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:
Jul. 02, 2002
Filed:
Oct. 13, 1999
Wolfgang Strehlau, Dossenheim, DE;
Ulrich Göbel, Hattersheim, DE;
Rainer Domesle, Alzenau-Kälberau, DE;
OMG AG & Co. KG, Hanau-Wolfgang, DE;
Abstract
A nitrogen oxide storage catalyst which contains at least one catalyst material and at least one nitrogen oxide storage component from the group of alkali and alkaline earth metals. The nitrogen oxide storage component, after completing catalyst preparation, is present as finely divided barium sulfate, strontium sulfate, a mixture or mixed crystals of the two sulfates, or as their complete or incomplete decomposition product with an average particle size of less than 1 &mgr;m. Barium sulfate and/or strontium sulfate act as feed materials for the active storage component in the storage catalyst according to the invention. As a result of the reductive exhaust gas compositions occurring under normal automobile driving conditions barium sulfate and strontium sulfate decompose to compounds which are able to store nitrogen oxides. This compensates for the loss of active storage components which occurs due to aging. Barium sulfate and/or strontium sulfate may be decomposed during production by means of reductive calcination in order to obtain a high initial loading of the catalyst with storage compounds. In this case, these sulfates are used as auxiliary agents in order to introduce the highest possible concentrations of storage compounds into the storage catalyst.