PRODUCTS, INTERMEDIATES, MASS BALANCES, AND REACTION PATHWAYS FOR THEOXIDATION OF TRICHLOROETHYLENE IN AIR VIA HETEROGENEOUS PHOTOCATALYSIS

Studies of the photocatalytic reaction of a solution of trichloroethyl ene in the air and in contact with UV-irradiated titanium dioxide have produced conflicting reports in regard to the composition of the prod uct mixture. This paper resolves these discrepancies by reporting the results of experiments designed to identify and quantify intermediates , products, and reaction pathways. Mass balances are closed in differe ntial and integral modes to ascertain the effects of factors such as t he extent of conversion, feed composition, and photon energy on the co mposition of the product stream. Dichloroacetyl chloride, phosgene, ca rbon dioxide, carbon monoxide, and hydrogen chloride were observed in the effluent of photocatalytic reactors featuring thin films of titani um dioxide catalyst. These observations were made with a gas-phase Fou rier transform infrared spectrometer. The instrument directly samples the effluent from the reactor without splitting or dilution. A direct sampling molecular beam mass spectrometer used in a parallel study has also identified molecular chlorine as a component of the effluent.