Exhaust gas purification catalyst with improved hydrocarbon conversion

US6080375A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Lothar Mussmann · Offenbach, DE
• Dieter Lindner · Hanau, DE
• Renee Van Yperen · Wertingen, DE
• Egbert Lox · Hanau, DE
• Thomas Kreuzer · Karben, DE

Key dates

• Filing date: Nov 12, 1997
• Grant date: Jun 27, 2000
• Expiry date: Nov 12, 2017

Classification

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

Abstract

An exhaust gas purification catalyst with improved hydrocarbon conversion is disclosed, which contains metals from the platinum group as its catalytically active components. Two superposed functional layers are applied to one support. The catalyst has a first functional layer with a mixture of a first catalyst with at least one zeolite and the second functional layer applied to the first functional layer which contains a mixture of a second catalyst and at least one zeolite. The zeolites exhibit a molar ratio of silicon dioxide/aluminum oxide of more than 40 and in that at least palladium and rhodium are present as the platinum group metals and are each contained separately from one another in only one of the two catalysts. The catalyst is distinguished by particularly good suppression of hydrocarbon emissions during cold-starting and exhibits particularly good long-term stability.