Photocatalytic performance of sulfated TiO2 and Degussa P-25 TiO2 during oxidation of organics

Photocatalytic oxidations (PCOs) of heptane, trichloroethylene (TCE), ethanol, acetaldehyde, and toluene were carried out on sulfated TiO2 (SO42−/TiO2) and Degussa P-25. Coverages of all organics on SO42−/TiO2 were significantly higher than on P-25, but P-25 was more active for PCO at room temperature. Pulse PCO at room temperature suggests that steady-state PCO rates of acetaldehyde on the two catalysts may be similar, however. During PCO of heptane at room temperature, SO42−/TiO2 deactivated slower than P-25 so that the CO2 formation rate on P-25 was only 11% greater than that on SO42−/TiO2 after five 110 μmol/g catalyst pulses of heptane. ulse and steady-state PCO of TCE showed that although P-25 was more active than SO42−/TiO2, the CO2 production rate decreased with time on P-25 but not on SO42−/TiO2. Furthermore, CO2 selectivity increased with time as PCO of TCE approached steady-state on SO42−/TiO2, whereas it decreased on P-25. Selectivity to phosgene formation on P-25 was twice that on SO42−/TiO2. ed TiO2 was more active and deactivated more slowly than P-25 during PCO of acetaldehyde above 373 K. Since acetaldehyde is an intermediate for PCO of several organics, SO42−/TiO2 may be preferable to Degussa P-25 for PCO at elevated temperatures.