Reactions of water vapor or molecular hydrogen with trichloroethylene in a microwave plasma reactor

The reaction of trichloroethylene (C₂HCl₃) with water vapor or molecular hydrogen has been studied in a low-pressure [ca. 5 Torr (0.67 kPa)] microwave plasma tubular flow reactor. The experimental apparatus included feed introduction systems, a microwave plasma reactor, and full product analysis by flame ionization and thermal-conductivity gas chromatography, mass spectrometry, and specific ion or pH detection for hydrogen chloride [HCl]. Conversions of C₂HCl₃ in the range 50 to almost 100% are achieved. Product analyses indicate conversion to HCl, some light hydrocarbons, nonparent chlorocarbons, and soot C_(s). For the H₂O case, carbon monoxide and trace carbon dioxide were produced in place of some light hydrocarbons and C_(s). At least 85 mole % of chlorine (Cl) from the converted parent C₂HCl₃ forms thermodynamically stable HCl at parent conversions of 80% or more. The remaining chlorine was present as nonparent chlorocarbons. Preliminary kinetic analyses were performed. The global reaction in the plasma was found to follow one-half-order kinetic dependence on each of C₂HCl₃ and H₂O or H₂. Elementary plasma reaction mechanisms are presented to account for C₂HCl₃ conversion and the observed product distribution.