Does hierarchical structure affect the shape selectivity of zeolites? Example of transformation of n-hexane in hydroisomerization

Sazama, Petr; Pastvová, Jana; Kaucký, Dalibor; Morávková, Jaroslava; Rathouský, Jiřı́; Jakubec, Ivo; Sádovská, Galina

doi:10.1016/j.jcat.2018.05.010

Cited by 54 publications

(24 citation statements)

References 61 publications

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“…Brønsted acid sites and the inner zeolite walls. 306 This conclusion implies that, in principle, the advantages of using mesoporous zeolites could be fully exploited to design more efficient catalysts while preserving the shape selectivity of the zeolite.…”

Section: Interplay Between Hydrogen Metal and Acid Sites In Pt/h-zementioning

confidence: 99%

New trends in tailoring active sites in zeolite-based catalysts

et al. 2019

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Section: Interplay Between Hydrogen Metal and Acid Sites In Pt/h-zementioning

confidence: 99%

New trends in tailoring active sites in zeolite-based catalysts

et al. 2019

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“…The introduction of a second level of intracrystalline porosity to the MOR pore system would be advantageous to the many acid‐catalyzed hydrocarbon conversion reactions that involve large paraffinic and aromatic molecules. A general “top‐down” approach to prepare mesoporous mordenite zeolites via desilication, dealumination or a combination of these approaches has been extensively examined. Even though these techniques are commercially available and can be scaled up, there is little control over the textural and acidic properties of the final materials.…”

Section: Introductionmentioning

confidence: 99%

Mordenite Nanorods Prepared by an Inexpensive Pyrrolidine‐based Mesoporogen for Alkane Hydroisomerization

et al. 2019

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We report the synthesis of hierarchical mordenite zeolite nanorods in one step using inexpensive mono‐quaternary ammonium N‐cetyl‐N‐methylpyrrolidinium (C16NMP) as mesoporogen to the synthesis gel. The presence of a small amount of C16NMP results in the formation of 0.6–1 μm rods‐like crystals oriented along the c‐axis with a high mesoporous volume (0.12 cm3 g−1) and external surface area (∼90 m2 g−1) compared to bulk mordenite. Acidity characterization shows that the presence of C16NMP during mordenite formation leads to a redistribution of aluminum in the zeolite framework: the amount of Brønsted acid sites in the side‐pockets (8MR channels) is increased at the expense of those in the 12MR main channels. As these latter acid sites are the ones involved in the conversion of alkene intermediates in bifunctional hydroconversion of alkanes, an optimized hierarchical mordenite prepared with C16NMP displays a more ideal hydrocracking selectivity than bulk MOR prepared solely with sodium.

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“…In addition, branched carbocations are unstable, reactive compounds, which spend a relatively long time in the zigzag channels of the ZSM-5 catalyst. It is a generally accepted fact that pore size of ZSM-5 does not favour the formation of multiple branched hydrocarbons having larger critical molecular size [51]. Moreover, cracking of the single-branched carbocations resulted in the formation of two linear hydrocarbons which can contribute to the lower isomer contents.…”

Section: Thermo-catalytic Pyrolysis (Catalyst In the 1st Reactor)mentioning

confidence: 99%

Value-Added Pyrolysis of Waste Sourced High Molecular Weight Hydrocarbon Mixtures

2022

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In this study, Fischer-Tropsch paraffin mixture, heavy residue of waste polyethylene pyrolysis, shredded and crashed agricultural polyethylene waste and their combinations were pyrolysed both thermally and catalytically in a two-stage reactor system. During the experimental work, yields and compositions of pyrolysis products were studied as function of feedstock composition and catalyst placement. It was found that the average molecular weight of feedstocks and the presence of ZSM-5 catalyst also have significant effects on the product yields and the compositions. Feedstocks with high concentration of Fischer-Tropsch paraffin and real waste polyethylene resulted in deeper fragmentation in both thermal and thermo-catalytic pyrolysis. Due to the deeper fragmentation, they seemed to be suitable feedstocks for the production of C6-C9 and C10-C14 hydrocarbons. Meanwhile, for production of C15-C21 hydrocarbons, the use of a higher concentration of heavy residue of waste polyethylene pyrolysis in the feedstocks is recommended. From the point of view of liquid hydrocarbon and isomer production, the placement of the catalyst into the 1st reactor proved to be more advantageous. When the catalyst was placed into the 2nd reactor, the product formation shifted to the more volatiles, isomers took part in secondary cracking reactions and aromatics formed in higher concentrations.

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Does hierarchical structure affect the shape selectivity of zeolites? Example of transformation of n-hexane in hydroisomerization

Cited by 54 publications

References 61 publications

New trends in tailoring active sites in zeolite-based catalysts

New trends in tailoring active sites in zeolite-based catalysts

Mordenite Nanorods Prepared by an Inexpensive Pyrrolidine‐based Mesoporogen for Alkane Hydroisomerization

Value-Added Pyrolysis of Waste Sourced High Molecular Weight Hydrocarbon Mixtures

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