Effects of the Zeolite Framework on the Adsorptions and Hydrogen-Exchange Reactions of Unsaturated Aliphatic, Aromatic, and Heterocyclic Compounds in ZSM-5 Zeolite: A Combination of Perturbation Theory (MP2) and a Newly Developed Density Functional Theory (M06-2X) in ONIOM Scheme

Boekfa, Bundet; Choomwattana, Saowapak; Khongpracha, Pipat; Limtrakul, Jumras

doi:10.1021/la901841w

Cited by 75 publications

(81 citation statements)

References 51 publications

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“…They also considered more accurate but also computationally more demanding methods which include contributions from the Møller‐Plesset perturbation theory (MP2) or methods where the exact exchange is combined with correlation treated in the random phase approximation . In addition, also hybrid functionals may be an interesting alternative . However, as it is the intention to compare static with molecular dynamics results the usage of these computationally more expensive levels of theory is beyond current computational feasibilities.…”

Section: Computational Methodologymentioning

confidence: 99%

Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations

et al. 2019

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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 Brønsted 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 Brønsted 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.

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Section: Computational Methodologymentioning

confidence: 99%

Insight into the Role of Water on the Methylation of Hexamethylbenzene in H‐SAPO‐34 from First Principle Molecular Dynamics Simulations

et al. 2019

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“…285 A compilation of their adsorption energies for methane, ethane and propane are given in Table 6. [287][288][289][290][291][292] For more detailed assessments of various exchange correlation functions and their performance to describe the adsorption of alkenes we refer to the work of Gomes and co-workers, who performed a benchmark study on the adsorption enthalpies of various light hydrocarbon molecules in MFI-based zeolites using various exchange correlation functionals and adopting a QM/MM approach on clusters of varying size. Four possibilities for the position of the BAS are possible as schematically shown in Fig.…”

Section: View Article Onlinementioning

confidence: 99%

Advances in theory and their application within the field of zeolite chemistry

et al. 2015

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Zeolites are versatile and fascinating materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities to obtain the best material for a given application. Over the last decades, theoretical modeling has matured to a level that model guided design has become within reach. Major hurdles have been overcome to reach this point and almost all contemporary methods in computational materials chemistry are actively used in the field of modeling zeolite chemistry and applications. Integration of complementary modeling approaches is necessary to obtain reliable predictions and rationalizations from theory. A close synergy between experimentalists and theoreticians has led to a deep understanding of the complexity of the system at hand, but also allowed the identification of shortcomings in current theoretical approaches. Inspired by the importance of zeolite characterization which can now be performed at the single atom and single molecule level from experiment, computational spectroscopy has grown in importance in the last decade. In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science. Directions for future model developments will be given.

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“…Boekfa et al [129] employed four dual-scale methods, namely MP2:M06-2X, MP2:B3LYP, MP2:HF, and MP2:UFF, to investigate the confinement effect on the adsorption and reaction mechanism of unsaturated aliphatic, aromatic, and heterocyclic compounds on the ZSM-5 zeolite. They found the best agreement with experiments for the energies of adsorption of ethene, benzene, ethylbenzene, and pyridine when M06-2X was used to describe the large-scale framework subsystem.…”

Section: Organometallic Complexes and Catalysismentioning

confidence: 99%