| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method of terephthalic acid including a catalyst recovery process using a pyridine ring-containing chelate resin column, the method for efficiently suppressing concentration fluctuations in a recovered catalyst liquid without using an expensive measurement and control device, decreasing concentration fluctuations of the catalyst component in a catalyst preparation tank to which the recovered catalyst liquid is returned, and thereby, stabilizing a liquid phase oxidation reaction and obtaining terephthalic acid with stable qualities.SOLUTION: The method includes comprises: cooling an oxidation reaction slurry obtained by liquid phase oxidation by continuous multi-stage crystallization; separating the cooled slurry into a terephthalic acid crystal and an oxidation reaction mother liquid by a solid-liquid separation operation; circulating 70 to 98% of the obtained oxidation reaction mother as a recycling mother liquid to a catalyst preparation tank for the liquid phase oxidation, while recovering a catalyst component from the rest of the oxidation reaction mother liquid. In the recovering process, a recovered catalyst liquid tank is installed, in which the recovered catalyst liquid from the chelate resin column is retained for 1.5 to 6 hours, and then the liquid is circulated in the liquid phase oxidation reaction system. |
