Catalyst system for oxidizing o-xylene and / or naphthalene to phthalic anhydride (PA)

摘要

A catalyst system for oxidizing o-xylene and / or naphthalene to phthalic anhydride (PA) The present invention relates to a catalyst system for oxidizing o-xylene and / or naphthalene to phthalic anhydride (PA). Comprising at least four catalyst regions arranged in succession in a reaction tube and filled with catalysts of different chemical composition, the active material of said catalyst comprising vanadium and titanium dioxide, the last in the direction of the reactor outlet Within the catalyst region, the active material of the catalyst relates to a catalyst system having an antimony (calculated as antimony trioxide) with a content of 0.7-3.0% by weight. The present invention is further a method of gas phase oxidation, wherein a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst system, the catalyst system being continuously disposed in a reaction tube and having a different chemistry. Comprising at least four catalyst regions filled with a catalyst of the composition, wherein the active material of the catalyst comprises vanadium and titanium dioxide, and the active material of the catalyst in the last catalyst region in the reactor outlet direction is antimony (antimony trioxide) Is calculated with a content of 0.7 to 3.0% by weight.