Investigation and characterization of silica-alumina aerogels

摘要

Three silica and silica-aumina aerogels have been prepared. One of these aerogels, prepared by complexing the alumina precursor before adding to the silica precursor solution, showed on OH band at 3610 cm~-1 often attributed to strong Bronsted acid sites. However, in this work the band is due to a stretching band from adsorbed water. Surprisingly, adsorption of ammonia onto the surface showed that ammonia dissociated to NH_4~+ and N_2~-_2. Therefore, acid/base sites are present. Finally, catalytic acitvity was found for the oligomerization of propene.