A steady-state isotopic transient kinetic analysis of the NO/O{sub 2}/H{sub 2} reaction over Pt/SiO{sub 2} catalysts
The NO/O{sub 2}/H{sub 2} reaction under strongly oxidizing conditions has been studied over a 5% Pt/SiO{sub 2} catalyst using Steady-State Isotopic Transient Kinetic Analysis (SSITKA). The {sup 14}N-containing reactants and products were monitored following a {sup 14}NO/O{sub 2}/H{sub 2}{r{underscore}arrow} {sup 15}NO/O{sub 2}/H{sub 2} switch. N{sub 2}O was found to be the isotopically first product and N{sub 2} the isotopically second. It was found that there was a constant desorption of NO from the catalyst surface under steady-state conditions. Recently introduced transformations (IDIMP, TRIMP, and the semilogarithmic plot of the {bar {alpha}} function versus time) of the product profiles, which concentrate on the isotopic distribution of the product molecules following the {sup 14}NO {r{underscore}arrow} {sup 15}NO switch, are used to analyze the mechanism of N{sub 2} formation from this reaction. These show that N{sub 2} formation is predominantly through an impact route in which gaseous or physisorbed NO reacts with a reduced N species on the catalyst in a modified Eley-Rideal mechanism. A second, less active, mode of N{sub 2} formation is through the interaction of two equivalent species on the surface, each of which gives one N atom to the N{sub 2} molecule. The presence of O{sub 2} results in a change in the relative contribution of each type of N{sub 2} production.
- Research Organization:
- Univ. of Reading, Berks (GB)
- OSTI ID:
- 20003852
- Journal Information:
- Journal of Catalysis, Vol. 188, Issue 1; Other Information: PBD: 15 Nov 1999; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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