Selective catalytic reduction

US7431906B2 · kind B2 · utility

Assignee

• Degussa AG · DE

Inventors

• Jurgen Lang · Ludwigsburg, DE
• Rudiger Schutte · Scheinfeld, DE
• Markus Rudek · Büttelborn, DE

Key dates

• Filing date: Mar 21, 2002
• Grant date: Oct 7, 2008
• Expiry date: May 9, 2024

Classification

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

Abstract

A process for the selective catalytic reduction of nitrogen oxides with ammonia in a lean-mix exhaust gas from a combustion process operated with a first, lean-mix air/fuel mixture, wherein the ammonia required for selective reduction is obtained from a second, rich-mix air/fuel mixture which contains nitrogen monoxide by reduction of the nitrogen monoxide in a NH3 synthesis step to give ammonia with the formation of a product gas stream, and where the nitrogen monoxide-containing second air/fuel mixture is supplied to the NH3 synthesis step for reduction of the nitrogen monoxide to ammonia over a three-way converter catalyst and the ammonia formed is separated from the product gas stream and is stored in a storage medium for use as and when required for selective catalytic reduction.