METHOD OF RECYCLING A CATALYST IN A REACTION INVOLVING THE DIRECT OXIDATION OF CYCLOHEXANE INTO ADIPIC ACID

摘要

Method of recycling a cobalt-containing catalyst in a reaction involving the direct oxidation of cyclohexane into adipic acid using an oxygen-containing gas. The method is characterized in that the reaction mixture, obtained in a preceding stage where the cyclohexane was oxidized into adipic acid, of which at least part of the intermediate oxidation products, such as cyclohexanol and cyclohexanone, the carboxylic acid solvent and water has been separated and of which at least part of the adipic acid formed has been recovered by crystallization, undergoes at least one extraction operation using at least one cosolvent or a mixture comprising a cosolvent and a carboxylic acid. The method is also characterized by the separation of a mixture containing at least part of the cobalt catalyst, part of the carboxylic acid and optionally residual quantities of other compounds and a solution containing the cosolvent and at least part of the glutaric and succinic acids formed during the oxidation reaction, and the carboxylic acid. The mixture containing at least part of the cobalt catalyst is involved in a novel operation for oxidizing cyclohexane into adipic acid, optionally after the addition of an additional quantity of the cobalt catalyst.