Role of ammonia oxidation in selective catalytic reduction of nitric oxide over vanadia catalysts
- Ohio State Univ., Columbus (United States)
The role of direct oxidation of ammonia in SCR reactions and the catalytic anisotropy of V[sub 2]O[sub 5] catalysts in this reaction network were investigated. The catalysts were characterized using BET surface area measurement, X-ray diffraction, laser Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and 3-D imaging. Temperature-programmed reduction experiments using ammonia and hydrogen as reducing agents and temperature-programmed desorption studies were also performed. A steady-state fixed-bed reactor system was used for activity and selectivity measurements. The product analysis was carried out by a combination of techniques including chemiluminescence NO[sub x] analysis, on-line gas chromatography and on-line mass spectrometry, and chemical titration methods. The results obtained in this study, when combined with our previous studies in SCR reactions, indicate that over vanadium pentoxide catalysts, ammonia oxidation and NO reduction reactions are closely coupled. The results suggest that ammonia adsorption takes place on at least two types of sites located on the (010) and (100) planes of V[sub 2]O[sub 5]. The sites that selectively reduce NO to N[sub 2] are the V-O-V sites located on the side planes, whereas V[double bond]O sites promote direct oxidation of ammonia to NO and the formation of N[sub 2]O from NO and NH[sub 3] interaction more readily. It is found that the V[double bond]O sites are more easily reduced with both hydrogen and ammonia. 35 refs., 13 figs., 2 tabs.
- OSTI ID:
- 5845866
- Journal Information:
- Journal of Catalysis; (United States), Vol. 142:1; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
33 ADVANCED PROPULSION SYSTEMS
NITRIC OXIDE
SELECTIVE CATALYTIC REDUCTION
VANADIUM OXIDES
CATALYTIC EFFECTS
AMMONIA
ANISOTROPY
CATALYSTS
CHEMILUMINESCENCE
DESORPTION
GAS CHROMATOGRAPHY
HETEROGENEOUS CATALYSIS
HYDROGEN
MASS SPECTROSCOPY
MILLER INDICES
NITROGEN OXIDES
OXIDATION
PHOTOELECTRON SPECTROSCOPY
RAMAN SPECTROSCOPY
REDUCING AGENTS
SURFACE AREA
TITRATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
CATALYSIS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMATOGRAPHY
COHERENT SCATTERING
DENITRIFICATION
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
LASER SPECTROSCOPY
LUMINESCENCE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
REDUCTION
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
330701 - Emission Control- Nitrogen Oxides