METHOD FOR PRODUCING HIGH-PURITY TEREPHTHALIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method for producing high-purity terephthalic acid without deteriorating its quality in which the amount of virgin water used in the process is reduced. SOLUTION: This method for producing high-purity terephthalic acid comprises the following process: p-xylene is oxidized by molecular oxygen in a liquid phase to obtain a reaction product containing crude terephthalic acid, which is then further oxidized by molecular oxygen at a temperature higher than that of the first oxidation without feeding any additional p-xylene to produce a slurry containing higher-purity terephthalic acid. Terephthalic acid is then separated as solid from the slurry and dissolved in a water- containing liquid to produce a solution, which is hydrogenated in the presence of a catalyst. The reaction product yielded is subjected to solid/liquid separation, thus obtaining high-purity terephthalic acid. Furthermore, at least part of the liquid component of the solid/liquid separation is returned to the hydrogenation process.