Hydrogen adsorption behavior and strong metal-support interaction (SMSI) on Rh-Pt bimetallic catalysts

Thesis/Dissertation · Wed Jan 01 00:00:00 EST 1986

OSTI ID:7183190

Huang, H

Chemisorption and catalytic activity studies have been used to probe the surface structure and the nature of metal-support interaction on rhodium-platinum bimetallic catalysts which were supported on two types of silica, and on alumina and titania. All of the results suggest that Rh is enriched relative to Pt on the surface of the bimetallic particles. The extent of Rh enrichment strongly depends on the surface properties of the supports. The hydrogen chemisorption equilibrium constant is found to be very much larger on Pt than on Rh. Using the observed equilibrium constant and the known slow desorption kinetics of H/sub 2/ from Pt, one can rationalize the relative rates of hydrogenolysis on Rh and Pt and the bimetallic catalysts as well as the observed apparent activation energies and their sensitivity to the kind of reactor (pulse or flow) used. Pulse-mode CO hydrogenation experiments demonstrate an effect of strong metal-support interaction in CO + H/sub 2/ reaction as well as in hydrocarbon hydrogenolysis on titania supported Rh-Pt bimetallic catalysts. The experiments support the surface migration model where a reduced TiO/sub x/ species moves onto the active metal surface. Hydrogen-oxygen titration experiments indicated that this species has the stoichiometry of TiO on Rh/TiO/sub 2/ catalyst and Ti/sub 2/O on Pt/TiO/sub 2/. These same experiments over the bimetallic catalysts indicate that SMSI does not affect the surface segregation situation, i.e., the surfaces of Rh-Pt/TiO/sub 2/ catalysts are enriched in Rh to a similar extent to that observed on other supports.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 7183190
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CARBON MONOXIDE
METHANATION
CATALYSTS
SURFACE PROPERTIES
PLATINUM
CATALYTIC EFFECTS
RHODIUM
ACTIVATION ENERGY
ALUMINIUM OXIDES
BIMETALS
CATALYST SUPPORTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTORS
CHEMISORPTION
COMPARATIVE EVALUATIONS
DESORPTION
ENRICHMENT
HYDROGEN
HYDROGENATION
MOLECULAR STRUCTURE
SILICA
TITANIUM OXIDES
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
ENERGY
KINETICS
METALS
MINERALS
NONMETALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
010408* - Coal
Lignite
& Peat- C1 Processes- (1987-)