Photocatalytic degradation of benzene in oxygen-containing gaseous feed streams was investigated using titania and platinized (0.1 wt.-%) titania photocatalysts. The titania catalyst was synthesized using sol-gel techniques. Results of this study indicate that, when using this particular photocatalyst, benzene was oxidized to carbon dioxide and water without forming any detectable organic reaction products in the reactor effluent, although only some of the benzene reacted. Both the overall conversion of benzene and its mineralization were improved by platinizing the titania. When the titania catalyst was platinized, both photocatalytic and thermocatalytic reactions were promoted. Rates of photocatalytic reactions were significantly enhanced at reaction temperatures between 70 and 90

The photocatalytic degradation of ethylene in airstreams has been studied over the temperature range 30-110

Catalytic hydrolysis of dichlorodifluoromethane (CFC-12) in a humid air stream was studied over pure and sulfate promoted TiO2 catalysts which were prepared by sol-gel methods. The results showed that complete conversion of CFC-12 on unmodified TiO2 was achieved at reaction temperatures higher than 340±C under the employed reaction conditions. The selectivity to CO2 ([CO2]produced/[CFC-12]converted) varied from 0.5 to 0.88 over the range of 250–350±C and CClF3 (CFC-13) was detected as the main by-product. Surface fluorination of the TiO2 catalyst during the reaction improved its activity, induced the formation of the fluorinated by-product CFC-13, and changed such properties of the catalyst as its specific surface area, pore size distribution, and crystal size. It was found that the catalytic and structural properties of TiO2 were greatly improved by sulfation. The sulfated TiO2 (TiO2/SO42-) exhibited excellent reaction activity and selectivity for CFC-12 catalytic decomposition at low reaction temperatures (190–250±C) while retaining a stable structure. Complete decomposition of CFC-12 with stoichiometric production of CO2 was observed over the TiO2/SO42- catalyst at 250±C under otherwise identical reaction conditions as used for pure TiO2. Results of catalyst characterization by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and N2 sorption analysis indicated that surface sulfate species formed on the sulfated TiO2. When compared to unmodified TiO2, the sulfated TiO2 exhibited higher resistance to crystal phase transformation from anatase to rutile, higher resistance to the deleterious effects of fluorination of the catalyst, and higher specific surface area. Fluorination of the catalyst did not improve the activity of sulfated TiO2 and no CFC-13 was detected as a by-product, indicating that fluorine was not involved in the formation of reaction sites over the sulfated TiO2 catalysts. °c 1997 Academic Press.

Macroporous nanocrystalline zinc ferrite with single spinel-phase was prepared by a facile self-propagating combustion method using zinc nitrate, iron nitrate and glycine. The as-prepared ZnFe2O4 were characterized by X-ray diffraction (XRD) analysis, N2 adsorption, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectrum (EDS). The magnetic properties of the prepared ZnFe2O4 were also studied.

Hollow metal oxide fibers [TiO2 and Fe2O3] have been prepared by using activated carbon fibers [ACFs] as the templates, through a simple impregnation and heat treatment. The resulting products, as compared to ACFs, possessed not only a similar morphological feature upward to the micrometer scale but also different surface nanostructures with unique morphology. The TiO2 fibers displayed overlapped “wormlike” surface and a hierarchical structure with two distinguishable layers, the inner layer and the outer layer, which were composed of the particles of 7 and 15 nm, respectively. It was also found that the reaction temperature had a significant effect on the TiO2 surface morphology. The Fe2O3 fibers exhibited a rough and crinkle-like surface and were also composed of hierarchical particles. Both TiO2 and Fe2O3 fibers possessed the hierarchical pore structure with mesopores in the walls of the large hollow channel. Such porous architecture favored the resultant TiO2 with better apparent photoactivity than P25 titania for degradation of gaseous acetone and would also make the materials useful for further application in other fields.