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

Journal Article · Mon Jun 01 04:00:00 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), Journal Name: Journal of Catalysis; (United States) Vol. 135:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

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Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ACTIVATION ENERGY
AMMONIA
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRYSTALS
DENITRIFICATION
ELEMENTS
ENERGY
FLUIDS
GASES
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
METALS
NITRIC OXIDE
NITROGEN
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NITROUS OXIDE
NONMETALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
POLYCRYSTALS
REACTION KINETICS
REDUCTION
SELECTIVE CATALYTIC REDUCTION
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENTS
VAPORS
WATER VAPOR