Preparation of SiO2-TiO2 aerogels using supercritical impregnation

The preparation of SiO2-TiO2 aerogels by supercritical impregnation of tita nium alkoxides into silica alcogels was investigated. A mixture of CO2 and 2-propanol with dissolved titanium tetraisopropoxide modified with acetylac etone was used as the impregnation medium. Prior to the experiments, the su percritical behaviour of the impregnation solution was investigated. The mi crostructure and properties of aerogels prepared by the supercritical impre gnation method were almost identical to those generated by the liquid impre gnation. However, the time for impregnation was substantially decreased and the homogeneity of the impregnated titanium distribution on the aerogel in creased.