Degussa Aktiengesellschaft

Evonik Operations Gmbh

Degussa - Huls Ag

Evonik Degussa Gmbh

Hans-Joachim Hasselbach

Klaus Huthmacher

Christoph Weckbecker

Martin Körfer

Jose Vanrobaeys

Herbert Tanner

Harald Heinzel

Bernd Drapal

Klaus Hentschel

Friedhelm Geiger

Martin Korfer

Ferdinand Theissen

Sven-Peter Mannsfeld

Baudouin Halsberghe

Klaus Willigerodt

Harald Jakob

Herbert Klenk

Steffen Krill

Horst Weigel

Ralf Goedecke

Stephan Kretz

Stephan Rautenberg

Axel Ronneburg

Imad Moussallem

Dieter Buss

Hermann Schmitt

Alexander Möller

Rainer Hahn

Volker Hafner

Wolfgang Taugner

Christian Renner

Rainer Peter

Wolfgang Böck

Stefan Reichert

Christian Kaiser

Axel Kleeman

Sebastian Bernhardt

Jürgen Stock

Christian Rückriegel

Johannes Wefer

Tobias Winkler

Danny De Corte

Hans-Albrechl Hasseberg

Benny Hartono

Theo Zarfl

Ron Stockfleth

Gundolf Hornung

Geert Van Eester

Sascha Braune

Claudia Dyballa

Christian RÜCKRIEGEL

The invention relates to a single cycle process for preparing D,L-methionine from an alkali methioninate solution obtained by alkaline hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in which the D,L-methionine is obtained by neutralizing the alkali methioninate solution with carbon dioxide at elevated temperature and subsequently crystallizing D,L-methionine in the presence of seed crystals.

Process for the preparation of D,L-methionine

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

A process for purifying COoffgas streams to free them of chemical compounds, and to the recycling of the purified gas streams into the production process.

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The invention relates to a method for the separation of methyl mercaptan from reaction gas mixtures obtained by means of the catalytic conversion of H2S with methanol, by means of converting the methyl mercaptan into MMP in the presence of the byproducts with acrolein, and separating the same.

Method for the separation of methyl mercaptan from reaction gas mixtures

The present invention is directed to an improved process for producing methionine in which the by-product methionyl-methionine is quickly converted to the product methionine by a hydrolysis reaction. The process is performed at high temperatures (200&#xb0; C. to 280&#xb0; C.) and short residence times (20 s to 200 s) and results in an improved yield of end product methionine.

Process for producing methionine

A process for the preparation of 3,5,5-trimethylcyclohexa-3-en-1-one (&bgr;-isophorone) by isomerization of 3,5,5-trimethylcyclohexa-2-en-1-one (&agr;-isophorone) in the liquid phase in the presence of a salt-like or organometallic catalyst. By using catalytic quantities of alkali-metal salts or alkaline-earth salts and/or their organometallic compounds, and without addition of a further auxiliary substance, the space-time yield in the preparation of &bgr;-isophorone is high. &bgr;-Isophorone is particularly suitable as an intermediate product for the preparation of ketoisophorone.

Process for the preparation of 3,5,5-trimethylcyclohexa-3-en-1-one (&bgr;-isophorone) by isomerization of 3,5,5- trimethylcyclohexa-2-en-1-one (&agr;-isophorone)

A method for obtaining 2-hydroxy-4-methylthiobutyric acid (methionine-hydroxy analog, MHA) in primarily free form which is stable in storage by distilling a product solution containing MHA and by producing MHA product mixtures with improved storage stability from such a distillate. The distillate can be produced directly starting from MHA raw products from any MHA production process, which can optionally also contain solvent or water. The starting material may also be a commercial MHA product.

Method for obtaining 2-hydroxy-4-methylthiobutyric acid (MHA) which is

A process for the preparation of methionine or a salt of methionine by reaction of the components 3-methylmercaptopropionaldhyde, hydrogen cyanide, ammonia and carbon dioxide or components from which the above-mentioned components can be prepared, optionally in the presence of water, to 5-(2-methylmercaptoethyl)-hydantoin and further reaction thereof to methionine or the salt thereof, characterised in that the reaction of the components is initiated by means of at least one premixture in such a way that a first mixture is formed containing at least the predominant proportion (at least 5/10) of the 3-methylmercaptopropionaldeyde and at least 1/10 of the hydrogen cyanide component or corresponding quantities of components from which these components can be prepared, and less than 5/10 of one of the components ammonia, carbon dioxide or of the components from which ammonia or carbon dioxide can be prepared, and in that this first mixture is combined with the other component(s) for the reactive conversion to 5-(2-methylmercaptoethyl)-hydantoin, wherein this (these) latter component(s) may be premixed in one or more other mixtures.

Process for the preparation of D,L-methionine or the salt thereof

Aqueous solutions of free, neutral .alpha.-amino acids are recovered from aqueous solutions of their alkali-metal salts. Two equally large rectifying columns filled with a strongly acidic cation exchanger in the H.sup.+ form are used, the discharge of the first column being connected to the head of the second column. The solution of the alkali-metal salt is at first delivered to the head of the first column, then the residual solution, reduced by the alkali-metal cations adsorbed in the exchanger, is displaced to the second column by means of the addition of water. A product-free forerun is first separated at the discharge of the second column and, when free .alpha.-amino acid begins to exit in the flow-off from the second column, the receiver is changed and the delivery of water to the head of the first column continues further until a mixed pH between 5 and 7 has been achieved in the receiver. Then, the previously first column is decoupled and regenerated, the previously second column, which is now the first column, is coupled to a freshly regenerated column as second column and the entire process is repeated as often as desired.

Method for the recovery of aqueous solutions of free, neutral

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Gelnhausen, Germany

Hans-Joachim Hasselbach