Deuterium exchange and hydrogenolysis of cyclopentane as catalytic reaction probes to detect bimetallic particle formation in supported PtRe catalysts
The H/D isotope exchange and the hydrogenolysis of cyclopentane (CP) as catalyzed by alumina or silica supported Pt, Re, the bimetallic catalyst and physical mixture, have been studied. The number of surface exposed metal atoms is determined by chemisorbing deuterium and exchanging it with hydrogen. The CP exchange reaction is found to be non-specific for the composition of the catalyzing ensembles: PtRe bimetallic catalyst exhibits the same turnover frequency (TOF) and exchange pattern as a physical mixture of these metals. The exchange rate can therefore be used to count exposed metal atoms. CP hydrogenolysis is highly ensemble-specific. The TOF for methane formation over PtRe/SiO{sub 2} exceeds that over the separate metals by a factor of 40. This finding is used to estimate the concentration of bimetallic particles in alumina supported PtRe catalysts. These reactions have also been used with temperature programmed reduction to develop a scheme by which the reduction of Re is facilitated when co-supported with Pt on {gamma}Al{sub 2}O{sub 3}. The feasibility of preparing {gamma}-Al{sub 2}O{sub 3} supported catalysts with bimetallic particles of fixed stoichiometry from the controlled deposition and decomposition of PtRe{sub 2}(CO){sub 12} was also investigated by the application of these probe reactions and FTIR. Finally, the effect of a chlorine on the metal function and degree of bimetallic interaction was investigated.
- Research Organization:
- Northwestern Univ., Evanston, IL (USA)
- OSTI ID:
- 7203908
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BIMETALS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
CHLORINE
CONTROL
CYCLOALKANES
DECOMPOSITION
DEHYDROGENATION
DEPOSITION
DEUTERIUM
ELEMENTS
FOURIER TRANSFORMATION
HALOGENS
HYDROCARBONS
HYDROGEN ISOTOPES
INFRARED SPECTRA
INTEGRAL TRANSFORMATIONS
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
METALS
METHANE
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
PROMOTERS
REDUCTION
REFORMER PROCESSES
RHENIUM
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SPECTRA
STABLE ISOTOPES
SURFACE PROPERTIES
SYNTHESIS
TEMPERATURE CONTROL
TRANSFORMATIONS
TRANSITION ELEMENTS