Rhodia Operations

Rhodia Polyamide Intermediates

Philippe Carvin

Jean-Claude Masson

Fabien Bellenger

Jean-Louis Grieneisen

Stéphanie Foucher

Serge Crottier-Combe

Christine Villard

A plant for the crystallization of adipic acid is described. A plant for the crystallization of adipic acid, some parts of which are made of a corrosion-resistant material, is also described. The corrosion-resistant material used can be a reference austenitic stainless steel of AISI 310L type, according to the AISI (USA) nomenclature, or X1 CrNi 25-21 (1.4335) type, according to the European nomenclature.

Plant for the crystallization of adipic acid

A method for producing crystals of adipic acid is described. In particular, a method for recovering adipic acid in the form of crystals with low impurity content, obtained by crystallization steps in particular using reaction media for synthesizing adipic acid is described. A purification method including a step of crushing the crystals for easier removal or the migration of the impurities in the crystals is also described.

Process for producing adipic acid crystals

The present invention relates to an improved process for preparing a fluid concentrated ingredient based on crystals based on a fatty acid ester, and also to the use of this fluid concentrated ingredient.

Process for preparing crystals based on a fatty acid ester

Hydroquinone devoid of impurities is prepared from a crude hydroquinone essentially containing hydroquinone and small amounts of impurities including at least resorcinol, pyrogallol and traces of pyrocatechol and comprises at least the following steps: dissolving the crude hydroquinone in water, crystallizing the hydroquinone, separating the purified hydroquinone, and, optionally, drying the purified hydroquinone.

Preparation of purified hydroquinone

A process is described for purifying lactams, in particular the lactams obtained by cyclizing hydrolysis of an aminoalkylnitrile, and more particularly to the purification by crystallization of &#x3b5;-caprolactam obtained by cyclizing hydrolysis of aminocapronitrile. This crystallization is carried out on the cyclization reaction medium after hydrogenation, removal of volatile compounds, and treatment with an ion-exchange resin.

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Lyons, France

Philippe Carvin