Effect of drying conditions on the textural, structural and catalytic properties of Cr/ZrO2–SO4: n-hexane conversion

Abstract

Aerogel and xerogel catalysts based on sulfated zirconia doped with chromium are prepared by sol–gel method. The effects of drying mode and calcination temperature are reflected in the characteristics of the final solids. The addition of chromium to aerogel sulfated zirconia not only provides an important development of the specific surface area from 100 to 213 m2 g−1; but also stabilizes a pure metastable ZrO2 tetragonal phase in a large calcination temperature domain. In addition, the aerogels develop active sulfate groups and preserve them on the surface even at high heating. Those characteristics contribute to the improvement of catalytic performances of sulfated zirconia in n-hexane conversion. However, in the case of xerogels, the increase of temperature treatment leads to the loss of sulfate active groups and porosity destruction which make them completely inactive in spite of the development of ZrO2 tetragonal phase.