High dispersed 10% MoO3/SiO2 catalysts were prepared by the sol–gel method using a precipitant (ammonium hydroxide) with different pH values, and investigated by XRD, FT-IR spectroscopy of pyridine adsorbed and Raman spectroscopy techniques, and so on. The results show that the catalytic performance of MoO3/SiO2 for the epoxidation of propylene with cumene hydroperoxide (CHP) is affected by pH value of precipitant, and MoO3/SiO2 ...