obtaining methionine

This disclosure relates to a process for preparing D,L-methionine by feeding carbon dioxide to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified. In this process an aqueous solution of the separated-off crude methionine is purified by recrystallization from a solution containing potassium ions and also a crystallization additive. The crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants. The recrystallization occurs by introducing a 60 to 110&#xb0; C.-hot methionine solution into a 35 to 80&#xb0; C.-warm methionine suspension, a temperature of which is lower than that of the introduced solution, such that the temperature of the methionine suspension being maintained between 35 and 80&#xb0; C. during the addition. The crystallization additive is a sorbitan fatty acid ester or a mixture of different sorbitan fatty acid esters.

Process for the preparation of methionine

The invention relates to a process for the preparation of D,L-methionine, in which carbon dioxide is fed to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified, where, for the purposes of purification, an aqueous solution of the separated-off crude methionine is prepared and subjected to a recrystallization, characterized in that the solution from which the recrystallization takes place contains potassium ions and also a crystallization additive, where the crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants, and that the recrystallization takes place by introducing a 60 to 110&#xb0; C.-hot methionine solution into a 35 to 80&#xb0; C.-warm methionine suspension, the temperature of which is lower than that of the introduced solution, the temperature of the methionine suspension being maintained between 35 and 80&#xb0; C. during the addition.

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Frankfurt-am-Main, Germany

Stefan Reichert