Selective catalytic reduction of NO with NH{sub 3} over supported vanadia catalysts
- Lehigh Univ., Bethlehem, PA (United States); and others
The selective catalyst reduction (SCR) of NO with NH{sub 3} was systematically investigated over a series of supported vanadia catalysts to obtain additional insight into this important industrial reaction. The influence of surface vanadia coverage, promoters (surface tungsten oxide, niobium oxide, and sulfate species), and the specific oxide support (TiO{sub 2}, Al{sub 2}O{sub 3}, and SiO{sub 2}) was examined. The molecular structures of the surface metal oxide species were determined by in situ Raman spectroscopy, and the corresponding surface acidity properties were monitored with infrared spectroscopy employing pyridine adsorption. The redox properties of the surface metal oxide species were probed with the sensitive methanol oxidation reaction and temperature-programmed reduction. The SCR reactivity of the various catalysts was determined over a wide temperature range. The current findings suggest that a dual-site (a surface vanadia redox site and an adjacent nonreducible metal oxide site) mechanism is required for the efficient selective catalytic reduction of NO with NH{sub 3} over supported vanadia catalysts. The SCR reaction is sensitive to the immediate environment of the surface vanadia species: overall surface coverage of the metal oxide overlayer (factor of 5 in turnover frequency), nature of adjacent surface metal oxide species (factor of 10 in turnover frequency) and oxide support ligands (factor of 3 in turnover frequency). 39 refs., 10 figs., 5 tabs.
- DOE Contract Number:
- FG02-93ER14350
- OSTI ID:
- 471618
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 161; ISSN JCTLA5; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
ALUMINIUM OXIDES
AMMONIA
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
HETEROGENEOUS CATALYSIS
NITRIC OXIDE
OXIDATION
RAMAN SPECTROSCOPY
SELECTIVE CATALYTIC REDUCTION
SILICA
TITANIUM OXIDES
VANADIUM OXIDES