A new low-cost synthetic route to obtain zirconium containing mesoporous silica A. Infantes-Molina a , J. Me ´rida-Robles a , P. Maireles-Torres a , E. Finocchio b , G. Busca b , E. Rodrı ´guez-Castello ´n a , J.L.G. Fierro c , A. Jime ´nez-Lo ´pez a, * a Departamento de Quı ´mica Inorga ´nica, Cristalografı ´a y Mineralogı ´a (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Ma ´laga, Campus de Teatinos, E-29071 Ma ´laga, Spain b Dipartimento di Ingegneria Chimica e di Processo, Universita ` di Genova, Ple. J.F. Kennedy, I-16129 Genova, Italy c Instituto de Cata ´lisis y Petroleoquı ´mica, CSIC, Campus Universidad Auto ´noma, E-28049 Madrid, Spain Received 17 March 2004; received in revised form 17 June 2004; accepted 17 June 2004 Available online 28 August 2004 Abstract A new alternative low-cost route to obtain zirconium doped mesoporous silica has been developed by using cheaper inorganic Zr and Si precursors different from alkoxides and a non-ionic surfactant template, polyethyleneoxide. A series of solids, with Si/Zr molarratiosrangingfrom5toinfty,wasprepared.Theresultingmaterialsarestableathightemperatures,exhibithighBET-surface areas, thick pore walls and high tunable acidity. These characteristics make them excellent candidates to be used in heterogeneous catalysis as both acid catalysts and catalytic supports, as well as adsorbents. The incorporation of zirconium into the silica frame- work provokes a linear increase of both the Lewis and Brønsted acidities as probed by adsorption of basic molecules, such as piv- alonitrile and pyridine, coupled to IR spectroscopy. This acid character has also been corroborated by the catalytic test of 2-propanol conversion, where the dehydration product, propene, is the only product formed at 200 °C. Ó 2004 Elsevier Inc. All rights reserved. Keywords: Mesoporous solids; Zirconium oxide; Non-ionic surfactant; Sodium silicate; Acidity 1. Introduction Since the discovery of MCM-41 in 1992 [1], several new series of mesoporous materials labeled as MCM- 48, MSU, SBA, HMS and TUD have been prepared to provide catalysts or adsorbents for a broader spec- trumofbulkymoleculesthaninthecaseofmicroporous materials such as zeolites, which are widespreadly used in chemical and petrochemical industry. Up to now, a great variety of cationic, anionic and neutral surfactant molecules,aswellasinorganicsourceshavebeenusedin the synthesis of ordered mesoporous silica- or non-silica [2–5]. It is well known that the pore diameter, the wall thickness and the resulting structure are largely affected by parameters such as the type of surfactant, the silica/ surfactant molar ratio, the pH and temperature of reac- tion and the use of hydrothermal conditions. The influ- ence of these and others synthetic parameters has been extensively discussed [6–8]. The preparation of mesoporous silica has been accomplished by different synthesis routes based on either ionic interactions of charged surfactant micelles and inorganic species [9] or neutral routes through hydrogen bond interactions between non-charged amines or polyethylene oxide surfactants and neutral inorganic species [10,11]. This last synthetic route pro- vides the family of mesoporous silica, so-called MSU, whose structures lack of regular long-range periodicity but possess uniform channel diameters over a range comparable to the M41S solids. 1387-1811/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2004.06.025 * Correspondingauthor.Tel.:+34952131876;fax:+34952137534/ 137431. E-mail address: ajimenezl@uma.es (A. Jime ´nez-Lo ´pez). www.elsevier.com/locate/micromeso Microporous and Mesoporous Materials 75 (2004) 23–32