Methane activation on unsupported platinum clusters

Trevor, D. J.; Cox, D. M.; Kaldor, A.

doi:10.1021/ja00166a005

Cited by 171 publications

(94 citation statements)

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“…30 Experimental studies of unsupported clusters containing up to 24 Pt atoms have also been reported for the activation of methane. 31 Among the smallest clusters, particular attention has been paid to Pt tetramers and methane dehydrogenation. 32,33 …”

Section: Introductionmentioning

confidence: 99%

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

Hauser

Gomes

Bajdich

et al. 2013

Phys. Chem. Chem. Phys.

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The reaction pathways for the dehydrogenation of ethane, propane, and butane, over Pt are analyzed using density functional theory (DFT). Pt nanoparticles are represented by a tetrahedral Pt 4 cluster. The objectives of this work were to establish which step is rate limiting and which one controls the selectivity for forming alkenes as opposed to causing further dehydrogenation of adsorbed alkenes to produce precursors responsible for catalyst deactivation due to coking. Further objectives of this work are to identify the role of adsorbed hydrogen, derived from H 2 fed together with the alkane, on the reaction pathway, and the role of replacing one of the four Pt atoms by a Sn atom. A comparison of Gibbs free energies shows that in all cases the rate-determining step is cleavage of a C-H bond upon alkane adsorption. The selectivity to alkene formation versus precursors to coking is dictated by the relative magnitudes of the activation energies for alkene desorption and dehydrogenation of the adsorbed alkene. The presence of an adsorbed H atom on the cluster facilitates alkene desorption relative to dehydrogenation of the adsorbed alkene. Substitution of a Sn atom in the cluster to produce a Pt 3 Sn cluster leads to a downward shift of the potential energy surface for the reaction and causes an increase of the activity of the catalyst as suggested by recent experiments due to the lower net activation barrier for the rate limiting step. However, the introduction of Sn does not alter the relative activation barriers for gas-phase alkene formation versus loss of hydrogen from the adsorbed alkene, the process leading to the formation of coke precursors.

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Section: Introductionmentioning

confidence: 99%

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

Hauser

Gomes

Bajdich

et al. 2013

Phys. Chem. Chem. Phys.

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“…[9] Aside from the standard approach to many nanoscale materials, more novel approaches have recently shown that Co 9 O 8 and Ni 2 P hollow nanocrystals can be prepared using the nanoscale Kirkendall effect. [10,11] Organometallic complexes have also been used for metal-oxide nanostructure formation, by employing their sensitivity to moisture and the resulting exothermic decomposition. [12] Many of the routes that result in controllable and phase-pure metallic and metal-oxide nanoparticles are limited to metals and oxides due to the nature of the organometallic complex and its coordinative properties.…”

Section: Introductionmentioning

confidence: 99%

Solid-state synthesis of embedded single-crystal metal oxide and phosphate nanoparticles and in situ crystallization

Dı́az

Valenzuela

Bravo

et al. 2011

Journal of Colloid and Interface Science

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“…The platinum tetramer anion is unique in this respect, reacting more efficiently than the corresponding cation. Indications for a correlation of reactivity with the availability of low coordination metal atoms was discussed by Trevor et al [6]. Thus, it was speculated that low coordination metal atoms activate CH 4 more readily than closed packed metal surface atoms [8].…”

Section: Introductionmentioning

confidence: 98%

“…In the gas phase it has been shown that already atomic metal ions reveal a very interesting chemistry with respect to hydrocarbons (see e.g., in the reviews by Schwarz and Schröder [2,3]). As an example Cox and Kaldor and their coworkers have studied palladium and platinum clusters interacting with a series of alkanes and aromatics [4][5][6]. In the case of CH 4 on Pt n with up to n = = 24 atoms, activation was realized for the first time on an unsupported metal cluster, and the reaction had a distinct cluster size dependence, with Pt 2 to Pt 5 being most reactive.…”

Section: Introductionmentioning

confidence: 99%

The polymerization of acetylene on supported metal clusters

Gilb

Arenz

Heiz

2006

Low Temperature Physics

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The polymerization of acetylene was studied by thermal programmed reaction on model catalysts consisting of size-selected Ag, Rh, and Pd atoms and Pd n (1 £ n £ 30) clusters on well-characterized MgO(111) thin films. In a single-pass heating cycle experiment, benzene, butadiene, and butane were catalyzed with different selectivities as function of cluster size: palladium and rhodium atoms selectively produce benzene, and the highest selectivity for butadiene is observed for Pd 6 , whereas Pd 20 reveals the highest selectivity for butane. Ag atoms are inert. These results provide an atom-by-atom observation of the selectivity of small cluster catalysts.

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Methane activation on unsupported platinum clusters

Cited by 171 publications

References 0 publications

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

Solid-state synthesis of embedded single-crystal metal oxide and phosphate nanoparticles and in situ crystallization

The polymerization of acetylene on supported metal clusters

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