Selective catalytic reduction of NO by propene has been investigated over n
oble metal (Pt, Pd, Rh)-based ZSM-5 catalysts. These samples were tested in
a gas mixture system in the presence of excess oxygen, simulating lean-bur
n exhaust gases. The sequence in activity for NO reduction was Pt > Rh simi
lar to Pd. Regarding the selectivity of the reaction to N-2, an opposite tr
end was observed: Rh > Pd similar to Pt. The catalytic systems have present
ed stable operation under isothermal conditions during time-on-stream exper
iments.