Selective oxidation over structured multicomponent molybdate catalysts

Zou, Joe Y; Schrader, Glenn L.

doi:10.1016/s0167-2991(08)63394-7

Cited by 7 publications

(1 citation statement)

References 21 publications

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“…In the present paper, we apply such a dual theoretical (DFT) and spectroscopic (Mo K-edge in situ X-ray absorption spectroscopy (XAS)) approach to investigate the redox properties of supported oxomolybdate species, which are active in CSO reactions. − More precisely, the Mo VI cation was reported to be active in the CSO of alcohols, , light alkanes, , and oxidative dehydrogenation reaction. , In CSO reactions, the cation is successively reduced and easily reoxidized by oxygen from the feed. Hence, the redox properties of Mo 6+ localized on the catalyst’s surface control the selectivity.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Reducibility of Supported Oxomolybdate Species for Mapping of Active Centers of Partial Oxidation Reaction: In Situ Mo K-Edge XAS and DFT Study

Souza

Berrier

et al. 2019

J. Phys. Chem. C

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We have investigated the molecular and electronic structure of a TiO 2supported oxomolybdate phase upon reduction under methanol or dihydrogen atmosphere. In situ Mo K-edge X-ray absorption spectroscopy, supported by density functional theory (DFT) calculations and ab initio X-ray absorption spectroscopy (XAS) spectra simulation showed that the reducibility of supported molybdate species is closely related to the geometric environment of Mo atoms. Indeed, Mo atoms not involved in terminal oxo sites are easily reducible whereas Mo dioxo species are not under the conditions we have applied. Between those extreme cases, Mo atoms involved in monooxo terminal sites exhibit intermediate reducibility, which varies according to their local environment and their interaction with the support. Spin density calculations showed that under CH 3 OH flow, the surface of the catalyst is partially reduced. The structure of the reduced phase after reaction with methanol was compared to that afforded after reduction by dihydrogen. Our results show that the reduction under H 2 flow does not increase the number of reduced Mo atoms but causes a higher spin density per Mo atom. On the basis of the individual mapping of the electronic structure of Mo species as drawn by DFT and XAS spectra simulation, a model that details the structure of the Mo active sites in the selective oxidation of methanol is proposed.

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