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 (CCl4(g) + 2CaO(s) --> CO2(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 degrees C, although AP-CaO reacted with reasonably high capacity as low as 300 degrees C. The effects of surface -OH, added water, CCl4 pressure, and a wide range of temperatures are discussed. Conditions for the suppression of by products C2Cl4 and Cl2CO are presented. Morphological changes in the particles after CCl4 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.