(688i) Single-Facet-Dominated Titania and Zirconia As Catalysts or Supports for Bio-Alcohol Dehydration and Oxidative Dehydrogenation
Research described in this work investigates the facet-dependent properties of two widely used metal oxides, TiO2 and ZrO2. Single-facet-dominated anatase titania were synthesized using hydrothermal methods. These TiO2 nanocrystals exhibited well-defined shapes of truncated tetragonal bipyramid, rod, and nano-sheet, with the exposed dominated facets of (101), (010), and (001), respectively. Using a similar hydrothermal method, monoclinic ZrO2 nanocrystals were also prepared in shapes of spheres and rods. In contrast to TiO2, these ZrO2 nanocrystals possessed more complex facets. The spheres were composed of (111),Â (1Ì?11), and (110) facets, while the rod appeared to be dominated by (011) and (001) facets on the longitudinal side and small portions of other facets on the ends. The synthesized TiO2 and ZrO2 model catalysts were tested for the dehydration of isopropanol, bio-diols, and triols to probe their acid activities. They were also employed as supports of VOX for the methanol ODH to evaluate the redox activities of the catalysts. A series of microscopic and spectroscopic techniques, such as scanning/transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), Raman and solid state nuclear magnetic resonance (NMR) spectroscopies were utilized to identify the active domains and correlate the structural properties of different facets to the catalytic performance. The key findings from the characterization studies will also be discussed in this talk.
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