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Insight into the role of water on the methylation of hexamethylbenzene in H‐SAPO‐34 from first principle molecular dynamics simulations

Simon Bailleul (UGent) , Sven Rogge (UGent) , Louis Vanduyfhuys (UGent) and Veronique Van Speybroeck (UGent)
(2019) CHEMCATCHEM. 11(16). p.3993-4010
Author
Organization
Project
  • DYNPOR (First principle molecular dynamics simulations for complex chemical transformations in nanoporous materials)
Abstract
The methylation of hexamethylbenzene with methanol is one of the key reactions in the methanol-to-olefins hydrocarbon pool reaction cycle taking place over the industrially relevant H-SAPO-34 zeolite. This methylation reaction can occur either via a concerted or via a stepwise mechanism, the latter being the preferred pathway at higher temperatures. Herein, we systematically investigate how a complex reaction environment with additional water molecules and higher concentrations of Bronsted acid sites in the zeolite impacts the reaction mechanism. To this end, first principle molecular dynamics simulations are performed using enhanced sampling methods to characterize the reactants and products in the catalyst pores and to construct the free energy profiles. The most prominent effect of the dynamic sampling of the reaction path is the stabilization of the product region where water is formed, which can either move freely in the pores of the zeolite or be stabilized through hydrogen bonding with the other protic molecules. These protic molecules also stabilize the deprotonated Bronsted acid site, created due to the formation of the heptamethylbenzenium cation, via a Grotthuss-type mechanism. Our results provide fundamental insight in the experimental parameters that impact the methylation of hexamethylbenzene in H-SAPO-34, especially highlighting and rationalizing the crucial role of water in one of the main reactions of the aromatics-based reaction cycle.
Keywords
density functional theory, enhanced sampling, H-SAPO-34, methylation, water, ZEOLITE-CATALYZED METHYLATION, TOTAL-ENERGY CALCULATIONS, TO-OLEFIN PROCESS, METHANOL CONVERSION, REACTION-MECHANISMS, DIMETHYL ETHER, UV/VIS MICROSPECTROSCOPY, HYDROCARBON FORMATION, SHAPE-SELECTIVITY, CHEMICAL ACCURACY

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Citation

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MLA
Bailleul, Simon, et al. “Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations.” CHEMCATCHEM, vol. 11, no. 16, 2019, pp. 3993–4010.
APA
Bailleul, S., Rogge, S., Vanduyfhuys, L., & Van Speybroeck, V. (2019). Insight into the role of water on the methylation of hexamethylbenzene in H‐SAPO‐34 from first principle molecular dynamics simulations. CHEMCATCHEM, 11(16), 3993–4010.
Chicago author-date
Bailleul, Simon, Sven Rogge, Louis Vanduyfhuys, and Veronique Van Speybroeck. 2019. “Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations.” CHEMCATCHEM 11 (16): 3993–4010.
Chicago author-date (all authors)
Bailleul, Simon, Sven Rogge, Louis Vanduyfhuys, and Veronique Van Speybroeck. 2019. “Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations.” CHEMCATCHEM 11 (16): 3993–4010.
Vancouver
1.
Bailleul S, Rogge S, Vanduyfhuys L, Van Speybroeck V. Insight into the role of water on the methylation of hexamethylbenzene in H‐SAPO‐34 from first principle molecular dynamics simulations. CHEMCATCHEM. 2019;11(16):3993–4010.
IEEE
[1]
S. Bailleul, S. Rogge, L. Vanduyfhuys, and V. Van Speybroeck, “Insight into the role of water on the methylation of hexamethylbenzene in H‐SAPO‐34 from first principle molecular dynamics simulations,” CHEMCATCHEM, vol. 11, no. 16, pp. 3993–4010, 2019.
@article{8627782,
  abstract     = {The methylation of hexamethylbenzene with methanol is one of the key reactions in the methanol-to-olefins hydrocarbon pool reaction cycle taking place over the industrially relevant H-SAPO-34 zeolite. This methylation reaction can occur either via a concerted or via a stepwise mechanism, the latter being the preferred pathway at higher temperatures. Herein, we systematically investigate how a complex reaction environment with additional water molecules and higher concentrations of Bronsted acid sites in the zeolite impacts the reaction mechanism. To this end, first principle molecular dynamics simulations are performed using enhanced sampling methods to characterize the reactants and products in the catalyst pores and to construct the free energy profiles. The most prominent effect of the dynamic sampling of the reaction path is the stabilization of the product region where water is formed, which can either move freely in the pores of the zeolite or be stabilized through hydrogen bonding with the other protic molecules. These protic molecules also stabilize the deprotonated Bronsted acid site, created due to the formation of the heptamethylbenzenium cation, via a Grotthuss-type mechanism. Our results provide fundamental insight in the experimental parameters that impact the methylation of hexamethylbenzene in H-SAPO-34, especially highlighting and rationalizing the crucial role of water in one of the main reactions of the aromatics-based reaction cycle.},
  author       = {Bailleul, Simon and Rogge, Sven and Vanduyfhuys, Louis and Van Speybroeck, Veronique},
  issn         = {1867-3880},
  journal      = {CHEMCATCHEM},
  keywords     = {density functional theory,enhanced sampling,H-SAPO-34,methylation,water,ZEOLITE-CATALYZED METHYLATION,TOTAL-ENERGY CALCULATIONS,TO-OLEFIN PROCESS,METHANOL CONVERSION,REACTION-MECHANISMS,DIMETHYL ETHER,UV/VIS MICROSPECTROSCOPY,HYDROCARBON FORMATION,SHAPE-SELECTIVITY,CHEMICAL ACCURACY},
  language     = {eng},
  number       = {16},
  pages        = {3993--4010},
  title        = {Insight into the role of water on the methylation of hexamethylbenzene in H‐SAPO‐34 from first principle molecular dynamics simulations},
  url          = {http://dx.doi.org/10.1002/cctc.201900618},
  volume       = {11},
  year         = {2019},
}

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