METHOD OF REMOVING IMPURITIES FROM MOTHER LIQUIDS DURING SYNTHESIS OF CARBOXYLIC ACID USING PRESSURE FILTRATION Russian patent published in 2010 - IPC C07C51/42 C07C51/43 C07C63/26 B01D33/06 B01D11/04 B01D24/46 B01D33/44 B01D33/58 B01J31/40 

FIELD: chemistry.

SUBSTANCE: method involves, for example: (a) evaporation of said oxidised discharge stream, containing terephthalic acid, metallic catalyst, impurities, water and solvent, in the first zone of an evaporator to obtain a vapour stream and a concentrated suspension of the discharge stream; and (b) evaporation of the said concentrated suspension of the discharge stream in the second zone of the evaporator to obtain a stream rich in solvent and a high-concentration suspension of the discharge stream, where the said second zone of the evaporator has an evaporator operating at temperature ranging from 20°C to 70°C, where from 75 to 99 wt % of the said solvent and water is removed by evaporation from the said oxidised discharge stream at step (a) and (b); (c) the said high-concentration suspension of the discharge stream is filtered in a zone for separating solid products and liquid to form a filtered product and a mother liquid; (d) washing the said filtered product using washing substances fed into the said zone for separating solid products and liquid to form a washed filtered product and washing filtrate; and dehydration of the said filtered product in the said zone for separating solid products and liquid to form a dehydrated filtered product; where the said zone for separating solid products and liquid has at least one pressure filtration device, where the said pressure filtration device works at pressure ranging from 1 atmosphere to 50 atmospheres; (e) mixing water and optionally extractive solvent with the said mother liquid and with all of the said washing filtrate or its portion in the mixing zone to form an aqueous mixture; (f) bringing the extractive solvent into contact with the said aqueous mixture in the extraction zone to form a stream of extract and a purified stream, where the said metallic catalyst is extracted from the said purified stream.

EFFECT: improved method of extracting metallic catalyst from an oxidised discharge stream obtained during production of terephthalic acid.

36 cl, 3 dwg, 2 tbl, 2 ex