The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 26, 2002
Filed:
Nov. 15, 2000
Thomas Heidemann, Weinheim, DE;
Heiko Arnold, Mannheim, DE;
Gerhard Hefele, Römerberg, DE;
Herbert Wanjek, Maxdorf, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
Abstract
In a process for preparing phthalic anhydride by catalytic gas-phase oxidation of o-xylene/naphthalene mixtures by molecular oxygen, use is made of a catalyst I in a first zone on the gas inlet side which makes up from 25 to 75 percent by volume of the total catalyst volume, comprising, in each case based on the catalytically active composition, from 1 to 10% by weight of vanadium oxide (calculated as V ), from 1 to 10% by weight of antimony oxide (calculated as Sb ) and from 80 to 98% by weight of titanium dioxide of the anatase type having a BET surface area of from 13 to 28 m /g and also from 0.05 to 1% by weight of cesium (calculated as Cs) applied to a steatite support and a catalyst II in a second zone which makes up the remaining 75 to 25 percent by volume of the total catalyst volume, comprising, in each case based on the catalytically active composition, from 1 to 10% by weight of vanadium oxide (calculated as V ), from 1 to 10% by weight of antimony oxide (calculated as Sb ) and from 80 to 98% by weight of titanium dioxide of the anatase type having a BET surface area of from 13 to 28 m /g and from 0.01 to 1% by weight of phosphorus oxide (calculated as P) and also from 0.01 to 0.2% by weight of cesium (calculated as Cs) applied to a steatite support, wherein the cesium content of the catalyst II is less than 15% by weight of the cesium content of the catalyst I and the catalyst I and the catalyst II have been prepared without addition of compounds of niobium.