β Scribed by T. Pignet; L.D. Schmidt
No coin nor oath required. For personal study only.
On-line mass spectrometry is used to examine the kinetics of NH,-oxidation on polycrystalline Pt wires for temperatures between 250 and 1500Β°C. A differentially pumped system is employed so that species concentrations can be continuously monitored and absolute reaction rates determined. Reactions studied under reaction controlled conditions are unimolecular decomposition of NO and of NH,, the bimolecular reaction of NH, and NO to form N,, and NH, oxidation to NO and to Nz. In all reactions and at all temperatures, unique steady-states were observed, and these were attained in less than 2 seconds after adjusting pressures and temperatures. Comparison is made with results obtained in a 1 atm flow reactor, and some possible effects of mass transfer limitation on the selectivity are discussed.
The selectivity of NO vs. N2 production appears to be controlled almost entirely by the NO-NH, reaction for T 5 lOCMI"C, and by unimolecular decomposition of NH, for higher temperatures. The rates of NH, decomposition and of NO reduction by NH, are semi-quantitatively described with simple Langmuir-Hinshelwood kinetics. Adsorbed oxygen is found to inhibit NH,-decomposition and may be necessary to promote the NO-NH, reaction.
π SIMILAR VOLUMES
units, or presence of other bulky substituents results in loss of this orientation capacity; moreover, such siloxanes spread considerably more slowly than those mentioned above. Siloxanes bearing hydrophilic groups, e.g. hydroxymethyl or aminomethyl substituents, exhibit a capacity for orientation a
## Abstract __H~1~ mesoporous platinum surfaces formed by electrodeposition from lyotropic liquid crystalline templates have high electroactive surface areas (up to 60 m^2^βg^β1^) provided by the concave surface within their narrow (β2 nm diameter) pores. In this respect, they are fundamentally dif