Structure-activity relations for Ni-containing zeolites during NO reduction I. Influence of acid sites

The influence of the zeolite structure on the catalytic properties for the reduction of NO with propane and propene was studied. A relation between concentration and strength of acid sites and the activity of Ni-exchanged ZSM-5, MOR, and MCM-22 was found. Ni/ZSM-5, which contains a high concentration of strong acid sites, is the most active catalyst for the NO reduction with propane. Using propene as reductant Ni/ZSM-5 and Ni/MCM-22 rapidly deactivate due to the acid site-catalyzed formation of carbonaceous deposits, while Ni/MOR is less affected by the deposits formed because of its larger pore size.