Hydrogenation of ethylene on supported platinum

Schlatter, James C.; Boudart, M.

doi:10.1016/0021-9517(72)90132-7

Cited by 161 publications

(85 citation statements)

References 11 publications

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“…For instance, most of the reported activation energies lie between the values of 9 and 11 Kcal/ mole [11][12][13][14][15]. Bond and coworkers studied the reaction of ethylene with deuterium over different platinum catalysts, and reported reaction rate orders in hydrogen and ethylene partial pressures of 1.2 and -o.5, respectively [5,16).…”

Section: Discussionmentioning

confidence: 99%

Hydrogenation of ethylene over platinum (111) single-crystal surfaces

Zaera¹,

Somorjai²

1984

J. Am. Chem. Soc.

352

243

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Section: Discussionmentioning

confidence: 99%

Hydrogenation of ethylene over platinum (111) single-crystal surfaces

Zaera¹,

Somorjai²

1984

J. Am. Chem. Soc.

352

243

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“…For ethylene hydrogenation, it was suggested that the spilledover hydrogen does not just combine stoichiometrically with the ethylene, but that it forms catalytic centers which were capable of multiple turnover cycles [ 11,12]. Other authors, however, observed no activity enhancement attributable to spilledover hydrogen [ 13,14], and suggested that the alumina diluent might act as a scavenger for impurities.…”

Section: Introductionmentioning

confidence: 95%

“…For example, it is possible that spilled-over hydrogen keeps the platinum surface clean by hydrogenation of coke precursors [ 31 ]. Alternatively, the higher activity with acidic supports could result from adsorption of feed poisons by the acidic support [ 14], also keeping the platinum surface clean. In either case, the lower activity for platinum on non-acidic supports would result from a reduction in the fraction of exposed metal surface by coking or adsorption of poisons.…”

Section: Hydrogenolysis Of Neopentane and Propanementioning

confidence: 99%

Role of spill-over hydrogen in the hydrogenolysis of neopentane

Modica¹,

Miller²,

Meyers³

et al. 1994

Catalysis Today

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A series of Pt/LTL zeolite catalysts with varying Pt loading and support acidity was studied by hydrogen temperature-programmed desorption (TPD) and reaction of neopentane and propane. Specific desorption peaks in the TPD were associated with hydrogen spilled-over onto the support. The ability of the spilled-over hydrogen to migrate on the support surface was limited to approximately 35 nm from the platinum cluster. Saturation capacity for spilled-over hydrogen was related to the support acidity/basicity, with a maximum of about 1018 atoms/m 2 for the most acidic support studied. Spilled-over hydrogen was inert to oxygen treatment at 100°C, and did not contribute to catalytic activity for neopentane or propane conversion. Instead, hydrogenolysis TOF and the amount of spilledover hydrogen were mutually dependent on support acidity/basicity. Both declined with increasing K/AI ratio of the support, and continued to decline even for basic supports with K/A1 ratios greater than 1. The continued decline in activity for K/A1 > 1 indicates than the metal-support interaction is not dependent on acidic hydroxyls.

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“…While typically inert on their own for a given reaction, the support can, by many different mechanisms, dramatically alter the catalytic performance of metal particles, or become an integral part of the catalytic process with active sites of its own. 31,16,32,33,34 I will be focusing on a few key examples relevant to the following work.…”

Section: Support Effects In Catalysismentioning

confidence: 99%

“…Because  (2) is zero for centrosymmetric media, SFG is only sensitive to a break in inversion symmetry which usually occurs at a surface or interface. 31 Consequently, SFG is useful for obtaining vibrational spectra of surfaces. In this study, SFG is used to obtain the vibrational spectrum of the nanoparticle capping layer in H2 and O2 atmospheres.…”

Section: Sum Frequency Generation Vibrational Spectroscopymentioning

confidence: 99%

Support effects in catalysis studied by in-situ sum frequency generation vibrational spectroscopy and in-situ x-ray spectroscopies

Kennedy

2017

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Kinetic measurements are paired with in-situ spectroscopic characterization tools to investigate colloidally based, supported Pt catalytic model systems in order to elucidate the mechanisms by which metal and support work in tandem to dictate activity and selectivity. The results demonstrate oxide support materials, while inactive in absence of Pt nanoparticles, possess unique active sites for the selective conversion of gas phase molecules when paired with an active metal catalyst.In order to establish a paradigm for metal-support interactions using colloidally synthesized Pt nanoparticles the ability of the organic capping agent to inhibit reactivity and interaction with the support must first be assessed. Pt nanoparticles capped by poly(vinylpyrrolidone) (PVP), and those from which the PVP is removed by UV light exposure, are investigated for two reactions, the hydrogenation of ethylene and the oxidation of methanol. It is shown that prior to PVP removal the particles are moderately active for both reactions. Following removal, the activity for the two reactions diverges, the ethylene hydrogenation rate increases 10-fold, while the methanol oxidation rate decreases 3-fold. To better understand this effect the capping agent prior to, and the residual carbon remaining after UV treatment are probed by sum frequency generation vibrational spectroscopy. Prior to removal no major differences are observed when the particles are exposed to alternating H2 and O2 environments. When the PVP is removed, carbonaceous fragments remain on the surface that dynamically restructure in H2 and O2. These fragments create a tightly bound shell in an oxygen environment and a porous coating of hydrogenated carbon in the hydrogen environment. This observation explains the divergent catalytic results. Reaction rate measurements of thermally cleaned PVP and oleic acid capped particles show this effect to be independent of cleaning method or capping agent. In all this demonstrates the ability of the capping agent to mediate nanoparticle catalysis.With this established the hydrogenation of furfural by Pt supported on SiO2 and TiO2 was investigated by an approach combining reaction studies with SFG in order to gain molecular level insight into the nature of the metal-support interaction. This is the first instance of SFG being 2 used to probe the factors governing selectivity in a supported catalyst system. This work revealed that TiO2 possessed sites, that while inactive without Pt, became highly active for the selective conversion of furfural to furfuryl alcohol. By SFG a TiO2 bound intermediate species was identified that could explain the highly selective nature of the reaction by Pt/TiO2. In combination with density functional theory calculations it was determined that furfural bound favorably to oxygen vacancy sites on the TiO2 surface through the aldehyde oxygen, which in turn activated the aldehyde group for hydrogenation by a charge transfer mechanism. This intermediate could then react with spillover hydrogen from the Pt surface...

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Hydrogenation of ethylene on supported platinum

Cited by 161 publications

References 11 publications

Hydrogenation of ethylene over platinum (111) single-crystal surfaces

Hydrogenation of ethylene over platinum (111) single-crystal surfaces

Role of spill-over hydrogen in the hydrogenolysis of neopentane

Support effects in catalysis studied by in-situ sum frequency generation vibrational spectroscopy and in-situ x-ray spectroscopies

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