Preparation of solid superacid S2O82−/TiO2–exfoliated graphite (EG) and its catalytic performance

S2O82−/TiO2–exfoliated graphite (EG) solid acid catalysts were prepared by a sol–gel method using Ti(OCH2CH2CH2CH3)4 and (NH4)2S2O8 as raw materials, as well as EG as support. The structure of the composite samples was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectrometry, and Fourier-transform infrared spectroscopy. The results demonstrate TiO2 anatase to be closely coated on the surface of exfoliated graphite. The effects of calcination temperature on the acidity, texture, and catalytic performance of S2O82−/TiO2–EG solid acid catalysts were further studied. Factors influencing the synthesis of acetalation were discussed, and the optimum reaction conditions were confirmed. Experimental results show that the yield of benzaldehyde glycol acetal was about 98.8% under the following conditions: molar ratio of benzaldehyde to glycol of 1:1.5, catalyst quantity of 0.5% of feedstock, and reaction time of 50 min.