Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A process for the manufacture of adipic acid carried out in devices made of material resistant to the corrosion of the synthesis medium is described. A process for the manufacture of adipic acid carried out in devices, some of which are made of a material resistant to corrosion by nitric acid, is also described. The corrosion-resistant material can be a “duplex” austenoferritic stainless steel of X2 CrNiN 23-4 (1.4362) type, according to the European nomenclature.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 ?-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.

Abstract: The invention relates to a method for purifying lactames, especially lactames obtained by cyclization hydrolysis of an aminoalkylnitrile, and more particularly, to the purification of &egr;-caprolactame obtained by cyclization hydrolysis of the aminocapronitrile. This crystallisation process can either be carried out directly on the cyclization reaction medium after removal of the volatile components or on a medium that has been subjected to different treatments or on a caprolactame extracted from the reaction medium, for example by distillation.