Gas Phase Formation of Chlorinated Aromatic Compounds from the Pyrolysis of Tetrachloroethylene

Abstract

The thermal degradation of tetrachloroethylene (C₂C1₄.,) has been compared to that of ethylene (C₂H₂) using a high-temperature flow reactor system. Kinetic studies were conducted in an oxygen-Tree helium carrier for reaction times of 2,0 s. Exposure temperatures for this reaction time were varied from 300-1050° C. Significant yields of perchlorinatcd olcfinic and aromatic species were observed from C₂C1₄ with similar yields of non-chlorinated aromatic species from C₂H₄. Acetylene (C₂H₄) was the major organic product from C₂H₄ while hexachlorobenzene (C₆Cl₆) was the major organic product from C₂Cl₄. Dichloroacetylene (C₂C1₄) 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.

Key words:

• Tetrachloroethylene
• ethylene
• kinetics
• pyrolysis
• PNAs