Novel silica-based adsorbents with activated carbon structure

Abstract

The preparation of silica adsorbances from chemical vapor infiltration of activated carbon with tetramethylsilane (TMS) is shown. The method bases on a two step process. In a first step, activated carbons are infiltrated at 943 K in a nitrogen-TMS-vapor atmosphere of 200 mbar. At these conditions, the carbon skeleton is covered with silicon. The resulting material is highly porous and well adapting the surface structure of the carbon templates. It is already partly oxidized at room temperature when coming into contact with air. In a second step, the infiltrated carbons are completely oxidized in air at 853 K. At these conditions, the supporting carbon skeleton is completely burned and the silicon becomes silicon oxide. The resulting materials are highly porous with extremely large surface areas around 835 m2/g. Overall, the novel material seems to well adapt the original macro- and microstructure of the activated carbon used.