An EXAFS study of the spreading of MoO3 on the surface of $gamma;-Al2O3

Kisfaludi, G.

doi:10.1016/0021-9517(91)90103-b

Cited by 30 publications

(9 citation statements)

References 13 publications

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“…However, there was no peak corresponding to the Mo–(O)–Mo shell observed for bulk MoO 3 at 3.2 Å (Figure S3d). These results revealed that both Pt 0 nanoparticles and Mo 6+ oxide clusters were highly dispersed on the surface of the H-β zeolite. , …”

Section: Resultsmentioning

confidence: 81%

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

Mizugaki

Togo

Maeno

et al. 2016

ACS Sustainable Chem. Eng.

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One-pot transformation of levulinic acid to 2methyltetrahydrofuran is facilely promoted by a H-β-zeolitesupported Pt−Mo bimetallic catalyst in water without any additives. The Pt−Mo species efficiently promotes hydrogenation of levulinic acid to 1,4-pentanediol, which is subsequently dehydrated to form 2-methyltetrahydrofuran by H-β zeolite in the aqueous phase. The Pt−Mo/H-β catalyst is recoverable and reusable while retaining its high activity and selectivity.

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Section: Resultsmentioning

confidence: 81%

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

Mizugaki

Togo

Maeno

et al. 2016

ACS Sustainable Chem. Eng.

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“…Leyrer et al studied the MoO 3 /alumina system by ISS and Kisfaludi et al by EXAFS and concluded from these techniques that thermal spreading occurred, although the Raman showed a spectrum very closely resembling the MoO 3 . Leyrer et al interpreted this as transformation of bulk MoO 3 into its MoO 4 , building up blocks onto the alumina surface as a result of the thermal treatment.…”

Section: Resultsmentioning

confidence: 99%

“…Several researchers have reported evidence of thermal spreading phenomenon of MoO 3 onto Al 2 O 3 , TiO 2 , SnO 2 , and MgO supports. − However some researchers using mainly Raman spectroscopy have shown that thermal spreading of MoO 3 does not occur onto silica surface. , They have attributed their results to the low interaction energy between these oxides and an insignificant decrease of surface free energy of SiO 2 that, therefore, would not favor this phenomenon on silica support.…”

Section: Introductionmentioning

confidence: 99%

Thermal Spreading of MoO₃onto Silica Supports

et al. 2000

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The thermal spreading of MoO3 onto silica was studied in comparison with the thermal spreading onto alumina using different characterization techniques. X-ray diffraction results showed that MoO3 crystals were transformed into Mo amorphous species on alumina and silica supports by thermal treatment. Laser Raman spectroscopy results also evidenced the transformation of MoO3 bulk into small Mo clusters and/or dispersed Mo species, which are highly distorted, interacting with alumina and silica supports. X-ray photoelectron spectroscopy and diffuse reflection spectroscopy (DRS) results gave better evidence of the presence of higher amounts of Mo species at the surface of both supports when compared with the respective physical mixtures. Fourier transform infrared spectroscopy also provided good evidence that a surface reaction may have occurred between MoO3 and hydroxyl groups on both supports. It was possible to infer that the original MoO3 crystal lattices were destroyed by reacting with the support surface as a result of thermal treatment and transformed into small Mo clusters, dispersed Mo species, or both. Moreover, Raman spectroscopy showed nicely that the interaction of Mo species was higher on alumina than silica surfaces. Raman and DRS also provide insight into Mo species dispersion on alumina and silica samples, whereas DRS provided better evidence of the presence of dispersed Mo species on these supports. It was possible to infer that all calcined physical mixtures exhibited dispersed Mo species and small Mo clusters together with a small quantity of bulk MoO3 that remained after thermal treatment. Therefore, similar results obtained on both supports demonstrated that the thermal spreading of MoO3 also occurred on silica and the same mechanism was observed as on alumina. However, the Mo dispersion and some Mo species were different on the supports that can be attributed to the different surface properties of silica and alumina.

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“…The spreading of an active catalyst component on a support material is one of the important processes during catalyst preparation . In typical monolayer-type catalysts the active phase consists of a metal oxide dispersed on a metal oxide support. , Alumina-supported Mo oxide catalysts belong to this class of catalysts. − The spreading and wetting of MoO 3 on Al 2 O 3 has been extensively studied during the last two decades. − It was shown that upon annealing in oxygen or in air MoO 3 completely wets the Al 2 O 3 support. When water is present in the gas phase during annealing, spreading takes place much faster than in a dry atmosphere, leading to a monolayer (1 ML) of a polymolybdate phase on the support surface .…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Transport during the Spreading of MoO₃ on Al₂O₃ Support Surfaces: Photoelectron Spectromicroscopic Study

et al. 2004

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The spreading of MoO 3 crystallites on a flat Al 2 O 3 support has been investigated by means of integrative X-ray photoelectron spectroscopy and laterally resolving photoelectron spectromicroscopy. The effect of different heat treatments on the spreading of the MoO 3 crystallites has been studied by systematically varying the temperature, the total pressure, and the humidity of the oxygen atmosphere. The chemical images and the quantitative analysis of the lateral expansion of the spread phase around a single MoO 3 crystallite provided insight in the effect of the parameter changes, since the same crystallite could be monitored and the spread layer was removed prior to each heat treatment. The obtained data set strongly supports that gas-phase transport is responsible for the spreading and wetting of molybdate species on the support surface. A model is discussed that consistently explains all experimental observations. † Part of the special issue "Gerhard Ertl Festschrift".

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An EXAFS study of the spreading of MoO3 on the surface of $gamma;-Al2O3

Cited by 30 publications

References 13 publications

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

Thermal Spreading of MoO₃onto Silica Supports

Gas-Phase Transport during the Spreading of MoO₃ on Al₂O₃ Support Surfaces: Photoelectron Spectromicroscopic Study

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An EXAFS study of the spreading of MoO3 on the surface of $gamma;-Al2O3

Cited by 30 publications

References 13 publications

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

One-Pot Transformation of Levulinic Acid to 2-Methyltetrahydrofuran Catalyzed by Pt–Mo/H-β in Water

Thermal Spreading of MoO3onto Silica Supports

Gas-Phase Transport during the Spreading of MoO3 on Al2O3 Support Surfaces: Photoelectron Spectromicroscopic Study

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Product

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Thermal Spreading of MoO₃onto Silica Supports

Gas-Phase Transport during the Spreading of MoO₃ on Al₂O₃ Support Surfaces: Photoelectron Spectromicroscopic Study