Crystallization under supercritical conditions in aerogels

In this work crystallization of organic compounds in silica aerogels is studied. The effect of density and surface properties of silica aerogels on crystallization of a model substance, naphthalene, from supercritical CO2 is investigated. It is shown that the surface properties of aerogels play a significant role in affecting the crystallization process. Loadings up to 55 wt% could be achieved for hydrophilic aerogels whereas hydrophobic aerogels could be loaded with ca. 40 wt% of naphthalene. Naphthalene crystals in the range of 500 nm–2 mm were obtained inside the aerogel matrix depending on the crystallization conditions. The potential of this process as “adsorptive crystallization” is discussed.