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Microwave-hydrothermally aged Zn,Al hydrotalcite-like compounds: Influence of the composition and the irradiation conditions

Benito, P. and Guinea, I. and Labajos, F. M. and Rocha, J. and Rives, V. (2008) Microwave-hydrothermally aged Zn,Al hydrotalcite-like compounds: Influence of the composition and the irradiation conditions. MICROPOROUS AND MESOPOROUS MATERIALS, 110 (2-3). pp. 292-302.

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Abstract

Zn,Al-CO3 compounds with the hydrotalcite-like (layered double hydroxide, LDH) structure were prepared by a co-precipitation method followed by hydrothermal treatment under microwave irradiation. The influence of the ageing treatment was studied in two series of samples with different Zn2+/Al3+ ratios, namely, 3/1 and 2/1. Moreover, the effects of the heating temperature and of the irradiation time were studied in order to select the optimum preparation conditions. The solids were fully characterised by powder X-ray diffraction (PXRD), Al-27 MAS-NMR, FT-IR spectroscopy, thermal analyses (DTA and TG), N-2 adsorption/desorption at -196 degrees C and TEM. The results showed that whatever the chemical composition of the starting mixture, HTlcs with Zn2+/Al3+ ratio equal to 2 were obtained, and it was impossible to overcome the ZnO segregation when the molar ratio was >2. These compounds were stable and their crystallinity could be quickly enhanced when the temperature treatment was 100 degrees C, whereas at 125 degrees C the ZnO segregation was not prevented. (C) 2007 Elsevier Inc. All rights reserved.

Item Type:Article
Uncontrolled Keywords:hydrotalcite; Zn; oxide; microwave heating; hydrothermal
Subjects:Material Science > Functional and hybrid materials
Analytical Science > Microscopy and probe methods
ID Code:6095
Deposited By:IoN
Deposited On:07 Sep 2009 10:49
Last Modified:07 Sep 2009 10:49

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