Process for crystallizing trimellitic acid

摘要

In crystallizing and separating trimellitic acid obtained by the oxidation of dimethylbenzaldehyde or its oxidation derivative with a molecular oxygen-containing gas in an aqueous solvent in the presence of a bromine ion or a bromine ion and a heavy metallic ion catalyst, a process for crystallizing trimellitic acid wherein the crystallization is carried out with at least two crystallization vessels connected in series, of which the first vessel is kept at a temperature of 40 DEG to 130 DEG C. and at a concentration of trimellitic acid of 20 to 60 wt. %.