THE EFFECT OF PREPARATION METHODS ON THE PROPERTIES OF ZIRCONIA SILICAS

Zirconia/silicas were prepared by three methods, namely complexing-age nt assisted sol-gel, coprecipitation and hydrogel kneading. The relati onship between the preparation methods and properties of the zirconia/ silicas was investigated by X-ray powder diffraction, solid-state magi c angle spinning nuclear magnetic resonance (MAS-NMR), ammonia tempera ture-programmed desorption (TPD) and nitrogen adsorption. Among the th ree methods, the complexing-agent assisted sol-gel method gave the mos t homogeneous zirconia/silicas and the Zr-O-Si bond formation. The spe cific surface area of the zirconia/silicas depended on the complexing agents used in the preparations and the Zr/Si ratios. In contrast, the kneaded zirconia/silicas were relatively heterogeneous and their prop erties did not depend on the Zr/Si ratio. In the dependence of propert ies of zirconia/silicas on the Zr/Si ratio, the coprecipitation zircon ia/silicas are intermediate between the complexing-agent assisted sol- gel and kneaded ones.