Effect of silica additive on the thermal stability of catalysts for NOx abatment

The aim of the present investigation was to study the effect of SiO2 addition on the thermal deactivation of V2O5/WO3/TiO2 catalysts used for NOx pollution abatement. The results suggest that the degradation of the catalytic properties is strongly correlated to the structural ageing which is, in turn, mainly related to the anatase-rutile phase transformation and to the WO3 phase segregation. The addition of SiO2 strongly influences the temperature at which these phenomena occur. In fact, it was found that the introduction of this oxide stabilizes the material, retarding the collapse of surface area, and increases the temperature of the anatase to rutile phase transition.