The reduction of nitric oxide by ammonia over polycrystalline platinum model catalysts in the presence of oxygen

Journal Article · Mon Jun 01 00:00:00 EDT 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90045-J· OSTI ID:7178068

Katona, T ^[1]; Guczi, L ^[2]; Somorjai, G A ^[3]

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1. Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley (United States) Jozsef A. Univ., Szeged (Hungary)
2. Lawrence Berkeley Lab., CA (United States) Inst. of Isotopes, Budapest (Hungary)
3. Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley (United States)

The reaction system of nitric oxide, ammonia, and oxygen was studied using batch-mode measurements in partial pressure ranges of 65-1000 Pa (0.5-7.6 Torr) on polycrystalline Pt foils over the temperature range 423-598 K. Under these conditions the oxidation of nitric oxide was not detectable. The ammonia oxidation reaction, using dioxygen, occurred in the temperature range 423-493 K, producing nitrogen and water as the only products. The activation energy of the nitrogen formation was found to be 86 kJ/mol. Above this temperature range, flow-mode measurements showed the formation of both nitrous oxide and nitric oxide. The reaction rate between ammonia and oxygen was greatly decreased (about a factor of 10) by nitric oxide, while the reaction rate between nitric oxide and ammonia was accelerated (about 10-fold) due to the presence of oxygen. Nitric oxide reduction by ammonia in the presence of oxygen occurred in the temperature range 423-598 K. The products of the reaction were nitrogen, oxygen nitrous oxide, and water. The Arrhenius plot of the reaction showed a break near 523 K. Below this temperature the activation energy of the reaction was 13 kJ/mol, and in the higher-temperature range it was 62 kJ/mol. At 473 K, the N[sub 2]/N[sub 2]O ratio was about 0.6 and O[sub 2] formation was also monitored. At 573 K, the N[sub 2]N[sub 2]O ratio was approximately 2 and oxygen was consumed in the course of the reaction as well.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7178068
• Journal Information: Journal of Catalysis; (United States), Vol. 135:2; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
01 COAL, LIGNITE, AND PEAT
33 ADVANCED PROPULSION SYSTEMS
AMMONIA
OXIDATION
NITRIC OXIDE
SELECTIVE CATALYTIC REDUCTION
PLATINUM
CATALYTIC EFFECTS
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
NITROGEN
NITROUS OXIDE
POLYCRYSTALS
TEMPERATURE RANGE 0400-1000 K
WATER VAPOR
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTALS
DENITRIFICATION
ELEMENTS
ENERGY
FLUIDS
GASES
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
REDUCTION
TEMPERATURE RANGE
TRANSITION ELEMENTS
VAPORS
540120* - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)
010800 - Coal
Lignite
& Peat- Waste Management
330701 - Emission Control- Nitrogen Oxides