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A simple template-free approach to generate spherical porous anatase nanoparticles by combining the sol-gel process with the inverse miniemulsion technique is reported. These as-synthesized particles of about 200 nm in diameter consist of aggregated small anatase crystallites of several nanometers, thus leading to a high specific surface area of more than 300 m 2 • g -1 , even after calcination at 400 °C. The only employed surfactant is a block copolymer (P(E/B-b-EO)), which stabilizes the aqueous droplets with the water-soluble precursor bis(2-hydroxyethyl)titanate (EGMT) in the organic phase but also leads to aggregation and pore formation inside the particles. The lower relative rates of hydrolysis and condensation compared to the commonly used titanium alkoxides allow convenient handling in miniemulsion. Here we report the effects of synthesis conditions, such as the amount of surfactant, the composition of the dispersed phase, and the reaction and calcination temperature, on the particle size, porosity, crystallite size, crystallite phase, and specific surface area of the obtained nanoparticulate material. After removing the continuous phase, the obtained powders were characterized before and after calcination by transmission (TEM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen sorption (BET).

Mesoporous silica particulate structures of different morphologies from particles to capsules have been prepared by combining the sol-gel process with the cooperative self-assembly in inverse miniemulsion. We report a novel synthetic approach at room temperature, with low surfactant concentrations (5 and 10 mol %, relative to the precursor), and a short synthesis time of only a few hours. As a precursor, glycol-modified silane (tetrakis(2-hydroxyethyl)orthosilicate, EGMS) is used, which shows the advantage of being highly water-soluble. The precursor (EGMS) and the structuring surfactant (cetyltrimethylammonium bromide, CTAB) were dissolved in hydrochloric acid and dispersed in a mixture of hydrocarbons (Isopar M) by ultrasonication. In this synthesis, two different surfactants were used simultaneously. One surfactant (CTAB) acts as a lyotropic template, whereas the second surfactant is an amphiphilic block copolymer (PE/B-b-PEO) that stabilizes the droplets. For template removal, the final material was calcined. The obtained materials were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and nitrogen sorption (Brunauer-Emmett-Teller (BET) methodology). The effect of synthesis conditions such as the amount of templating surfactant (CTAB), the temperature during ultrasonication, the reaction time, the pH value, and the amount of stabilizing surfactant (PE/B-b-PEO) on cooperative self-assembly, morphology, and specific surface area were investigated. Shortly after ultrasonication, porous particles a few hundreds of nanometers in size are formed, which are transformed to capsules and finally to porous flakes with increasing reaction time. This transformation is strongly influenced by the amount of stabilizing surfactant (PE/B-b-PEO). By simply varying the amount of PE/B-b-PEO, the morphology and mesostructural ordering, as well as the porosity, can be tuned over a wide range.

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The activity and stability of structurally well defined mesoporous Au/TiO 2 catalysts with different support morphologies and pore sizes for low temperature CO oxidation was investigated by kinetic measurements and in-situ IR spectroscopy. The resulting catalysts with Au particle sizes of *3 nm exhibit a high activity for CO oxidation, similar to or exceeding that of highly active standard Au/TiO 2 catalysts with similar size Au nanoparticles and loading, and a significantly lower tendency for deactivation. Possible reasons for the improved performance of these catalysts are discussed.

We herein report a water-based sol-gel approach towards porous mixed Si/Ti oxides using co-precipitated glycol-modified precursors. By adjusting synthesis parameters such as the pH value and the Si/Ti ratio of the precursor, the morphology as well as the Si/Ti-composition of the resulting mixed oxide particles can be varied in a wide range. The behaviour of the mixed oxides as substrates for Au catalysts and the performance of the resulting catalysts in the CO oxidation reaction was investigated and compared to catalysts supported on mesoporous anatase and rutile synthesized analogously. For comparable Au particle sizes and Au loadings, the composition of the mixed oxide support was found to significantly affect the reactivity and reaction behaviour, with mixed oxide supported Au catalysts synthesized at pH=5 or 10 and with a Si/Ti-ratio of 1:19 and 1:34 exhibiting the maximum activity. In contrast to the enhanced activity, the mixed oxide supports do not lead to a significant improvement in deactivation behaviour and catalyst stability.