Mechanisms and Reaction Intermediates for Photocatalytic Oxidation

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Prof. Falconer will study the overall reaction, surface processes, and deactivation mechanisms of gas-phase photocatalytic oxidation (PCO). The focus will be on organic and chlorinated organic environmental contaminants over catalysts illuminated with near-UV light, at near room temperature. Probe reactants will be ethanol, trichloroethylene, and toluene. Photocatalysts will be based on TiO2, Pt/TiO2, and MnO, and will be deposited as 0.5 micron layers on the inside of a Pyrex annular reactor wall illuminated from the outside. The concentration of adsorbed and co-adsorbed organic species at steady state, the fraction of surface sites active for PCO, and the decay of all of the above over time on stream, are to be determined. The influence of supported Pt on the activity, surface chemistry, and deactivation of TiO2, will also be studied. A major goal is to determine the selectivity of the various adsorbed species towards partial or total oxidation, and the conditions needed to control such selectivity. Techniques to be used include: steady state and transient isothermal reaction, steady state and transient 13C isotope tracing, temperature-programmed desorption, oxidation and hydrogenation, and FTIR. The research outcome is of high significance for the elimination of VOC from waste air streams, as well as for the photochemical synthesis of organic intermediates.