The effect of Au on TiO2 catalyzed selective photocatalytic oxidation of cyclohexane

Gold does not induce visible light activity of anatase Hombikat UV100 in the selective photo-oxidation of cyclohexane, as can be concluded from in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurements. Extremely small conductance values measured at 530 nm in Time Resolved Microwave Conductivity (TRMC) experiments are in agreement with this conclusion. Upon UV activation, gold enhances the initial rate of formation of surface adsorbed cyclohexanone, but is detrimental to the overall production rate determined in a conventional top illuminated slurry reactor. The latter is the result of strongly modified surface properties of TiO2 by gold deposition, affecting the adsorption/desorption equilibrium of cyclohexanone.