Characterization of amorphous silica based catalysts using DFT computational methods

Tielens, Frederik; Gierada, Maciej; Handzlik, Jarosław; Calatayud, Mònica

doi:10.1016/j.cattod.2019.03.062

Cited by 86 publications

(70 citation statements)

References 158 publications

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“…4, the Si-O distribution of CN indicates a mainly 4fold environment with a percentage of 97%. A small percent of 5-fold coordinated Si is also detected, implying a small distortion of the [SiO 4 ] tetrahedra [47]. The distribution of CN for Fe atoms appears to be broader, compared to the Si atoms, consisting mainly of 4-fold and 5fold coordination with a percentage of 41% and 47%, respectively.…”

Section: O and Ca-o Respectively)mentioning

confidence: 92%

Unraveling the nano-structure of a glassy CaO-FeO-SiO2 slag by molecular dynamics simulations

Siakati

Macchieraldo

Kirchner

et al. 2020

Journal of Non-Crystalline Solids

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Non-ferrous metallurgy slags are gaining significant interest as a resource in the production of alternative lowenergy cementitious materials. Their atomistic structures, however, are still not fully understood due to their glassy nature. In the work presented herein, a comprehensive description of the nano-structure of a CaO-FeO-SiO 2 slag was obtained by using molecular dynamic simulations in conjunction with previously obtained experimental data from X-ray and neutron pair distribution function studies. Iron was predominately 4-and 5-fold coordinated with oxygen, forming polyhedra in tetrahedral and pyramidal/triangular bipyramidal configuration. The [FeO x ] polyhedra were corner-shared to the silica tetrahedra, while the higher coordinated fractions (x = 5 or 6) seemed to prefer to be next to each other, sharing edges. Ca was mostly surrounded by 6 or 7 oxygens in polyhedra that are predominantly edge-sharing with other units. The obtained results fit the experimental data well and as such provide an accurate and realistic picture of the iron-rich slag structure.

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Section: O and Ca-o Respectively)mentioning

confidence: 92%

Unraveling the nano-structure of a glassy CaO-FeO-SiO2 slag by molecular dynamics simulations

Siakati

Macchieraldo

Kirchner

et al. 2020

Journal of Non-Crystalline Solids

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“…This resulted in the development of one of the first hydroxylated amorphous silica models in 2008 [80], published simultaneously with the model of the group of Ugliengo [79]. Recently, we reviewed the last decade on silica modelling with DFT [81,82].…”

Section: Outlook On Silica Dft Studiesmentioning

confidence: 99%

Opportunities given by density functional theory in pathological calcifications

Tielens¹,

Vekeman²,

Bazin³

et al. 2022

Comptes Rendus. Chimie

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Density Functional Theory has made the study of biomaterials feasible in the past years leading to better understanding of causes and possible treatments of related pathologies. Although it has been successfully applied in many fields, it has not yet consistently found its way into the field of pathological calcifications. An overview will be given of the studies where this technique has been applied in order to outline the important contributions that it can bring in the field of biomineralization. More specifically, studies on DFT calcifications from calcium oxalates and calcium phosphates, with relevance to bone formation and kidney stones, will be reviewed. Finally, a short outlook on silica mineralization will be presented as well.

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“…a-SiO2 has been extensively studied with DFT methods. 6,[23][24] Two types of computational models have been commonly used for describing a-SiO2, periodic slab models, 6,[23][24] which use a unit cell representation of the surface, and cluster models [24][25][26][27][28][29][30] , a finite fragment of the solid. As amorphous surfaces have nonuniform composition and the need for more realistic and larger surface models increases, modeling amorphous supports with periodic slab models becomes increasingly challenging.…”

Section: Electronic Structurementioning

confidence: 99%

Computational Investigation of the Role of Active Site Heterogeneity for a Supported Organovanadium(III) Hydrogenation Catalyst

Patel

Wells²,

Kaphan³

et al. 2021

Preprint

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<div> <div> <p></p><p><a>A crucial consideration for supported heterogeneous catalysts is the non-uniformity of the active sites, particularly for Supported Organometallic Catalysts (SOMCs). Standard spectroscopic techniques, such as X-ray absorption spectroscopy (XAS), reflect the nature of the most populated sites, which are often intrinsically structurally distinct from the most catalytically active sites. With computational models, often only a few representative structures are used to depict catalytic active sites on a surface, even though there are numerous observable factors of surface heterogeneity that contribute to the kinetically favorable active species. A previously reported study on the mechanism of a surface organovanadium(III) catalyst [(SiO)V<sup>III</sup>(Mes)(THF)] for styrene hydrogenation yielded two possible mechanisms: heterolytic cleavage and redox cycling. These two mechanistic scenarios are challenging to differentiate experimentally based on the kinetic readouts of the catalyst are identical. To showcase the importance of modeling surface heterogeneity and its effect on catalytic activity, density functional theory (DFT) computational models of a series of potential active sites of [(SiO)V<sup>III</sup>(Mes)(THF)] for the reaction pathways are applied in combination with kinetic Monte Carlo (kMC) simulations. Computed results were t then compared to the previously reported experimental kinetic study</a><a>.: 1) DFT free energy reaction pathways indicated the likely active site and pathway for styrene hydrogenation; a heterolytic cleavage pathway requiring a bare tripodal vanadium site. 2) From the kMC simulations, a mixture of the different bond lengths from the support oxygen to the metal center was required to qualitatively describe the experimentally observed kinetic aspects of a supported organovanadium(III) catalyst for olefin hydrogenation. </a>This work underscores the importance of modeling surface heterogeneity in computational catalysis.</p><p></p></div></div>

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Characterization of amorphous silica based catalysts using DFT computational methods

Cited by 86 publications

References 158 publications

Unraveling the nano-structure of a glassy CaO-FeO-SiO2 slag by molecular dynamics simulations

Unraveling the nano-structure of a glassy CaO-FeO-SiO2 slag by molecular dynamics simulations

Opportunities given by density functional theory in pathological calcifications

Computational Investigation of the Role of Active Site Heterogeneity for a Supported Organovanadium(III) Hydrogenation Catalyst

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