Selective catalytic reduction of NOx by C2H5OH over Ag/Al2O3/cordierite: Effect of the surface concentration of silver

The present paper studies effect of silver and alumina loadings on the catalytic activity of Ag/Al2O3/cordierite for the selective reduction of NO by ethanol. It is shown that activity of the silver–alumina catalysts depends not only on the loading of components, but also on the surface concentration of silver. High conversion of NO, around 100%, is achieved when the surface concentration of silver is equal to 0.09–0.13 mg/m2. The Ag/Al2O3/cordierite catalyst, as shown by UV–visible diffuse reflectance spectroscopy, under such surface concentration contains silver mainly in the oxidized state (Ag+ cations and Agnδ+ clusters). It is also shown that activity of the structured catalysts with equal silver loading enhances with increasing alumina loading from 18 to 48 wt.%.