Selective reduction of nitric oxide with propene over sol-gel silver supported on alumina catalysts

Abstract

The selective catalytic reduction of NO with propene in the presence of oxygen was studied over silver supported on alumina catalysts. The catalysts were prepared by sol-gel method. In this study the silver loading was varied in the range of 0, 1.0, 2.0, 4.0, 5.0, 6.0, and 10.0% in order to clarify the effect of metal loading. From the results, the 5% Ag/Al₂O₃ is much more effective at lean NO reduction than other silver loading catalysts and the best reaction temperature is 450 °C. For the study of the promoting effect of oxygen on the rate of the NO reduction, it was found that the conversion of NO to N₂ over Ag/Al₂O₃ catalyst increased as the concentration of oxygen increased from 5 to 20 vol%. The study of the two different function (reduction and oxidation) catalysts was also performed by mixing Ag/Al₂O₃ and Mn₂O₃ physically. The oxidation catalyst, manganese oxide (Mn₂O₃), was obtained by thermal decomposition of manganese precipitate prepared from precipitation method. It was found that Mn₂O₃ catalyst exhibited the negative effect on the conversion of NO to N₂.