Abstract: A process is described for recycling catalysts in the reaction for the oxidation of alcohols and/or ketones to carboxylic acids and more particularly the oxidation of cyclic alcohols and/or cyclic ketones to dicarboxylic acids, such as the oxidation of cyclohexanol and/or cyclohexanone to adipic acid. This process involves treating the solution comprising the oxidation catalyst, before it is recycled, with an ion-exchange resin which makes it possible to selectively separate the iron from the other metal elements, in particular from copper and from vanadium.

Abstract: The invention relates to a process for selectively separating iron from other metal ions, in particular ions present in certain oxidation catalysts. It also relates to a process for recycling catalysts in the reaction for the oxidation of alcohols and/or ketones to carboxylic acids and more particularly the oxidation of cyclic alcohols and/or cyclic ketones to dicarboxylic acids, such as the oxidation of cyclohexanol and/or cyclohexanone to adipic acid. This process consists in treating the solution comprising the oxidation catalyst, before it is recycled, with an ion-exchange resin which makes it possible to selectively separate the iron from the other metal elements, in particular from copper and from vanadium.

Abstract: The invention concerns a method for evaporating aminonitrile and water in conditions limiting or eliminating the formation of heavy by-products in particular amino-carboxylic acid oligomers. To avoid said inconvenience, said method for evaporating aminonitrile and water is characterised in that the water in vapour state serves as balance gas for evaporation.

Abstract: The present invention relates to a process for the manufacture of adipic acid, more particularly of adipic acid crystals. It relates more specifically to a process for the treatment of the adipic acid crystals obtained on conclusion of crystallization, which consists in dispersing the adipic acid crystals collected on conclusion of crystallization in a liquid medium, in stirring the said liquid medium and in then separating the said crystals from the said liquid medium and optionally drying them. The form of the crystals is modified in order to obtain pebbles with a substantially smooth surface.

Abstract: The invention relates to a process for selectively separating iron from other metal ions, in particular ions present in certain oxidation catalysts.

Abstract: The present invention relates to the treatment of the reaction mixtures resulting from an oxidation reaction of cyclohexane to adipic acid and more particlarly to the separation of the various constituents of the said mixtures and to the purification of the adipic acid.

Abstract: The present invention relates to a process for regenerating a catalyst for the cyclizing hydrolysis of an aminonitrile for the manufacture of lactams. It relates more particularly to the regeneration of the solid catalysts used in the processes for producing lactams by the cyclizing hydrolysis of aminonitriles. This regeneration process consists in treating the spent catalyst or the catalyst at the end of the cycle at a temperature of between 300° C. and 600° C. with an oxidizing atmosphere.

Abstract: The present invention relates to a process for separating the water from an aqueous lactam solution. It applies more particularly to a mixture resulting from the reaction between an aminonitrile and water (this reaction also being called cyclizing hydrolysis). The subject of the invention is a process for separating the water from an aqueous lactam solution, which process is economical both from the standpoint of the investment necessary for its implementation and from the standpoint of the operating cost.

Abstract: Water-soluble sulfonated organophosphorus compounds are purified by at least partially removing contaminating sulfite values therefrom, by decreasing the pH of a solution of such sulfonated organophosphorus compounds to a value of less than or equal to 4, and maintaining the pH of the solution at this value of 4 or less for such period of time as to reduce the weight concentration of sulfite in the solution to less than 100 ppm; the organophosphorus compounds thus purified are well suited for the two-phase cocatalysis of a wide variety of organic reactions.

Abstract: The present invention relates to an improved process for processing the reaction mixture from the direct oxidation of hydrocarbon into carboxylic acid, using molecular oxygen or a gas containing it, in the liquid phase, in a solvent and in the presence of a catalyst dissolved in the reaction medium, characterized in that the said process comprises: when the composition of the reaction mixture allows it, a decantation into two liquid phases: a nonpolar upper phase and a polar lower phase; a distillation of the said lower phase or, where appropriate, of all of the reaction mixture, thus separating, on the one hand, a distillate and, on the other hand, the distillation residue comprising the acids formed, the catalyst, the heavy compounds, at least some of the solvent and, if any, the reaction intermediates and side products; a purification treatment by oxidation, using molecular oxygen or a gas containing it or using oxygen donors, of the distillation residue obtained above, a distillation of the reaction s

Abstract: The present invention relates to a process for the crystallization of carboxylic acid, more particularly adipic acid, and a process for manufacturing crystalline carboxylic acid, more specifically a process for treating the reaction medium resulting from the direct oxidation of a hydrocarbon into carboxylic acid such as adipic acid, for example. More specifically, the invention relates to the crystallization of adipic acid from an organic solvent, thus removing the organic impurities contained in the said acid and thus optionally facilitating its purification by a crystallization from water.

Abstract: The present invention relates to a process for the purification of aliphatic aminonitriles and more particularly of 6-aminocapronitrile. It consists more specifically in subjecting 6-aminocapronitrile to a hydrogenation with molecular hydrogen in the presence of a catalyst comprising at least one metal chosen from palladium, platinum, ruthenium, osmium, iridium or rhodium and a promoter agent or a preconditioning in order to improve the selectivity of the hydrogenation.

Abstract: The invention discloses a method for purifying adipic acid by crystallization or recrystallization in at least one carbolyxic acid. More precisely, it discloses an improvement in adipic acid crystallization or recrystallization, characterised in that the said crystallization or recrystallization is effected in at least one carboxylic acid with a melting point below 20° C. The presence of carbon monoxide during crystallization or recrystallization can have a favourable effect on the adipic acid purity, in particular by reducing the content of metal catalyst traces of the adipic acid. The adipic acid purity can also be improved when the crystallization or recrystallization is effected in presence of a strong proton acid.

Abstract: The invention concerns the hydrogenation in amine function of a nitrile function of a dinitrile to obtain the corresponding aminonitrile. More precisely, the invention concerns the hemihydrogenation of a dinitrile into the corresponding aminonitrile, in a liquid medium, characterized in that it consists in operating in the presence of a Raney nickel or cobalt catalyst containing copper and/or silver and/or gold and in the presence of an alkaline or alkaline-earth metal hydroxide. The hemihydrogenation of adiponitrile provides amino-6 capronitrile, compound which can be easily transformed by cyclization hydrolysis into caprolactam, the starting product for the synthesis of polyamide-6.

Abstract: The invention concerns a method for regenerating a hydrogenation catalyst, and hydrogenation methods carried out with a catalyst comprising at least one regenerated catalyst. More particularly, it concerns a method for regenerating Raney catalysts used in total or partial hydrogenating processes of compounds comprising nitrile functions into amine functions. Said method consists in treating the spent catalyst with a basic solution and optionally in subjecting said catalyst to hydrogenation before stripping to eliminate the impurities present on the catalyst. Thus, the regenerating method enables to recuperate up to 100% of the catalytic activity.

Abstract: The invention concerns novel organometallic complexes comprising cationic heterocyclic carbenes. It also concerns a method for preparing said complexes from dicationic heterocyclic precursor compounds. It further concerns the use as catalysts of said organometallic complexes for a certain number of chemical reactions.

Abstract: The present invention relates to an improved process for distilling ammonia from a mixture, more particular from a mixture resulting from the reaction between aminonitrile and water (which reaction is also called cyclizing hydrolysis). The process for distilling the ammonia contained in an aqueous caprolactam solution, uses a column with a bottom temperature less than or equal to 160° C. and at an absolute pressure less than or equal to 5 bar, the ammonia distilled at the top of the column being compressed to a pressure greater than or equal to 10 bar and then condensed at a temperature of 25° C. to 60° C.

Abstract: The invention relates to a process for the cyclizing hydrolysis of an aminonitrile compound into a lactam in the presence of a catalyst. The invention relates more particularly to a process for the cyclizing hydrolysis of an aminonitrile compound in the presence of a macroporous particulate catalyst obtained by deposition/impregnation of an oxygenated compound onto a macroporous support such as alumina. The invention applies in particular to the preparation of &egr;-caprolactam by cyclizing hydrolysis of aminocapronitrile.

Abstract: A method for filtering a three phase reaction mixture comprising a liquid phase, an undissolved solid catalytic phase and a gas phase includes tangentially filtering through a membrane filter at least part of the three phased reaction mixture, and recycling the catalyst while recuperating at least part of the filtrate comprising the reaction products.

Abstract: Ethylenically unsaturated organic compounds, for example diolefins, olefinic nitriles and monoolefins, are noncontaminatingly hydrocyanated into corresponding nitriles by (a) reacting such ethylenically unsaturated organic compounds with hydrogen cyanide in the presence of an aqueous solution containing a catalytically effective amount of a catalyst which comprises at least one nickel compound and at least one water-soluble phosphine, (b) thereafter separating the organic phase from the aqueous phase which result, the separated aqueous phase comprising a solid phase formed during hydrocyanation, and (c) thence treating the separated aqueous phase, or a solid phase removed therefrom, with hydrogen cyanide to thus at least partially dissolve said solid phase contained therein or removed therefrom.