| abstract |
The invention is a selective reduction catalyst useful for converting exhaust gases generated by a lean-burn engine where the atmosphere is oxidizing. The catalyst comprises zeolite containing two forms or rhodium, small metal particles and ion-exchanged into the zeolite, the latter being in significant excess. In addition, the catalyst contains a rare-earth metal having primarily a +3 or higher valence such as lanthanum in a significantly higher amount relative the total amount of rhodium. |