Tailored syntheses of nanostructured silicas: Control of particle morphology, particle size and pore size

Ordered mesoporous silicas with spherical morphology and average particle size in the range between 100 nm and 2 μm were synthesised according to two novel routes. Both synthesis routes used tetraethoxysilane, water, alcohol and aqueous ammonia for producing spherical silica beads. The porosity was created by adding two different kinds of pore structure directing agents to the starting solution: one was an n-alkyltrialkoxysilane which was covalently bonded to the silica framework, the other was an n-alkylamine which acted as a nonionic template. After calcination and post treatment the resulting particles showed a specific surface area up to 1000 m² g^-1, a specific pore volume of up to 0.8 cm³g^-1 and an average pore diameter between 2 and 6 nm.