Alkane adsorption in Na-exchanged chabazite: The influence of dispersion forces

Göltl, Florian; Häfner, J.

doi:10.1063/1.3549815

Cited by 64 publications

(86 citation statements)

References 47 publications

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“…Interaction energies range from -37 kJ mol -1 to -58 kJ mol -1 for SAPOs containing main group cations, and from -23 kJ mol -1 to -34 kJ mol -1 for the TM-exchanged systems. The interaction energy computed for Na-SAPO-34 agrees well with a previous value obtained with a very similar method for sodium-exchanged chabazite (-38.7 kJ mol -1 and d(Na-CH 4 ) = 2.61 Å) [34], indicating that the framework composition has only little influence on the interaction with this guest molecule. A comparison of the total interaction energy and the non-dispersive…”

Section: Resultssupporting

confidence: 81%

“…The inclusion of dispersion is important in the system under study because weak dispersion forces will constitute a significant fraction of the total interaction between the porous host material and the adsorbed guest species. While more sophisticated methods to include dispersion corrections in DFT give more accurate results in some cases [34,38], this method (also termed DFT-D for simplicity) was chosen as a reasonable compromise between accuracy and computational cost. The same method has been applied successfully in previous studies of light gases adsorbed in zeolites and related materials, both by our group and by others [40,[55][56][57][58][59].…”

Section: Models and Computational Methodsmentioning

confidence: 99%

“…Many more recent computational investigations have used periodic models. Examples include the studies of methane, larger hydrocarbons and carbon monoxide in chabazite-type zeolites reported by Göltl et al [34][35][36], the combined experimental-theoretical investigations addressing the interaction of CO with multiple cation sites in different zeolites performed by Otero Areán, Nachtigall and co-workers [37,38], as well as previous studies of light gases in chabazite and SAPO-34 [39][40][41].…”

Section: Introductionmentioning

confidence: 95%

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A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

Fischer¹,

Bell

2014

Zeitschrift Für Kristallographie - Crystalline Materials

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Density-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH 4 , CO, N 2 ) with the cation sites in the silicoaluminophosphate SAPO-34. Eight different cations from three different groups (alkali cations, alkaline earth cations, transition metals) are included in the study. For each case, the total interaction energy as well as the non-dispersive contribution to the interaction are analysed. Electron density difference plots are used to investigate the nature of this non-dispersive contribution in more detail. Despite a non-negligible contribution of polarisation interactions, the total interaction remains moderate in systems containing main group cations. In SAPOs exchanged with transition metals, orbital interactions between the cations and CO and N 2 lead to a very strong interaction, which makes these systems attractive as adsorbents for the selective adsorption of these species. A critical comparison with experimental heats of adsorption shows reasonable quantitative agreement for CO and N 2 , but a pronounced overestimation of the interaction strength for methane. While this does not affect the conclusions regarding the suitability of TM-exchanged SAPO-34 materials for gas separations, more elaborate computational approaches may be needed to improve the quantitative accuracy for this guest molecule.

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Section: Resultssupporting

confidence: 81%

Section: Models and Computational Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

Fischer¹,

Bell

2014

Zeitschrift Für Kristallographie - Crystalline Materials

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“…This combination of exchange correlation functional and dispersion model was successfully used in earlier zeolite catalysis work [48,63,64]. Since ab initio molecular dynamics calculations performed on the complete zeolite model are computationally very expensive, more advanced methods using hybrid functionals or many body dispersion models are not feasible for simulations of considerable time length as emphasized here [65,66]. The cell parameters were determined from a preliminary NPT run on the empty zeolite unit cell at 323 K and 1 atm and are found to be a = 20.14 Å, b = 20.33 Å, c = 13.56 Å, a = 89.82°, b = 89.47°, c = 90.15°.…”

Section: Methodsmentioning

confidence: 96%

On the stability and nature of adsorbed pentene in Brønsted acid zeolite H-ZSM-5 at 323 K

Hajek

Mynsbrugge

Wispelaere

et al. 2016

Journal of Catalysis

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Herewith we have the pleasure to resubmit the paper entitled : "On the stability and nature of adsorbed pentene in Brønsted acid zeolite H-ZSM-5 at 323 K" by J. Hajek , J. Van der Mynsbrugge, K. De Wispelaere , P. Cnudde, L. Vanduyfhuys, M. Waroquier and V. Van Speybroeck, for publication in Journal of Catalysis.We have received the comments of two reviewers which were very positive and which suggest publication subject to some major/minor revisions. We have taken them all into account in the revised version. In separate documents we give a substantial reply to the reviewers that carefully addresses the issues raised in the reviewer's comments. We have added an author (Louis Vanduyfhuys) in the list. During the revision process he has given a very constructive contribution in a correct thermodynamic analysis of the metadynamics results. As requested by one of the reviewers, we re-analyzed all our MD results. We hope that you are willing to accept this slight change in the author list.We further hope that the manuscript is now suitable for publication. Reply to reviewer #1 :We thank the reviewer for his/her careful reading of the manuscript with manuscript number JCAT-16-151. We try to give a valuable reply to all comments which were all very constructive. Reviewer's comments are printed in blue.1. The DFT calculations have been carried out at 0 K by optimizing the geometry at the RPBE+D3 level and then conducting single point calculations with other functionals. While the general conclusions drawn from the calculations are independent of the functional chosen, it would be very useful to know whether geometry optimization with a better functional would change the conclusion about the relative stability of the -complex and alkoxide structures.The authors completely agree with the major concern of the reviewer regarding the reliability of the geometry optimization based on one level of theory (PBE+D3). This functional has proven to be reliable in many periodic static calculations on nanoporous materials, but to remove any doubt we performed new geometry optimizations and frequency calculations for 2-pentene π-complex and 2-pentoxide using BEEF-vdW functional .[1] Geometrical details of the selected structures with PBE-D3 and BEEF-vdW functionals are given in Table 1. The comparison of free energy ΔG and enthalpy ΔH differences between BEEF-vdW //PBE D3 and BEEF-vdW // BEEF-vdW is given in Table 2. The energy differences are very similar with each other, and support the conclusions made in the paper. These additional results have been included in *Revision NotesWe thank the reviewer for this remark and reformulated the sentence slightly. The origin of larger adsorption enthalpies for the -complex is indeed related to usage of optimized geometries, which take into account only one point on the potential energy surface. Our MD simulations show that in reality at finite temperatures, the -complex can adopt various geometries leading to a probability distribution as shown in Figure 3 of the main manuscript. This dis...

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“…They conclude that the absorption is ideal and that excess absorption on zeolite surfaces depends on the cut as well as the orientation of the zeolite crystal. Goltl and Hafner 136 have looked at alkane absorption in Na-exchanged chabazite comparing DFT (GGA), two variants of DFT-D (one due to Grimme 8 and one with a van der Waals exchange-correlation functional 137 ) and a random phase approximation method (RPA). The most accurate description is found at the RPA level with HF exchange energies.…”

Section: Zeolitesmentioning

confidence: 99%

Computational modelling of inorganic solids

Moore

2012

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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Alkane adsorption in Na-exchanged chabazite: The influence of dispersion forces

Cited by 64 publications

References 47 publications

A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

On the stability and nature of adsorbed pentene in Brønsted acid zeolite H-ZSM-5 at 323 K

Computational modelling of inorganic solids

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