Sud-Chemie Ag

Markus Niedermeier

Marvin Estenfelder

Christian Guckel

Christian Gückel

The present invention relates to a catalyst for preparing phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, comprising at least three catalyst zones which have different compositions and, from the gas inlet side toward the gas outlet side, are referred to as first, second and third catalyst zone, the catalyst zones having in each case an active composition comprising TiOwith a content of Na of less than 0.3% by weight, and the active composition content decreasing from the first catalyst zone disposed toward the gas inlet side to the third catalyst zone disposed toward the gas outlet side, with the proviso that

Multi-layer catalyst for producing phthalic anhydride

The present invention relates to a catalyst for preparing phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, comprising at least three catalyst zones which have different compositions and, from the gas inlet side toward the gas outlet side, are referred to as first, second and third catalyst zone, the catalyst zones having in each case an active composition comprising TiO, and the active composition content decreasing from the first catalyst zone disposed toward the gas inlet side to the third catalyst zone disposed toward the gas outlet side, with the proviso that Also described is a preferred process for preparing such a catalyst and the preferred use of the titanium dioxide used in accordance with the invention.

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Bad Aibling, Germany

Markus Niedermeier