pH control of the structure, composition, and catalytic activity of sulfated zirconia

We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to � 2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to � 80 m 2 /g) and simultaneously to decrease in sulfate content and total acidity of