US Patent 9080056 Process for preparing silica microparticles

Silica core-shell microparticles are prepared by growing a porous silica shell from a silica precursor onto the surface of non-porous silica particle dispersed in a mixed surfactant solution under basic pH conditions. The particles are hydrothermally treating in an oil-in-water emulsion system and the particles are calcined to remove residual surfactants. Optionally, the particles of may be base etched to expand the size of the pores in the silica shell. Core-shell silica particles with an ordered mesoporous layer are produced.