Mechanistic aspects of the reduction of stored NOx over Pt–Ba/Al2O3 lean NOx trap systems

✍ Scribed by Isabella Nova; Luca Lietti; Pio Forzatti

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 837 KB
• Volume: 136
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2008.01.006

✦ Synopsis

In this paper the mechanisms that rule the reduction by hydrogen of NO x species adsorbed at different temperatures were investigated over a model LNT Pt-Ba/Al 2 O 3 catalyst and over the corresponding Ba/Al 2 O 3 system to address the role of the noble metal component in such mechanisms.

It was found that the reduction proceeds according to a dual-step mechanism in which hydrogen reacts fast and at low temperature with nitrates producing ammonia, which however is not a terminal product as it can further react with other nitrate species leading selectively to N 2 .

The results collected in the analysis of each of the dual-step reactions showed that they both occur through a Pt-catalyzed pathway active at very low temperatures, which does not involve the thermal decomposition of the adsorbed NO x species as a preliminary step.