THERMAL-DESTRUCTION OF CHLORINATED HYDROCARBONS BY REDUCTIVE PYROLYSIS

A rigorous thermochemical analysis of the pyrolysis of aromatic chlori des shows that destruction efficiencies in excess of 99.999 percent ar e possible in a reducing atmosphere at temperatures near 1000 K. This process used for the destruction of chlorinated organic ompounds yield s non-halogenated hydrocarbons and hydrochloric acid as reaction produ cts. Qualitative batch experiments on chloromethane and polychlorinate d biphenyls (PCBs) showed that such efficiencies could be obtained in residence times below 7 minutes at 1273 K. Qualitative continuous flow experiments demonstrated that these efficiencies are actually obtaine d in residence times less than 1.8 seconds for chloromethane and 4.4 s econds for the PCB mixture Arochlor 1254. A simple kinetic analysis sh ows that the Aroclor 1254 radicals are produced by the decomposition o f hydrocarbon solvents (n-hexane and iso-octane) used to provide the r educing atmosphere. The difference in residence times between batch an d continuous flow reactors is explained by temperature gradient effect s in batch reactors and the associated beat flux limiting rate phenome non due to endothermic reaction steps.