Pd/SiO/sub 2/. I. In situ x-ray diffraction studies during treatment and hydrogenolysis. [Methylcyclopropane hydrogenolysis]

Journal Article · Sat Aug 01 04:00:00 EDT 1981 · J. Catal.; (United States)

OSTI ID:6040917

Nandi, R K; Pitchai, R; Wong, S S; Cohen, J B; Burwell, Jr, R L; Butt, J B

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), Journal Name: J. Catal.; (United States) Vol. 70:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
CYCLOALKANES
DATA
DEUTERIUM
DIFFRACTION
ELEMENTS
EXPERIMENTAL DATA
FLUIDS
GASES
HELIUM
HYDRIDES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROGENATION
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
LATTICE PARAMETERS
LIGHT NUCLEI
METALS
MINERALS
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PALLADIUM COMPOUNDS
PALLADIUM HYDRIDES
PARTICLE SIZE
PLATINUM METALS
RARE GASES
SCATTERING
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SIZE
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION