A Study of the Preparation Procedures of Sulfated Zirconia Prepared from Zirconia Gel. The Effect of the pH of the Mother Solution on the Isomerization Activity of n-Pentane

Solid superacids of sulfated zirconia were prepared by the sulfation of zirconia gels, which were obtained from mother solutions with different pH values. The gel precipitated at pH = 8 gave the sulfated zirconia, which showed the highest catalytic activity and selectivity for the skeletal isomerization of n-pentane. The active superacid was obtained with high reproducibility upon heating the mother solution, followed by washing the precipitate with hot water; this preparation procedure provided the oxide of small particle size. The catalytic activity of sulfated zirconia could be estimated from the exothermal peak caused by crystallization of the zirconia gel in DTA.