Effects of supercritical impregnation conditions on the properties of silica-titania aerogels

The preparation of silica-titania aerogel by supercritical impregnation of titanium isopropoxide (TP) or modified with acetylacetone (TPAA) using flow type apparatus was performed. The influence of the physical state of TP/CO2 TPAA/CO2 mixture was investigated. Homogeneous and rapid impregnation on monolithic silica alcogel was achieved using supercritical TP/CO2 or TPAA/CO2 mixtures at the single phase condition (353 K, 20 MPa). Crystallization of impregnated titania using this system was attained by increasing temperature Juring the depressurization process after impregnation. (C) 2001 Elsevier Science B.V. All rights reserved.