Characterization of supported vanadium oxide species on silica: a periodic DFT investigation

Mazharul M. Islam; Dominique Costa; Monica Calatayud; Frederik Tielens

doi:10.1021/jp902818m

Characterization of supported vanadium oxide species on silica: a periodic DFT investigation

Mazharul M. Islam, Dominique Costa, Monica Calatayud, Frederik Tielens

Department of Chemistry

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76 Citations (SciVal)

Abstract

The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported vanadium oxide catalysts are studied using periodic density functional calculations. Isolated vanadia units deposed on amorphous silica are modeled at low coverage, 0.44 atoms nm^-2. The models are built following the grafting process through the reaction of a vanadium precursor with surface silanols: OV(OH)₃ + (Si - OH) ₃ → OV(OH)_{3 - n}(O - Si)_n + nH₂O (with n = 1-3). The most stable grafted structures involve one vanadyl group together with n(V - O - Si) bonds. The predominance of the vanadate groups is analyzed as a function of hydration by means of atomistic thermodynamics. At dehydrated conditions, the trigrafted pyramidal OV(O - Si)₃ species are predominant, whereas partial hydration stabilizes digrafted OV(OH)(O - Si)₂ and monografted OV(OH)₂(O - Si) species. The harmonic vibrational spectra for selected models are compared to recent experimental infrared and Raman data, for representative bands, and vibrational modes. Hydration effects are discussed in terms of thermodynamic stability and vibrational spectra. The results obtained in this study show that the pyramidal OV(O - Si)₃, digrafted OV(OH)(O - Si)₂, and monografted OV(OH)₂(O - Si) models can exist at a support surface, a trend in agreement with recent experimental findings.

Original language	English
Pages (from-to)	10740-10746
Number of pages	7
Journal	Journal of Physical Chemistry C
Volume	113
Issue number	24
Early online date	26 May 2009
DOIs	https://doi.org/10.1021/jp902818m
Publication status	Published - 18 Jun 2009

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Energy
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

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title = "Characterization of supported vanadium oxide species on silica: a periodic DFT investigation",

abstract = "The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported vanadium oxide catalysts are studied using periodic density functional calculations. Isolated vanadia units deposed on amorphous silica are modeled at low coverage, 0.44 atoms nm-2. The models are built following the grafting process through the reaction of a vanadium precursor with surface silanols: OV(OH)3 + (Si - OH) 3 → OV(OH)3 - n(O - Si)n + nH2O (with n = 1-3). The most stable grafted structures involve one vanadyl group together with n(V - O - Si) bonds. The predominance of the vanadate groups is analyzed as a function of hydration by means of atomistic thermodynamics. At dehydrated conditions, the trigrafted pyramidal OV(O - Si)3 species are predominant, whereas partial hydration stabilizes digrafted OV(OH)(O - Si)2 and monografted OV(OH)2(O - Si) species. The harmonic vibrational spectra for selected models are compared to recent experimental infrared and Raman data, for representative bands, and vibrational modes. Hydration effects are discussed in terms of thermodynamic stability and vibrational spectra. The results obtained in this study show that the pyramidal OV(O - Si)3, digrafted OV(OH)(O - Si)2, and monografted OV(OH)2(O - Si) models can exist at a support surface, a trend in agreement with recent experimental findings.",

author = "Islam, {Mazharul M.} and Dominique Costa and Monica Calatayud and Frederik Tielens",

year = "2009",

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T1 - Characterization of supported vanadium oxide species on silica

T2 - a periodic DFT investigation

AU - Islam, Mazharul M.

AU - Costa, Dominique

AU - Calatayud, Monica

AU - Tielens, Frederik

PY - 2009/6/18

Y1 - 2009/6/18

N2 - The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported vanadium oxide catalysts are studied using periodic density functional calculations. Isolated vanadia units deposed on amorphous silica are modeled at low coverage, 0.44 atoms nm-2. The models are built following the grafting process through the reaction of a vanadium precursor with surface silanols: OV(OH)3 + (Si - OH) 3 → OV(OH)3 - n(O - Si)n + nH2O (with n = 1-3). The most stable grafted structures involve one vanadyl group together with n(V - O - Si) bonds. The predominance of the vanadate groups is analyzed as a function of hydration by means of atomistic thermodynamics. At dehydrated conditions, the trigrafted pyramidal OV(O - Si)3 species are predominant, whereas partial hydration stabilizes digrafted OV(OH)(O - Si)2 and monografted OV(OH)2(O - Si) species. The harmonic vibrational spectra for selected models are compared to recent experimental infrared and Raman data, for representative bands, and vibrational modes. Hydration effects are discussed in terms of thermodynamic stability and vibrational spectra. The results obtained in this study show that the pyramidal OV(O - Si)3, digrafted OV(OH)(O - Si)2, and monografted OV(OH)2(O - Si) models can exist at a support surface, a trend in agreement with recent experimental findings.

AB - The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported vanadium oxide catalysts are studied using periodic density functional calculations. Isolated vanadia units deposed on amorphous silica are modeled at low coverage, 0.44 atoms nm-2. The models are built following the grafting process through the reaction of a vanadium precursor with surface silanols: OV(OH)3 + (Si - OH) 3 → OV(OH)3 - n(O - Si)n + nH2O (with n = 1-3). The most stable grafted structures involve one vanadyl group together with n(V - O - Si) bonds. The predominance of the vanadate groups is analyzed as a function of hydration by means of atomistic thermodynamics. At dehydrated conditions, the trigrafted pyramidal OV(O - Si)3 species are predominant, whereas partial hydration stabilizes digrafted OV(OH)(O - Si)2 and monografted OV(OH)2(O - Si) species. The harmonic vibrational spectra for selected models are compared to recent experimental infrared and Raman data, for representative bands, and vibrational modes. Hydration effects are discussed in terms of thermodynamic stability and vibrational spectra. The results obtained in this study show that the pyramidal OV(O - Si)3, digrafted OV(OH)(O - Si)2, and monografted OV(OH)2(O - Si) models can exist at a support surface, a trend in agreement with recent experimental findings.

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Characterization of supported vanadium oxide species on silica: a periodic DFT investigation

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