Effect of Zr/Si molar ratio and sulfation on structural and catalytic properties of ZrO2–SiO2 mixed oxides

Abstract

ZrO2–SiO2 mixed xerogel and aerogel samples with varied molar ratios were prepared by sol–gel method followed by oven drying and supercritical drying using n-propanol as a solvent, respectively. Sulfation was carried out to further enhance the acidic properties of the mixed oxides. Effect of drying, Zr/Si molar ratio and sulfation have been studied and correlated with the structural, textural and catalytic properties of ZrO2–SiO2 mixed oxides. Both xerogel and aerogel mixed oxides have different structural and textural features, however, the total number of acid sites per unit surface area (0.0021–0.0029 mmol NH3 m−2) and thus the catalytic activity for cyclohexanol conversion (31–41%) was found in the similar range. Sulfated mixed oxide aerogel and xerogel samples showed significant enhancement of cyclohexanol conversion (91–99%).