NO reduction by propylene over Pt/SiO2: An in situ FTIR study

The selective catalytic reduction (SCR) of nitric oxide (NO) by propylene ( C3H6) Over a 1 wt.% Pt/SiO2 catalyst was studied by the use of in situ Four ier transform infrared (FTIR) spectroscopy at 250 degrees C. At this temper ature, introduction of NO to the catalyst did not result in the formation o f any significant amounts of adsorbed NOx-type species on either the cataly st or the SiO2 support. On the contrary, introduction of C3H6 to the same c atalyst resulted in the formation of surface carboxylates. Experiments cond ucted under reaction conditions resulted in the formation of a surface cyan ide (-CN) species, and a gas phase/weakly adsorbed nitrous oxide (N2O) spec ies. The surface cyanide is the product of the reaction between an oxygen-a ctivated hydrocarbon derivative and NO and is reactive toward NO, NO2, and O-2, resulting in the formation of N-2 and N2O. Its behavior, as observed i n this study, is consistent with a role as a potential intermediate in the selective reduction of NO by propylene over the Pt/SiO2 catalyst. (C) 2000 Academie Press.