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Title: Thermal degradation of supported catalysts: coarsening kinetics of platinum particles on flat and curved oxide substrates

Abstract

A theory was developed for the coarsening kinetics of small-faceted particles on flat support surfaces where the experimentally observed coarsening rates were far slower than those predicted by noninhibited coarsening modes. The continued growth of the faceted crystal surfaces of the small particles probably occurs by repeated pillbox nucleation events. Experimental data on the coarsening kinetics of platinum particles on alumina substrates at 900/sup 0/-1100/sup 0/C with initial average particle size of 35-120 nm were consistent with coarsening by the inhibited mode. The predicted increase in coarsening rate with smaller initial average particle sizes was also observed. For the case of particle behavior on a curved substrate, a simple theory was derived that particles will migrate to concave sites and the initial growth rates may be enhanced by this particle migration. These effects will only occur when the particle size is close to that of the radius of curvature of the substrate, and the coarsening rates may be retarded after long time annealing. Platinum particle behavior on curved alumina substrates with sinusoidal gratings produced by a photoresist and ion beam micromachining technique was consistent with predictions.

Authors:
Publication Date:
OSTI Identifier:
7138960
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALUMINIUM OXIDES; CATALYTIC EFFECTS; CATALYST SUPPORTS; THERMAL DEGRADATION; CATALYSTS; PLATINUM; PARTICLE SIZE; REACTION KINETICS; CRYSTAL GROWTH; EXPERIMENTAL DATA; OXIDES; SURFACE PROPERTIES; VERY HIGH TEMPERATURE; ALUMINIUM COMPOUNDS; CHALCOGENIDES; DATA; ELEMENTS; INFORMATION; KINETICS; METALS; NUMERICAL DATA; OXYGEN COMPOUNDS; PLATINUM METALS; SIZE; TRANSITION ELEMENTS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Ahn, T M. Thermal degradation of supported catalysts: coarsening kinetics of platinum particles on flat and curved oxide substrates. United States: N. p., 1978. Web.
Ahn, T M. Thermal degradation of supported catalysts: coarsening kinetics of platinum particles on flat and curved oxide substrates. United States.
Ahn, T M. Sun . "Thermal degradation of supported catalysts: coarsening kinetics of platinum particles on flat and curved oxide substrates". United States.
@article{osti_7138960,
title = {Thermal degradation of supported catalysts: coarsening kinetics of platinum particles on flat and curved oxide substrates},
author = {Ahn, T M},
abstractNote = {A theory was developed for the coarsening kinetics of small-faceted particles on flat support surfaces where the experimentally observed coarsening rates were far slower than those predicted by noninhibited coarsening modes. The continued growth of the faceted crystal surfaces of the small particles probably occurs by repeated pillbox nucleation events. Experimental data on the coarsening kinetics of platinum particles on alumina substrates at 900/sup 0/-1100/sup 0/C with initial average particle size of 35-120 nm were consistent with coarsening by the inhibited mode. The predicted increase in coarsening rate with smaller initial average particle sizes was also observed. For the case of particle behavior on a curved substrate, a simple theory was derived that particles will migrate to concave sites and the initial growth rates may be enhanced by this particle migration. These effects will only occur when the particle size is close to that of the radius of curvature of the substrate, and the coarsening rates may be retarded after long time annealing. Platinum particle behavior on curved alumina substrates with sinusoidal gratings produced by a photoresist and ion beam micromachining technique was consistent with predictions.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1978},
month = {1}
}

Thesis/Dissertation:
Other availability
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