Preparation, characterization and catalytic activity of sulfated zirconia―silica nanocrystalline catalysts

摘要

Sulfated zirconia―silica (SO_4~(2-)/ZrO_2―SiO_2) precursors were prepared by chemical methods in three steps. The precursors were calcinated at different temperatures to form the SO_4~(2-)/ZrO_2―SiO_2 nanocrystalline catalysts. The reaction conditions were optimized, such as ZrO_2 content, volume ratio of water―ethanol, amount of HNO_3 and reactive temperature and time. The specific surface area, heat stability and structure properties of catalysts were examined by X-ray diffraction (XRD), IR and differential thermal analysis (DTA). The specific surface areas of ZrO_2―SiO_2 and SO_4~(2-)/ZrO_2―SiO_2 are 800 and 400 m~2/g, respectively. They are higher than that of ZrO_2 and SO_4~(2-)/ZrO_2. It was shown that there are very strong interactions between SO_4~(2-) and ZrO_2―SiO_2. The acidic properties of SO_4~(2-)/ZrO_2―SiO_2 were tested by Hammett indicator method. Through the acetic acid (HAc) reaction with glycerin, it was shown that the SO_4~(2-)/ZrO_2―SiO_2 catalyst has highly active sites and high catalytic activity.