CATALYST SYSTEM FOR OXIDIZING O-XYLOL AND/OR NAPHTHALENE INTO PHTHALIC ANHYDRIDE

摘要

The present invention relates to a catalyst system for oxidation of o-xylene and/or naphthalene to phthalic anhydride (PA), comprising a plurality of catalyst zones arranged in succession in the reaction tube, which have been produced using antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm. The present invention further relates to a process for gas phase oxidation, in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst system which comprises a plurality of catalyst zones arranged in succession in the reaction tube and which has been produced using an antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm.