On the thermal stability of metal particles supported on a thin alumina film

Heemeier, M.; Stempel, Sascha; Shaikhutdinov, Sh.K.; Libuda, Jörg; Bäumer, Marcus; Oldman, R. J.; Jackson, S. David; Freund, Hans‐Joachim

doi:10.1016/s0039-6028(02)02404-4

Cited by 81 publications

(71 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1a. As previously shown for other metal deposits on the alumina film, the particle spatial distribution basically reflects the degree of metal support interaction [21,22]. The absence of preferential nucleation for niobia, as shown in Fig.…”

Section: Methodssupporting

confidence: 71%

“…Figure 4 shows STM images of the 0.5 Å niobia/alumina sample after a thermal flash to elevated temperatures (500 -900 K) in UHV. Annealing to 700 K basically decreases the particle density partially due to sintering of the particles (some particles gain in size) and also due to niobia migration into the film, which is more clearly observed after annealing to 900 K. As previously shown for other metal particles [22], the interdiffusion probably goes through the line defects of the alumina film, thus resulting in their decoration (see Fig. 4d).…”

Section: Methodssupporting

confidence: 62%

“…The thin alumina films were grown on a NiAl(110) single crystal as described elsewhere [21][22][23] [19].…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Preparation and structure of alumina supported niobia model catalysts

et al. 2007

View full text Add to dashboard Cite

Abstract.Niobia/alumina model catalysts were prepared by physical vapor deposition of Nb in an oxygen atmosphere onto thin alumina films. Structural characterization, performed with scanning tunneling microscopy and infrared reflection absorption spectroscopy, revealed highly dispersed N 2 O 5 nanoparticles exposing Nb=O groups. Thermal stability of the system was also examined. The results are compared with those obtained on thin niobia films and previously studied vanadia/alumina systems.

show abstract

Section: Methodssupporting

confidence: 71%

Section: Methodssupporting

confidence: 62%

See 1 more Smart Citation

Preparation and structure of alumina supported niobia model catalysts

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Figure 13 shows STM images of the 0.5Å niobia/ alumina sample after a thermal flash to elevated temperatures (500-900 K) in UHV. Annealing to 700 K basically decreases the particle density partially due to sintering of the particles (some particles gain in size) and also due to niobia migration into the film, which is more clearly observed after annealing to 900 K. As previously shown for other metal particles (Heemeier et al 2003), the interdiffusion probably goes through the line defects of the alumina film, thus resulting in their decoration (see Fig. 13d).…”

Section: Martin Schmal and Hans-joachim Freundsupporting

confidence: 61%

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Schmal¹,

Freund

2009

An. Acad. Bras. Ciênc.

View full text Add to dashboard Cite

The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science?Real catalysts of monometallic and bimetallic Co/Nb 2 O 5 and Pd-Co/Nb 2 O 5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993. The presence of a noble metal increased the C + 5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support materials. Growth, morphology and structure of both pure metal and alloy particles were studied. It is possible to support the strong metal support interaction suggested by studies on real catalysts via the investigation of model systems for niobia in comparison to alumina support in which this effect does not occur. Formation of Co 2+ penetration into the niobia lattice was suggested on the basis of powder studies and can be fully supported on the basis of model studies. It is shown for both real catalysts and model systems that oxidation state of Co plays a key role in controlling the reactivity in Fischer-Tropsch reactions systems and that the addition of Pd is a determining factor for the stability of the catalyst. It is demonstrated that the interaction with unsaturated hydrocarbons depends strongly on the state of oxidation.

show abstract

“…444 The importance of step edges for adsorption can even be enhanced by artificially decreasing the intrinsic oxide-adsorbate interaction, for instance via surface hydroxylation. revealed for many thin-film systems, for instance for Pd and Rh on alumina/NiAl(110), 48,445 for Co on alumina/CoAl(001) 446 and for Au on MgO/Mo(001). 252 Even the self-organized growth on nano-particles can be observed, if the structural relaxation of a thin oxide film includes the formation of an ordered dislocation network.…”

mentioning

confidence: 99%

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Nilius

2009

Surface Science Reports

221

233

View full text Add to dashboard Cite

The preparation of thin oxide films on metal supports is a versatile approach to explore the properties of oxide materials that are otherwise inaccessible to most surface science techniques due to their insulating nature. Although substantial progress has been made in the characterization of oxide surfaces with spatially averaging techniques, a local view is often essential to provide comprehensive understanding of such systems. The scanning tunneling microscope (STM) is a powerful tool to obtain atomic-scale information on the growth behavior of oxide films, the resulting surface morphology and defect structure.

show abstract

On the thermal stability of metal particles supported on a thin alumina film

Cited by 81 publications

References 21 publications

Preparation and structure of alumina supported niobia model catalysts

Preparation and structure of alumina supported niobia model catalysts

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Contact Info

Product

Resources

About