Oxidation Reactions over Supported Metal Oxide Catalysts: Molecular/Electronic Structure – Activity/Selectivity Relationships

Wachs, Israel E.; Kim, Tae-Jin

doi:10.1002/9783527626113.ch11

Cited by 4 publications

(6 citation statements)

References 48 publications

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“…V, Mo, W, and Re) and many pertinent reviews are available. [12][13][14][15][16][17][18][19][20][21][22][23][24] Despite the extent of the literature, the reports on key aspects such as the termination configuration (i.e. discriminating between the mono-oxo, di-oxo and/or trioxo termination configurations) of dehydrated MO x sites and the eventual heterogeneity of the dispersed oxometallic phase (i.e.…”

Section: Introductionmentioning

confidence: 99%

Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

et al. 2022

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Section: Introductionmentioning

confidence: 99%

Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

et al. 2022

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“…For low conversions in excess oxygen, the kinetics are first-order in methanol and zero-order in oxygen, with an activation energy of 19.6 kcal/mol (82 kJ/mol) at atmospheric pressure set by the C–H bond within the adsorbed methoxy group . The rate expression is generally written as where K ads incorporates CH 3 OH adsorption, k rds accounts for the rate-determining step, and P CH 3 OH denotes the partial pressure of methanol.…”

Section: Conceptual Backgroundmentioning

confidence: 99%

“…Partial oxidation of methanol to formaldehyde was chosen as a test reaction, with an overall reaction stoichiometry of Over V 2 O 5 , the reaction is highly selective toward the formaldehyde and water products, with minimal side reactions and simple first-order kinetics. , The mechanism and rate-determining step are well understood. Reaction conditions are mild with relatively safe, easy-to-detect reactants and products.…”

Section: Conceptual Backgroundmentioning

confidence: 99%

“…However, the combined use of these tools to predict the variation of a catalytic reaction rate as a function of heterojunction variables such as overlayer thickness and support donor concentration has not yet been attempted. Methanol oxidation on TiO 2 -supported vanadia offers a test case, as the reaction follows a Mars–van Krevelen mechanism , that is well understood and should respond to the position of the surface Fermi energy.…”

Section: Introductionmentioning

confidence: 99%

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Manipulating Reaction Rates of Metal-Oxide Heterogeneous Catalysts via Semiconductor Heterojunctions

Nandakumar

Seebauer

2018

J. Phys. Chem. C

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Heterojunctions of metal oxide semiconductors enable the manipulation of surface chemistry for heterogeneous catalysts or sensors without introducing dopants and their attendant complications. If one of the semiconductors is sufficiently thin, charge exchange between the two semiconductors leads to charge buildup at the free surface. The excess charge influences the Lewis acid−base character of the surface and propagates into properties such as catalytic activity. Although the available literature offers evidence for such effects, published work does not outline a quantitative framework that links heterojunction behavior to catalytic activity. The present work develops and demonstrates such a framework for the oxidation of methanol to formaldehyde with a heterojunction of thin polycrystalline V 2 O 5 grown on polycrystalline anatase TiO 2 . The framework accurately reproduces activity changes by a factor of 20 in response to V 2 O 5 thickness and TiO 2 donor concentration.

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“…They are good adsorbents and efficient catalysts [11]. They consist of dispersed surface metal oxide species and catalytic active sites supported on high surface area oxides [12]. Mixed metal oxide catalysts are used in heterogeneous catalysis for chemical processes and being further developed for their catalytic performance and durability [13].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Different Sonication Times of Nickel Oxide and Zirconium Oxide Catalysts in Syngas Production

2018

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Heterogeneous catalytic cracking is currently one of the most effective ways for both reducing tar content and enhancing hydrogen (H2) content in syngas at relatively low temperature, besides being environmental friendly. Sonochemical treatment has also been shown to lower reaction times with enhanced reaction rate and enables production of particles with high surface area. In this study, two different types of metal oxides, which are Nickel oxide (NiO) and Zirconium oxide (ZrO2) at a combination of 1:1 ratio with Zeolite as the supporter are synthesized via sonochemical treatment in durations of 30, 60 and 90 minutes. The catalysts are then characterized using X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR-H2), Brunauer-Emmett-Teller surface measurement (BET), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). From SEM and TEM analysis, Nickel tends to agglomerate and form sizable globular shapes, Zirconium forms coral-like branching structure and Zeolite forms stacks of cubic clumps. The most promising sonication treatment duration for the catalysts is 30 minutes because it removes decent amount of reactive oxygen at a rate of 0.83 x 1021 atoms/g during hydrogen reduction, possesses the highest surface area of 506.52 m2/g as well as smallest average crystallite size of 56.9 nm compared to other durations. Generally sonochemical treatment also increases the catalysts surface area and oxygen removal as well as lowers the reduction temperature which is favourable in term of production cost. Catalysts with sonochemical treatment duration of 30 and 60 minutes generally show higher reactive oxygen removal and surface area compared to catalysts with 90 minute treatments.

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Oxidation Reactions over Supported Metal Oxide Catalysts: Molecular/Electronic Structure – Activity/Selectivity Relationships

Cited by 4 publications

References 48 publications

Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

Manipulating Reaction Rates of Metal-Oxide Heterogeneous Catalysts via Semiconductor Heterojunctions

The Effects of Different Sonication Times of Nickel Oxide and Zirconium Oxide Catalysts in Syngas Production

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Oxidation Reactions over Supported Metal Oxide Catalysts: Molecular/Electronic Structure – Activity/Selectivity Relationships

Cited by 4 publications

References 48 publications

Rethinking the molecular structures of WVIOxsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

Rethinking the molecular structures of WVIOxsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

Manipulating Reaction Rates of Metal-Oxide Heterogeneous Catalysts via Semiconductor Heterojunctions

The Effects of Different Sonication Times of Nickel Oxide and Zirconium Oxide Catalysts in Syngas Production

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Product

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Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations

Rethinking the molecular structures of W^VIO_xsites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations