| This is a study of the gas phase synthesis of nanostructured titania particles, doped titania and titania thin film coatings using flame aerosol reactors and their selected applications in green chemistry. The synthesized particles and thin films have been used as photocatalysts and applied to the partial oxidation of organic compounds to produce highly desired oxygenates.; A new flame synthesis technology has been developed to synthesize nanostructured titania powders, doped titania, and thin film coatings. The obtained catalyst powders and thin films have been characterized by various techniques, such as Raman spectroscopy, SEM, TEM, BET surface area, UV-VIS, ICP spectroscopy, Mossbauer spectroscopy and X-ray diffraction. The optimized catalysts were used in the organic synthesis.; In order to lower the activation energy of titanium dioxide and increase the usable fraction of solar energy, metal-doped titanium dioxide was synthesized to increase the energy efficiency. The doping materials used in this study include vanadium and iron. The doped nanosize catalyst powders were evaluated with respect to crystal structure, atomic composition, band gap energy, light absorption wavelength shift and the performance in liquid phase photocatalytic partial oxidation of 1-phenylethanol to acetophenone. At the optimal doping concentration the doped titanium dioxide synthesized from the flame aerosol process showed higher conversion compared to the neat titania. The solvent effect on the photocatalytic reaction was studied using water and acetonitrile as the reaction solution.; In order to overcome the shortcoming of powder titania in application, we developed a unique flame coating technique to synthesize catalyst thin film. The substrates being coated include ceramic mat, glass, and stainless steel sheet. The catalyst thin films synthesized in this study showed higher photocatalytic activity and more durable mechanic properties compared to the thin films coated by other methods, such as sol-gel process. To optimize the thin film coating, different coating parameters, like the coating temperature, coating composition, anatase to rutile ratio, different coating configuration and coating thickness were studied. Partial oxidation of cyclohexane to produce cyclohexanol and cyclohexanone in gas phase was used as a model of the photocatalytic reaction to test the coated thin films. |
