We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Roles of surface nitrogen oxides in propene activation and NO reduction on Ag/Al<sub>2</sub>O<sub>3</sub>.
- Authors
Ouyang, F.; Haneda, M.; Sun, W.; Kindaichi, Y.; Hamada, H.
- Abstract
The activation of propene in selective catalytic reduction (SCR) of NO on 4% Ag/Al2O3 has been studied by in situ infrared (IR) spectroscopy. Distinctive propene activation products were detected in the SCR of NO, depending on the nature of surface oxygen and nitrogen oxide species on Ag/Al2O3. C3H6 was oxidized to acetate species in an O2 + C3H6 atmosphere on Ag/Al2O3 above 573 K. The addition of NO to the C3H6 + O2 feed gas suppressed the formation of acetate species but increased the proportion of acrylate species. Acrylate species were further confirmed to be formed preferentially from C3H6 oxidation without the O2 atmosphere on Ag/Al2O3 or nitrate-adsorbed Ag/Al2O3. On the other hand, adsorption of NO led to the formation of nitrito species on Ag/Al2O3, but the nitrito was barely oxidized to nitrate species unless there was an O2 atmosphere at 473–673 K. Thus, the oxidation of propene to acetate species, or the formation of nitrate from nitrito, is attributed to two competitive electrophilic reactions. The formation of nitrate from nitrito species decreased electrophilic oxygen species that oxidized propene to acetate. Nevertheless, the first dehydrogenation of propene to form acrylate species on nitrate-adsorbed Ag/Al2O3 is a nucleophilic reaction, as it is on Ag/Al2O3. Furthermore, there was no decrease in reaction activity for formation of acrylate species on nitrate-adsorbed Ag/Al2O3 compared to Ag/Al2O3. This led to the total reaction occurring easily through the propene nucleophilic oxidation branch because the presence of the adsorbed nitrogen oxides changed selectively the formation rates of the surface reductants. IR spectra data further demonstrate that acrylate and acetate species, as the surface reductants, reacted with nitrate to generate isocyanate intermediates in the SCR of NO. The effect of structures of different reductants on NO reduction is discussed.
- Subjects
NITROGEN oxides; PROPENE; INFRARED spectroscopy; SPECTRUM analysis; ACETATES
- Publication
Kinetics & Catalysis, 2008, Vol 49, Issue 2, p236
- ISSN
0023-1584
- Publication type
Article
- DOI
10.1134/S0023158408020110