SO/sub 2/ deactivation in NO reduction by NH/sub 3/. IV. Auger studies of deactivated catalysts in selective NO reduction
Deactivation of supported metal catalysts by SO/sub 2/ in the selective reduction of NO by NH/sub 3/ was studied in a differential, packed-bed flow reactor as a function of the gas-phase O/sub 2/ concentration, and foils of the same metal as the catalyst were placed in the reactor with the catalyst. Auger electron spectroscopy (AES) was used to analyze the metal foils subsequent to reaction. With no SO/sub 2/ in the feed gas, the rate of NO reduction over Pt/Al/sub 2/O/sub 3/, Ru/Al/sub 2/O/sub 3/, and Ni/Al/sub 2/O/sub 3/ was enhanced by the presence of 0.5 mole% O/sub 2/, whereas that for Pd/Al/sub 2/O/sub 3/ was reduced. AES studies confirm that the deactivation of Pd in the sulfur-free system is due to oxidation of the metal. Although SO/sub 2/ severely poisons the catalytic activity in the NO-NH/sub 3/-SO/sub 2/ system, addition of 0.5 mole% O/sub 2/ to the feed gas largely restores the activity of all catalysts. This elimination of severe SO/sub 2/ deactivation correlates well with the incorporation of oxygen to high conentrations into the subsurface layers of the metal: oxygen appears to counteract the presence of sulfur incorporation. Only metal oxides and metal sulfides were formed; there was no evidence of sulfate formation. 18 references, 11 figures, 2 tables.
- Research Organization:
- Univ. of Delaware, Newark
- OSTI ID:
- 5440252
- Journal Information:
- J. Catal.; (United States), Vol. 61:1
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
33 ADVANCED PROPULSION SYSTEMS
AMMONIA
CHEMICAL REACTIONS
AMMONIUM COMPOUNDS
CHEMICAL REACTION YIELD
NICKEL
CATALYTIC EFFECTS
DEACTIVATION
NITRIC OXIDE
NITRITES
NITROGEN
OXYGEN
PALLADIUM
PLATINUM
RUTHENIUM
ALUMINIUM OXIDES
AUGER ELECTRON SPECTROSCOPY
CATALYST SUPPORTS
EXPERIMENTAL DATA
FOILS
GAS CHROMATOGRAPHY
HELIUM
HIGH TEMPERATURE
ISOLATED VALUES
REDUCTION
STEADY-STATE CONDITIONS
TEMPERATURE DEPENDENCE
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHROMATOGRAPHY
CRYOGENIC FLUIDS
DATA
DATA FORMS
ELECTRON SPECTROSCOPY
ELEMENTS
FLUIDS
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
MECHANICAL STRUCTURES
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
RARE GASES
REFRACTORY METALS
SEPARATION PROCESSES
SPECTROSCOPY
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TRANSITION ELEMENTS
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400201* - Chemical & Physicochemical Properties
330701 - Emission Control- Nitrogen Oxides