The catalytic activation of primary alcohols on niobium oxide surfaces unraveled: the gas phase reactions of NbxOy− clusters with methanol and ethanol

Jackson, P.; Fisher, Karen R.; Willett, Gary D.

doi:10.1016/s0301-0104(00)00304-9

Cited by 45 publications

(34 citation statements)

References 38 publications

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“…25,31,32 As for anionic clusters, Jackson and co-workers have reported that Nb x O y − compounds undergo different reactions with methanol and ethanol depending on the oxidation state of Nb and the number of Nb−O double bonds. 29 In our previous study, we showed that the combination of coverage-dependent 2PPE measurements and DFT calculations is a highly effective tool for understanding electron transfer at the cluster−support interface for a series of metal oxide nanoclusters on Cu(111). 10 Here, we first extend this study to Nb oxide nanoclusters.…”

Section: O 10mentioning

confidence: 99%

Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Nakayama

Xue

et al. 2015

J. Phys. Chem. C

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Size-selected niobium oxide nanoclusters (Nb 3 O 5 , Nb 3 O 7 , Nb 4 O 7 , and Nb 4 O 10 ) were deposited at room temperature onto a Cu(111) surface and a thin film of Cu 2 O on Cu(111), and their interfacial electronic interactions and reactivity toward water dissociation were examined. These clusters were specifically chosen to elucidate the effects of the oxidation state of the metal centers; Nb 3 O 5 and Nb 4 O 7 are the reduced counterparts of Nb 3 O 7 and Nb 4 O 10 , respectively. From twophoton photoemission spectroscopy (2PPE) measurements, we found that the work function increases upon cluster adsorption in all cases, indicating a negative interfacial dipole moment with the positive end pointing into the surface. The amount of increase was greater for the clusters with more metal centers and higher oxidation state. Further analysis with DFT calculations of the clusters on Cu (111) indicated that the reduced clusters donate electrons to the substrate, indicating that the intrinsic cluster dipole moment makes a larger contribution to the overall interfacial dipole moment than charge transfer. X-ray photoelectron spectroscopy (XPS) measurements showed that the Nb atoms of Nb 3 O 7 and Nb 4 O 10 are primarily Nb 5+ on Cu(111), while for the reduced Nb 3 O 5 and Nb 4 O 7 clusters, a mixture of oxidation states was observed on Cu(111). Temperature-programmed desorption (TPD) experiments with D 2 O showed that water dissociation occurred on all systems except for the oxidized Nb 3 O 7 and Nb 4 O 10 clusters on the Cu 2 O film. A comparison of our XPS and TPD results suggests that Nb 5+ cations associated with NbO terminal groups act as Lewis acid sites which are key for water binding and subsequent dissociation. TPD measurements of 2-propanol dehydration also show that the clusters active toward water dissociation are indeed acidic. DFT calculations of water dissociation on Nb 3 O 7 support our TPD results, but the use of bulk Cu 2 O(111) as a model for the Cu 2 O film merits future scrutiny in terms of interfacial charge transfer. The combination of our experimental and theoretical results suggests that both Lewis acidity and metal reducibility are important for water dissociation.

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Section: O 10mentioning

confidence: 99%

Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Nakayama

Xue

et al. 2015

J. Phys. Chem. C

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“…Dehydrogenation of methanol over TMOs in the gas phase has been extensively investigated; most researchers focus on the reactions of cation or anion metal oxide clusters [59,[147][148][149][150][151][152][153][154].…”

Section: Methanol Oxidation To Formaldehydementioning

confidence: 99%

Gas phase chemistry of neutral metal clusters: Distribution, reactivity and catalysis

Yin

Bernstein

2012

International Journal of Mass Spectrometry

162

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“…[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In particular, studies of the reactivity of the vanadium oxide cluster ions with alcohols is driven by the industrial applications of heterogeneous vanadium oxide catalysts in the oxidation of methanol, and the likely intermediacy of vanadium alkoxide species in other oxidation reactions mediated by vanadium oxides. [25][26][27][28][29][30][31][32] Heavier niobium and tantalum gas-phase clusters have also been examined, [25,26,29,[33][34][35][36][37] again in the context of the catalytic application of niobium and tantalum oxide surfaces. [38,39] The majority of these gas-phase studies have been supported by theoretical calculations.…”

Section: H T U N G T R E N N U N G (H 2 -Ochr)]mentioning

confidence: 99%

Gas‐Phase Reactivity of Metavanadate [VO₃]⁻ towards Methanol and Ethanol: Experiment and Theory

Waters¹,

Wedd²,

O’Hair³

2007

Chemistry A European J

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The gas-phase reactivity of the metavanadate anion [VO3]- towards methanol and ethanol was examined by a combination of ion-molecule reaction and isotope labelling experiments in a quadrupole ion-trap mass spectrometer. The experimental data were interpreted with the aid of density functional theory calculations. [VO3]- dehydrated methanol to eliminate water and form [VO2(eta2-OCH2)]-, which features an [eta2-C,O-OCH2]2- ligand formed by formal removal of two protons from methanol and which is isoelectronic with peroxide. [VO3]- reacted with ethanol in an analogous manner to form [VO2(eta2-OCHCH3)]-, as well as by loss of ethene to form [VO2(OH)2]-. The calculations predicted that important intermediates in these reactions were the hydroxo alkoxo anions [VO2(OH)(OCH2R)]- (R: H, CH3). These were predicted to undergo intramolecular hydrogen-atom transfer to form [VO(OH)2(eta1-OCHR)]- followed by eta1-O-->eta2-C,O rearrangements to form [VO(OH)2(eta2-OCHR)]-. The latter reacted further to eliminate water and generate the product [VO2(eta2-OCHR)]-. This major product observed for [VO3]- is markedly different from that observed previously for [NbO3]- containing the heavier Group 5 congener niobium. In that case, the major product of the reaction was an ion of stoichiometry [Nb, O3, H2]- arising from the formal dehydrogenation of methanol to formaldehyde. The origin of this difference was examined theoretically and attributed to the intermediate alkoxo anion [NbO2(OH)(OCH3)]- preferring hydride transfer to form [HNbO2(OH)]- with loss of formaldehyde. This contrasts with the hydrogen-atom-transfer pathway observed for [VO2(OH)(OCH3)]-.

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The catalytic activation of primary alcohols on niobium oxide surfaces unraveled: the gas phase reactions of NbxOy− clusters with methanol and ethanol

Cited by 45 publications

References 38 publications

Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Gas phase chemistry of neutral metal clusters: Distribution, reactivity and catalysis

Gas‐Phase Reactivity of Metavanadate [VO₃]⁻ towards Methanol and Ethanol: Experiment and Theory

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The catalytic activation of primary alcohols on niobium oxide surfaces unraveled: the gas phase reactions of NbxOy− clusters with methanol and ethanol

Cited by 45 publications

References 38 publications

Influence of Cluster–Support Interactions on Reactivity of Size-Selected NbxOy Clusters

Influence of Cluster–Support Interactions on Reactivity of Size-Selected NbxOy Clusters

Gas phase chemistry of neutral metal clusters: Distribution, reactivity and catalysis

Gas‐Phase Reactivity of Metavanadate [VO3]− towards Methanol and Ethanol: Experiment and Theory

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Product

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Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Influence of Cluster–Support Interactions on Reactivity of Size-Selected Nb_xO_y Clusters

Gas‐Phase Reactivity of Metavanadate [VO₃]⁻ towards Methanol and Ethanol: Experiment and Theory