Physicochemical and Catalytic Properties of Vanadia/Titania Catalysts. V. Selective Catalytic Reduction of NO with NH 3

Vanadia/titania catalysts were prepared containing 6.0 or 8.0 wt% V₂O₅ via the impregnation method. The samples as prepared were calcined at 400°C or 600°C, respectively. Selective catalytic reduction (SCR) of NO with NH₃ was carried out at 257°C over the prepared catalysts. NO conversion as a function of time was followed and the stationary conversion versus the amount of catalyst employed was also investigated.

It was found that the vanadia/titania catalysts calcined at 400°C were more active in the SCR of NO with NH₃ relative to those calcined at 600°C. This was attributed to such catalysts possessing complete monolayer coverage of vanadia on the titania substrate. It was established that V⁵⁺ was not the active vanadia species but V⁴⁺ and V³⁺ may act as such for the SCR of NO with NH₃.