A series of V,O5/Al,O, catalysts have been examined for the selective catalytic reduction (SCR) of N O with NH, as a function of vanadia loading, metal oxide additives (Mo, W, Ni, Co), and reaction temperature. Increasing the vanadia loading, or surface vanadia coverage, increased the Brernsted acidity and reactivity of the V,O5/Al,O, catalysts. introducing additives that increased the Brernsted acidity, Mo oxide and W oxide, also increased the reactivity. Introducing additives that did not

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... uence the Brernsted acidity, Ni oxide and Co oxide, did not affect the reactivity. However, the addition of Ni oxide and Co oxide increased the ratio of polymerized to isolated surface vanadium oxide species on alumina, which reveals that the SCR reaction is not sensitive to the surface vanadia structure on alumina. A model that explains these observations consists of a dual site: a surface redox site and an adjacent surface Brornsted acid site. Consequently, increasing the surface vanadium oxide coverage and introducing additives that increase the surface concentration of Brmsted acid sites is beneficial for the SCR of N O with NH, .