LIQUID PHTHALIC ANHYDRIDE RECOVERY PROCESS

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 in the range of about 130 DEG C or greater with a first stream comprising maleic anhydride and/or at least one compound selected from the group consisting of: citraconic anhydride, benzoic acid and phthalic anhydride in a rectification tower 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 the by-products contained in 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 between about 5 to 20 is exhibited within the rectification tower, 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.