Title: Heteropolyacids with Keggin structure supported on silica-alumina

Authors: Patricia Vazquez, Nancy Quaranta

Addresses: Centro de Investigacion y Desarrollo en Ciencias Aplicadas 'Dr. Jorge J. Ronco' (CINDECA), CONICET-UNLP, 47 N 257 1900 La Plata, Argentina. ' Facultad Regional San Nicolas Centro de Desarrollo y Tecnologia de Materiales (DEYTEMA), Universidad Tecnologica Nacional, Colon 332 2900, San Nicolas, Argentina

Abstract: The behaviour of molybdophosphoric acid, with Keggin structure, supported on different silica-alumina mixtures, obtained by sol-gel method, was studied. Different techniques were used to synthesise the supports. In one of them, commercial alumina was added to a tetraethyl orthosilicate (TEOS) solution, and then this was hydrolysed. In the other preparations, TEOS and aluminium tri-sec-butoxide were hydrolysed, simultaneously or with TEOS prehydrolysis. The catalysts were prepared by incipient wetness impregnation, and different thermal treatments were applied after their leaching with toluene. The specific surface area of the solids was measured, and the nature of the Keggin heteropolyacid species present in the catalysts was characterised by diffuse reflectance spectroscopy and X-ray diffraction. In addition, their acidic properties were evaluated by potentiometric titration with n-butylamine.

Keywords: Keggin heteropolyacids; molybdophosphoric acid; silica-alumina; sol-gel synthesis; leaching; toluene; thermal treatments; acidic behaviour; acidic properties.

DOI: 10.1504/IJMPT.2006.010676

International Journal of Materials and Product Technology, 2006 Vol.27 No.1/2, pp.101 - 109

Published online: 16 Aug 2006 *

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