Hydroconversion of methylcyclohexane on TEOS-modified H-ZSM-5 zeolite catalysts: Production of a high-quality synthetic steamcracker feedstock

Berger, C.; Raichle, Andreas; Rakoczy, Rainer A.; Traa, Yvonne; Weitkamp, Jens

doi:10.1016/s1387-1811(03)00270-1

Cited by 15 publications

(11 citation statements)

References 22 publications

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“…It caused a marginal increase in AlO 6 -c sites (15% mole), exhibiting Lewis acidity in dry form (Table 6). These results are similar to those of Berger et al 7 who studied H-ZSM-5 (Si/Al ) 36) silylated by CLD of TEOS.…”

Section: Discussionsupporting

confidence: 91%

“…CLD on zeolites with tetra-alkoxysilanes (usually TEOS) is far more practiced (e.g., refs − and − ) than CLD with cyclic organosiloxanes. , Regardless of the silylating agent used, long-range structure (crystallinity) is always found, or considered, to be preserved. Silylation effects are usually gauged by analyzing adsorptive and catalytic properties.…”

Section: Introductionmentioning

confidence: 99%

“…Silylation effects are usually gauged by analyzing adsorptive and catalytic properties. Aluminum coordination has seldom been addressed . Solid state 27 Al NMR spectroscopy is a powerful structural tool routinely used to characterize zeolite beta, especially its dealuminated forms. − But, studies of silylated betas ,,, are lacking NMR analysis.…”

Section: Introductionmentioning

confidence: 99%

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Unexpected Destructive Dealumination of Zeolite Beta by Silylation

et al. 2010

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Zeolite beta was silylated in a novel way, by chemical liquid deposition (CLD) of a cyclic organosiloxane, and characterized. Despite its large size, octamethyl-cyclotetrasiloxane (OMTS) did not provide a surface modification, as did the traditional tetra-alkoxysilanes (ethoxy, propoxy, and butoxy). OMTS treatment with minor Si deposition influenced the internal parts of the zeolite with destructive dealumination, as revealed by 27 Al MAS NMR, IR, and XRD studies. Three types of AlO 6 sites were found, (a) 17 ppm 27 Al shift, (b) 0 ppm shift, 3782 cm -1 IR frequency, and (c) -20 ppm shift, exhibiting no Brønsted and Lewis acidity, respectively, toward pyridine. Apparently, OMTS's low reactivity toward condensation with the less acidic external hydroxyl groups promoted ring-opening at pore-mouth sites. This allowed the resulting linear siloxane tetramer to penetrate the pores and cause dealumination during calcination. Catalysts modified with OMTS had the lowest amounts of AlO 4 sites, Lewis acidity, large void volume, and crystallinity.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unexpected Destructive Dealumination of Zeolite Beta by Silylation

et al. 2010

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“…Dabei ist die sorgfältige Kontrolle der experimentellen Bedingungen von entscheidender Bedeutung für die katalytischen Eigenschaften der so modifizierten Zeolithe. Die katalytische Aktivität der Zeolithe ist nach der Modifizierung teilweise signifikant erhöht [1,2] oder auch deutlich verringert [2,3]. Eine erhöhte Aktivität kann durch mit der Calcinierung der Proben nach der Behandlung mit Siliciumverbindungen einhergehende milde Wasserdampfbehandlung (mild steaming) [4,5] erklärt werden.…”

Section: Problemstellungunclassified

Tetraethylorthosilicat–modifizierte Zeolithe als Katalysatoren für die Dehydroalkylierung von Toluol mit Ethan

Traa

Singer

2007

Chemie Ingenieur Technik

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“…The preparation method, characterization, and molecular shape-selectivity of the CVD zeolite in the early stage of the study are summarized in review articles. , The pore size engineering in zeolites was also extensively reviewed by Vansant, which comprises all kinds of measures to modify the external and/or internal surface of zeolite crystallintes . Hydroconversion of methylcyclohexane on HZSM-5 zeolite modified by tetraethoxysilane (TEOS) of CVD was studied very recently in addition to the transformation of 1,2,4-trimethylbenzene on the CVD-modified HZSM-5 crystals. , It should be added that Halgeri and Das modified zeolites with 16 wt % of CVD silica and used them for dealkylation and realkylation of ethylbenzene, toluene disproportionation, para-disubstituted aromatics .…”

Section: Introductionmentioning

confidence: 99%

Ultra-fine Tuning of Microporous Opening Size in Zeolite by CVD

Kondo

Domen

et al. 2004

J. Phys. Chem. B

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The porous structure of a CVD (chemical vapor deposition) layer on silicalite zeolite was studied in detailed by TEM (transmission electron microscopy). The pore mouth of silicalite was suggested to be narrowed by CVD on the basis of the adsorption results, where the rate of 1-methylpentane adsorption decreased as the amount of CVD is increased, while that of the isomer, n-hexane, was not affected. The CVD layer was oberved as amorphous in TEM images and distinguished from silicalite when the focus was adjusted so that zeolite pores were clearly observable. The CVD layer was found to uniformly cover all faces of crystals. The thickness of the CVD layer increased as more silicon alkoxide was deposited, and the observed thickness in TEM images was in agreement with that estimated from the amount of deposition. The lattice fringe pattern was observed continuing from silicalite to the edge of a particle through the CVD layer, which seemed amorphous at the just-focus point for the observation of zeolite pores. Therefore, one-dimensional channels were considered to exist in the CVD layer, and we suggest that the opening size of the micropore in the CVD layer can be tuned in the region of 0.1 nm, which is quite important on the shape-selectivity.

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Hydroconversion of methylcyclohexane on TEOS-modified H-ZSM-5 zeolite catalysts: Production of a high-quality synthetic steamcracker feedstock

Cited by 15 publications

References 22 publications

Unexpected Destructive Dealumination of Zeolite Beta by Silylation

Unexpected Destructive Dealumination of Zeolite Beta by Silylation

Tetraethylorthosilicat–modifizierte Zeolithe als Katalysatoren für die Dehydroalkylierung von Toluol mit Ethan

Ultra-fine Tuning of Microporous Opening Size in Zeolite by CVD

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