Impact of long-range electrostatic and dispersive interactions on theoretical predictions of adsorption and catalysis in zeolites

Mansoor, Erum; Mynsbrugge, Jeroen Van der; Head‐Gordon, Martin; Bell, Alexis T.

doi:10.1016/j.cattod.2018.02.007

Cited by 42 publications

(71 citation statements)

References 164 publications

(210 reference statements)

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“…This is in agreement with previous findings devoted to the investigation of various non-cyclic carbocations. [42][43][44]51,[80][81][82][83] These observations generalize our findings made before in the case of TS2 tested at all the active sites, even if the step corresponding to TS2 is not the rate-determining one for all sites.…”

Section: Ts2supporting

confidence: 90%

Location of the Active Sites for Ethylcyclohexane Hydroisomerization by Ring Contraction and Expansion in the EUO Zeolitic Framework

et al. 2019

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Identifying the location of the active sites in a zeolite is a current challenge, impeding the design of optimal catalysts. In this work, we identify the location of the most active sites of 1-ethylcyclohexene isomerization in the EUO framework (10 MR channels, 12 MR side pockets), thanks to DFT calculations corroborated by experiments. Skeletal isomerization of cycloalkenes is a crucial industrial reaction for the bifunctional isomerization of ethylbenzene. Ethylcyclohexene is protonated by framework protons into cyclic carbenium ions, which undergo ring contraction-expansion reactions through protonated cyclopropane (PCP) like transition states. Ab initio calculations clearly show that the acid sites located at the intersection between the channel and the pocket stabilize much less the cyclic carbenium ions involved in the reaction than 12 MR pockets and 10 MR channel sites, due to stronger dispersion stabilizing interactions. This computational finding is fully confirmed experimentally by the comparison of the catalytic performances of the H-EU-1 and H-ZSM-50 zeolites in ethylcyclohexane hydroisomerization. Both zeolites possess the EUO structure, but with different location of the acid sites. The ratio in turnover frequencies is quantitatively rendered by the DFT calculated free energy profiles. Diffusion measurements reveal similar ethylcyclohexane diffusion times for the two zeolites, supporting that the difference in activity is primarily driven by the location of the active sites.

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Section: Ts2supporting

confidence: 90%

Location of the Active Sites for Ethylcyclohexane Hydroisomerization by Ring Contraction and Expansion in the EUO Zeolitic Framework

et al. 2019

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“…23 Although structurally they are very different than enzymes, the same interplay between electric fields and nanopore structure is also applicable to zeolite catalysts. 24 Zeolites are microporous aluminosilicate minerals widely used in industry due to the uniformity of its pores as well as the adjustability of its structure and acidity. 25 Diffusion is highly constrained within the zeolite framework, protecting reactive species from undesired bulk reactions 26 , similar to the design principles of supramolecular capsules.…”

Section: Porous Supermolecular Capsules and Zeolite Catalystsmentioning

confidence: 99%

Computational optimization of electric fields for better catalysis design

2018

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Although the ubiquitous role that long-ranged electric fields play in catalysis has been recognized, it is seldom used as a primary design parameter in the discovery of new catalytic materials. Here we illustrate how electric fields have been used to computationally optimize biocatalytic performance of a synthetic enzyme, and how they could be used as a unifying descriptor for catalytic design across a range of homogeneous and heterogeneous catalysts. While focusing on electrostatic environmental effects may open new routes toward the rational optimization of efficient catalysts, much more predictive capacity is required of theoretical methods to have a transformative impact in their computational design-and thus experimental relevance-when using electric field alignments in the reactive centres of complex catalytic systems.

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“…[27] The advent of more powerful computers supports attempts to close the gap between computational models and the real material, and the use of periodic cells to obtain electronic and structural information pertaining to a model with a complete physical description has evolved as state-of-the-art. [28][29][30][31][32][33][34] To advance the predictive capabilities for the design of metal-exchanged zeolites, there is a growing need to develop an improved understanding of structure-performance relationships of Brønsted and Lewis acid sites in zeolites. [35] Application of DFT is especially appealing when it can be used to guide the selection of a potential metal-exchanged zeolite through a computational screening protocol, [36,37] which can provide an estimate of desired properties of the zeolite.…”

Section: Introductionmentioning

confidence: 99%

“…[35] Application of DFT is especially appealing when it can be used to guide the selection of a potential metal-exchanged zeolite through a computational screening protocol, [36,37] which can provide an estimate of desired properties of the zeolite. The incorporation of van der Waals (vdW) interactions [34,38,39] within the pores of a zeolite further improve the physical description of zeolite models.…”

Section: Introductionmentioning

confidence: 99%

Quantification and Statistical Analysis of Errors Related to the Approximate Description of Active Site Models in Metal‐Exchanged Zeolites

2019

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Metal‐exchanged zeolites are complex catalytic systems with great potential for applications in hydrocarbon conversion processes. The numerous combinations of zeotypes and metal‐based Lewis acid motifs create a vast material space that can only be effectively navigated with robust structure‐function relationships. Exhaustive modeling of extraframework metal sites in all crystallographically distinct framework positions is not practical; thus, we quantified the uncertainties arising from the use of simplified active site representations using the C−H bond activation in methane as a probe reaction. Density functional theory calculations and statistical analysis of associated error ensembles suggest that the Lewis acid identity primarily determines the reactivity of the zeolite towards methane activation, with other factors such as zeolite model characteristics deemed secondary. The error ensemble distributions were used to predict the relative probability of creating active C−H bond scission fragments in metal‐exchanged zeolites, and thus can be used to efficiently screen various metal‐exchange candidates in their efficacy towards hydrocarbon conversion.

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Impact of long-range electrostatic and dispersive interactions on theoretical predictions of adsorption and catalysis in zeolites

Cited by 42 publications

References 164 publications

Location of the Active Sites for Ethylcyclohexane Hydroisomerization by Ring Contraction and Expansion in the EUO Zeolitic Framework

Location of the Active Sites for Ethylcyclohexane Hydroisomerization by Ring Contraction and Expansion in the EUO Zeolitic Framework

Computational optimization of electric fields for better catalysis design

Quantification and Statistical Analysis of Errors Related to the Approximate Description of Active Site Models in Metal‐Exchanged Zeolites

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