منابع مشابه
On the reactivity of surface methoxy species in acidic zeolites.
The in situ preparation and isolation of surface methoxy species on acidic zeolites are followed by further investigations of their reactivity in heterogeneously catalyzed reactions. For the first time, the following solid-state NMR evidence for the high reactivity of surface methoxy species has been obtained: (i) Surface methoxy species react readily with ammonia on acidic zeolites at room tem...
متن کاملEntropy considerations in monomolecular cracking of alkanes on acidic zeolites
Compensation between adsorption entropies and enthalpies results in less than a two-fold variation in adsorption equilibrium constants for C3–C6 alkanes at temperatures relevant for monomolecular cracking; the size-independent activation energy for C–C bond activation in C3–C6 alkanes indicates that the marked increase in monomolecular cracking turnover rates observed with alkane chain size ref...
متن کاملAcid]Base Catalysis in Zeolites from First Principles
Zeolite materials are microporous aluminosilicates with various uses, including acting as important catalysts in many processes. One such process is the methanol to gasoline reaction, used widely in industry. This reaction is known to be associated with Brønsted acid sites in the zeolite, formed when Si is substituted by Al in the framework, with an associated Hq being bound nearby to maintain ...
متن کاملSolvation and acid strength effects on catalysis by faujasite zeolites
Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids r...
متن کاملExamples of Organic Reactions on Zeolites: Methanol to Hydrocarbon Catalysis
Solid (heterogeneous) catalysts (1–4) are favored in industrial processes because they eliminate the need to separate the catalyst from the products. Heterogeneous catalysts can be solid acids, bases, supported metals, mixed metal oxides, or multifunctional materials. Commercial processes based on solid acids outnumber all others, and zeolites (and closely related materials) are usually the sol...
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ژورنال
عنوان ژورنال: Journal of the Mineralogical Society of Japan
سال: 1985
ISSN: 1883-7018,0454-1146
DOI: 10.2465/gkk1952.16.455