Synthesis of borneol from α-pinene catalyzed by a SO42−/TiO2–La3+ nanometer rare-earth solid superacid

Abstract

ABSTRACTThe SO42−/TiO2–La3+ solid superacids were prepared by the impregnation method. The structure, acidity strength, acid property, and morphology of catalysts were characterized by TEM, XRD, XPS, NH3-TPD, Py-IR, and TG. The optimum synthesis conditions were obtained as follows: calcination temperature at 500°C, 0.998 mol/L La3+ content, a dosage of catalyst 6%, reaction temperature at 80°C, reaction time 7 h, and n (α-pinene):n (oxalic acid) = 1:0.4. Under the optimal condition, the solid superacid SO42−/TiO2–La3+ catalyst showed the best catalytic performance. α-pinene was completely converted, and borneol exhibited a higher selectivity (62.60%). In addition, the solid superacid SO42−/TiO2–La3+ catalyst also showed a high-stability aspect during the recycled reaction.