Kinetik- und Katalysatorstudien bei der Phthalsäureanhydrid-Herstellung

Abstract

After fifty years of evolution of the phthalic anhydride process modern plants basically differ only in the type of reactor (fluid or fixed bed). The yields are still not more than about 2/3 of the theorical value. By optimizing a three component vanadiumoxide catalyst the yield from o-xylene could be improved to nearly 70% of the theory.
In kinetic experiments, o-toluic acid, phthalide, phthalic anhydride, benzoic acid and maleic anhydride were fed to a pilot plant reactor. The yields of phthalic anhydride increase in the sequence o-xylene, o-toluic acid, phthalide. Benzoic and maleic acid are formed as decomposition products of phthalic anhydride. This confirms the hypothesis that the o-xylene oxidation is basically a consecutive reaction.