Influence of particle size on catalytic properties of alumina-supported rhodium catalysts

Journal Article · Thu Jan 31 23:00:00 EST 1980 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(80)90391-7· OSTI ID:6454971

Fuentes, S; Figueras, F

Alumina-supported catalysts containing 0.08-2.35 rhodium were prepared by ion exchange or impregnation and hydrogen-reduced at 400/sup 0/-830/sup 0/C. Their degree of dispersion varied from 7.5 to 100%. The dispersion was determined by electron microscopy, hydrogen and oxygen adsorption, and titration of adsorbed oxygen with hydrogen. The stoichiometry of hydrogen and oxygen adsorption on the rhodium was 1:1, and oxygen adsorption did not change with dispersion as it did on platinum and palladium. The turnover number for benzene hydrogenation on these catalysts decreased slightly with increasing dispersion, which indicated that small particles were less active for hydrogenation than larger particles. The turnover number for the hydrogenolysis of cyclopentane decreased by a factor of eight and the selectivity for methane formation went through a maximum with increasing dispersion of the rhodium. An analysis of the data and comparison with available studies of hydrogenolysis on other metals suggested that particle size effects depend on variations of activity of crystal planes, i.e., the availability of facetted rather than spherical; particles, and not on the properties of edge, corner, and face atoms.

• Research Organization: Inst. Rech. Catal., C.N.R.S., Villeurbanne
• OSTI ID: 6454971
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 61:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ADSORPTION
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AROMATICS
BENZENE
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
CYCLOALKANES
DATA ANALYSIS
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN
HYDROGENATION
IMPREGNATION
ION EXCHANGE
METALS
METHANE
MICROSCOPY
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PALLADIUM
PARTICLE SIZE
PLATINUM
PLATINUM METALS
REDUCTION
RHODIUM
SIZE
SORPTION
SPECIFICITY
SYNTHESIS
TITRATION
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE