Alkylation of benzene with ethylene over faujasite zeolite investigated by the ONIOM method

Namuangruk, Supawadee; Pantu, Piboon; Limtrakul, Jumras

doi:10.1016/j.jcat.2004.04.016

Cited by 101 publications

(33 citation statements)

References 52 publications

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“…This ONIOM3 model has successfully been employed for studying adsorptions of ethylene, benzene, and ethylbenzene in zeolite and alkylation of benzene with ethylene in the zeolite. [12,13] The model produced a reasonable structure of faujasite zeolite which compared well with the structure obtained for the fully optimized 20T cluster at the B3LYP/6-31G(d,p) level [13] (see Table 1) and was also in agreement with the experimental structure, for example, the computed Al···H distance of 2.462 is comparable to the NMR measured value of 2.48 AE 0.04 . [16] The computed adsorption energies for ethylene, benzene, and ethylbenzene (À8.73, À13.91, and À20.11 kcal mol À1 , respectively) closely match the experimental data (À9.0, À14.0 and À20.4 kcal mol…”

Section: Zeolite Modelsupporting

confidence: 71%

“…Hence, small quantum cluster calculations which basically neglect these interactions can give erroneous results. However, hybrid methods such as QM/MM and ONIOM can reasonably describe these interactions [12][13][14][15] with only a small increase in computational demand. Therefore, we used the ONIOM method to investigate ethylene dimerization inside faujasite zeolite.…”

Section: Resultsmentioning

confidence: 99%

“…The recent development of hybrid methods, such as embedded cluster or combined quantum mechanics/molecular mechanics (QM/MM) methods, as well as the more general ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) method [11] has brought obtaining accurate results on larger systems within reach. Recent theoretical studies [12][13][14][15] have shown that the ONIOM scheme can be efficiently used for characterizing the reactivity of active sites inside zeolites.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] Moreover, this model has recently been used for studying the alkylation of benzene with ethylene [12] and has proved to be an accurate and practical model for exploring the structure, adsorption, and mechanisms of reactions taking place inside zeolite pores. Therefore, we used this model to study the ethylene dimerization inside faujasite zeolite.…”

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confidence: 99%

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Investigation of Ethylene Dimerization over Faujasite Zeolite by the ONIOM Method

2005

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Ethylene dimerization was investigated by using an 84T cluster of faujasite zeolite modeled by the ONIOM3(MP2/6-311++G(d,p):HF/6-31G(d):UFF) method. Concerted and stepwise mechanisms were evaluated. In the stepwise mechanism, the reaction proceeds by protonation of ethylene to form the surface ethoxide and then C--C bond formation between the ethoxide and the second ethylene molecule to give the butoxide product. The first step is rate-determining and has an activation barrier of 30.06 kcal mol(-1). The ethoxide intermediate is rather reactive and readily reacts with another ethylene molecule with a smaller activation energy of 28.87 kcal mol(-1). In the concerted mechanism, the reaction occurs in one step of simultaneous protonation and C--C bond formation. The activation barrier is calculated to be 38.08 kcal mol(-1). Therefore, the stepwise mechanism should dominate in ethylene dimerization.

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Section: Zeolite Modelsupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Investigation of Ethylene Dimerization over Faujasite Zeolite by the ONIOM Method

2005

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“…Furthermore, they often introduce an unrealistic perfect symmetry into the model. Hybrid methods, such as the embedded cluster or combined quantum mechanics/molecular mechanics (QM/MM) methods [23][24][25][26][27][28][29][30][31], as well as the more general ONIOM ('Our-own-N-layer integrated molecular orbital + molecular mechanics') method [32][33][34][35][36][37][38][39][40][41][42] provide a cost effective computational strategy for including the effects of the zeolite framework.…”

Section: Introductionmentioning

confidence: 99%

Structure and adsorption of a basic probe molecule on H-ZSM-5 nanostructured zeolite: An embedded ONIOM study

Lomratsiri

Probst

Limtrakul

2006

Journal of Molecular Graphics and Modelling

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Comparison of Ethylation at External Surface and Internal Cavity of H‐MCM‐22 Zeolite from Theoretical Calculations

Wang

Yang

et al. 2019

Chin. J. Chem.

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Summary of main observation and conclusionUnderstanding and optimizing structure of active sites is of significance in zeolite catalysis. Benzene ethylation is an industrially important process catalyzed by H‐MCM‐22 zeolite; while the active sites still remain elusive. In this work, density functional theory (DFT) calculations were employed to investigate the benzene ethylation at two different types of Brønsted acid sites (BAS) in H‐MCM‐22 zeolite, namely the internal cavity (IC) acid site and the external surface (ES) acid site. Both the stepwise and concerted pathways were addressed. The comparison of the calculated energetics of two pathways indicates that the benzene ethylation reaction primarily proceeds via the concerted pathway at both the IC and ES acid sites of H‐MCM‐22. The calculated overall Gibbs free energies at reaction condition (473 K and 3.5 MPa) on the IC and ES acid sites are 90 and 86 kJ/mol, with the rate constants of 1.20 × 103 and 2.92 × 103 s–1, respectively. It indicates that benzene ethylation could occur both on the IC and ES acid sites, with the catalytic activity of IC acid site being slightly lower than that of ES acid site. Furthermore, we theoretically reveal that the acid strength at the ES site is slightly weaker than that at the IC site via the frequency shift after the adsorption of CO. The differences in dispersion interaction between ES and IC sites are also quantified by the adsorption of base molecules with different sizes. The calculated results in this work demonstrate that the acid sites at the external surface of H‐MCM‐22 zeolites are suitable for benzene ethylation to produce ethylbenzene, providing theoretical implications for tailoring the distribution of active sites in H‐MCM‐22 zeolite.

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Alkylation of benzene with ethylene over faujasite zeolite investigated by the ONIOM method

Cited by 101 publications

References 52 publications

Investigation of Ethylene Dimerization over Faujasite Zeolite by the ONIOM Method

Investigation of Ethylene Dimerization over Faujasite Zeolite by the ONIOM Method

Structure and adsorption of a basic probe molecule on H-ZSM-5 nanostructured zeolite: An embedded ONIOM study

Comparison of Ethylation at External Surface and Internal Cavity of H‐MCM‐22 Zeolite from Theoretical Calculations

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