Exhaust gas purification process and apparatus with internal generation of ammonia for reducing nitrogen oxide

US6338244B1 · kind B1 · utility

Assignee

• Daimlerchrysler AG · US

Inventors

• Josef Guenther · Marbach am Neckar, DE
• Brititte Konrad · Blaustein, DE
• Bernd Krutzsch · Köngen, DE
• Arno Nolte · Stuttgart, DE
• Dirk Voigtlaender · Ditzingen, DE
• Michel Weibel · Großburgwedel, DE
• Marko Weirich · Mannheim, DE
• Guenter Wenninger · Stuttgart, DE

Key dates

• Filing date: Mar 6, 2000
• Grant date: Jan 15, 2002
• Expiry date: Mar 6, 2020

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F01N2610/02
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A method and apparatus for purifying an exhaust gas of an internal combustion engine includes an ammonia generating catalyst for generating ammonia from nitrogen oxides contained in the exhaust gas to be purified, and a nitrogen oxide reducing catalyst downstream of the ammonia generating catalyst, for reduction of nitrogen oxides contained in the exhaust gas to be purified. Generated ammonia is used as the reducing agent. A nitrogen oxide adsorption catalyst is arranged upstream of the ammonia generating catalyst, or the ammonia generating catalyst is arranged in an exhaust pipe branch which pertains to only a part of several separately controllable internal-combustion sources. One or more additional exhaust pipe branches assigned to the other internal-combustion sources and lead to the nitrogen oxide reducing catalyst, while bypassing the ammonia generating catalyst. The part of the internal-combustion sources pertaining to the exhaust pipe branch of which contains the ammonia generating catalyst is operated either continuously or intermittently in a rich mode. Also, one or more combustion sources which feed their exhaust gas to the nitrogen oxide adsorption catalyst may be opera…