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:
Jun. 24, 2008
Filed:
May. 15, 2004
Samuel Neto, Mannheim, DE;
Jürgen Zühlke, Speyer, DE;
Sebastian Storck, Mannheim, DE;
Frank Rosowski, Mannheim, DE;
Samuel Neto, Mannheim, DE;
Jürgen Zühlke, Speyer, DE;
Sebastian Storck, Mannheim, DE;
Frank Rosowski, Mannheim, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
Abstract
The invention relates to a process for preparing phthalic anhydride, in which the catalytic gas-phase oxidation of o-xylene and/or naphthalene is carried out over at least three zones of catalysts of increasing activity, with only the last zone of the catalyst system containing phosphorus and the last zone also comprising at least 10% by weight of vanadium (calculated as VO) based on the active composition of the catalyst and having a ratio of vanadium (calculated as VO) to phosphorus of greater than 35.