Synthesis of ZrO₂ and ZrO₂-Al₂O₃ nanocomposites and their characterization

The advances in nanotechnology have led to an increasing demand for multifunctional materials. Highly ordered mesoporous materials function as excellent catalysts due to high surface areas and surface functionalities. These materials in particular, with high surface area and tunable pore structure has attracted much attention. The development of new solid acid catalyst has been essential in terms of replacing conventional homogenous catalysts, which are not only harmful to environment, but also a problem for separation. A number of solid acids have been examined, Zirconia is one of them. ZrO₂ and its nanocomposite solid acid, and its supported metal oxides are potential candidates for replacing conventional mineral acids, which are harmful to the environment. Zirconia and its composites with alumina (10 - 80 wt %) were prepared via sol gel and alkali method. A comparative study was done. The acidity of the material was determined by NH₃ - TPD. The FT-IR pyridine adsorption identified the presence of different acidic surface sites. The thermal analysis (TG-DTA) of the precursors were performed to determine the decomposition temperature. SEM images showed the morphology of the nanocomposites. The XRD studies were also done, it proves to be an important tool for identification of the tetragonal, monoclinic crystallite phases of ZrO₂ and gamma alumina. The BET surface area of the material was measured at liquid N₂ temperature and isotherm studies were carried out. ZrO₂- Al₂O₃ nanocomposites could be tested for various alcohol dehydration reactions, alcohol decomposition and esterification reactions. (author)