A DETAILED KINETIC-MODEL OF THE HIGH-TEMPERATURE PYROLYSIS OF TETRACHLOROETHENE

Comprehensive product yield determinations from the high-temperature, gas-phase pyrolysis of tetrachloroethene (C2Cl4) using two fused-silic a tubular flow reactors are reported. The effects of reactor surface a rea to volume (S/V) ratio were evaluated by conducting detailed produc t analyses with 0.1-cm i.d. and 1.0-cm i.d. reactors. Under low S/V ra tio, initial decomposition was observed at 1123 K with formation of di chloroacetylene (C2Cl2) and hexachlorobenzene (C6Cl6(cy)). Molecular c hlorine was also observed as a product at higher temperatures. Under h igh S/V ratio, C2Cl4 decomposition was initiated at 973 K. Reaction pr oducts included Cl-2, carbon tetrachloride (CCl4), hexachlorobutadiene (C4Cl6), and C6Cl6(cy). Product yields under low S/V ratio indicated that yields of C6Cl6(cy) were a factor of 4 larger than observed for h igh S/V ratios. A previously published detailed pyrolysis mechanism fo r trichloroethene (C2HCl3) was incorporated into a C2Cl4 pyrolysis mod el to provide predictions of the high-temperature reaction behavior of C2Cl4. The model predictions are in much better agreement with produc t distributions obtained using the 1 cm i.d. reactor versus the 0.1 cm i.d. reactor. Minor revisions of the C2HCl3 model significantly impro ved comparisons with the observed C2Cl4 product distributions without compromising previous agreement with C2HCl3 product distributions. Imp ortant radical-molecule addition reactions leading to C6Cl6(cy) are id entified using sensitivity analysis and production rate calculations.