SOLVENT ASSISTED PROCESS FOR RECOVERY OF PHTHALIC ANHYDRIDE IN THE LIQUID PHASE BY DISTILLATION

摘要

A process for recovering phthalic anhydride as a liquid from a vapor phase oxidation product which comprises mixing the vapor phase oxidation product having a temperature of about 130 DEG C or greater with a first stream comprising a solvent having a boiling point in the range between about 150 to 350 DEG C and a freezing point of less then 40 DEG C, and, optionally, at least one by-product selected from the group consisting of: maleic anhydride, citraconic anhydride, benzoic acid and phthalic anhydride, in a contacting means such that a substantial portion of the phthalic anhydride contained within the vapor phase oxidation product transfers from the vapor phase to a liquid phase and a substantial portion of the first stream which are more volatile than phthalic anhydride transfer from the liquid phase to the vapor phase and wherein a vapor-to-liquid weight ratio in the range of 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.%, preferably 90-100 wt.%, without the formation of an intermediate solid phase.