Crystallization and solid-liquid separation process in preparation of terephthalic acid

摘要

The invention from a slurry containing terephthalic acid and reaction intermediates produced by the oxidation of p-xylene a crystallization and solid-liquid separation step of separating the terephthalic acid in the solid phase, the reaction intermediates are p-toluic acid and 4-carboxy benzaldehyde, and include, the terephthalic acid is in a high-temperature high-pressure filter to filter the slurry after the crystallization and the solid phase separated in the The mother liquor containing the reaction intermediate comprising the step of separating the liquid phase, the operation temperature of the high-temperature high-pressure filter is 130 ~ 220 , the operating pressure is 10 ~ 20kgf / cm ² g of features provides the crystallization and solid-liquid separation step. The p-toluic acid is more than 10wt% of the slurry, preferably may be one that contains more than 20wt%, the crystallization may proceed in a crude crystal.