Preparation And Characterization Of Mesoporous ZrO₂ And Yttria-stabilized ZrO₂ Spherical Particles By Quasi-gaseous State Reaction

Zirconia is the unique material with both acidic and basic centers, coupled with its good ion-exchange and charge transfer properties. Therefore, Zirconia is an ideal multi-functional catalyst. With the advance on technologies of the preparation and characterization of mesoporous Zirconia, mesoporous Zirconia materials are increasingly applied to abroad areas, for example, photoluminescence materials, catalyst and its carrier, drug delivery, absorption materials for sewage treatment, chromatographic column packing, and so on. In this thesis, using quasi-gaseous state reaction method, mesoporous Zirconia and Yttria-stabilized Zirconia were prepared and characterized by SEM, TEM, XRD, TG/DTA, N2 gas absorption-desorption, laser particle size analyzer, and etc.Firstly, the equipment and process for quasi-gaseous state reaction were improved, which involved making sieve-like holes on the outlet of the feed tube of collector, expanding the diameter of reactor, fixing a vacuum meter on the outlet tube of reactor, sealing the cover of atomizer and adding flow meter before the atomizer, and aging the collected suspensions in the collector. By above improvements, the synthesis reaction conditions and results are becoming stable.Secondly, the optimal synthesis conditions for Zirconia precursor spherical particles were determined by the orthogonal experiment (L1837):WZrOCl2·H2O=30%, QNH3=60L/h, Pvacuum=0.02MPa, Qair/QNH3=1, aging for 72h. The Zirconia precursor particles synthesized using this optimal process are spherical shape with smooth surface, its average size is about 4μm, and there are scarcely hollow spheres present. Moreover, according to orthogonal experimental results, the concentration of Zirconium oxychloride solution is the main factor affecting the results, and effect of the ammonia gas flow and the system vacuum were little relatively.Zirconia powders were obtained via hydrothermal method and calcining precursor spherical particles after dried at room temperature. And Zirconia powders obtained by calcining were better than those obtaining via hydrothermal method, in which the particles were still spherical shape and broken little.Finally, zirconia powder were obtained via calcining spherical particles of the precursor dried at room temperature or hydrothermal method. The results, obtained via calcining spherical particles of the precursor dried at room temperature, were better than obtaining via hydrothermal method, in which the particles were still spherical, and only a few were broken.Finally, through the above optimal preparation conditions for Zirconia, mesoporous Yttria-stabilized Zirconia spherical particles were prepared as well, marked as ZrYO series (1.5mol% Y2O3 doped) and ZrOY series (3mol% Y2O3 doped), respectively. The post-processing method for the ZrO2/Y2O3 precursor utilizes calcining the precursor spherical particles after dried at room temperature. By the characterizations of TG/DTA, XRD, SEM, TEM and nitrogen gas absorption-desorption, it can be concluded that the two series of ZrO2/Y2O3 particles are all spherical shape and hardly any hollow, whose phase compositions are major tetragonal ZrO2 after calcined at 500-1200℃, and BET surface area is around 34.3887 m2/g.