| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing aromatic carboxylic acids in which it is possible to simplify and miniaturize the structure of an agitator so as to reduce vibration and driving force, to effectively utilize the space of a reactor and the upper part of a crystallization vessel and also to enlarge a reactor and a crystallization vessel. SOLUTION: When forming aromatic carboxylic acid crystals by the liquid- phase oxidation of an alkylaromatic compound with oxygen-including gas in the presence of an oxidation catalyst in a reaction solvent including an aliphatic carboxylic acid in an oxidation reactor, followed by extracting slurry including the crystals to purify the crystals, by recrystallizing the crystals in a crystallization vessel and by recovering the crystals from the slurry subjected to recrystallization, the oxidation reactor or crystallization vessel of this invention is equipped with an agitation vessel having an agitating element in its lower part, from which the shaft of an agitator extends to the space below the vessel by passing through the lower wall of the vessel. The agitation is performed in a controlled state that the average particle diameter of crystals included in the slurry in the agitation vessel is maintained to be <=500μm and the concentration of the slurry is maintained to be <=60 wt.%.
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