The thermal, hydrothermal, and mechanical stabilities of a wide range of ordered mesoporous materials, in particular, the molecular sieves MCM-41, MCM-48, HMS, FSM-16, KIT-1, PCH, and SBA-15, have been studied in detail using X-ray diffraction (XRD) and nitrogen sorption. The thermal stability was found to be strongly related to the wall thickness and the silica precursor used during synthesis, and the following stability trend was observed: MCM-41 (fumed silica), MCM-48 (fumed silica), KIT-1 (colloid silica) > SBA-15 (TEOS) > FSM-16 (layered silicate), PCH (layered silicate) > MCM-41 (TEOS), MCM-48 (TEOS), HMS (TEOS). The hydrothermal stability is influenced by the wall thickness and the polymerization degree and decreases according to the following trend: KIT-1 > SBA-15 > MCM-48 (fumed silica and TEOS), PCH > FSM-16, MCM-41 (fumed silica and TEOS), HMS. The mechanical stability is little influenced by the nature of the mesoporous molecular sieves. All materials collapsed at a maximum pelletizing pressure of 450 MPa.

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A synthesis route to mesoporous titania with remarkable thermal stability was developed using an amine or cetyltrimethylammonium-templating procedure. By a treatment of the titania hybrids in aqueous ammonia, a method has been developed to overcome the lack of thermal stability above 350 °C. As for most mesoporous titanias described in the literature, this thermal instability originates from the uncontrolled phase transformation of amorphous template-free titania into massive anatase grains. In situ Raman spectroscopy, X-ray Diffraction, Differential Scanning Calorimetry and Thermogravimetrical Analysis demonstrated that parts of the amorphous titania walls of the NH 3 -treated titania hybrids were transferred into walls built up of rutile nanobuilding blocks before the template was thermally removed. We further found that, after a subsequent increase of temperature to remove the template, the remaining amorphous particles were transformed into anatase in such a way that this crystallographic transformation is accompanied by a retention of the pore structure without massive segregation of anatase nuclei. This leads to ordered high surface area (up to 600 m 2 g -1 ) mesostructured titania having pore volumes up to 0.28 cm 3 g -1 . XRD and N 2 adsorption-desorption data showed an outstanding thermal stability; the mesoscale order of NH 3 -treated titanias was retained after thermal treatment up to 600 °C.

A new and generally applicable synthesis procedure is developed in order to synthesise micelle-templated mesoporous titania built up of nanosized anatase walls with thermal stability up to 600 degrees C.

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