The effect of 1-propanol on structure and hydrothermal stability of MSU-4 silica spheres

Abstract 1-Propanol/water system was employed to prepare MSU-4 silica by using oxyethylene sorbitan monooleate (Tween-80) as structure-directing surfactant and tetraethyl orthosilicate (TEOS) as silica precursor. It was shown that volume content of 1-propanol has great effect on structure and hydrothermal stability of the resulting silica. As the volume content of 1-propanol was in the range of 40–90 vol%, the resulting silica were spherical in shape and their diameter decreased from 2 μm to 500 nm with increased volume content of 1-propanol attributed to the co-solvent effect of 1-propanol. In the range of the volume content from 40 vol% to 60 vol%, 1-propanol also acted as co-surfactant which made the pore size of the silica spheres increase from 2.70 nm to 3.83 nm with increasing the volume content from 40 vol% to 60 vol%. When the volume content was below 40 vol%, 1-propanol only acted as co-surfactant and silica irregular in shape was obtained. MSU-4 silica spheres prepared under the volume content of 40–60 vol% showed higher condensation degree and thus improved hydrothermal stability when 1-proponal acted as both co-surfactant and co-solvent.