Energetics of the Adsorption of Propene, Water, Dioxygen on Bismuth Molybdate (2:1)

Stradella, L.; Vogliolo, Gianfranco

doi:10.1524/zpch.1983.137.1.099

Cited by 7 publications

(10 citation statements)

References 24 publications

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“…The energy of adsorption of 3 kcal/mol found here is somewhat less than the heat of condensation of propene liquid (4.4 kcal/mol). The heat of adsorption of propene has been measured , to be 7–14 kcal/mol on BiMoO 6 and at 8–12 kcal/mol on Bi 2 Mo 2 O 9 . While the heat of adsorption of propene on Bi 2 Mo 3 O 12 does not appear to have been reported, it is expected to fall within the range for the other phases of bismuth molybdate.…”

Section: Resultsmentioning

confidence: 99%

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

2013

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The mechanism by which propene is selectively oxidized to acrolein over bismuth molybdate has been investigated using the DFT+U variant of density functional theory. In agreement with experiment, the kinetically relevant step is found to be the initial abstraction of hydrogen by lattice oxygen. Several candidate lattice oxygen sites have been examined, the most active of which is found to be a bismuth-perturbed molybdenyl MoO oxygen. Hydrogen abstraction generates an allyl radical intermediate, which can diffuse freely across the catalyst surface and ultimately binds to a second molybdenyl oxygen to form an allyl alkoxy intermediate. A second hydrogen is abstracted from this intermediate to produce acrolein. Calculations suggest that only molybdenum centers are reduced during the reaction. However, presence of bismuth in the catalyst is essential for providing the requisite structural and electronic environment at the active site.

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Section: Resultsmentioning

confidence: 99%

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

2013

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“…Stradella and Vogliolo (1983) have determined the integral molar heat of adsorption of dioxygen over reduced Bi2O3.M0O3 to be 297 kJ .mol-'. Therefore, one can estimate the M = O parameter to be 398 kJ .mol-' for MOO,, given that the presence of Bi203 at a Bi203/Mo03 ratio of 1 does not appear to effect the energetics of 0 bonding, as demonstrated byKlissurski (1979).…”

Section: Formulation Of the Microkinetic Modelmentioning

confidence: 99%

“…Stradella and Vogliolo (1983) measured the heat of adsorption of water to be 200 kJ .mol-l on either reduced or oxidized Bi203*Mo03, which corresponds to an M-OH value of 327 kJ .mol-'. Bond order conservation (BOC) calculations (Shustorovich, 1986) can also be employed to provide an estimate of M-OH, given the value of M = 0.…”

Section: Formulation Of the Microkinetic Modelmentioning

confidence: 99%

Simulation of methane partial oxidation over silica‐supported MoO₃ and V₂O₅

et al. 1991

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“…In this adsorption mode, the pi-bonding electrons of propene donate electron density to the under-coordinated Bi 3+ via a dative type interaction, resulting in a calculated internal energy of adsorption of −11.5 kcal/mol. For comparison, the experimental value for the enthalpy of adsorption of propene on bismuth molybdate is ∼8 kcal/mol …”

Section: Results and Discussionmentioning

confidence: 99%

“…For comparison, the experimental value for the enthalpy of adsorption of propene on bismuth molybdate is ∼8 kcal/mol. 45 The second step (1 → 2) is abstraction of a hydrogen atom from the methyl group of propene by a bismuth-perturbed molybdenyl oxo. This key step has been previously investigated in our group and has been found to involve a singlet−triplet spin-crossing transition state.…”

Section: Resultsmentioning

confidence: 99%

A DFT Investigation of the Mechanism of Propene Ammoxidation over α-Bismuth Molybdate

Licht

Bell

2016

ACS Catal.

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The mechanisms and energetics for the propene oxidation and ammoxidation occurring on the (010) surface of Bi2Mo3O12 were investigated using density functional theory (DFT). An energetically feasible sequence of elementary steps for propene oxidation to acrolein, propene ammoxidation to acrylonitrile, and acrolein ammoxidation to acrylonitrile are proposed. Consistent with experimental findings, the rate limiting step for both propene oxidation and ammoxidation is the initial hydrogen abstraction from the methyl group of propene, which is calculated to have an apparent activation energy of 27.3 kcal/mol. The allyl species produced in this reaction is stabilized as an allyl alkoxide, which can then undergo hydrogen abstraction to form acrolein or react with ammonia adsorbed on under-coordinated surface Bi 3+ cations to form allylamine. Dehydrogenation of allylamine is shown to produce acrylonitrile, whereas reaction with additional adsorbed ammonia leads to the formation of acetonitrile and hydrogen cyanide. The dehydrogenation of allyalkoxide species is found to have a significantly higher activation barrier than reaction with adsorbed ammonia, consistent with the observation that very little acrolein is produced when ammonia is present. Rapid reoxidation of the catalyst surface to release water is found to be the driving force for all reactions involving the cleavage of C-H or N-H bonds, since practically all of these steps are endothermic.

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Energetics of the Adsorption of Propene, Water, Dioxygen on Bismuth Molybdate (2:1)

Cited by 7 publications

References 24 publications

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

Simulation of methane partial oxidation over silica‐supported MoO₃ and V₂O₅

A DFT Investigation of the Mechanism of Propene Ammoxidation over α-Bismuth Molybdate

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Energetics of the Adsorption of Propene, Water, Dioxygen on Bismuth Molybdate (2:1)

Cited by 7 publications

References 24 publications

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

DFT+U Investigation of Propene Oxidation over Bismuth Molybdate: Active Sites, Reaction Intermediates, and the Role of Bismuth

Simulation of methane partial oxidation over silica‐supported MoO3 and V2O5

A DFT Investigation of the Mechanism of Propene Ammoxidation over α-Bismuth Molybdate

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Simulation of methane partial oxidation over silica‐supported MoO₃ and V₂O₅