Photocatalysis of the reaction between ammonia and nitric oxide on TiO sub 2 surfaces
- Macquarie Univ., New South Wales (Australia)
The photocatalytic reaction between ammonia and nitric oxide on TiO{sub 2} wafers under near ultraviolet illumination has been investigated. The reaction produces nitrogen and nitrous oxide with a ratio slightly above two. When {sup 15}NH{sub 3} and {sup 14}NO are used, {sup 14}N{sup 15}N and {sup 14}N{sup 14}NO are formed almost exclusively. Comparative measurements have been made for the related photocatalytic reaction between ammonia and oxygen, and for nitric oxide photodecomposition. The rate of the latter is approximately one-sixth that of the ammonia plus nitric oxide reaction. It yields nitrogen and nitrous oxide with a ratio less than 0.5 and is accompanied by some deposition of nitrates on the TiO{sub 2} wafer. The ammonia plus oxygen reaction is of intermediate rate and is also accompanied by nitrate formation. The nitrogen/nitrous oxide ratio is approximately four when using 10 Torr of each reactant. Both reactions involving ammonia exhibit a small deuterium kinetic isotope effect, the rate ratio for NH{sub 3} versus ND{sub 3} being about 1.3. Nitrous oxide production is zero order in ammonia and shows a Langmuir-like dependence on oxidant pressure. Both oxidation reactions exhibit similarly curved Arrhenius plots with low apparent activation energies. The dependencies on light intensity are nonlinear, with an apparent order of approximately 0.6 in both cases. A model which can explain the overall characteristics of the three reactions is presented.
- OSTI ID:
- 6977333
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 134:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500* -- Photochemistry
ACTIVATION ENERGY
AMMONIA
AMMONOLYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DEUTERIUM
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIQUID WASTES
NITRIC OXIDE
NITROGEN
NITROGEN 14
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN ISOTOPES
NITROGEN OXIDES
NITROUS OXIDE
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
RADIATIONS
REACTION KINETICS
SOLVOLYSIS
STABLE ISOTOPES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
ULTRAVIOLET RADIATION
WASTE WATER
WASTES
WATER
WATER TREATMENT