The thermal stabilization mechanism of silica and effect of preparation conditions on the thermal stability of silica-modified alumina have been investigated by low temperature nitrogen adsorption-desorption, XRD, TEM and 27Al MAS NMR. The results show that the addition of silica is effective in suppressing αphase transformation and therefore, in maintaining large surface area of alumina after heating at elevated temperatures. The stabilization effect of the silica species increases with the rise of silica content, however, the overabundance of silica species weakens its stabilization effect. The preparation conditions influence the thermal stability of alumina and stabilization effect of silica. Employing solgel and supercritical drying methods, silica-doped alumina materials with high thermal stability were prepared using NaAlO2 and water-soluble sodium silicate.
