Combining theoretical description with experimental in situ studies on the effect of alkali additives on the structure and reactivity of vanadium oxide supported catalysts

A periodic model has been selected to model the structure and reducibility of vanadia/titania catalysts and the effect of alkali doping for Li, Na and K. Alkali interact with both the surface vanadia units and the support. The calculated changes on vanadia structure are consistent with the changes evidenced by Raman spectroscopy. Reducibility is modeled by adsorption of one hydrogen atom, forming hydroxyl groups with the bridging V–O–Ti present in the model. The adsorption energy decreases in the series Li > Na > K, in agreement with experimental TPR results.