The <i>tert‐</i>Butyl Cation in H‐Zeolites: Deprotonation to Isobutene and Conversion into Surface Alkoxides

Tuma, Christian; Kerber, Torsten; Sauer, Joachim

doi:10.1002/anie.200907015

Cited by 99 publications

(194 citation statements)

References 27 publications

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“…However, as our investigations show, this good agreement is fortuitous. It should be noticed that the works of Hansen et al [46] on alkylation of benzene and Tuma et al [47] on deprotonation of a tertbutyl cation using similar computational scheme to ours showed good results compared with experiments. More investigations will be needed to explain this discrepancy.…”

Section: Apparent Reaction Barrierssupporting

confidence: 60%

Proton exchange reactions of C2–C4 alkanes sorbed in ZSM-5 zeolite

et al. 2012

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An extensive theoretical study has been carried out to determine barriers for the proton exchange reactions of C2-C4 alkanes in ZSM-5. It was found that cluster size and cavity structure are very important for predicting this barrier. A decrement of up to 20 kcal/mol was observed when employing the periodic model instead of using the small cluster model. Effects of basis set quality and electron correlation to the activation energy are positive and in combination could contribute up to 8 kcal/mol. An extrapolation scheme for estimating the reaction barrier that takes into account effects of cluster size, basis set quality, and electron correlation has been proposed. The regioselectivity and the chain length were discussed.

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Section: Apparent Reaction Barrierssupporting

confidence: 60%

Proton exchange reactions of C2–C4 alkanes sorbed in ZSM-5 zeolite

et al. 2012

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“…Both methods have successfully been applied to model the adsorption of short alkanes in zeolites. 24 By understanding the similarities and differences between them, we find that confinement lowers the activation energy for this reaction by more than 50% and that the application of RPA as a high-level theory leads to qualitatively different results from most commonly used methods.…”

mentioning

confidence: 90%

“…It is a zeolite in the chabazite structure, which has the smallest primitive unit cell, and therefore allows the application of high-level methods in fully periodic calculations at a reasonable cost. 24 In this unit cell the Fe-oxo group is located in the six ring of the structure , where two Si atoms are substituted by Al on the opposite sides of the ring as displayed on the left hand side of Fig. 2 Two possible pathways have been suggested for the conversion of methane-to-methanol, namely the rebound mechanism 32,33 and a concerted mechanism.…”

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confidence: 99%

Computationally Exploring Confinement Effects in the Methane-to-Methanol Conversion Over Iron-Oxo Centers in Zeolites

et al. 2016

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Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to methanol. Here we study this reaction over Fe-oxo sites in the zeolite SSZ-13. By comparing calculations for the fully periodic structure and a cluster for two different methods, the standard van der Waals corrected semi-local density functional PBE-D2 and ACFDT-RPA, a method where correlation is calculated fully non-locally, we find that it is actually the confining environment in the zeolite that reduces the barrier for this reaction by more than 50 % and that the two applied methods lead to qualitatively different results.

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“…For alkenes much less information is available also from a theoretical point of view. In a series of papers by Sauer and coworkers various theoretical methods were used to study the adsorption behavior of C 4 species in H-FER [26,27]. The methods varied in the treatment of the molecular environment, the method to account for the long range dispersion interactions and the degree to which finite temperature effects were accounted for.…”

Section: Introductionmentioning

confidence: 99%

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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The tert‐Butyl Cation in H‐Zeolites: Deprotonation to Isobutene and Conversion into Surface Alkoxides

Cited by 99 publications

References 27 publications

Proton exchange reactions of C2–C4 alkanes sorbed in ZSM-5 zeolite

Proton exchange reactions of C2–C4 alkanes sorbed in ZSM-5 zeolite

Computationally Exploring Confinement Effects in the Methane-to-Methanol Conversion Over Iron-Oxo Centers in Zeolites

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

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