Journal ArticleDOI
Palladium clusters: H2, D2, N2, CH4, CD4, C2H4, and C2H6 reactivity and D2 saturation studies
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In this paper, deuterium saturation measurements and gas phase kinetic measurements of chemisorption of H2, D2, N2, CD4, CH4, and C2H6 on neutral palladium clusters are reported.Abstract:
In this paper both deuterium saturation measurements and gas‐phase kinetic measurements of chemisorption of H2, D2, N2, CD4, CH4, C2H4, and C2H6 on neutral palladium clusters are reported Saturation studies with D2 show that small palladium clusters can bind up to three deuterium atoms per palladium atom in the cluster, in contast to H/M ratios near unity typically reported for metal surfaces In addition, the small palladium clusters exhibit pronounced discontinuities in deuterium uptake which may be indicative of structural transformations or selective desorption of deuterium From the kinetic studies we find that, in general, the rate constants for a given size cluster towards different reagents tend to order as D2, H2>N2>C2H4>CD4, CH4, C2H6 The shape of the reactivity pattern with the different reagents varies strongly with cluster size for clusters containing less than 25 atoms Finally, an inverse hydrogen isotope effect is observed for both hydrogen and methane, ie, the D2 and CD4 rate constants are significantly larger than those of H2 and CH4, respectivelyread more
Citations
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References
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Journal ArticleDOI
H2 dissociation at metal surfaces.
J. Harris,S. Andersson +1 more
TL;DR: It is shown that the d holes of a transition metal serve initially as sinks for s electrons, which reduces the Pauli repulsion and so the entrance channel activation barrier and allows the formation of metal-H bonds with only a moderate weakening of the metal-metal bonds.
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Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS
TL;DR: In this paper, the H M ratio determined by hydrogen chemisorption is a linear function of the average metal coordination number determined by extended X-ray absorption fine structure (EXAFS) measurements.
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Palladium areas in supported catalystsDetermination of palladium surface areas in supported catalysts by means of hydrogen chemisorption
TL;DR: In this paper, the surface area and hydrogen chemisorption measurements made on palladium-black samples were used to determine surface areas of particles of a size where other techniques, such as electron microscopy, X-ray linebroadening and small-angle scattering, often fail through interference of the support.
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Gas phase reactions of iron clusters with hydrogen. I. Kinetics
TL;DR: The kinetics of the gas phase reactions of hydrogen and deuterium with iron clusters in the range Fe6 to Fe68 have been investigated in this paper, and it is found that reaction rate constants are a strong function of cluster size, varying by more than five orders of magnitude in this size range.
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Metal cluster ion photofragmentation
TL;DR: In this paper, a photodissociation method was used for mass-selected transition metal cluster ions cooled in a supersonic expansion to reveal the thresholds and time scales of various fragmentation pathways.