Flame-made MoO3/SiO2–Al2O3 metathesis catalysts with highly dispersed and highly active molybdate species

Debecker, Damien P.; Schimmoeller, Bjoern; Stoyanova, Mariana; Poleunis, Claude; Bertrand, Patrick; Rodemerck, Uwe; Gaigneaux, Éric M.

doi:10.1016/j.jcat.2010.11.003

Cited by 91 publications

(101 citation statements)

References 34 publications

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“…Most importantly, the molybdenum oxide surface species consist of a mixture of monomeric and connected molybdenum oxide centres. Very recently, the use of TOF-SIMS as an alternative experimental approach to differentiate between isolated and connected molybdenum oxide species was demonstrated for alumina and mixed silica/alumina supported molybdenum oxide [67,68].…”

Section: Resultsmentioning

confidence: 99%

Structure of molybdenum oxide supported on silica SBA-15 studied by Raman, UV–Vis and X-ray absorption spectroscopy

Thielemann

Ressler

Walter

et al. 2011

Applied Catalysis A: General

103

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The structure of molybdenum oxide supported by silica SBA-15 has been studied by visible Raman spectroscopy, diffuse reflectance UV-Vis spectroscopy and X-ray absorption spectroscopy in the dehydrated state obtained after thermal treatment at elevated temperatures (≥350°C). No dependence of the molybdenum oxide structure on preparation procedure or loading has been observed within the range of loadings studied in detail (0.2 to 0.8 Mo/nm 2 ). X-ray absorption spectroscopy (XAS) reveals that the dehydrated state consists of a mixture of monomeric and connected molybdenum oxide centres. While the presence of crystalline MoO3 can be excluded by Raman spectroscopy, tetrahedrally and octahedrally coordinated MoO4 and MoO6 units are identified by XAS. The MoO6 units possess connectivity similar to that of MoO3 building blocks, whereas the MoO4 units are isolated or connected to other MoxOy units. These results are supported by UV-Vis spectra showing intensity at wavelengths (>300 nm) typical for dimeric and/or oligomeric species.

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Section: Resultsmentioning

confidence: 99%

Structure of molybdenum oxide supported on silica SBA-15 studied by Raman, UV–Vis and X-ray absorption spectroscopy

Thielemann

Ressler

Walter

et al. 2011

Applied Catalysis A: General

103

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“…The various catalyst assessment metrics are as follows . The apparent activity is defined as the number of moles of 2‐butene converted to propene per gram of catalyst per hour

true X_{2 - b u t e n e} = \frac{{[2 - b u t e n e]}_{i n} - {[2 - b u t e n e]}_{o u t}}{{[2 - b u t e n e]}_{i n}} \times 100 %

true S_{p r o p e n e} = \frac{{([], p, r, o, p, e, n, e)}_{o u t}}{{{[2 - b u t e n e]}_{i n} - [2 - b u t e n e]}_{o u t}} \times 100 %

true Y_{p r o p e n e} = X_{2 - b u t e n e} \times S_{p r o p e n e} \times 100 %

true M a s s b a l a n c e c l o s u r e = \frac{[T o t a l c a r b o n i n p r o d u c t s]}{[T o t a l c a r b o n i n f e e d c o m p o n e n t s]} \times 100 %

…”

Section: Methodsmentioning

confidence: 99%

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Ramanathan

Kersting³

et al. 2020

ChemCatChem

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Tungsten and niobium incorporated KIT‐6 (WNb‐KIT‐6) materials were synthesized by a one‐pot sol‐gel method. During 2‐butene+ethylene metathesis with these materials at 450 °C, the propene yield is maximized (∼70 %) at a certain metal composition (∼20 wt% W and ∼1 wt% Nb), significantly surpassing those reported with an industrial WO3/SiO2 catalyst. The enhanced propene yield is attributed to better dispersion of W species on the catalyst surface and the formation of new active site precursors (O=)2W(O−Si)(O−Nb), as confirmed by XRD, TEM, H2‐TPR, XPS, EXAFS, and ToF‐SIMS techniques. Complementary DFT calculations reveal a positive correlation between the O=W=O bond angle and the propene yield. We therefore speculate that the −O−Nb moiety tunes the electronic environment around the W atom and increases the propene yield.

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“…different precursors, acids and pH values. For comparison a high surface area α-MoO3 was prepared by onestep flame spray pyrolysis [41]. All samples were calcined under the same conditions to exclude a possible influence of the temperature treatment on the catalytic performance [22,42].…”

Section: Introductionmentioning

confidence: 99%

Systematic study on the influence of the morphology of α-MoO3 in the selective oxidation of propylene

Schuh

Kleist

Høj

et al. 2015

Journal of Solid State Chemistry

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Flame-made MoO3/SiO2–Al2O3 metathesis catalysts with highly dispersed and highly active molybdate species

Cited by 91 publications

References 34 publications

Structure of molybdenum oxide supported on silica SBA-15 studied by Raman, UV–Vis and X-ray absorption spectroscopy

Structure of molybdenum oxide supported on silica SBA-15 studied by Raman, UV–Vis and X-ray absorption spectroscopy

Enhanced Olefin Metathesis Performance of Tungsten and Niobium Incorporated Bimetallic Silicates: Evidence of Synergistic Effects

Systematic study on the influence of the morphology of α-MoO3 in the selective oxidation of propylene

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