Abstract
The reaction of H2 and O2 to water are studied over a Ag–Pd/TiO2 anatase catalyst, under dark and photo-irradiation conditions in the gas and liquid phases. The catalyst consisted of metal particles of mean size of ca.1 nm dispersed over 10–15 nm TiO2 particles. Kinetic parameters including order of reaction (n), rate constant (k), and activation energy (Ea), were evaluated. Ea for the thermal reaction was found to be 49-47 kJ mol−1. The oxidation reaction rate constant was found to be ca. 3 times higher in the presence of photons when compared to dark reaction at room temperature. The overall quantum yield of the reaction in the slurry phase was found to be 0.09. Considering the number of metal particles on TiO2, the photon yield per metal particle was found to be 0.16. A possible explanation of the changes in kinetics with respect to experimental conditions is given.
•Reaction kinetics of H2 and O2 to water is studied over Ag–Pd/TiO2-anatase.•The study was conducted under dark and photo-irradiation conditions.•The apparent activation for the gas phase thermal reaction was found to be 49 kJ mol−1.•The photoreaction rate constants, and reaction order in the gas and liquid phases were obtained.•The photon yield per metal particle at RT was found to be close to 0.16.