| Trichloroethylene in air reacts when in contact with a semiconductor catalyst irradiated with ultraviolet photons. The catalyst used in this investigation was the anatase form of titanium dioxide. This process is referred to as gas-solid heterogeneous photocatalysis.; A laboratory scale kinetic apparatus was constructed at the National Renewable Energy Laboratory in Golden, Colorado, where the experiments were performed. The principal photocatalytic reactors had annular geometries, and the catalyst was applied to the inside surface of the outer cylinder in a thin film. Ultraviolet photons were supplied by fluorescent black light lamps and low pressure mercury arc lamps, which formed the inner cylinder of the annular photocatalytic reactors.; Dichloroacetyl chloride, phosgene, carbon dioxide, carbon monoxide, and hydrogen chloride were observed in the effluent of the photocatalytic reactors. These compounds were identified and quantified with a gas-phase Fourier transform infrared spectrometer. The instrument directly samples the effluent from the photocatalytic reactor without splitting or dilution. Molecular chlorine is also a component of the effluent mixture.; The stoichiometry of the reaction was explored and two reaction pathways are proposed. The rate of mass transport, relative to the rate of the surface reaction, defined two distinct operating regimes; a mass transport limited regime and a surface reaction limited regime. Kinetic parameters were measured, and a kinetic model is proposed that predicts the reaction rate and the effluent partial pressures of reactant and intermediate as a function of the feed partial pressure and the residence time within the photocatalytic reactor.; Differential and integral data have been collected and analyzed to ascertain the effect of ultraviolet light wavelength and intensity, water vapor partial pressure, oxygen partial pressure, and extent of conversion. Finally, the reactions of similar compounds studied within the context of this investigation are discussed. |
