Role of vanadium sites in NO and O2 adsorption processes over VOx/CeO2-ZrO2 catalysts – EPR and IR studies

The interaction of NO and O2 with 5 mol.% of vanadia deposited on Ce0.10Zr0.90O2 and Ce0.69Zr0.31O2 supports by wet impregnation was studied by means of EPR and IR. The supports were structurally characterized by XRD and Raman spectroscopy. Influence of the phase composition of the support on vanadium speciation as well as on surface architecture of the oxovanadium entities was discussed. The NO forms adsorbed on vanadium-containing systems were compared to those observed on bare CeO2-ZrO2 supports. The main products appearing on the catalysts surface during the consecutive reaction with NO and O2 were identified and their thermal evolution was observed. Changes in vanadium speciation accompanying redox processes related to NO and O2 activation were also observed and discussed.