A series of Cu-beta zeolites with different Cu contents have been prep
ared. Their activity for selective catalytic reduction (SCR) of NO wit
h C3H8 has been studied and compared with that of Cu-ZSM5 zeolites. Cu
-beta samples are stable SCR catalysts giving activities as high as th
ose of Cu-ZSM5 zeolites. Their behaviour toward reaction temperature a
nd oxygen content is practically the same as that of Cu-ZSM5. Similar
results were achieved when the adsorption of NO over the zeolites was
followed by i.r. spectroscopy.