Preparation and properties of ultrafine SO42-/ZrO2 superacid catalysts

Ultrafine SO42-/ZrO2 superacid catalysts were prepared in a two-step synthesis by impregnating ultrafine crystalline ZrO2 with sulfuric acid. Ultrafine crystalline zirconia was obtained by supercritical drying of an alcogel. The crystallization, crystal size, surface area, sulfur content, acid strength and catalytic activity for n-butane isomerization of sulfated amorphous and ultrafine crystalline zirconia were tested and compared. The catalyst prepared from ultrafine crystalline zirconia has smaller crystallite size, larger surface area, greater sulfur content and higher superacidity. Hence, it displays higher catalytic activity and stability for n-butane isomerization.