Application of Temperature-Programmed Diffuse Reflectance Infrared Fourier Transform Spectroscopy to the Study of the Thermal Evolution of the Species Present in a Reacted Selective Catalytic Reduction V2O5 /TiO2 Catalyst

Temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy (TPDRIFTS) has been used to characterize a reacted selective catalytic reduction (SCR) vanadia/titania catalyst. At room temperature the reacted catalyst presents ammonium ions adsorbed on the surface. On heating under N 2 flow, a surface redox reaction takes place; ammonium ions are oxidized to bridged nitrosyls species, while V 5+ = O groups are reduced to V 3+ . Reduction of V 5+ species to V 3+ ions occurs at lower temperatures than those observed in conventional TPR processes under H 2 atmospheres. At higher temperatures, bridged nitrosyls species become monodentate, first in an angular configuration and then in a linear one. Previous data on the SCR reaction let us propose that they are desorbed from the surface as gaseous N 2 O.