Reaction between nitric oxide and ammonia on polycrystalline platinum. 2. Rate oscillations
Sustained reaction rate oscillations were observed during the reduction of nitric oxide by ammonia over polycrystalline wires at pressures between 0.2 and 1.0 torr, temperatures between 360 and 550/sup 0/C, and feed gas concentrations P/sub NO//P/sub NH/sub 3// of 1.5 to 4.0. Single-, double-, and triple-peaked oscillations with periods between 15 s and 5 min were observed. These oscillations were strongly dependent on the surface temperature, feed gas composition, and total pressure, although oscillatory behavior was stable over long periods of time. Qualitatively similar behavior was observed in adiabatic operation (..delta..T/sub s/ approx. 100/sup 0/C) using constant power input or with the wire temperature held constant. Because oscillations arise isothermally under conditions where transport limitations are absent and the catalyst surface is clean and remains unchanged morphologically, they must be caused mainly by the kinetics of the reactions. The model used to describe steady-state kinetics can also predict oscillations in this system although no quantitative model for this behavior is proposed.
- Research Organization:
- Univ. of Minnesota, Minneapolis
- OSTI ID:
- 6254095
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 87:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
AMMONIA
CHEMICAL REACTION KINETICS
NITRIC OXIDE
PLATINUM
CATALYTIC EFFECTS
MATHEMATICAL MODELS
OSCILLATIONS
POLYCRYSTALS
PRESSURE DEPENDENCE
TEMPERATURE DEPENDENCE
WIRES
CHALCOGENIDES
CRYSTALS
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENTS
550200* - Biochemistry
090310 - Inorganic Hydrogen Compound Fuels- Properties- (1976-1989)