Direct Chlorination of Carbon by Copper Chloride in a Thermal Process

A high concentration of chlorinated organic compounds such as dioxins, PCBs, and chlorobenzenes, etc., has been found in the fly ash of the postcombustion zone in a thermal process, i.e., waste incineration. The behavior of Cu and Cl in model fly ash was studied by using in situ X-ray absorption fine structure and diffraction technique using synchrotron radiation. Copper chloride changed its chemical state during rising temperature. These chemical states of copper played three types of roles: First, a two-step dechlorination at around 300 degrees C (the reduction Of CuCl(2) to CuCl) and 400 degrees C (the oxidation CuCl to CuO) and chlorination of the carbon matrix occurs. Chlorides from reduced copper chloride directly bonded aromatic or aliphatic carbon at the temperature that most of the chlorinated organic compounds formed. Second, catalyzed by CuO and CuCl, carbon gasification is promoted over 250 degrees C. Third, the formation of surface oxygen complexes may be catalyzed by CuCl at 300-350 degrees C. The control of copper may be important to reducing the formation of chlorinated organic compounds.