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:
Feb. 26, 2013
Filed:
Apr. 16, 2008
Stephan Eckhoff, Alzenau, DE;
Meike Wittrock, Biebergemuend, DE;
Ulrich Goebel, Hattersheim, DE;
Ina Grisstede, Mannheim, DE;
Ruediger Hoyer, Alzenan-Hörstein, DE;
Wilfried Mueller, Karben, DE;
Thomas Kreuzer, Karben, DE;
Maria Cristina Casapu, Waldshut-Tiengen, DE;
Jan-dierk Grunwaldt, Kgs. Lyngby, DK;
Marek Maciejewski, Warsaw, PL;
Aflons Baiker, Opfikon, CH;
Stephan Eckhoff, Alzenau, DE;
Meike Wittrock, Biebergemuend, DE;
Ulrich Goebel, Hattersheim, DE;
Ina Grisstede, Mannheim, DE;
Ruediger Hoyer, Alzenan-Hörstein, DE;
Wilfried Mueller, Karben, DE;
Thomas Kreuzer, Karben, DE;
Maria Cristina Casapu, Waldshut-Tiengen, DE;
Jan-Dierk Grunwaldt, Kgs. Lyngby, DK;
Marek Maciejewski, Warsaw, PL;
Aflons Baiker, Opfikon, CH;
Umicore AG & Co., KG, Hanau, DE;
Abstract
Nitrogen oxide storage catalysts are used to remove the nitrogen oxides present in the lean exhaust gas of lean-burn engines. As a result of the stress due to high temperatures in vehicle operation, they are subject to thermal aging processes which affect both the nitrogen oxide storage components and the noble metals present as catalytically active components. The present invention provides a process with which the catalytic activity of a nitrogen oxide storage catalyst which comprises, in addition to platinum as a catalytically active component, basic compounds of strontium and/or barium on a support material comprising cerium oxide, said catalytic activity being lost owing to the thermal aging process, can be at least partly restored. The two-stage process is based on the fact that strontium and/or barium compounds formed during the thermal aging with the support material, which also comprise platinum, are recycled to the catalytically active forms by controlled treatment with specific gas mixtures.