Method for operating a purification device for gases as well as a purification device for gases

US6027703A · kind A · utility

Assignee

• Daimlerchrysler AG · US

Inventors

• Martin Hartweg · Erbach, DE
• Rolf-Dirc Roitzheim · Blaustein, DE
• Andrea Seibold · Blaustein, DE
• Leonhard Walz · Rastatt, DE
• Thomas Fetzer · Speyer, DE
• Bernd Morsbach · Ludwigshafen, DE

Key dates

• Filing date: Dec 12, 1996
• Grant date: Feb 22, 2000
• Expiry date: Dec 12, 2016

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 for operating a catalyst for gases, especially for exhaust gases of stoichiometrically operated gasoline engines, wherein a catalyst is exposed to a gas stream and pollutants are catalytically converted. To improve the elimination of pollutants in the starting phase, hydrocarbons present in the gas are temporarily stored by the catalyst at temperatures below a response temperature of the catalyst, particularly below 200.degree. C., and preferably below 150.degree. C. The hydrocarbons are then released at temperatures above the response temperature and the pollutants, such as nitrogen oxides, are catalytically converted with reducing agents, such as hydrocarbons, carbon monoxide and mixtures thereof. The catalyst is a spinel, such as (MgCu)Al.sub.2 O.sub.4, which may also include a catalytically active species, such as WO.sub.3, V.sub.2 O.sub.5 and TiO.sub.2.