Realumination of zeolite Y under acidic conditions

Oumi Yasunori

Takahashi Jou

Takeshima Kazuyoshi

Jon Hery

Sano Tsuneji

Journal of Porous Materials

Dealuminated zeolites Y were treated with aqueous solutions of various acids and ammonium salts to investigate the realumination behavior under acidic conditions. From the results of 27Al MAS NMR, 29Si MAS NMR and FT-IR measurements, it was found that a part of non-framework aluminum species in the dealuminated zeolite Y is effectively reinserted into the zeolite framework in CHCOONHand CHCOONH34 654 aqueous solutions. Pyridine adsorption experiments also revealed that most of incorporated aluminum species generate tetrahedrally coordinated framework aluminum species, namely Brönsted acid sites. Although the realumination also proceeded in H2SO and CH43COOH aqueous solutions, large amounts of incorporated aluminum species were not necessarily responsible for generation of Brönsted acid sites. Framework connected aluminum species, presumably as 3-fold-coordinated Lewis acidic framework aluminum species, were mainly generated. In the TEM image of the realuminated zeolite Y, needle-like crystals with ca. 25-80 nm in length were observed, which are probably due to AlOOH generated from non-framework aluminum species.

Zeolite Y

Dealumination

Realumination

Ammonium salt

Chemistry [ 430 ]

eng

Springer

Copyright (c) 2007 Springer "The original publication is available at www.springerlin.com"

[ISSN] 1380-2224

[DOI] 10.1007/s10934-006-9003-4

[NCID] AA11053751

[DOI] http://dx.doi.org/10.1007/s10934-006-9003-4