Understanding the effect of the MFI framework on the mechanism and kinetics of direct CH3COOH formation from the Co-activation of CO2 and CH4

Nowadays, theoretical calculations are playing a pivotal role in understanding the underlying reaction mechanism and at the same time used for exploration of the zeolite-based catalysts. For such systems, an inconsistency is seen in formulating the active site and choosing the size of the zeolite fr...

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Bibliographic Details
Published in:Journal of molecular graphics & modelling 2021-06, Vol.105, p.107896-107896, Article 107896
Main Authors: Shahzad, Nasir, Khan, Basharat
Format: Article
Language:English
Subjects:
Acetic acid formation
Co-activation
MFI Framework
ONIOM modal
Zeolites-based catalysis
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Summary:Nowadays, theoretical calculations are playing a pivotal role in understanding the underlying reaction mechanism and at the same time used for exploration of the zeolite-based catalysts. For such systems, an inconsistency is seen in formulating the active site and choosing the size of the zeolite framework. Herein, we have formulated the standard theoretical model for the MFI-based catalytic systems considering the most recent experimental findings.[1] The formulated model is used for the explanation of the mechanism of acetic acid formation by the co-activation of CO2 and CH4 over the MFI based catalyst, which excellently justifies the experimental results. The following conclusions are drawn from the work, a sufficiently large zeolite framework is critical to validate the experimental findings. The extended zeolite framework is crucial for accurate optimization of the active site, drawing the plausible mechanisms and predicting the correct rate-limiting step of the reaction. Moreover, the neighbor Al–Al atoms must be kept away from each other by at-least two Si-centers to be consistent with the experiment. T437 versus T34 model clusters used for the mechanistic studies. [Display omitted] •Effect of the MFI ring size is computed for the energetics of elementary steps.•A standard theoretical model for the MFI-based catalytic systems is designed.•Sufficiently large MFI framework is decisive for mechanistic steps energetics.•Two Al–Al neighbors’ atoms should be separated, at least by the two Si centers.
ISSN:1093-3263
1873-4243
DOI:10.1016/j.jmgm.2021.107896