Pd/SiO/sub 2/. I. In situ x-ray diffraction studies during treatment and hydrogenolysis. [Methylcyclopropane hydrogenolysis]
Simple techniques for studies of x-ray diffraction from Pd/SiO/sub 2/ catalysts during catalytic reactions are reported here. The catalytic activity of Pd/SiO/sub 2/ of low percentage metal exposed for methylcyclopropane hydrogenolysis at 0/sup 0/C is less for catalyst cooled from 450/sup 0/C in H/sub 2/ than for that cooled in He. This effect appears to result from differing amounts of hydride formation. Ease of formation of hydride decreases with decreasing Pd particle size. Exposing the catalysts with D/sub h/ = 13.8 and 29.3% to hydrogen at approx. 25/sup 0/C results in nearly complete conversion of particles of Pd to hydride. Purging with helium (even at 0/sup 0/C) reconverts the hydride to palladium, but this reconversion exhibits an induction period; hydride formation is more rapid. Passing hydrogen plus methylcyclopropane results in the conversion into hydride of a substantial fraction of catalyst particles originally present as palladium. The palladium hydride particles of catalyst produced by cooling from 450/sup 0/C in H/sub 2/ remain as PdH/sub 0/ /sub 7/ during the hydrogenolysis reaction. The lattice parameter of palladium particles is indistinguishable from that of bulk palladium, at least for particle diameters greater than or equal to 45 A.
- Research Organization:
- Northwestern Univ., Evanston, IL
- DOE Contract Number:
- AC02-77ER04254
- OSTI ID:
- 6040917
- Journal Information:
- J. Catal.; (United States), Vol. 70:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CYCLOALKANES
HYDROGENATION
PALLADIUM
CATALYTIC EFFECTS
CRYSTAL STRUCTURE
SILICA
DEUTERIUM
EXPERIMENTAL DATA
HELIUM
HYDROGEN
ISOTOPE EFFECTS
LATTICE PARAMETERS
PALLADIUM HYDRIDES
PARTICLE SIZE
X-RAY DIFFRACTION
ALKANES
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DATA
DIFFRACTION
ELEMENTS
FLUIDS
GASES
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
METALS
MINERALS
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM COMPOUNDS
PLATINUM METALS
RARE GASES
SCATTERING
SILICON COMPOUNDS
SILICON OXIDES
SIZE
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)