Chemical reactions of alkenes and alkynes with solid-state defects on ZSM-5

Shih, S.

doi:10.1016/0021-9517(83)90332-9

Cited by 95 publications

(35 citation statements)

References 11 publications

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“…A topic which has been less studied, but is now receiving increasing attention, is the role of lattice defects in zeolitecatalyzed reactions. [20][21][22][199][200][201][202][203][204][205][206] From a 2D correlation analysis of in situ IR spectroscopy data, Thibault-Starzyk et al found a correlation between the formation of coke and the presence of silanol defects in the isomerization of ortho-xylene over H-…”

Section: Internal Defectsmentioning

confidence: 99%

Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity

et al. 2012

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Liquid hydrocarbon fuels play an essential part in the global energy chain, owing to their high energy density and easy transportability. Olefins play a similar role in the production of consumer goods. In a post-oil society, fuel and olefin production will rely on alternative carbon sources, such as biomass, coal, natural gas, and CO(2). The methanol-to-hydrocarbons (MTH) process is a key step in such routes, and can be tuned into production of gasoline-rich (methanol to gasoline; MTG) or olefin-rich (methanol to olefins; MTO) product mixtures by proper choice of catalyst and reaction conditions. This Review presents several commercial MTH projects that have recently been realized, and also fundamental research into the synthesis of microporous materials for the targeted variation of selectivity and lifetime of the catalysts.

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Section: Internal Defectsmentioning

confidence: 99%

Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity

et al. 2012

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“…[20][21][22][199][200][201][202][203][204][205][206] Aus einer 2D-Korrelationsanalyse in situ aufgenommener IR-Spektroskopiedaten fanden Thibault-Starzyk und Mitarbeiter einen Zusammenhang zwischen Koksbildung und dem Vorhandensein von Silanoldefekten bei der Isomerisierung von ortho-Xylol an H-ZSM-5. [20][21][22][199][200][201][202][203][204][205][206] Aus einer 2D-Korrelationsanalyse in situ aufgenommener IR-Spektroskopiedaten fanden Thibault-Starzyk und Mitarbeiter einen Zusammenhang zwischen Koksbildung und dem Vorhandensein von Silanoldefekten bei der Isomerisierung von ortho-Xylol an H-ZSM-5.…”

Section: Interne Defekteunclassified

“…Ein wenig untersuchtes Thema, das jedoch zunehmend an Interesse gewinnt, ist die Rolle von Gitterdefekten bei zeolithkatalysierten Reaktionen. [20][21][22][199][200][201][202][203][204][205][206] [201,203] Trotz der klaren experimentellen Beweise für die Bedeutung von inneren Gitterdefekten bei der Deaktivierung von MFI, ist der exakte Mechanismus, der zu einem beschleunigten Aktivitätsverlust während der MTH-Reaktion führt, weiterhin ungeklärt. Barbera [20] Das Vorhandensein dieser Elektronenakzeptorzentren würde die Oligomerisierung und Wasserstofftransferreaktionen unterstützen, welche dann zur Koksbildung führen.…”

Section: Interne Defekteunclassified

Umwandlung von Methanol in Kohlenwasserstoffe: Wie Zeolith‐Hohlräume und Porengröße die Produktselektivität bestimmen

et al. 2012

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Flüssige Kohlenwasserstoffe nehmen aufgrund ihrer hohen Energiedichte und guten Transportfähigkeit eine Schlüsselrolle in der globalen Energieversorgung ein. Eine vergleichbare Bedeutung haben niedere Alkene wie Ethylen und Propylen in der Produktion von Verbrauchsgütern. In einer Gesellschaft der Nach‐Erdöl‐Zeit wird die Produktion von Kraftstoffen und Alkenen auf alternative Quellen wie Biomasse, Kohle, Erdgas und CO2 angewiesen sein. Die Umwandlung von Methanol in Kohlenwasserstoffe, bekannt als Methanol‐to‐ Hydrocarbons(MTH)‐Reaktion, könnte eine zentrale Rolle auf diesem Weg einnehmen, weil je nach Wahl des Katalysators und der Reaktionsbedingungen gezielt Benzin (Methanol‐to‐Gasoline, MTG) oder Alkene (Methanol‐to‐Olefins, MTO) hergestellt werden können. Dieser Aufsatz beschreibt eine Reihe von industriellen MTH‐Projekten, die in den letzten Jahren realisiert wurden, sowie den aktuellen Stand der Grundlagenforschung zur Synthese und Anwendung von mikroporösen Materialien für die gezielte Veränderung von Selektivität und Lebensdauer der Katalysatoren.

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“…[33] tential redox site. [17,26] The electron-deficient sites are located on one of the oxygen atoms that surround the framework aluminum atom, but could be delocalized. [13] These sites can be responsible for the variations in the kinetic parameters and in the product distribution observed here and should lead to a reaction mechanism different from the protolytic mechanism.…”

Section: Effect Of Sample Treatment On Propane Conversion and Selectimentioning

confidence: 99%

High‐Temperature Produced Catalytic Sites Selective for n‐Alkane Dehydrogenation in Acid Zeolites: The Case of HZSM‐5

2011

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The effect of high‐temperature treatment on the catalytic activity and selectivity of two HZSM5 samples has been investigated by using propane activation as the test reaction. The samples have been characterized by using X‐ray powder diffraction, nitrogen adsorption, FTIR spectroscopy, and ammonia temperature‐programmed desorption (TPD). Before high‐temperature treatment, the samples have activation energies and selectivity toward propane cracking versus dehydrogenation comparable with similar samples reported in the literature. After high‐temperature treatment (825 °C in N2), the sample’s microporous and crystalline structure remains nearly intact, but a clear decrease in the number of Brønsted‐acid sites is detected by using FTIR and ammonia TPD. Despite the decrease (≈70 %), the rate of reaction is about the same before and after heating. The selectivity toward dehydrogenation, however, increases by at least a factor of 2, whereas the activation energy for dehydrogenation decreases considerably. This is evidence that new catalytic sites are formed upon dehydroxylation. By using naphthalene as a probe molecule, it is shown that the new sites have the ability to form stable radical cations out of the neutral naphthalene, which suggests that the new sites activate propane by a redox mechanism. The kinetic isotope effect on the rate of dehydrogenation is also consistent with a redox process. The effect of heating in an oxygen atmosphere at lower temperatures was also investigated and only minor effects on reaction rates and selectivity were observed. Naphthalene adsorption experiments on oxygen‐treated samples, however, produce more radical cations than on the samples treated at high temperatures, a result that does not correlate with the dehydrogenation activity of oxygen‐treated samples.

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Chemical reactions of alkenes and alkynes with solid-state defects on ZSM-5

Cited by 95 publications

References 11 publications

Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity

Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity

Umwandlung von Methanol in Kohlenwasserstoffe: Wie Zeolith‐Hohlräume und Porengröße die Produktselektivität bestimmen

High‐Temperature Produced Catalytic Sites Selective for n‐Alkane Dehydrogenation in Acid Zeolites: The Case of HZSM‐5

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