GAS-PHASE FORMATION OF CHLORINATED AROMATIC-COMPOUNDS FROM THE PYROLYSIS OF TETRACHLOROETHYLENE

The thermal degradation of tetrachloroethylene (C2C14) has been compared to that of ethylene (C2H4) using a high-temperature flow reactor system. Kinetic studies were conducted in an oxygen-free helium carrier for reaction times of 2.0 s. Exposure temperatures for this reaction time were varied from 300-1050° C. Significant yields of perchlorinated olcfinic and aromatic species were observed from C2Cl4with similar yields of non-chlorinated aromatic species from C2H4. Acetylene (C2H:) was the major organic product from C2H4while hexachlorobenzene (C6Cl6) was the major organic product from C2C14. Dichloroacetylene (C2C12) was not observed from C2C14, which is attributed to a rapid polymerization pathway. Chlorine atom displacement reactions involving perchlorinated olefinic radical attack on per-chlorinated olefins and acetylenes are proposed as key steps in molecular growth pathways. This study has demonstrated that C2CI4has a propensity for formation of higher molecular weight aromatic species that is similar to that of its non-chlorinated analogue, C2H4. Chemically activated pathways involving Cl displacement and cyclization reactions are implied. Although the exact species which are involved cannot. © 1990, Taylor & Francis Group, LLC. All rights reserved.