Solid-solid wetting and formation of monolayers in supported oxide systems

Leyrer, J.; Margraf, R.; Taglauer, E.; Knözinger, Helmut

doi:10.1016/0039-6028(88)90505-5

Cited by 136 publications

(68 citation statements)

References 42 publications

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“…The experimental dispersion capacity was calculated from the residual amount of crystalline MoOa, as calculated from the area of the peak at 329 pm in the XRD patterns, after the mixtures of MoO3 and A1103 had been calcined at 770 K for 2 h. Table II lists The present results undoubtedly demonstrate that dispersion can also take place in the absence of water vapour (sample MD-0.4), but its presence does favour the dispersion for even relatively low heating periods [16]. For samples containing 0.7 monolayers of MoO3 (i.e.…”

Section: Mechanical Mixturesmentioning

confidence: 62%

“…Margraf et al [15] reported that the formation of highly dispersed molybdena species on MoO3/AI/O3 mixtures takes place exclusively in the presence of water vapour. In a recent paper, the authors [16], using ion-scattering spectroscopy, have shown that spreading of molybdenum species occurs during calcination of physical mixtures in flowing oxygen, in the absence and in the presence of water vapour.…”

Section: -2461 9 1992mentioning

confidence: 99%

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Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

et al. 1992

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Section: Mechanical Mixturesmentioning

confidence: 62%

Section: -2461 9 1992mentioning

confidence: 99%

Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

et al. 1992

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“…The use of absolute LEIS intensities rather than signal ratios proved to be very useful and lead to quite a different model for the alumina supported molybdena catalysts (see sectien 2.3.2). Since bath molybdena and vanadium are classified in the category of monolayer-type catalysts [17,25] it seems interesting to investigate the structure of V 2 0 5 /y-AI203 catalysts.…”

Section: Introduetionmentioning

confidence: 99%

Study of the Surface Structure of V2O5/γ-Al2O3 Catalysts by LEIS

Jacobs

Leerdam

Brongersma

1991

Fundamental Aspects of Heterogeneous Catalysis Studied by Particle Beams

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MASTERStudy of the surface structure of V2O5/-Al2O3 catalysts by LEIS Jacobs, J. Award date: 1991Disclaimer This document contains a student thesis (bachelor's or master's), as authored by a student at Eindhoven University of Technology. Student theses are made available in the TU/e repository upon obtaining the required degree. The grade received is not published on the document as presented in the repository. The required complexity or quality of research of student theses may vary by program, and the required minimum study period may vary in duration. 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 Take down policy If 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. ABSTRACTWithin the scope of the catalytic research of the Schuit lnstitute of Catalysis at the Eindhoven Univarsity of Technology, the surface structure of V20s/y-AI20 3 catalysts has been investigated by low energy ion scattering (LEIS). LEIS is a unique surface analysis technique because its information depth is limited to the topmost atomie layer.Supported vanadium oxides are widely used as oxidation catalysts. This investigation is performed in cooperation with the Delft Univarsity of Technology. The scientists from Delft are interestad in the use of Pd/V 2 0 5 /y-AI 2 0 3 catalysts in the heterogeneaus Wacker oxidation.The LEIS experiments on the V 2 0 5 /y-AI 2 0 3 catalysts have been used to study the surface structure of these catalysts as a tunetion of V 2 0 5 loading. At low loadings ( < 7 wt%) the vanadium species are found to be optimally dispersedover the support, while at medium loadings ( < 11 wt%) multilayered structures are formed. In this thesis a three-dimensional model is presented for the surface structure of V 2 0 5 /y-AI 2 0 3 catalysts. SAMENVATTINGIn het kader van het katalytisch onderzoek van het Schuit Katalyse Instituut aan de Technische Universiteit Eindhoven is de oppervlakte struktuur van V 2 0 5 /y-AI 2 0 3 katalysatoren met behulp van lage ionen verstrooiing (LEIS) onderzocht. LEIS is een unieke oppervlakte analyse techniek omdat de informatie diepte beperkt blijft tot de bovenste atoomlaag.Gedragen vanadium oxides worden veel gebruikt als oxidatie katalysator. Dit onderzoek is in samenwerking met de Technische Universiteit Delft gedaan. De wetenschappers uit Delft zijn geïnteresseerd in het gebruik van Pd/V 2 0 5 /y-AI 2 0 3 katalysatoren in de heterogene Wacker oxidatie.Met de LEIS experimenten van V 2 0 5 /y-AI 2 0 3 katalysatoren...

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“…Subject to the current model, the OSWD depends on a gradient of the surface free energy. [20][21][22][23][24][25] Hence, assuming the situation of a γQAC crystal contacting a HOPG substrate, if the attractive forces towards the substrate surface exceed the binding forces within the adsorbed semiconductor crystal, then an OSWD should take place. Comparing the surface free energies of graphite (54.8 mJ/m 2 , 43 ) and γQAC (49.1 mJ/m 2 , 44 ) revealed, that the binding forces within the graphite surface are stronger than within a γQAC crystal.…”

Section: The Dispersing Agent Determines Structure and Quantity Of Thmentioning

confidence: 99%

“…Immediately afterwards, highly ordered supramolecular arrays covering the substrate surface are formed. The self-assembly is driven by a solid-solid wetting effect, [23][24][25] with a gradient of the surface free energy acting as the driving force. In this publication we show that via the OSWD technique, 3D crystalline particles can be transformed directly into several, distinctly defined 1D and 2D supramolecular structures.…”

Section: Introductionmentioning

confidence: 99%

Growing low-dimensional supramolecular crystals directly from 3D particles

et al. 2017

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We show that one-dimensional (1D) nanostructures and two-dimensional (2D) supramolecular crystals of organic semiconductors can be grown on substrates under ambient conditions directly from three-dimensional (3D) organic crystals. The approach does not require dissolving, melting or evaporating of the source crystals and is based on the Organic SolidSolid Wetting Deposition (OSWD). We exemplify our approach by the pigment quinacridone (QAC). Scanning Tunnelling Microscopy (STM) investigations show that the structures of the resulting 2D crystals are similar to the chain arrangement of the alpha and beta QAC polymorphs and are independent of the 3D source crystal polymorph (gamma). Furthermore, distinct 1D chains can be produced systematically.

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Solid-solid wetting and formation of monolayers in supported oxide systems

Cited by 136 publications

References 42 publications

Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

Study of the Surface Structure of V2O5/γ-Al2O3 Catalysts by LEIS

Growing low-dimensional supramolecular crystals directly from 3D particles

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