Destructive Adsorption of Chlorinated Hydrocarbons on Ultrafine (Nanoscale) Particles of Calcium Oxide. 2

As a one-step approach to the safe destruction of chlorocarbons, the reaction of carbon tetrachloride with ultrafine particles of calcium oxide to give calcium chloride and carbon dioxide (CCl 4 (g) + 2CaO(s) → CO 2 (g) + 2CaCl 2 (s)) has been studied in detail. Calcium oxide prepared by an aerogel/hypercrytical drying method (AP−CaO) is superior to a conventionally prepared (CP−CaO) sample, and both are vastly superior to commercial CaO (CM−CaO). Optimum temperature for this gas−solid reaction is 450 °C, although AP−CaO reacted with reasonably high capacity as low as 300 °C. The effects of surface −OH, added water, CCl 4 pressure, and a wide range of temperatures are discussed. Conditions for the suppression of byproducts C 2 Cl 4 and Cl 2 CO are presented. Morphological changes in the particles after CCl 4 reaction were studied by atomic force microscopy. A wide range of other techniques have been applied toward complete characterization of the process and products, including FT-IR, pulsed U-tube reaction studies, gravimetric adsorption, X-ray diffraction, and GC-MS.