USE OF A MULTI-LAYER CATALYST FOR PRODUCING PHTHALIC ANHYDRIDE

摘要

The invention relates to the use of a catalyst containing at least one first catalyst layer on the gas entry side, a second catalyst layer laying closer to the gas exit side and a third catalyst layer lying even closer to or on the gas exit side, for producing phthalic anhydride by the gas phase oxidation of o-xylol and/or naphthalene, each of said catalyst layers preferably comprising an active substance containing TiO₂. The invention is characterised in that the catalyst action of the first catalyst layer is more intense than the catalyst action of the second catalyst layer. The invention also relates to a preferred method for producing phthalic anhydride.