Silica-titania mixed oxides

C. Ingemar Odenbrand, S. Andersson, L. Andersson, J. Brandin, and G. Busca, Characterization of silica-titania mixed oxides, J. Catal. 125,541-553 (1990). 

Figure 8.5 Plot of volume fraction ratio Vro/Vrf characterizing the swelling of an unfilled PDMS network relative to that of a filled PDMS network, against filler loading expressed as volume ratio of filler to PDMS is the volume fraction of filler).40 Types of filler were silica-titania mixed oxides ( ), silica (O), and titania (A).

Zhu and co-workers [102] have combined sol-gel processing with a liquid crystalline templating approach in order to synthesise meso-structured silica-titania mixed oxide monoliths, in which the nanocrystalline titania was well dispersed inside the silicate framework. It was shown that the mixed oxide monoliths were excellent support materials for Au catalysts. 

Silica-Titania and Alumina-Silica-Titania Mixed Oxides... 

Figure 35.4. Schematic pathway to mesostructured silica / titania mixed oxide films.

Keywords nanoparticles, sol-gel processing, silica-titania mixed oxides, inorganic-organic hybrid materials... 

Wen, J. Mark, J. E., Precipitation of Silica-Titania Mixed-Oxide Fillers into Poly(dimethylsiloxane) Networks. Rubber Chem. Technol. 1994, 67, 806-819. 

Hilsing N., Launay B., Doshi D., Kickelbick G. Mesostructured silica-titania mixed oxide thin films. Chem. Mater. 2002 14 2429-2432... 

Figure 1.11 Titanium alkoxide derivative with a p-diketonate-substituted silane as a ligand, as a precursor for a silica-titania mixed oxide.

Udomsak, S., Anthony, R.G., 1996. Isobutane dehydrogenation on chromia/silica—titania mixed oxide and chromia/Y-alumina catalysts. Industrial Engineering Chemistry Research 35... 

Both the Toth and Alcoa processes provide aluminum chloride for subsequent reduction to aluminum. Pilot-plant tests of these processes have shown difficulties exist in producing aluminum chloride of the purity needed. In the Toth process for the production of aluminum chloride, kaolin [1332-58-7] clay is used as the source of alumina (5). The clay is mixed with sulfur and carbon, and the mixture is ground together, pelletized, and calcined at 700°C. The calcined mixture is chlorinated at 800°C and gaseous aluminum chloride is evolved. The clay used contains considerable amounts of silica, titania, and iron oxides, which chlorinate and must be separated. Silicon tetrachloride and titanium tetrachloride are separated by distillation. Resublimation of aluminum chloride is requited to reduce contamination from iron chloride. 

An interesting recent example of successful application of the SSG process combined with ensuing supercritical drying is the design of titania-silica mixed oxides for the epoxidation of bulky olefins [16-18]. This example will be used to illustrate the opportunities the combined use of SSG and SCD provide for tailoring the chemical and structural properties of mixed oxides. 

Chromium oxide-based catalysts, which were originally developed for the manufacture of HDPE resins, have been modified for cthylcnc-< -olcfin copolymerization reactions. These catalysts use. a mixed silica-titania support containing from 2 to 20 wt % of Ti. 

Figure 9. Surface content of (a) A1 in fumed silica/alumina and (b) Ti in titania/silica and the maximum adsorption of (a) Pb(II) and (b) Ni(II) as a function of the total (a) alumina or (b) titania content in mixed oxides.

Figure 2. Optical spectra of (dimethylamino) azobenzene, DMAAB, adsorbed onto individual fumed alumina, silica A-300, and titania, and mixed oxides Si02/Ti02 (37 wt% Ti02), Al203/Si02 (30 wt% A1203) and Al203/Si02/Ti02 (22, 28, and 50 wt% res-pecttively).

---