EXAFS studies of supported metal catalysts

Conference · Sat Mar 01 04:00:00 EST 1980 · Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States)

OSTI ID:5252990

Via, G H ^[1]; Sinfelt, J H; Lytle, F W

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1. Exxon Research and Engineering Co., Linden, NJ

Extended x-ray absorption fine structure (EXAFS) was used to study the average structure of metal clusters in a number of highly dispersed monometallic catalysts. Clusters of osmium, iridium, and platinum dispersed on silica or alumina were investigated. The metal clusters in the catalysts constituted 1.0 wt % of the total mass, and measurements were made following thorough reduction of the catalysts at elevated temperature. The EXAFS data on the metal clusters and were compared to data on the metal clusters were compared to data on the corresponding bulk metals in the analysis. The general conclusions of this work are: (1) first neighbor bond distances in the metal clusters differed from these in the bulk metals by <0.02 A. (2) First neighbor coordination numbers for the metal clusters ranged between 7 and 10 as compared to 12 for the bulk metals. These low coordination numbers are consistent with the high state of dispersion for the catalysts. (3) The thermal or static disorder, sigma/sub 1/, for atoms in the metal clusters was found to be larger by a factor of 1.4 to 2 rather than sigma/sub 1/ for the bulk metals, which reflects the high percentage of surface atoms in the metal clusters.

• OSTI ID: 5252990
• Report Number(s): CONF-800303-(Vol.25No.2)
• Conference Information: Journal Name: Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical &amp; Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
ELEMENTS
FINE STRUCTURE
IRIDIUM
MECHANICAL STRUCTURES
METALS
MINERALS
OSMIUM
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
REFRACTORY METALS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SUPPORTS
TRANSITION ELEMENTS