Catalyst for reducing the nitrogen oxide concentration in a flowing medium and method for producing the catalyst

US6054408A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Erich Hums · Prüm, DE
• Gunther Spitznagel · Erlangen, DE
• Klaus Huttenhofer · Heroldsberg, DE
• Peter Fischer · Bad Neustadt an der Saale, DE
• Ronald Neufert · Aichach, DE

Key dates

• Filing date: Dec 2, 1996
• Grant date: Apr 25, 2000
• Expiry date: Dec 2, 2016

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01J23/28
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

An SCR catalyst containing titanium, molybdenum and vanadium has the particular characteristic that its catalytic activity is significantly less than that of a tungsten-containing catalyst. That disadvantage has been compensated for in the past by using a comparatively large volume of catalyst. In contrast to the conventional practice of using a molybdenum oxide proportion of about 10 to 12% by weight, the invention proposes that the molybdenum proportion of the catalyst, in the form of molybdenum trioxide MoO.sub.3, is about 0.01 to 5% by weight, preferably 1.5 to 4% by weight, relative to the weight of the catalyst mass. A catalyst containing this amount of molybdenum thus has an activity comparable to that of a tungsten-containing catalyst. The invention is applicable to all deNO.sub.x catalytic converters which call for the simultaneous presence of a reducing agent, in particular plate-type and honeycomb-type catalytic converters.