Comparative DFT study of the adsorption of 1,3-butadiene, 1-butene and 2-cis/trans-butenes on the Pt(111) and Pd(111) surfaces

Valcárcel, Ana; Clotet, Anna; Ricart, Josep M.; Delbecq, Françoise; Sautet, Philippe

doi:10.1016/j.susc.2003.11.036

Cited by 94 publications

(133 citation statements)

References 51 publications

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“…[9,10] Weakly bonded ethene in a p configuration desorbs at temperatures below 200 K, while the high-temperature (HT) state at about 300 K is associated with di-s-bonded molecules, which is in agreement with calculations showing that di-s-bonded alkenes (e.g., ethene, various butene isomers) are more strongly bound on the Pd(111) surface. [8,15,17] A similar desorption behavior is observed for various pentene isomers. [18,19] Weakly bound pentene in a p-bonded geometry desorbs at about 170 K. Accordingly, the HT state at about 230 K is associated with di-s-bonded molecules.…”

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confidence: 70%

Surface‐Bonded Precursor Determines Particle Size Effects for Alkene Hydrogenation on Palladium

2005

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Reactions of linear alkenes with metal surfaces have been previously studied on model catalyst systems with varying degrees of complexity, from single crystals to metal particles deposited on well-ordered oxide films. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Based on these studies, the majority of which were conducted with ethene, it has been suggested that alkene hydrogenation is structure insensitive. This means that the reaction only depends on the number of metal atoms on the surface and is independent of the crystallographic orientation of the particle facets and particle size. These size effects are difficult to study in real catalytic systems because the mean particle size and distribution cannot be controlled accurately. Herein, we report the particle size effects on alkene reactivity (ethene and trans-2-pentene) using well-defined Pd/Al 2 O 3 model catalysts, where the particle size can be varied in a controllable manner. Temperature-programmed desorption (TPD) indicated that alkene adsorption exhibits site-specific behavior, which is assigned to the reactions occurring separately on facets and on low-coordination-number atoms such as edge and corner atoms. A strong particle size effect (within the 1-5-nm range) is observed for the hydrogenation of pentene over a hydrogen-precovered surface, whereas the reaction for ethene is independent of size. These effects are explained by the reactions proceeding via di-s-bonded pentene, which is favored on the terrace sites of large particles, and p-bonded ethene.The morphology of the Pd model system has been studied intensively in our laboratory by scanning tunneling microscopy. [9,16] Thin alumina films were grown on a clean NiAl(110) single crystal, and subsequently Pd was vapordeposited onto the films (see the Experimental Section for details). An average particle size was determined from the amount of Pd deposited and could be varied within the range 1-5 nm with a narrow particle-size distribution (20 %); [16] the corresponding relationship is presented in reference [9]. To exclude any effects of morphology changes on Pd particles during TPD measurements, the samples were preannealed at 500 K before the adsorption experiments.

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confidence: 70%

Surface‐Bonded Precursor Determines Particle Size Effects for Alkene Hydrogenation on Palladium

2005

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“…Because of the stronger adsorption energy of the most unsaturated molecules (21)(22)(23)(24)(25) and in spite of the fact that the rate of hydrogenation of alkenes is higher than that of alkadienes (or alkynes) (5), butadiene adsorption inhibits alkene hydrogenation, thus palladium catalysts are selective (more subtle details can be found in the two recent reviews of Borodzinski and Bond (18,26)). This remains true as long as dienes (or alkynes) are present in the gas mixture.…”

Section: B Comparison With Pd Catalystsmentioning

confidence: 99%

Influence of the reactant concentration in selective hydrogenation of 1,3-butadiene over supported gold catalysts under alkene rich conditions: A consideration of reaction mechanism

2009

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This article is about the reaction of selective hydrogenation of 1,3-butadiene performed in an excess of alkenes (propene/butadiene ratio = 100) over supported gold catalysts, so as to mimic the conditions of purification of light alkenes (C4 cuts) from the presence of impurities (highly unsaturated compounds, 1-3%). Gold was found highly selective (close to 100%, no propane or butane formation) for the hydrogenation of butadiene to butenes at 100% conversion of butadiene. The influence of the concentrations of the various reactants, i.e. hydrogen, butadiene and propene, on the rates of butadiene and propene hydrogenation was investigated, and the apparent reaction orders were deduced from the dependence of rate on partial pressure in the gas phase. The reason for the high selectivity of gold catalysts is that the reaction of hydrogenation of alkenes occurs at much higher temperature (0.1% conversion at 300°C) than that of selective hydrogenation of butadiene (100% at T <170°C).

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“…300 K auf di-s-gebundene Moleküle zurückgeht; in Übereinstimmung mit Rechnungen sind di-s-gebundene Alkene (Ethen, Buten-Isomere) demnach stärker an die Pd(111)-Oberfläche gebunden. [8,1,17] Ein ähnliches Desorptionsverhalten wird für verschiedene Penten-Isomere beobachtet. [18,1,9] [19] Dies impliziert, dass di-sgebundene Alkene zügig H-Atome gegen auf der Oberfläche vorhandene D-Atome austauschen, wobei teilhydrierte Spezies wie Ethyl und Pentyl durchlaufen werden.…”

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Oberflächengebundene Intermediate verursachen Teilchengrößeneinflüsse bei der Hydrierung von Alkenen auf Palladium

2005

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Comparative DFT study of the adsorption of 1,3-butadiene, 1-butene and 2-cis/trans-butenes on the Pt(111) and Pd(111) surfaces

Cited by 94 publications

References 51 publications

Surface‐Bonded Precursor Determines Particle Size Effects for Alkene Hydrogenation on Palladium

Surface‐Bonded Precursor Determines Particle Size Effects for Alkene Hydrogenation on Palladium

Influence of the reactant concentration in selective hydrogenation of 1,3-butadiene over supported gold catalysts under alkene rich conditions: A consideration of reaction mechanism

Oberflächengebundene Intermediate verursachen Teilchengrößeneinflüsse bei der Hydrierung von Alkenen auf Palladium

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