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Article Dans Une Revue Journal of Physical Chemistry C Année : 2011

Crystal Size-Acid Sites Relationship Study of Nano- and Micrometer-Sized Zeolite Crystals

Résumé

H/D isotope exchange was employed to quantify the total number of Bronsted acid sites present in zeolites of different crystal size. The latter method was complemented by XRD, SEM, FT-IR, multinuclear MAS NMR, and N(2) adsorption measurements to obtain an entire picture of zeolite characteristics. The acidities of two zeolite-type materials, MFI and BEA, having crystal sizes in the range 50 nm to 20 mu m (ZSM-5) and 50 nm to 2 mu m (BEA) and close Si/Al ratios were investigated in detail. The number of Bronsted add sites in the series of ZSM-5 zeolite crystals does not depend on the crystal size. In contrast, BEA nanocrystals exhibit a higher amount of OH groups than do micrometer-sized crystals, which was attributed to the intergrowth of two polymorphs and the contribution of the external surface of zeolite nanocrystallites as demonstrated by solid-state NMR analysis.

Domaines

Chimie
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Dates et versions

hal-01840382 , version 1 (16-07-2018)

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Benoit Louis, Aurelie Vicente, Christian Fernandez, Valentin Valtchev. Crystal Size-Acid Sites Relationship Study of Nano- and Micrometer-Sized Zeolite Crystals. Journal of Physical Chemistry C, 2011, 115 (38), pp.18603-18610. ⟨10.1021/jp204234d⟩. ⟨hal-01840382⟩
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