- The structure of crystalline hydrous zirconias and their methods of formation are described. A mechanism for the hydrolytic polymerization of ZrIV to obtain the several forms of hydrous oxide is presented. The method by which sulfate ion binds to the surface of zirconia particles is explored. It is concluded that the superacidity of sulfated zirconia arises from the presence of isolated bisulfate groups acting in conjunction with strong adjacent Lewis acid sites. Thus, both Brnsted and Lewis acid sites are present in sulfated oxides. 1994.