Rhodia Polyamide Intermediates

Rhodia Operations

Invista Technologies S.a.r.l.

Daniel Amoros

Philippe Leconte

Pierre Coqueret

Maria Ignez Broglio

Jean-Pierre Simonato

Frédéric Augier

Didier Bonnet

Didier Letourneur

Jean Vannier

Dider Letourneur

Denis Rachez

Jérôme Gerber

Mathias Brehelin

Alexandre Tresmondi

Impure hexamethylenediamines and more particularly those hexamethylenediamines containing contaminating amounts of tetrahydroazepine (THA), or more generally contaminating amounts of imines, are purified by distillation carried out with a short retention time of the impure hexamethylenediamine in the distillation column; the hexamethylenediamine obtained has a very low concentration of THA.

Purification of impure hexamethylenediamines

A method and a plant are disclosed for purifying lactams, particularly lactams obtained by cyclizing hydrolysis of aminonitrile. The purification of &#x3b5;-caprolactam obtained by cyclizing hydrolysis of aminocapronitrile is described which includes eliminating the ammonia from the reaction medium of the hydrolysis, then recovering the lactam from the medium in purified form. The recovery is carried out by performing at least a distillation of the lactam in the presence of a base producing optionally a fronts fraction having compounds more volatile than the lactam, a fraction having the lactam to be recovered to the degree of desired purity and a distillation tails having the lactam and compounds less volatile than the lactam. The distillation tails are treated by various processes such as evaporation in thin layers to recover the major part of the caprolactam and recycling the latter in the purification process.

Process for the purification of lactams

Primary diamines are prepared by hydrogenation of a dinitrile compound in the presence of a catalyst, in particular hexamethylenediamine is prepared by hydrogenation of adiponitrile; the product diamines are recovered by distillation in several distillation columns mounted in series and the heavy impurities are separated from the second distillation.

Preparation of primary diamines

The present invention relates to a process for producing carboxylic acids. It relates more particularly to a process for producing carboxylic acids by oxidation of a hydrocarbon with oxygen or a gas containing oxygen, and even more particularly to the oxidation of cyclohexane to adipic acid. The invention relates to a process for producing carboxylic acids by oxidation with oxygen or a gas containing oxygen of a cycloaliphatic hydrocarbon in the presence of an oxidation catalyst and of a monocarboxylic oxidation solvent that is lipophilic in nature, comprising a step of extraction of the dicarboxylic acids formed in the oxidation step, consisting in carrying out, in liquid phase, an extraction of the diacids using water.

Method for making carboxylic acids

The present invention relates to a process for the manufacture and separation of dinitrile compounds. It relates more particularly to a process for the manufacture and separation of dinitrile compounds from a medium originating from the hydrocyanation of unsaturated mononitriles. The invention consists in feeding the medium comprising the dinitriles to a distillation column and then recovering the purified dinitriles as intermediate fraction, the heavy products being removed as column tail fraction and the light products, including the unsaturated mononitriles, being recovered as top fraction.

Method of producing and separating dinitrile compounds

A method and a plant are disclosed for purifying lactams, particularly lactams obtained by cyclizing hydrolysis of aminonitrile. The purification of &#x3b5;-caprolactam obtained by cyclizing hydrolysis of aminocapronitrile is described which includes eliminating the ammonia from the reaction medium of the hydrolysis, then recovering the lactam from said medium in purified form. The recovery is carried out by performing at least a distillation of the lactam in the presence of a base producing optionally a fronts fraction comprising compounds more volatile than the lactam, a fraction comprising the lactam to be recovered to the degree of desired purity and a distillation tails comprising the lactam and compounds less volatile than the lactam. The distillation tails are treated by various processes such as evaporation in thin layers to recover the major part of the caprolactam and recycling the latter in the purification process. The method and plant enables a high rate of recovery of the caprolactam contained in the hydrolysis medium, while observing required criteria of purity.

Growing community of inventors

Venissieux, France

Daniel Amoros