Titania-Based Aerogel

Titania is often combined with other oxides to form binary systems. Cao et al. [248,249] and Yoda et al. [250,251] have investigated the applicability of titania and titania-silica aerogels as potential oxidation catalysts for removal organics from air (VOCs) or water. The concept is to combine the gas adsorption properties of silica with the photocatalytic activity of titania in a mixed catalysis system. Bismuth-molybdenum-titanium xerogel and aerogels are promising catalysts for the oxidation of butadiene to ftiran, where reported activities and selectivities are comparable to state-of-the-art industrial catalysts [252]. 

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Schneider, M. Titania Based Aerogel Catalysts, PhD Dissertation, ETH, Zurich, 1994. 

M. Schneider and A. Baiker, Titania-Based Aerogels, Catal. Today, 35, pp. 339-65, 1997. 

It is also interesting to compare various types of solid catalysts in the epoxidation of a-isophorone. Unfortunately, a real comparison is rather difficult, as the reaction conditions (temperature, oxidant, concentrations) are different for each catalyst. Due to the lack of information, the comparison shown in Table 2 is based only on the productivity, i.e. the amount of isophorone oxide produced in unit time using unit amount of catalyst. Two set of data were chosen for the 20 wt% titania - 80 wt% silica aerogel, and the best published data were chosen for the hydrotalcite [16, 17] and the alumina-supported KF [17, 18]. We assumed that the... 

Very recently, hierarchically arranged aerogel monoliths [209], silica-based monoliths from swollen liquid crystals [210] or heptane/water/ethanol/sodium dodecylsulfate microemulsion [211], monolith-based hybrid components such as the PMOs [212], and silicon oxycarbide monoliths with better thermal properties than the pure (organo) silica monoliths [213] have been reported. These approaches have been extended also to alumina or aluminumsilicates [214, 215], titania [216, 217], zirconia [218], or ceramic-based [219] systems. 

Pietron J J, Rolison D R (2004) Improving the efficiency of titania aerogel-based photovoltaic electrodes by electrochemically grafting isopropyl moieties on the titania surface. J Non-Cryst Solids 350 107-112 Tursiloadi S, Imai H, Hirashima H (2004) Preparation and characterization of mesoporous titania-alumina ceramic by modified sol-gel method. J Non-Cryst Solids 350 271-276... 

Morris et al. [14] demonstrated that the base-catalyzed, acid-modified (BCAM) approach they used for silica aerogels, and which showed considerable promise for entrapment of sensor moieties, could also be applied to titania aerogel preparation. 

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