Aerogel mixed-metal oxide

The aerogel-prepared metal oxide nanoparticles constitute a new class of porous inorganic materials because of their unique morphological features such as crystal shape, pore structure, high pore volume, and surface areas. Also, it is possible to load catalytic metals such as Fe or Cu at very high dispersions on these oxide supports and hence the nanocrystalline oxide materials can also function as unusual catalyst supports. Furthermore, these oxides can be tailored for desired Lewis base/Lewis acid strengths by incorporation of thin layers of other oxide materials or by preparation of mixed metal oxides. 

The epoxide-initiated approach has been used to prepare a wide variety of metal oxide, mixed metal oxide, and composite aerogel materials, as illustrated in Figure 8.7. This section is intended to provide a general overview of the different aerogel materials prepared using... 

Gibiat V., Lefeuvre 0., Woignier T., Pelous J., Phalippou J. Acoustic properties and potential applications of silica aerogels. J. Non-Cryst. Solids 1995 186 244-255 Hair L.M., Owens L., Tillotson T., Froba M., Wong J., Thomas GJ., Medlin DI.., Local, nano-and micro-structures of mixed metal oxide aerogels for catalyst applications. J. Non-Cryst. Solids 1995 186 168-176... 

G. E. E. Gardes, G. Pajonk, and S. J. Teichner, Preparation and Properties of Aerogels of Simple or Mixed Inorganic Oxides Containing Metallic Nickel, Bull. Soc. Chim. Fr. 9-10, pp. 1327-32, 1976. 

Two kinds of titania aerogels have been discussed pure titania and mixed- or composite oxides. The better photocatalytic activity of titania aerogel was reported already in early 1970s [3]. In order to improve its catalytic activity, addition of other transition metal oxides to titania aerogels, such as vanadia, was discussed [11,12]. Also, composite aerogels with highly adsorbable oxides, silica, and alumina were reported [13-18]. 

Transition-metal mixed oxides active in combustion catalysis have been prepared by two main procedures i) classical coprecipitation / calcination procedures starting from metal nitrates and/ or alkoxides ii) preparation based on the supercritical drying of gels prepared from organic complexes (alkoxides, acetylacetonates or acetates), producing aerogels . Details on the second preparation can be found in Ref. 13. 

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