METHOD FOR SEPARATING PHTHALIC ANHYDRIDE/MALEIC ANHYDRIDE MIXTURES BY DISTILLATION

摘要

A process for recovering phthalic anhydride and maleic anhydride from a maleic anhydride-rich vapor phase oxidation product comprising the step of: contacting the vapor phase oxidation product with: (i) at least one by-product stream having a freezing point which is lower than the freezing point of pure phthalic anhydride; and/or (ii) a solvent having a boiling point in the range between about 150 DEG to 350 DEG C and a freezing point of less than 40 DEG C; whereina vapor-to-liquid weight ratio in the range between about 2 to 20 is exhibited within the contacting means, thereby forming a liquid phase phthalic anhydride product having a phthalic anhydride concentration in the range between about 50-100 wt.% and a first vapor stream.