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. 28, 2011
Filed:
Nov. 28, 2005
Christian Guckel, Grafing, DE;
Markus Niedermeier, Bad Aibling, DE;
Marvin Estenfelder, Karlsruhe, DE;
Christian Guckel, Grafing, DE;
Markus Niedermeier, Bad Aibling, DE;
Marvin Estenfelder, Karlsruhe, DE;
Sud-Chemie AG, Munich, DE;
Abstract
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