Structure–performance descriptors and the role of Lewis acidity in the methanol-to-propylene process

Yarulina, Irina; Wispelaere, Kristof De; Bailleul, Simon; Goetze, Joris; Radersma, Mike; Abou-Hamad, Edy; Vollmer, Ina; Goesten, Maarten G.; Mezari, Brahim; Hensen, Emiel J. M.; Martínez-Espín, Juan S.; Mortén, Magnus; Mitchell, Sharon; Pérez‐Ramírez, Javier; Olsbye, Unni; Weckhuysen, Bert M.; Speybroeck, Véronique Van; Kapteijn, Freek; Gascón, Jorge

doi:10.1038/s41557-018-0081-0

Cited by 247 publications

(316 citation statements)

References 56 publications

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“…As a result, the undesirable consecutive reactions such as isomerization, alkylation and oligomerization occur on the external surface acid sites are largely suppressed . Interesting results could be found in a recent publication by Gascon et al, in which a subtle interplay between BAS and LAS sites is confirmed, from both experimental and theoretical calculation results, to obtain an optimally ZSM‐5‐based MTP catalysts . Similar phenomena occurred to here synthesized HSZs catalyst.…”

Section: Resultssupporting

confidence: 77%

Mesoporogen‐Free Synthesis of High‐Silica Hierarchically Structured ZSM‐5 Zeolites and their Superior Performance for the Methanol‐to‐Propylene Reaction

Guo

et al. 2018

Eur J Inorg Chem

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A series of hierarchically structured ZSM‐5 zeolites (ZSM‐5 HSZs) with a Si/Al ratio of about 200 have been successfully synthesized in the absence of additional mesoporous agents. XRD, N2 sorption isotherms, SEM, TEM and NH3‐TPD results showed that the obtained HSZs materials possess high crystallinity, interconnected micro/mesoporous structures and similar total acid amounts. Meanwhile, in the methanol‐to‐propylene (MTP) reaction, compared to the microporous counterpart, all synthesized ZSM‐5 HSZs demonstrated superior performance benefitting from their hierarchical porous structures. Interestingly, 27Al MAS NMR and Py‐FTIR results confirmed the inter‐transformation of framework and extra‐framework Al species with the extension of materials crystallization duration and consequently the variation of materials surface acidity. As a result, the optimized catalyst achieved the highest initial propylene selectivity of 54.4 % and the longest catalyst lifetime (t90) of 175 h under the weight hourly space velocity (WHSV) of 1.0 g g–1 h–1. Moreover, a new “in situ alkali etching‐hydrothermal restoring“ mechanism has been proposed to elucidate the structural evolution of here reported high‐silica ZSM‐5 HSZs during the synthesis.

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Section: Resultssupporting

confidence: 77%

Mesoporogen‐Free Synthesis of High‐Silica Hierarchically Structured ZSM‐5 Zeolites and their Superior Performance for the Methanol‐to‐Propylene Reaction

Guo

et al. 2018

Eur J Inorg Chem

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“…The static periodic DFT calculations are performed using the Vienna Ab Initio Simulation Package (VASP 5.3) using a methodology frequently applied in literature . We here opted to use the revPBE functional due to its improved performance for solid‐state calculations compared to the commonly used PBE functional .…”

Section: Computational Methodologymentioning

confidence: 99%

“…As earlier work showed that a partial Hessian vibrational analysis (PHVA) is able to predict adsorption entropies within a 10–15 J/(mol K) error of computationally more demanding full Hessian calculations (FHVA) and experimental data, it has become a frequently applied and attractive methodology . For this reason, it is also used for the normal mode analysis (NMA) in this work using TAMkin .…”

Section: Computational Methodologymentioning

confidence: 99%

“…The static periodic DFT calculations are performed using the Vienna Ab Initio Simulation Package (VASP 5.3) [83][84][85][86] using a methodology frequently applied in literature. [87][88][89][90] We here opted to use the revPBE functional due to its improved performance for solid-state calculations compared to the commonly used PBE functional. [91] However, for this particular reaction the differences in reaction barriers and energies are relatively small at the temperature of interest.…”

Section: Static Calculationsmentioning

confidence: 99%

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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

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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“…Besides Brønsted acid sites, Lewis acid sites on zeolites play important role in the MTH reaction, which significantly influence the product selectivity and catalyst lifetime . Since the MTH reactions are usually performed at high temperature, zeolites are prone to be dealuminated, generating extra‐framework Al (EFAL) species which can serve as Lewis acid sites .…”

Section: C1 Species and C−c Bond Formationmentioning

confidence: 99%

Mechanism of Methanol‐to‐hydrocarbon Reaction over Zeolites: A solid‐state NMR Perspective

Wang¹,

Xu²

2020

ChemCatChem

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The versatile methanol‐to‐hydrocarbon (MTH) process on acidic zeolites allows for a production of olefins, aromatics and gasoline from a wide range of non‐fossil resources. Elucidation of the MTH reaction mechanism is helpful to improve product selectivity as well as develop high performance catalysts. The application of solid‐state NMR in the investigation of MTH reaction has significantly contributed to get insight into the MTH chemistry. In this review, we summarize mechanistic insight that has been gained into the MTH reaction by using solid‐state NMR spectroscopy. Special emphasis is given to the observation and determination of C1 species and active intermediates particularly cyclic carbocations to uncover the exact reaction route for the initial C−C bond formation and the hydrocarbon pool mechanism. The detection of host‐guest interactions involved in the MTH reaction with the advanced 13C‐27Al double‐resonance NMR is discussed for a better understanding of the active sites and the reactivity of hydrocarbon pool species.

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Structure–performance descriptors and the role of Lewis acidity in the methanol-to-propylene process

Cited by 247 publications

References 56 publications

Mesoporogen‐Free Synthesis of High‐Silica Hierarchically Structured ZSM‐5 Zeolites and their Superior Performance for the Methanol‐to‐Propylene Reaction

Mesoporogen‐Free Synthesis of High‐Silica Hierarchically Structured ZSM‐5 Zeolites and their Superior Performance for the Methanol‐to‐Propylene Reaction

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

Mechanism of Methanol‐to‐hydrocarbon Reaction over Zeolites: A solid‐state NMR Perspective

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