Process and apparatus for reducing nitrogen oxides in engine emissions

US5921076A · kind A · utility

Assignee

• Daimler-Benz AG · DE

Inventors

• Bernd Krutzsch · Köngen, DE
• Christian Goerigk · Hemmingen, DE
• Stefan Kurze · Brunsbüttel, DE
• Gunter Wenninger · Stuttgart, DE
• Walter Boegner · Waiblingen, DE
• Friedrich Wirbeleit · Eßlingen, DE

Key dates

• Filing date: Jan 9, 1997
• Grant date: Jul 13, 1999
• Expiry date: Jan 9, 2017

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/12
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A process and apparatus for reducing the nitrogen oxide content in oxygen-containing emissions is provided, particularly for internal-combustion engines, particularly of diesel engines and directly injecting Otto engines for motor vehicles. The nitrogen oxides contained in the exhaust gas are reduced by a suitable reducing agent, such as hydrogen or hydrocarbons, on a DENOX catalyst. For achieving an improved conversion rate for the nitrogen oxides, a combination of hydrogen and hydrocarbons are used as reducing agents. In different operating ranges of the internal-combustion engine only hydrogen, only hydrocarbons, or hydrogen and hydrocarbons are added. Preferably, for this purpose, the quantity of supplied hydrogen or hydrocarbons is reduced or increased with an increasing engine load and/or catalyst temperature and/or rotational engine speed.