| abstract |
(57) [Summary] [PROBLEMS] By combining distillation and membrane separation, aliphatic carboxylic acids can be efficiently removed from by-products such as water and alcohol unnecessary for the reaction even when the tower height is reduced. A method for producing an aromatic carboxylic acid, which can be separated and recovered well and can be easily treated for wastewater, is obtained. SOLUTION: An alkyl aromatic compound is liquid-phase oxidized with an oxygen-containing gas in a reaction solvent containing an aliphatic carboxylic acid in an oxidation reactor 1 in the presence of an oxidation catalyst to produce an aromatic carboxylic acid under high temperature and high pressure. The oxidation exhaust gas to be introduced is introduced into the distillation column 2 to perform distillation, the fraction containing the reaction solvent is refluxed to the oxidation reactor 1, and the exhaust gas from the distillation column 2 is cooled by the condenser 3 to generate condensed water. The condensed water is membrane-separated by the membrane separation device 8, water and methanol are permeated to the permeate side 15 and the aliphatic carboxylic acid is concentrated and collected in the concentrate side 14. |