科研之友
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摘要
The reaction between nanometer TiO2 and CCl4 in the presence of oxygen has been studied in order to investigate the potential of nanometer TiO2 as a destructive reagent for chlorinated hydrocarbons. Two kinds of nanometer TiO2 of different size were synthesized. The properties of the destructive adsorption of CCl4 over nanometer TiO2 of about 40 nm in size were compared with that over nanometer TiO2 of about 80 nm in size. The reactivity toward CCl4 of nanometer TiO2 of about 40 nm in size was remarkably higher than that of nanometer TiO2 of about 80 nm in size. The products produced included CO2, COCl2, Cl-2, titanium oxychloride, TiCl4, carbon, CO and HCl. HCl was a major gaseous product. Hydrogen of HCl came from traces of water in the carrier gas and surface OH groups of TiO2. The formation of TiCl4 made the interaction surface renew so that CCl4 could further interact with the bulk of the particles. TiO2 was regenerated through the exchange of chlorine with oxygen at 550degreesC in the carrier gas so that larger quantities of CCl4 are decomposed over nanometer TiO2 in the presence of oxygen. A mechanism has been proposed for the destructive adsorption and desorption of CCl4 over nanometer TiO2 in the presence of oxygen.
