A new method to prepare silica- or alumina-supported sulfated zirconia

Zirconium sulfate that has been calcined at high temperature is very active for hexane conversion. Interaction between tetragonal zirconia and the retained sulfate ions forms the active sites for hexane conversion. The optimum temperature for the formation of active sites is 750 degrees C but the efficiency for the formation of tetragonal zirconia at that temperature is very low. On silica or alumina surface, zirconium sulfate disperses up to a capacity of 1.2 g/g (0.26 g/100 m(2)) or 0.9 g/g (0.42 g/100 m(2)), respectively. The decomposition of dispersed zirconium sulfate is enhanced. On calcination at 750 degrees C, the dispersed zirconium sulfate decomposes completely to tetragonal zirconia. Supporting also promotes the retention of sulfate ions. Larger amounts of tetragonal zirconia and retained sulfate ions lead to the higher activity of supported materials for hexane conversion. The optimum zirconium sulfate loadings are equivalent to its apparent dispersion thresholds. (C) 1998 Elsevier Science B.V. All rights reserved.