New Theoretical Insights into the Contributions of Poly(methylbenzene) and Alkene Cycles to the Methanol to Propene Process in H-FAU Zeolite

Sun, Yi; Zheng, Dan; Pei, Supeng; Fan, Dongli

doi:10.1021/acs.jpcc.7b01991

Cited by 12 publications

(54 citation statements)

References 73 publications

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“…Wang et al pointed out that the propene was produced via both the polyMB and alkene cycles on H-ZSM-5 and the contribution of the alkene cycle was probably larger than that of the polyMB cycle . In previous work, we predicted that the polyMB cycle was more competitive than the alkene cycle for the MTP process in the H-FAU zeolite . In current work on the ETP mechanism, we tested the polyMB mechanism through constructing the reaction of benzene with ethanol (Scheme S2).…”

Section: Resultsmentioning

confidence: 99%

“…On the basis of the previous published works, , we have proposed the possible reaction mechanisms for the ETP process on acid zeolites. The corresponding pathways are given in Schemes – .…”

Section: Resultsmentioning

confidence: 99%

“…In the UFF, the charge parameters were not optimized to represent the electrostatic energies in zeolites . However, the electrostatic interactions between the cation-like TSs and anion-like zeolitic frameworks were crucial, and thus, we used the MM atomic charge values by fitting the electrostatic potential (ESP) energies as done in our earlier published work . The mechanical embedding scheme was used to evaluate the electrostatic interaction energies between QM and MM regions.…”

Section: Computational Modeling and Methodsmentioning

confidence: 99%

“…They further investigated the catalysis abilities of different pores on H-MCM-22 and pointed out that the formation of propene in both cycles was more favorable in the supercage channels of the zeolite. , Sun et al used a two-layer ONIOM method to study the contribution of these two cycles in MTP in the acidic FAU zeolite. Their calculations showed that the polyMB cycle was more competitive than the alkene cycle …”

Section: Introductionmentioning

confidence: 99%

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Understanding the Nanoconfinement Effect on the Ethanol-to-Propene Mechanism Catalyzed by Acidic ZSM-5 and FAU Zeolites

et al. 2021

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We have carried out a two-layer our own n-layered integrated molecular orbital and molecular mechanics (MM) study on the mechanism of ethanol to propene on H-ZSM-5 and H-FAU zeolites. The entire mechanism is divided into four reaction pathways (I, II, III, and IV). In reaction pathways I and II, ethanol is converted into propene in acidic zeolites. In reaction pathways III and IV, the coreaction of ethanol with propene was investigated. The rate-determining steps are the dehydration of ethanol (pathways I and II) and the ethylation of propene, 1-pentene, and 2-pentene by ethanol (pathways III and IV) over two zeolites. Four pathways have almost the same reactivity on two zeolites, and H-ZSM-5 and H-FAU are both favorable for the formation of propene. Six types of reaction steps are involved in all four pathways, and the calculated results demonstrate the following order of reactivity on two zeolites: proton transfer > deprotonation > dimerization > β-scission > ethylation ≈ dehydration of ethanol. The medium-pore ZSM-5 leads to entropy-increased transition-state (TS) structures more easily than the large-pore FAU zeolite in pathway I. The ZSM-5 framework has a stronger stabilizing effect on the formation of TS structures than the FAU framework in pathways I, II, and IV on the basis of the analysis of MM energy values; no clear variation trend of MM energies is found in pathway III. The difference charge density, reduced density gradient, and localized orbital locator plots reveal the nature of TS structures and explain the complicated van der Waals attractive interaction and spatial repulsive interaction between different molecular fragments in the TSs from the point of view of electron transfer. The diffusion behaviors of ethanol and olefin molecules are investigated by molecular dynamics simulations. The ZSM-5 and FAU zeolites describe different diffusion pictures for different sizes of molecules at low and high temperatures because of their different zeolitic topological channels.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Computational Modeling and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the Nanoconfinement Effect on the Ethanol-to-Propene Mechanism Catalyzed by Acidic ZSM-5 and FAU Zeolites

et al. 2021

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“…It is important to describe accurately the electrostatic interaction between the cationic transition state and the anionic framework of zeolite. In present study, the QM atomic charges were obtained from the DFT calculations and the MM charges were taken from our previous work [36]. Gaussian 09 and Multiwfn software packages were employed for the ONIOM calculations and the analysis of DCDs, RDGs and LOLs functions respectively [37,38].…”

Section: Methodsmentioning

confidence: 99%

A Theoretical Investigation on the Hydrodesulfurization Mechanism of Hydrogenated Thiophene Over Cu-mo Modified Fau Zeolite

Sun

Han

et al. 2021

Preprint

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We have carried out a two-layer our own n-layered integrated molecular orbital and molecular mechanics (ONIOM) study on the hydrodesulfurization (HDS) mechanism of three hydrogenated thiophene derivatives over Cu-Mo modified FAU zeolite. The thiophene is hydrogenated relatively easily to 2,3-dihydrothiophene (2,3-DHT), 2,5-dihydrothiophene (2,5-DHT) and tetrahydrothiophene (THT) due to low free energy barriers. Hydrogenolysis desulfurization (HYD) and direct desulfurization (DDS) are discussed. Ring-opening, hydrogen transfer and C−S bond cleavage steps of thiophene derivatives are involved in the HYD process. The rate-determining steps are the hydrogen transfer step for 2,5-DHT and C−S bond cracking step for 2,3-DHT and THT. The concerted DDS pathway is probably more favorable than the HYD pathway in the desulfurization of 2,5-DHT. The hydrogenation of thiophene to 2,5-DHT, 2,3-DHT and THT and their HDS process are entropy-decreased; the formation of sulfur vacancy is entropy-increased. The difference charge density (DCD) analysis reveals that for the ring-opening process, the electrons are migrated from the organic chain to the Cu-Mo catalytic center. The reduced density gradient (RDG) plots indicate that both a steric hindrance and a weak van der Waals attractive interaction exist between organic fragment and catalytic center for all transition states (TSs). The localized orbital locator (LOL) maps for all TSs suggest that there are strong covalent interactions between the atoms in the forming chemical bonds and weak van der Waals interactions between the atoms in the breaking chemical bonds.

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A reactive molecular dynamics simulation on the mechanism of the transformer oil pyrolysis at the high temperature

Wang,

Chen,

et al. 2023

Res Chem Intermed

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New Theoretical Insights into the Contributions of Poly(methylbenzene) and Alkene Cycles to the Methanol to Propene Process in H-FAU Zeolite

Cited by 12 publications

References 73 publications

Understanding the Nanoconfinement Effect on the Ethanol-to-Propene Mechanism Catalyzed by Acidic ZSM-5 and FAU Zeolites

Understanding the Nanoconfinement Effect on the Ethanol-to-Propene Mechanism Catalyzed by Acidic ZSM-5 and FAU Zeolites

A Theoretical Investigation on the Hydrodesulfurization Mechanism of Hydrogenated Thiophene Over Cu-mo Modified Fau Zeolite

A reactive molecular dynamics simulation on the mechanism of the transformer oil pyrolysis at the high temperature

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