Photocatalytic Methanol Oxidation by Supported Vanadium Oxide Species: Influence of Support and Degree of Oligomerization

Kortewille, Bianca; Wachs, Israel E.; Cibura, Niklas; Pfingsten, Oliver; Bacher, G.; Strunk, Jennifer

doi:10.1002/ejic.201800490

Cited by 13 publications

(6 citation statements)

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“…At 250°C, a small band at 2896 cm À 1 appears and it is probably associated to symmetrical CÀ H stretching of surface formate species (HCOO À ) generated by the re-adsorption of the formaldehyde produced during the reaction. [49] In the low wavenumber region ( Figure S8), bands at 1434 and 1451 cm À 1 , related to symmetric and asymmetric deformation modes of methoxy species, [49] and at 1745 cm À 1 related to C=O stretching of molecularly adsorbed formaldehyde, [50] confirmed the observations of high wavenumber spectra. Considering that intensities are proportional to the concentration of species adsorbed on surface, [51] the evolution of adsorbed methanol on the silica surface and methoxy species on V sites were monitored by band intensities at 2958 and 2933 cm À 1 , respectively, during methanol flow for 30 min, and the results are shown in Figure 6D.…”

Section: Resultssupporting

confidence: 76%

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

et al. 2019

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Supported transition metal catalysts have been extensively applied to oxidative and reductive processes. The understanding of surface speciation and active site‐support interactions in these materials play a substantial role in developing improved heterogeneous catalysts. Herein, a series of impregnated 3D ferrierite and 2D ITQ‐6 siliceous supports with variable loading of vanadium oxide was prepared. Chemical and structural properties of the materials were studied by X‐ray diffraction, N2 physisorption, inductively coupled plasma – optical emission spectrometry, X‐ray absorption, Fourier transform infrared and diffuse reflectance UV‐vis spectroscopies, and temperature‐programmed reduction with H2. Reactivity of the catalyst surface, associated with the incidence of isolated silanol groups, was found to be more effective when vanadium oxides were better dispersed and stabilized than increases in surface area. Differences in activation and the oxidation state dynamic behavior of active sites were then probed by methanol oxidation as a model reaction monitored by in situ FTIR spectroscopy and XANES/MS. By applying isothermal periods of reaction under non‐oxidizing atmosphere and regeneration of catalysts by O2, it was found that, even at distinct rates, all types of sites are accessible during reaction, since a complete reduction to V4+ was observed. However, reoxidation of sites to V5+ is limited and sensitive to the different vanadium species on the surface, and probably, the determinant factor of the distinct V5+/V4+ equilibrium reached for the catalysts when the reaction is carried out under constant oxidizing atmosphere.

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Section: Resultssupporting

confidence: 76%

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

et al. 2019

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“…125 Besides, Strunk et al investigated the effects of supported vanadium oxide species and degree of oligomerization on photocatalytic methanol oxidation. 126 Fang and co-workers reported a Cu−V bimetallic catalyst (CuVO x ) catalyzed heterogeneous Fenton process for the degradation of fluconazole. 127 It was found that this novel catalyst had higher catalytic activity and better reusability than those of monometallic Cu compounds.…”

Section: Oxidationmentioning

confidence: 99%

“…It was proposed that the difference was related to the activation energy for the C–H bond cleavage of the V–OCH 3 . Besides, Strunk et al investigated the effects of supported vanadium oxide species and degree of oligomerization on photocatalytic methanol oxidation …”

Section: Organic Synthesismentioning

confidence: 99%

Applications of Vanadium, Niobium, and Tantalum Complexes in Organic and Inorganic Synthesis

Wang

Tan

et al. 2022

ACS Org. Inorg. Au

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Organometallic catalysis is a powerful strategy in chemical synthesis, especially with the cheap and low toxic metals based on green chemistry principle. Thus, the selection of the metal is particularly important to plan relevant and applicable processes. The group VB metals have been the subject of exciting and significant advances in both organic and inorganic synthesis. In this Review, we have summarized some reports from recent decades, which are about the development of group VB metals utilized in various types of reactions, such as oxidation, reduction, alkylation, dealkylation, polymerization, aromatization, protein synthesis, and practical water splitting.

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“…13 such hydrated conditions, vanadia is known to interact with adsorbed moisture, stimulating a structural change as a thin aqueous layer forms on the oxide support that enables vanadia to migrate and form new molecular structures. 14 To obtain a detailed molecular picture of these structures of vanadium oxide supported on titania under such conditions, nuclear magnetic resonance (NMR) was exploited as a tool to discriminate and quantify the vanadia species present on hydrated supported vanadium oxide catalytic materials.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Hydration is of particular interest because of its relevance to the initial state of manufactured catalysts prior to their use and to the photocatalytic performance of vanadium-based heterogeneous catalysts because water molecules are not driven from the surface under ambient conditions . Under such hydrated conditions, vanadia is known to interact with adsorbed moisture, stimulating a structural change as a thin aqueous layer forms on the oxide support that enables vanadia to migrate and form new molecular structures . To obtain a detailed molecular picture of these structures of vanadium oxide supported on titania under such conditions, nuclear magnetic resonance (NMR) was exploited as a tool to discriminate and quantify the vanadia species present on hydrated supported vanadium oxide catalytic materials.…”

Section: Introductionmentioning

confidence: 99%

Impact of Hydration on Supported V₂O₅/TiO₂ Catalysts as Explored by Magnetic Resonance Spectroscopy

Jaegers

Wang

et al. 2021

J. Phys. Chem. C

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Supported vanadium oxide catalysts are important industrial materials for a wide array of chemical transformations. The condition of surface hydration is of particular interest as a reflection of the state of freshly manufactured catalysts prior to their activation in catalytic reactors or under the conditions of photocatalysis where surface vanadia are exposed to moisture. Under such conditions, the surface vanadia species undergo structural changes, as evidenced by 51V magic-angle spinning nuclear magnetic resonance (51V MAS NMR) in this study. For low surface vanadia densities on titania, a modest trend toward the formation of dimeric and oligomeric vanadia species was observed under hydrated conditions when compared to the corresponding dehydrated catalyst, which contains a large abundance of monomeric vanadia species. The incorporation of tungsten oxide into the V2O5/TiO2 catalyst with low surface vanadia density, however, is found to better stabilize the surface vanadia species on the titania support upon hydration than its tungsta-free counterpart. This stabilization is not an intrinsic property of more extensively oligomerized surface vanadia species in the presence of tungsten oxide, which is evidenced by the conditions of high concentrations of surface vanadia oligomers on titania that exhibit dramatic structural changes upon hydration. At high surface vanadia coverage under hydrated environments, the simultaneous observation of polycrystalline V2O5 nanoparticles and a mobile phase of surface vanadia species is apparent, where vanadia species are dissolved in a thin hydration layer on the titania support. These new findings have broad implications on the behavior of other metal-oxide species on high surface oxide supports under hydrated conditions.

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Photocatalytic Methanol Oxidation by Supported Vanadium Oxide Species: Influence of Support and Degree of Oligomerization

Cited by 13 publications

References 80 publications

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Applications of Vanadium, Niobium, and Tantalum Complexes in Organic and Inorganic Synthesis

Impact of Hydration on Supported V₂O₅/TiO₂ Catalysts as Explored by Magnetic Resonance Spectroscopy

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Photocatalytic Methanol Oxidation by Supported Vanadium Oxide Species: Influence of Support and Degree of Oligomerization

Cited by 13 publications

References 80 publications

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Applications of Vanadium, Niobium, and Tantalum Complexes in Organic and Inorganic Synthesis

Impact of Hydration on Supported V2O5/TiO2 Catalysts as Explored by Magnetic Resonance Spectroscopy

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Impact of Hydration on Supported V₂O₅/TiO₂ Catalysts as Explored by Magnetic Resonance Spectroscopy