EXTRACTION METHOD OF REMOVING IMPURITIES FROM MOTHER SOLUTION DURING SYNTHESIS OF CARBONIC ACID (VERSIONS) Russian patent published in 2009 - IPC C07C51/48 B01J23/92 

FIELD: chemistry.

SUBSTANCE: present invention pertains to extraction of a metallic catalyst from a mother solution, obtained during synthesis of carbonic acid, usually terephthalic acid. In the first version, the method of separating metallic catalyst from a stream of mother solution involves the following stages: (a) evaporation of the mother solution, containing carbonic acid, the metallic catalyst, impurities, water and a solvent, in the zone of the first evaporator, obtaining a vapour, containing water and solvent, and concentrated mother solution; (b) evaporation of the concentrated mother solution in the zone of the second evaporator, where evaporation in the zone of the second evaporator is carried out at 150-220°C temperature, forming a stream rich in solvent and a stream of super-concentrated mother solution in molten dispersion state, where a total of 95-99 wt % of solvent and water is removed from the mother solution during evaporation stages (a) and (b); (c) mixing the water-solvent solution in the mixing zone, with super-concentrated mother solution, forming an aqueous mixture; (d) separation of organic impurities in the aqueous mixture in the separation zone of solid substance/liquid phase, forming a pure aqueous mixture; (e) addition of extraction solvent to the aqueous mixture or pure aqueous mixture in the extraction zone, forming an extract or rafinate, containing the metallic catalyst; and (f) separation of the extract and the solvent rich stream in the separation zone, forming a stream of organic impurities with high boiling point and a stream of extraction solvent. The invention has three versions.

EFFECT: extraction of expensive metallic catalyst in active form, suitable for repeated use, and acetic acid, contained in the mother solution with removal of most impurities present in the extracted stream.

20 cl, 1 tbl, 1 dwg