Remarkable promoting effect of rhodium on the catalytic performance of Ag/Al2O3 for the selective reduction of NO with decane

The addition of small amounts of rhodium enhanced the activity of Ag/Al2O3 catalyst for the selective reduction of NO with decane at low temperatures. The Rh-promoted Ag/Al2O3 showed its high performance even in the presence of low concentrations of SO2. Based on the catalytic activity for elementary reactions, it was suggested that the role of added rhodium is to enhance the reaction between NOx and decane-derived species, leading to NO reduction. Catalyst characterization by UV-Vis spectroscopy indicated that the major silver species on Rh-promoted Ag/Al2O3 is Agnδ+ clusters, which would be responsible for the high activity. FT-IR measurements revealed that the formation rate of isocyanate species, which is a major reaction intermediate, is higher on Rh-promoted Ag/Al2O3.