Method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine and exhaust-gas purification system therefor

US7313911B2 · kind B2 · utility

Assignee

• UMICORE AG & CO. KG · DE

Inventors

• Markus Pfeifer · Nuremberg, DE
• Barry Van Setten · Salmünster, DE
• Paul Spurk · Weiterstadt, DE
• Yvonne Demel · Frankfurt am Main, DE
• Tobias Kuhl · Hanau, DE
• Jurgen Gieshoff · Bad Orb, DE
• Egbert Lox · Hanau, DE
• Thomas Kreuzer · Karben, DE

Key dates

• Filing date: Feb 26, 2004
• Grant date: Jan 1, 2008
• Expiry date: Feb 26, 2024

Classification

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

Abstract

The present invention relates to a method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine by selective catalytic reduction (SCR) using ammonia. The exhaust gas is routed first over a platinum-containing pre-catalyst and then over an SCR catalyst. The ammonia needed for the selective catalytic reduction is added to the exhaust gas upstream of the pre-catalyst at an exhaust-gas temperature below 250° C., while it is supplied to the exhaust gas between the pre-catalyst and the SCR catalyst at an exhaust gas temperature above 150° C. By adopting this procedure, a very large temperature range for the selective catalytic reduction with high nitrogen conversion rates is obtained.