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Title: Thermal degradation of supported catalysts: coarsening kinetics of alloy platinum-palladium particles on oxide substrates. With appendix on palladium loss due to oxide volatilization

Abstract

A systematic method for analysis of coarsening kinetics of small metal alloy particles supported on flat surfaces was developed and applied to data from coarsening experiments on 5.0 at. Vertical Bar3< platinum-palladium particles on alumina substrates. The initial average particle radii were about 5 nm, and the heat treatment was at 600/sup 0/-900/sup 0/C. The technique used for particle size measurements was based on a thin film sputtering and transmission electron microscopy. The results are described by interparticle transport of PtO/sub 2/ molecules for the platinum at all temperatures and for the palladium PdO molecules at 600/sup 0/ and 700/sup 0/C and palladium atoms at 800/sup 0/ and 900/sup 0/C. The dominant interparticle transport path was the substrate surface. The compositions remained nearly constant during coarsening. Transport of PdO was rate-controlling at 600/sup 0/C, and at each of the higher temperatures, transport by either platinum or palladium species gave the same coarsening rates. The dominant mode of coarsening after long heat treatment times was nucleation-inhibited, although the early time coarsening at 700/sup 0/ and 800/sup 0/C and all coarsening at 900/sup 0/ was noninhibited.

Authors:
Publication Date:
OSTI Identifier:
6971653
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; PALLADIUM ALLOYS; REACTION KINETICS; PALLADIUM OXIDES; EVAPORATION; PLATINUM ALLOYS; HIGH TEMPERATURE; PARTICLE SIZE; PLATINUM OXIDES; SURFACE PROPERTIES; TEMPERATURE EFFECTS; ALLOYS; ALUMINIUM COMPOUNDS; CHALCOGENIDES; KINETICS; OXIDES; OXYGEN COMPOUNDS; PALLADIUM COMPOUNDS; PHASE TRANSFORMATIONS; PLATINUM COMPOUNDS; PLATINUM METAL ALLOYS; SIZE; TRANSITION ELEMENT COMPOUNDS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Clark, R W. Thermal degradation of supported catalysts: coarsening kinetics of alloy platinum-palladium particles on oxide substrates. With appendix on palladium loss due to oxide volatilization. United States: N. p., 1978. Web.
Clark, R W. Thermal degradation of supported catalysts: coarsening kinetics of alloy platinum-palladium particles on oxide substrates. With appendix on palladium loss due to oxide volatilization. United States.
Clark, R W. Sun . "Thermal degradation of supported catalysts: coarsening kinetics of alloy platinum-palladium particles on oxide substrates. With appendix on palladium loss due to oxide volatilization". United States.
@article{osti_6971653,
title = {Thermal degradation of supported catalysts: coarsening kinetics of alloy platinum-palladium particles on oxide substrates. With appendix on palladium loss due to oxide volatilization},
author = {Clark, R W},
abstractNote = {A systematic method for analysis of coarsening kinetics of small metal alloy particles supported on flat surfaces was developed and applied to data from coarsening experiments on 5.0 at. Vertical Bar3< platinum-palladium particles on alumina substrates. The initial average particle radii were about 5 nm, and the heat treatment was at 600/sup 0/-900/sup 0/C. The technique used for particle size measurements was based on a thin film sputtering and transmission electron microscopy. The results are described by interparticle transport of PtO/sub 2/ molecules for the platinum at all temperatures and for the palladium PdO molecules at 600/sup 0/ and 700/sup 0/C and palladium atoms at 800/sup 0/ and 900/sup 0/C. The dominant interparticle transport path was the substrate surface. The compositions remained nearly constant during coarsening. Transport of PdO was rate-controlling at 600/sup 0/C, and at each of the higher temperatures, transport by either platinum or palladium species gave the same coarsening rates. The dominant mode of coarsening after long heat treatment times was nucleation-inhibited, although the early time coarsening at 700/sup 0/ and 800/sup 0/C and all coarsening at 900/sup 0/ was noninhibited.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1978},
month = {1}
}

Thesis/Dissertation:
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