Preparation of SO_4~(2-)/TiO_2-WO_3 solid superacid and its catalytic activity in acetalation and ketalation

摘要

SO_4~(2-)/TiO_2-WO_3 was prepared and its catalytic activity under different synthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions are found that the mass fraction of H_2WO_4 used in the compound is 12.5 percent, the calcination temperature is 580 deg C, the calcination time is 3 h, and the soaked consistency of H_2SO_4 is 1.0 mol centre dot L~(-1). Then SO_4~(2-)/TiO_2-WO_3 was applied as the catalyst in the catalytic synthesis of eight similar important ketals and acetals under the optimum conditions and revealed high catalytic activity. On condition that the molar ratio of aldehyde/ketone to glycol is 1:1.5, the mass fraction of the catalyst used in the reactants is 0.5 percent, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 64.2 percent-95.1 percent. Moreover, it can be easily recovered and reused.