In situ x-ray absorption spectroscopic study of a highly dispersed platinum-tin/alumina catalyst

Caballero, A.; De×pert, H.; Didillon, B.; LePeltier, Fabienne; Clause, O.; Lynch, John P.

doi:10.1021/j100145a028

Cited by 26 publications

(40 citation statements)

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“…The intensity of the white line in these catalysts and in PtSn/C(SI) is lower than that in platinum foil and in the reference sample a/A2. A similar result was previously observed in a PtSn/Al2O3 catalyst 20) . This effect is explained by the formation of a Pt _ Sn alloy resulting in increased d-electron density of platinum atoms.…”

Section: Reduced Samplessupporting

confidence: 90%

“…There is also disagreement about the assignation of the peak at lower distances (< 2.10 Å). This peak has been assigned to the interaction of platinum clusters with the support via Pt _ O _ Sn 2+ species 20) , not clearly defined 49) , explained as an interference phenomenon between the Pt _ Pt and Pt _ Sn bonds 21), 52) , and as a Pt _ O interaction at 1.99 Å related to interaction with the SiO2 support 16) . These discrepancies reveal the difficulty in accurate quantification of the EXAFS oscillations and show that the use of appropriate references and complementary techniques is necessary for the correct assessment of bond distances and co-ordination numbers.…”

Section: Reduced Samplesmentioning

confidence: 96%

“…Ramallo et al 16) also report that the Pt _ Sn distance is slightly lower than the Pt _ Pt distance (2.68 versus 2.71 Å). However, in the work of Caballero et al 20) a peak at 2.68 Å was assigned to the Pt _ Pt bond and a peak at 2.93 Å to the Pt _ Sn bond. There is also disagreement about the assignation of the peak at lower distances (< 2.10 Å).…”

Section: Reduced Samplesmentioning

confidence: 98%

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Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Román-Martı́nez

Cazorla‐Amorós

Miguel

et al. 2004

J. Jpn. Petrol. Inst.

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Carbon-supported PtSn catalysts were prepared by impregnation using a commercial activated carbon after purification and oxidation (H2O2, 20 v/v%) treatments. The support surface chemistry of the carbon after purification and the oxidized carbon, and successive impregnation or coimpregnation procedures were the variables investigated. The catalysts obtained were characterized using the following techniques: TPD and TPR experiments, H2 chemisorption, XPS and XAFS, and activity assessment in the following reactions: cyclohexane dehydrogenation (reaction insensitive to structure), cyclopentane hydrogenolysis (reaction sensitive to structure) and carvone hydrogenation, which allows analysis of the selectivity of PtSn catalysts (carvone contains one C=O group and two C=C bonds for hydrogenation). The objective of the study is to find any relationships between the preparation procedure and the support properties, the characteristics of the resulting catalysts, and the catalytic behavior. The porosity of the carbon support together with the surface oxidation determines the accessibility of reactants to the active sites. Unusual selectivity to alcohols was found. Addition of tin caused blocking and dilution of the platinum clusters. The carbon support also affected the selectivity either because of its electronic properties or because of the particular metal structures developed.

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Section: Reduced Samplessupporting

confidence: 90%

Section: Reduced Samplesmentioning

confidence: 96%

Section: Reduced Samplesmentioning

confidence: 98%

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Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Román-Martı́nez

Cazorla‐Amorós

Miguel

et al. 2004

J. Jpn. Petrol. Inst.

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“…When alumina is used as a support, it interacts strongly with the Sn and hinders the reduction of SnO. [32][33][34].…”

Section: X-ray Photoelectronic Spectroscopymentioning

confidence: 99%

Effect of Sn addition to Pt/CeO2–Al2O3 and Pt/Al2O3 catalysts: An XPS, 119Sn Mössbauer and microcalorimetry study

Serrano‐Ruiz

Huber

Sánchez-Castillo

et al. 2006

Journal of Catalysis

144

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The effect of Sn addition to Pt/CeO 2 -Al 2 O 3 and Pt/Al 2 O 3 catalysts was studied with X-ray photoelectron spectroscopy (XPS), 119 Sn Mössbauer spectroscopy and adsorption microcalorimetry of CO at room temperature. Catalysts were reduced in situ at 473 ("non-SMSI state") and 773 K ("SMSI state"). 119 Sn Mössbauer and XPS results indicated that the presence of cerium in bimetallic catalysts inhibited reduction of tin.Furthermore, it was found that tin facilitated reduction of cerium (IV) to cerium (III).Microcalorimetric analysis indicated that cerium addition caused the appearance of a more heterogeneous distribution of active sites, whereas tin addition led to a higher homogeneity of these sites.

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“…To make progress in this area and allow a better control of the active phase, the elaboration of structural models for bimetallic platinum‐tin subnanometric particles supported on γ‐alumina, is of fundamental and practical importance. Density functional theory (DFT) calculations are useful in that respect, due to the challenging characterization of supported clusters, that are often sub‐nanometric and non‐regular in shape . Significant amount of work has been devoted so far for the proposal of relevant dispersed monometallic Pt/Al 2 O 3 models, particularly in the case of the gamma polymorph of alumina .…”

Section: Introductionmentioning

confidence: 99%

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

et al. 2019

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Supported platinum‐based sub‐nanometric particles play a central role in many catalytic applications. In particular, platinum‐tin active phases supported on γ‐Al2O3 are largely employed for dehydrogenation of alkanes and catalytic reforming of naphtha cuts, although geometric and electronic effects of the active phase in the presence of hydrogen still remains highly debated. Thanks to periodic density functional theory (DFT), we propose structural models of such systems containing thirteen metal atoms (PtxSn13‐x with 0≤x≤13) deposited on the (100) γ‐Al2O3 surface. We thus unravel the intricate effects of the composition (Pt/Sn ratio), of the support (γ‐Al2O3) and the hydrogen coverage on the stability of platinum‐tin sub‐nanometric clusters, in the case where tin is reduced (Sn0). A detailed investigation of the interaction of the supported Pt10Sn3 cluster with hydrogen by velocity‐scaled molecular dynamics provides a mapping of the hydrogen coverage as a function of the operating conditions (T, P(H2)). Our study highlights significant differences between Pt13 and PtxSn13‐x clusters in terms of ductility and dilution (also called ensemble) effects which may be at the origin of the different reactivities usually reported for Pt and PtSn supported catalysts.

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In situ x-ray absorption spectroscopic study of a highly dispersed platinum-tin/alumina catalyst

Cited by 26 publications

References 2 publications

Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Effect of Sn addition to Pt/CeO2–Al2O3 and Pt/Al2O3 catalysts: An XPS, 119Sn Mössbauer and microcalorimetry study

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

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In situ x-ray absorption spectroscopic study of a highly dispersed platinum-tin/alumina catalyst

Cited by 26 publications

References 2 publications

Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Carbon-supported PtSn Catalysts: Characterization and Catalytic Properties

Effect of Sn addition to Pt/CeO2–Al2O3 and Pt/Al2O3 catalysts: An XPS, 119Sn Mössbauer and microcalorimetry study

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al2O3 Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

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Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen