The porosity, acidity, and reactivity of dealuminated zeolite ZSM-5 at the single particle level: the influence of the zeolite architecture.

Autor: Aramburo LR; Inorganic Chemistry and Catalysis, Debye Institute for NanoMaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands., Karwacki L, Cubillas P, Asahina S, de Winter DA, Drury MR, Buurmans IL, Stavitski E, Mores D, Daturi M, Bazin P, Dumas P, Thibault-Starzyk F, Post JA, Anderson MW, Terasaki O, Weckhuysen BM
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2011 Dec 02; Vol. 17 (49), pp. 13773-81. Date of Electronic Publication: 2011 Nov 03.
DOI: 10.1002/chem.201101361
Abstrakt: A combination of atomic force microscopy (AFM), high-resolution scanning electron microscopy (HR-SEM), focused-ion-beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), confocal fluorescence microscopy (CFM), and UV/Vis and synchrotron-based IR microspectroscopy was used to investigate the dealumination processes of zeolite ZSM-5 at the individual crystal level. It was shown that steaming has a significant impact on the porosity, acidity, and reactivity of the zeolite materials. The catalytic performance, tested by the styrene oligomerization and methanol-to-olefin reactions, led to the conclusion that mild steaming conditions resulted in greatly enhanced acidity and reactivity of dealuminated zeolite ZSM-5. Interestingly, only residual surface mesoporosity was generated in the mildly steamed ZSM-5 zeolite, leading to rapid crystal coloration and coking upon catalytic testing and indicating an enhanced deactivation of the zeolites. In contrast, harsh steaming conditions generated 5-50 nm mesopores, extensively improving the accessibility of the zeolites. However, severe dealumination decreased the strength of the Brønsted acid sites, causing a depletion of the overall acidity, which resulted in a major drop in catalytic activity.
(Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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