Supercritical drying, aerogel synthesis

Sol-gel synthesis conditions, supercritical drying conditions, catalytic activity in bcnzylation of benzene, surface area and overall pore volumes of xerogcl and aerogel catalyst are shown in Table 3. 

Silica and, to a less extent, alumina aerogels are detailed below because most of the catalytic aerogels are silica- or alumina-based composites. As mentioned in the Abstract section, the synthesis of an aerogel results from a two-step process First, a solution-to-sol-to-gel is prepared, and second, this gel is supercritically dried in an autoclave. 

Suh D J, Park T J (2002) Synthesis of high-surface-area zirconia aerogels with a well-developed mesoporous texture using CO2 supercritical drying. Chem Mater 14 1452-1954... 

Bedilo A F, Klabunde K J (1997) Synthesis of high surface area zirconia aerogels using high temperature supercritical drying. J Nano Mater 8 119-135... 

The silica aerogel investigated was a one-step base-catalyzed supercritically dried silica gel (TMOS). For details of the synthesis see e.g. references [5,6]. To increase the stiffiiess of the as-prepared sample and thus to avoid a significant volume change due to capillary forces [2] we sintered the silica aerogel to a density of about 0.29 g/cm (initial density 0.26 g/cm ). 

For a more extensive analysis of aerogel synthesis and recent developments, readers are recommended to refer to Ref. [41]. In addition. Ref. [15] may be referred to for a recent life cycle assessment (LCA) of transparent aerogel made by supercritical drying. 

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