Hydrogen Bond vs Proton Transfer in HZSM5 Zeolite. A Theoretical Study

Solans‐Monfort, Xavier; Sodupe, Mariona; Mó, Otília; Yáñez, Manuel; Elguero, José

doi:10.1021/jp051919d

Cited by 23 publications

(35 citation statements)

References 63 publications

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“…According to the minimum of the association energies, the most stable interaction is that corresponding to the H of water and an O atom of the zeolite cluster. It is around 2.0 Å, and agrees with data in literature that is reported around 1.8 Å 15.…”

Section: Resultssupporting

confidence: 92%

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Multiple minima hypersurfaces studies of aluminosilicate hydration

Pérez-Badell

Montero

2009

Int J of Quantum Chemistry

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Hydrothermal zeolite synthesis is a complex process that is difficult toanalyze experimentally. In this work, the role of water as solvent on the formation of aluminate and aluminosilicate clusters is described by quantum chemical calculations. The multiple minima hypersurfaces approach was used. It combines quantum chemical Hamiltonians for the calculation of the internal energy with statistical modeling and formulae for the calculation of thermodynamic functions of association. The structures of most probable hydration clusters are proposed and some of their association properties are calculated. Ab initio and semiempirical calculations of the structures and relevant reactions of aluminate and aluminosilicate fragments were reported. The results could be employed for an interpretation of the aluminosilicate synthesis. Calculations demonstrate the importance of considering other than the deepest minimum structures, giving a significant role to consider entropy of association.

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Section: Resultssupporting

confidence: 92%

“…On the other hand, the adsorption of water molecule on acid zeolites is a process of interest from both empirical and theoretical points of view. Experimental techniques and theoretical methods have been used to study these interactions on zeolites 8–15.…”

Section: Introductionmentioning

confidence: 99%

Multiple minima hypersurfaces studies of aluminosilicate hydration

Pérez-Badell

Montero

2009

Int J of Quantum Chemistry

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“…The most obvious way for both two-and three-layer ONIOM models is to isolate the QM layer (capped with H atoms to saturate the dangling bonds) and perform a counterpoise correction on it and the substrate molecule; we follow this approach here as well. 21,23,24,26 The adsorption schemes are summarized in eqn (4) and (5). In those cases where the most stable adsorbed state is the one with the acidic proton on the adsorbate, the counterpoise corrections were performed on the protonated adsorbate and the zeolite conjugate base.…”

Section: B Theory Levelsmentioning

confidence: 99%

Adsorption in zeolites using mechanically embedded ONIOM clusters

Patet

Caratzoulas

Vlachos

2016

Phys. Chem. Chem. Phys.

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We have explored mechanically embedded three-layer QM/QM/MM ONIOM models for computational studies of binding in Al-substituted zeolites. In all the models considered, the high-level-theory layer consists of the adsorbate molecule and of the framework atoms within the first two coordination spheres of the Al atom and is treated at the M06-2X/6-311G(2df,p) level. For simplicity, flexibility and routine applicability, the outer, low-level-theory layer is treated with the UFF. We have modelled the intermediate-level layer quantum mechanically and investigated the performance of HF theory and of three DFT functionals, B3LYP, M06-2X and ωB97x-D, for different layer sizes and various basis sets, with and without BSSE corrections. We have studied the binding of sixteen probe molecules in H-MFI and compared the computed adsorption enthalpies with published experimental data. We have demonstrated that HF and B3LYP are inadequate for the description of the interactions between the probe molecules and the framework surrounding the metal site of the zeolite on account of their inability to capture dispersion forces. Both M06-2X and ωB97x-D on average converge within ca. 10% of the experimental values. We have further demonstrated transferability of the approach by computing the binding enthalpies of n-alkanes (C1-C8) in H-MFI, H-BEA and H-FAU, with very satisfactory agreement with experiment. The computed entropies of adsorption of n-alkanes in H-MFI are also found to be in good agreement with experimental data. Finally, we compare with published adsorption energies calculated by periodic-DFT for n-C3 to n-C6 alkanes, water and methanol in H-ZSM-5 and find very good agreement.

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“…The origin of this stabilization was investigated in detail and led to the conclusion that the initiation rate of the complexes is governed by p-electron delocalization of the chelate ring. [17] However, some aspects of the (pre)catalyst initiation remain under debate, [18] and numerous synthetic studies are being targeted towards this essential process by the preparation of new complexes with modified chelating ligands.…”

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confidence: 99%