Selective Catalytic Reduction of NO by NH sub(3) over High Surface Area Vanadia-Silica Catalysts

Scientists used three different sol-gel routes for the production of a series of vanadia-silica catalysts. Samples of these catalysts exhibit high surface areas, even for samples characterized as macroporous. Findings from XRD and Raman spectroscopic analyses indicated that V in the catalysts is present in a different surrounding and coordination, depending on the type of preparative sol-gel route used. Data from room temperature NH sub(3)-DRIFT analyses suggested the presence of both Bronsted and Lewis acid sites. These bands disappeared with heating to 523 K. Results from XPS tests indicated that the majority of the V is encapsulated in the silica framework. Values for the SCR activities of NO by NH sub(3) are reported for tests conducted in the presence of sulfur dioxide.