Patent · US Expired

Process and catalyst for reducing nitrogen oxides

US6843971B2 · kind B2 · utility

47Cited by

6References

10Claims

0Family size

Assignee

UMICORE AG & CO. KG · DE

Inventors

Adolf Schafer-Sindlinger · Frankfurt, DE
Marcus Pfeifer · Mannheim, DE
Paul Spurk · Weiterstadt, DE
Yvonne Demel · Frankfurt am Main, DE
Thomas Kreuzer · Karben, DE
Egbert Lox · Hanau, DE

Key dates

Filing date	Apr 20, 2001
Grant date	Jan 18, 2005
Priority date	—
Expiry date	Sep 16, 2021

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY02T10/12
WIPO fieldChemical engineering
WIPO sectorChemistry

Abstract

A process for reducing the nitrogen oxides present in a lean exhaust gas from an internal combustion engine by selective catalytic reduction on a reduction catalyst using ammonia, wherein a fraction of the nitrogen monoxide present in the exhaust gas is oxidized to nitrogen dioxide before the exhaust gas, together with ammonia, is passed over the reduction catalyst. The reduction catalyst contains a zeolite exchanged with transition metals and oxidation of the nitrogen monoxide is performed in such a way that the exhaust gas contains 30 to 70 vol. % of nitrogen dioxide before contact with the reduction catalyst.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.