Microwave-assisted sol–gel process for production of spherical mesoporous silica materials

Spherical mesoporous SiO2 and SiO2–TiO2 particles were synthesized by sol–gel method using W/O emulsion under microwave irradiation. In SiO2 system, W/O emulsion was prepared by mixing partially hydrolyzed Si(OC2H5)4 aqueous solution including C18TAC as template with n-hexane solution including polyglycerol polyricinalate as emulsifier. In SiO2–TiO2 system, Ti(OC2H5)4 capped by acetylacetone was added to the aqueous phase. In both cases, spherical products were synthesized by heating of W/O emulsion for 30 min under microwave irradiation. The specific surface area and pore size of spherical products were 800 m2/g and 1.6 nm, respectively, which indicates that the spherical products are mesoporous. These results suggest that sol–gel reaction in water phase proceeds rapidly because microwave quickly and selectively heats up the aqueous solution.