Realistic surface science models of industrial catalysts

Niemantsverdriet, J.W.; Engelen, A.F.P; Jong, A.M. de; Wieldraaijer, W.; Kramer, G.J.

doi:10.1016/s0169-4332(98)00749-1

Cited by 33 publications

(24 citation statements)

References 25 publications

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“…35,36 The Rh 0 binding energy of 307.0 eV is bulk like, suggesting that the Rh particles contain at least hundreds of atoms. 37,21 The Rh/ Si ratio for this sample was found to be 0.16-0.20, which is somewhat lower than 0.24-0.35 for comparable systems with a Rh loading of ϳ5 atoms/ nm 2 reported in the literature. 21 It is shown by AFM that the particles become smaller after reduction.…”

Section: Discussioncontrasting

confidence: 52%

“…37,21 The Rh/ Si ratio for this sample was found to be 0.16-0.20, which is somewhat lower than 0.24-0.35 for comparable systems with a Rh loading of ϳ5 atoms/ nm 2 reported in the literature. 21 It is shown by AFM that the particles become smaller after reduction. This is consistent with the literature 35,36 where it is shown that upon reduction a change of particle shape and distribution can occur.…”

Section: Discussioncontrasting

confidence: 52%

“…Any thin oxide layer on the bevels and backside resulting from this treatment is much thinner than the silica layer. Then, the ATR crystal was spin coated with a 1 mMol/ l solution of RhCl 3 · xH 2 O ͑Alfa/ Johnson Matthey͒ in water under N 2 atmosphere at a rotation speed of 5000 rpm, 21 which resulted in dispersed nanoparticles. The RhCl 3 particles were then reduced to Rh 0 in a tube reactor under flowing H 2 at a pressure of 1 bar.…”

Section: A Sample Preparationmentioning

confidence: 99%

“…On these crystals, Rh nanoparticles are deposited, which are easily prepared by spincoat impregnation from a solution of RhCl 3 in water or ethanol. 21 The effects of the silica layer and the nanoparticles on the detection of adsorbed species by the evanescent wave are discussed below.…”

Section: Introductionmentioning

confidence: 99%

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Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

Leewis

Kessels

Sanden

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A sensitive method is presented for studying adsorption of gaseous species on metal surfaces in vacuum by attenuated total internal reflection Fourier transform infrared spectroscopy ͑ATR͒. The method is illustrated by CO adsorption experiments on silica supported Rh nanoparticles. An experimental setup and a procedure are described in detail to obtain a sensitivity of reflectance change of ϳ5 ϫ 10 −5 absorbance units. Here, a silicon ATR crystal with a 50 nm layer of hydroxylated silica acts as the support for the Rh nanoparticles. These particles are easily prepared by spincoat impregnation from a RhCl 3 solution followed by H 2 reduction. X-ray photoelectron spectroscopy before and after reduction shows that rhodium is reduced to Rh 0 and that all chlorine is removed. Atomic force microscope images the distribution of the particles, which are 3 -4 nm in height. When the crystal is exposed to pressures up to 1 mbar of CO, a gas which is inert to the silica support, the stretch vibration of linearly adsorbed CO on the Rh nanoparticles is detected at 2023 cm −1 , while no bridged CO or geminal dicarbonyl species can be distinguished. The minimum detectable coverage is estimated ϳ0.005 CO per nm 2 substrate area or ϳ5 ϫ 10 −4 ML.

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Section: Discussioncontrasting

confidence: 52%

Section: Discussioncontrasting

confidence: 52%

Section: A Sample Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

Leewis

Kessels

Sanden

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Alternatively, model systems may consist of particles supported on thin oxide or carbon films. The films are deposited on flat, inert, and conducting substrates, [13,14] and significant charge accumulation during experiments can be avoided, even if the film is an insulator. Such materials are inherently more complex than flat, continuous single-crystalline films and better mimic industrial, supported catalysts.…”

Section: Introductionmentioning

confidence: 99%

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Lloyd

Hansen

Ranke

et al. 2011

Applied Catalysis A: General

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Nanocrystalline thin films of the alkane skeletal isomerisation catalyst sulfated zirconia were successfully deposited on a silicon substrate in order to allow the application of surface science techniques. Thermal treatment of the films was optimised to chemically mimic the powder preparation process, resulting in films possessing the essential features (including tetragonal phase, nanocrystallinity and sulfur content of ~3 atomic %) of active powder catalysts. The n-butane adsorption-desorption equilibrium under isobaric conditions (10 -8 to 10 -6 hPa) over the temperature range 300-100 K was monitored by photoelectron spectroscopy. Analysis of the isobars revealed strong and weak n-butane chemisorption sites, releasing heats of between 59-40 and 47-34 kJ/mol, corresponding to 5 and 25% of a monolayer coverage, respectively. The total amount of chemisorbed n-butane coincides with the estimated number of surface sulfate groups. An increase in adsorption heat was observed between coverages of ~5-8% of a monolayer, indicating adsorbate-adsorbate interactions. It follows that adjacent sites are present and isomerisation by a bimolecular surface reaction is feasible. Physisorption on the films generates heats of ~28 kJ/mol, for coverages from 30% up to a complete monolayer. Multilayer adsorption results in the formation of an electrically insulating adsorbate structure. It is proposed that the strong chemisorption sites correspond to an interaction with a minority disulfate species.

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Case Studies in Catalyst Characterization

Niemantsverdriet

2007

Spectroscopy in Catalysis

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Realistic surface science models of industrial catalysts

Cited by 33 publications

References 25 publications

Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Case Studies in Catalyst Characterization

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