The formation and degradation of active species during methanol conversion over protonated zeotype catalysts

Olsbye, Unni; Svelle, Stian; Lillerud, Karl Petter; Wei, Zhihong; Chen, Y. Y.; Li, J. F.; Wang, J. G.; Fan, Weibin

doi:10.1039/c5cs00304k

Cited by 358 publications

(464 citation statements)

References 150 publications

(405 reference statements)

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“…23 The operation of each catalytic cycle during methanol conversion seems to depend on process conditions such as reaction temperature, the nature and composition of the feed and the catalyst topology and acidity. 13,14,19,25,26 Note that each catalytic cycle is initiated by a methylation reaction (highlighted area in Scheme 2). Therefore, the influence of process conditions on methylation reactions is assessed in the current study (vide infra).…”

Section: Introductionmentioning

confidence: 99%

Towards molecular control of elementary reactions in zeolite catalysis by advanced molecular simulations mimicking operating conditions

Wispelaere

Bailleul

Speybroeck

2016

Catal. Sci. Technol.

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Title: Towards molecular control of elementary reactions in zeolite catalysis by advanced molecular simulations mimicking operating conditions Advanced ab initio molecular dynamics techniques enable study of the infl uence of catalyst topology and acidity, reaction temperature and the presence of additional guest molecules on methylation reactions of benzene and propene, which are crucial reaction steps in the conversion of methanol into hydrocarbons. Our advanced simulations provide detailed insight into how operating conditions impact the competition of the concerted and stepwise methylation mechanism and thus the reaction kinetics. As featured in:See and mechanism of individual reaction steps at operating conditions. Herein we use state-of-the-art advanced ab initio molecular dynamics techniques to study the influence of catalyst topology and acidity, reaction temperature and the presence of additional guest molecules on elementary reactions. Such advanced modeling techniques provide complementary insight to experimental knowledge as the impact of individual factors on the reaction mechanism and kinetics of zeolite-catalyzed reactions may be unraveled. We study key reaction steps in the conversion of methanol to hydrocarbons, namely benzene and propene methylation. These reactions may occur either in a concerted or stepwise fashion, i.e. methanol directly transfers its methyl group to a hydrocarbon or the reaction goes through a framework-bound methoxide intermediate. The DFT-based dynamical approach enables mimicking reaction conditions as close as possible and studying the competition between two methylation mechanisms in an integrated fashion. The reactions are studied in the unidirectional AFI-structured H-SSZ-24, H-SAPO-5 and TON-structured H-ZSM-22 materials. We show that varying the temperature, topology, acidity and number of protic molecules surrounding the active site may tune the reaction mechanism at the molecular level. Obtaining molecular control is crucial in optimizing current zeolite processes and designing emerging new technologies bearing alternative feedstocks.

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Section: Introductionmentioning

confidence: 99%

Towards molecular control of elementary reactions in zeolite catalysis by advanced molecular simulations mimicking operating conditions

Wispelaere

Bailleul

Speybroeck

2016

Catal. Sci. Technol.

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“…Arguably, SAPO-34 is of most interest when the target products are lower olefins (MTO-an interesting alternative to energy intensive steam cracking routes) and H-ZSM-5 for gasoline range hydrocarbons (MTH) [24,25]. The so-called hydrocarbon pool mechanism, wherein an active hydrocarbonaceous pool is the source of activity, has gained widespread acceptance in this reaction [25][26][27]. As reviewed in detail elsewhere, the exact nature of the hydrocarbon pool and its formation is under refinement and it may depend upon the nature of framework with larger hydrocarbonaceous species occurring in the case of larger pore zeolites and zeotypes.…”

Section: Methanol To Hydrocarbonsmentioning

confidence: 99%

Methane dehydroaromatisation and methanol activation over zeolite catalysts: an overview

Hargreaves

2016

Appl Petrochem Res

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A brief overview of methane dehydroaromatisation over MoO 3 /H-ZSM-5 derived catalysts, the deposition of carbonaceous residues from methanol over H-mordenite and the role of binders in zeolite catalysed reactions is presented. The selective poisoning of methane cracking catalysts is proposed as a potential strategy for the development of methane dehydroaromatisation catalysts. In the case of methanol conversion over H-mordenite, evidence is presented for the formation of larger alkylated aromatics, such as methylnaphthalenes. Binders, ubiquitous components of technical catalysts, have been documented to have a number of important effects often outweighing laboratory based modifications, and therefore, consideration of their effects should be made at an early stage of catalyst development.

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“…At present, light olefins are mainly manufactured by thermal cracking of naphtha, which requires high energy consumption with low yield of light olefins. Furthermore, in view of the depletion of world oil reserves, it is urgent to develop new routes to produce light olefins using non-oil feedstocks [1]. During the past decades, methanol-to-olefin (MTO) conversion, as an alternative route for the production of light olefins, has attracted much attention, because methanol can be conveniently manufactured from any carbon-containing resources such as coal, natural gas and biomass [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…In the process of MTO, the dual-cycle mechanism was widely accepted, the initial step is the formation of dimethyl ether (DME) through dehydration of methanol, and then reacts to produce light olefins. Meanwhile, light olefins could further react to paraffins, aromatics via hydrogen transfer reaction [1].…”

Section: Introductionmentioning

confidence: 99%

Methanol-to-olefin conversion over H-MCM-22 catalyst

Zhang

Wang

Liu

et al. 2016

Journal of Molecular Catalysis A: Chemical

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a b s t r a c t H-MCM-22 zeolites with different Si/Al ratios were hydrothermally synthesized, also the parent sample was dealuminated by ammonium hexafluorosilicate (AHFS). Then all of the samples were characterized and evaluated for the methanol-to-olefin (MTO) conversion. The correlation of structural and acidic properties of H-MCM-22 with catalytic performance was investigated. The H-MCM-22 (Si/Al = 35.1) exhibits best catalytic stability in all the samples because of its suitable acid site amount and distribution. As for the H-MCM-22 (Si/Al = 35.1) after dealumination by AHFS, most of the extra-framework Al species were selectively removed, the selectivity of light olefin was enhanced further and the coke deposition seems to be inhibited.

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The formation and degradation of active species during methanol conversion over protonated zeotype catalysts

Cited by 358 publications

References 150 publications

Towards molecular control of elementary reactions in zeolite catalysis by advanced molecular simulations mimicking operating conditions

Towards molecular control of elementary reactions in zeolite catalysis by advanced molecular simulations mimicking operating conditions

Methane dehydroaromatisation and methanol activation over zeolite catalysts: an overview

Methanol-to-olefin conversion over H-MCM-22 catalyst

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