Arrangement for reducing nitrogen oxides in exhaust gases

US8398943B2 · kind B2 · utility

Assignee

• MAN Truck &Bus AG · DE

Inventors

• Andreas Döring · Unterhaching, DE
• Florian Walde · Dietenhofen, DE

Key dates

• Filing date: Dec 15, 2010
• Grant date: Mar 19, 2013
• Expiry date: Mar 23, 2031

Classification

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

Abstract

An arrangement and method for reducing the nitrogen oxide content in the exhaust gas of an internal combustion engine with the aid of ammonia and/or ammonia-releasing reduction agents, whereby ammonia and/or ammonia-containing reduction agent is added to the exhaust gas stream upstream of a catalyst combination composed of an SCR catalyst and a subsequent NH3-oxidation catalyst in such a way that a homogeneous mixture of exhaust gas and ammonia is present upstream of the SCR catalyst. To optimize the reaction or conversion of nitrogen oxides, disposed downstream of the combination of a first SCR catalyst and a first NH3-oxidation catalyst is at least one second catalyst having SCR activity in order in this way to reduce the nitrogen oxides formed at the first NH3-oxidation catalyst due to insufficient selectivity of the catalyst to nitrogen with not yet oxidized NH3.