Selective catalytic reduction of NO by NH3 over high surface area vanadia-silica catalysts

A series of vanadia-silica catalysts (6.5 wt.% V2O5) have been prepared by three different sol–gel routes. All samples display high surface areas, even for the macroporous samples. XRD and Raman spectroscopy suggests that vanadium is present in a different surrounding and coordination, depending on the specific preparative sol–gel route applied. Room temperature NH3–DRIFT analysis indicated the presence of both Bronsted and Lewis acid sites. After heating at 523 K these bands disappeared. XPS analysis show that most of the vanadium is encapsulated in the silica framework. SCR activities of NO by NH3 were investigated in the presence of SO2. It was demonstrated that the choice of preparative route is important in obtaining NO reduction below 573 K.