Synthesis of nanometer-sized mesoporous silica and alumina spheres

Mesoporous silica and alumina spheres with a few hundred nanometer-sized have been synthesized in the presence of the organic solvent with aqueous ammonia as the morphological catalyst. Mesoporous silica spheres templated by the cationic surfactant cetyltrimethylammonium bromide (CTAB) show hexagonal mesostructure with monodispersed pore sizes (∼ 2.4 nm) and high surface areas (∼ 1020 m²/g) similar to MCM-41. The diameter sizes (80-800 nm) of the silica spheres can be tunable by changing the ratio of water to N,N-dimethylformamide (DMF) and ammonia concentration in the solution. A large pore mesoporous alumina sphere templated by amphophilic triblock copolymer has nanometer size range of 100-900 nm and is thermally stable. Calcined alumina sphere shows disordered mesoporous arrays with pore size of 10 nm and high surface areas (∼ 360 m²/g).