Mesoporous Silica and Titania by Glycol-Modified Precursors
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1007-S04-13
Mesoporous Silica and Titania by Glycol-modified Precursors Jasmin Geserick1, Nicola Hüsing1, Renate Roßmanith2, Clemens K. Weiss2, Katharina Landfester2, Yvonne Denkwitz3, R. Jürgen Behm3, Ute Hörmann4, and Ute Kaiser4 1 Institute of Inorganic Chemistry I, Ulm University, Ulm, 89081, Germany 2 Institute of Organic Chemistry III, Ulm University, Ulm, 89081, Germany 3 Institute of Surface Chemistry and Catalysis, Ulm University, Ulm, 89081, Germany 4 Electron Microscopy Group of Material Sciences, Ulm University, Ulm, 89081, Germany ABSTRACT Ethylene glycol modified precursors, such as tetrakis(2-hydroxyethyl)orthosilicate (EGMS) or bis(2-hydroxyethyl)titanate (EGMT), have distinct advantages in the synthesis of mesoporous materials by sol-gel processing compared to the commercially available tetraalkoxide precursors. The glycols released upon hydrolysis have proven to be compatible with lyotropic surfactant mesophases and in addition, these precursors allow for processing in purely aqueous conditions. Besides the standard characterization of the resulting titania and silica-based materials by XRD, electron microscopy, and nitrogen sorption, the potential of the titania-based materials for catalytic applications was tested using Au/TiO2 catalysts in low temperature CO oxidation reactions.
INTRODUCTION Since Mobile discovered the M41S phases in 19921 a large variety of novel mesostructured materials have been synthesized relying on the self assembly of surfactants as templates in the formation of the inorganic matrix. Not only silica, but also mesoporous nonsilica oxides, phosphates, etc., have been prepared for various applications.2-7 Among the mesoporous transition metal oxides, crystalline porous titanium dioxide with a high surface area is a very attractive material due to its well-known activity in catalytic reactions.8 In the past years, not only the chemical composition of the matrix was extended to almost the full periodic table, but also the morphology of the final material was controlled from powders via particles to monolithic systems.9-12 Research in this field not only included the development of novel amphiphilic precursors as more efficient structure-directing agents, but also the synthesis of new network-forming precursors with deliberately designed properties. An example for the latter case are the glycol/polyol-modified silanes that were successfully applied in the preparation of hierarchically structured (organo)silica monoliths.13-17 In this study, the synthesis of glycol-modified silanes such as tetrakis(2hydroxyethyl)orthosilicate (EGMS) is extended to titanate systems. As one example, bis(2hydroxyethyl)titanate (EGMT) was chosen and the applicability of both precursors in the synthesis of mesostructured/ mesoporous materials is compared. Only very few publications discuss the application of glycol-modified precursors in general.18-20 In addition, one has to distinguish between wet chemical processing and simple thermal decomposition of the glycolate precursors as discussed by Froe
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