Aerosol Route to TiO2–SiO2 Catalysts with Tailored Pore Architecture and High Epoxidation Activity

Herein, we present the aerosol-assisted sol-gel preparation of hierarchically porous TiO2–SiO2 catalysts having a sphere-like shell morphology and a high Ti dispersion. In order to control the porosity at the micro-, meso- and macro- levels, we use the evaporation-induced self assembly (EISA) of a surfactant, possibly combined with polymer beads as hard templates. These catalysts are tested for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant, and their performance is compared to the reference TS-1 zeolite. The high catalytic performance observed with the catalysts prepared by aerosol stems from their high specific surface area, but also from the short diffusion path length generated by the meso-/macro-pore architecture which provide entryways for bulky reactants and products. Besides, these materials can incorporate a higher Ti loading than TS-1 zeolite, while ensuring a good control over the Ti speciation. Thus, the unique features of the aerosol pro-cess – which is also known to be s...