METHOD FOR PRODUCING AROMATIC CARBOXYLIC ACID

摘要

A method for producing an aromatic carboxylic acid, which includes (A) an oxidation step of oxidizing an alkylaromatic compound under a pressure higher than an ordinary pressure, in an acetic acid solvent, in the presence of a catalyst, at 140 to 230˚C, to form an aromatic carboxylic acid, (B) a solid-liquid separation step of subjecting a slurry containing crystals of the above aromatic carboxylic acid formed to a solid-liquid separation into the aromatic carboxylic acid and a mother liquor under a pressure higher than an ordinary pressure, (C) a mother liquor recycling step of dividing the above mother liquor into two portions, while retaining a pressure higher than an ordinary pressure, and feeding the one of the two portions back to the above oxidation step (A), and (D) a concentration step of concentrating the other portion being divided in the above mother liquor recycling step (C), wherein in the above concentration step (D), the pressure of the mother liquor is released to a pressure not higher than the vapor pressure thereof at the temperature thereof, to thereby vaporize a part of the mother liquor, concentrate the mother liquor, and precipitate the aromatic carboxylic acid, and then the precipitated aromatic carboxylic acid is recovered. The above method allows the efficient utilization of the energy being held by the separated mother liquor and also the recovery of a useful component.