Abstract
Silica is introduced into the interlamellar region of the swelling clays by hydrolysis and/or oxidation of tris (acetylacetonato) silicon (IV) cations, Si (acac) 3+, and polychlorosiloxanes, (-SiOCl2-) n. At high temperature (i. e. 620°C), the intercalated silica is available for keeping the layer apart with an (001) spacing of 12.6 Å and N2 BET surface area of around 240 m2/g. The clay intercalated silica swells to higher spacings upon adsorption of water, glycerol and pyridine, but the silica is not expelled from the interlayers when the interlayers swell and contract in successive adsorption/desorption cycles. The intercalated silica does not inhibit the ability of the interlayers for exchange reactions, as judged from Cu2+ binding experiments. Infrared studies of NH3, pyridine and NO2 adsorptions indicate the presence of Brönsted acidity and the absence of Lewis acidity in the interlayer regions. The application of the clay-silica complex is considered for catalyst supports, adsorbents, molecular sieve and so forth.
