METHOD AND APPARATUS FOR RECOVERING TEREPHTHALIC ACID

摘要

A method and an apparatus for recovering terephthalic acid which can continuously prepare a higher-purity terephthalic acid. Crude terephthalic acid prepared by the oxidation of p-xylene in a liquid phase is dissolved in water at a temperature high enough to completely dissolve the crude terephthalic acid in water. The aqueous solution is brought into contact with a group VIII metal catalyst to conduct purification and then subjected to flash evaporation to recover terephthalic acid dissolved in the aqueous solution. In this case, the operation temperature range for each crystallization tank is specified by the approximate expression y = 266exp(-0.61x) (wherein x represents a value obtained by dividing 1 by the total number of stages and multiplying the value by the stage number value in each stage; and y represents the temperature, DEG C), whereby terephthalic acid crystals having a low impurity content can be obtained.