Highly active and stable Pt-USY in the low-temperature de-NOx HC-SCR

Selective catalytic reduction of NOx by propene has been investigated on Pt -USY and compared to other Pt-catalysts. The catalyst was characterized by XRD, Ar adsorption at 87 K, TEM, and CO chemisorption, and tested in a gas mixture system in excess oxygen, Pt-USY shows an excellent activity in the reaction, with a molar NOx conversion of 90% at 475 K. Stability during tim e-on-stream and resistance to SO2 and H2O in the feed stream has also been investigated. Pt-USY performs better under lean-burn conditions than other Pt-catalysts on ZSM-5, Al2O3, or SiO2. The selectivity to N-2 was similar f or all the catalysts (similar to 30%), the other major product being N2O.