Effects of preparation procedure in sol–gel method on performance of MoO3/SiO2 catalyst for liquid phase epoxidation of propylene with cumene hydroperoxide

Abstract

The 15% MoO3/SiO2 catalysts were synthesized by a modified base-catalyzed sol–gel method and characterized by Raman, XRD, FT-IR, UV–vis, NH3-TPD and ICP. The catalytic performance of MoO3/SiO2 for the liquid phase epoxidation of propylene with cumene hydroperoxide (CHP) and the effects of preparation procedure on its physicochemical and catalytic properties were studied. The results show that, in the processes of preparing catalyst, the solvent of ammonium heptamolybdate and the sequence of feeding would affect the existing states of molybdenum species on silica support significantly. When 1,2-propanediol was used as the solvent and an appropriate sequence of feeding was adopted, the β-MoO3 species and monomeric molybdenum species can form on silica to make for the promotion of MoO3/SiO2 catalyst. Without any depressor in the reaction system, at 80°C and 2.2MPa for 4h, the conversion of CHP is above 99% and the selectivity to PO reaches 85.3%.