Evidence for the formation, isomerization and decomposition of organo-nitrite and -nitro species during the NOx reduction by C3H6 on Ag/Al2O3

The formation of organo-nitrite and -nitro species (R-ONO and R-NO2) as intermediates during the selective catalytic reduction (SCR) of NOx by C3H6 over Ag/Al2O3 was investigated by temperature-programmed desorption (TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The addition of KBr to Ag/Al2O3 catalyses the isomerization of R-NO2 to R-ONO on KBr-Ag/Al2O3, which confirms the presence of R-NO2 on Ag/Al2O3.