Time-resolved in situ DRIFTS study on NH3-SCR of NO on a CeO2/TiO2 catalyst

Ce-Ti catalysts were considered as a promising replacement for V-Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, a CeO2/TiO2 catalyst was prepared by the impregnation method and studied by a series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. The results showed that CeO2 particles grew along TiO2 faces and amorphous cerium in the lattice of TiO2, both of which are present on the CeO2/TiO2 catalyst. NH4+ might adsorb on the Ti-O-Ce structures or TiO2-CeO2 interface as Bronsted acid sites, while two types of NH4+ species were distinguished by the time-resolved spectroscopic method due to the different increasing trends. Based on the temporal evolution transient in situ DRIFTS spectra, L-NH3 had higher activity than coordinated NH3 species, which suggested that gas phase NO reacted preferentially with L-NH3. The NH4NO3 intermediate dominated the SCR reactions over the CeO2/TiO2 catalyst, which followed the Eley-Rideal mechanism.

Automated summary

CeO2/TiO2 catalyst was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy, and it was found that CeO2 particles grew along TiO2 faces and amorphous cerium in the lattice of TiO2. NH4+ could adsorb on the Ti-O-Ce structures or TiO2-CeO2 interface as Bronsted acid sites, and NH4NO3 intermediate dominated the SCR reactions.