Selective Aerobic Oxidation of Aromatic Alcohols Catalyzed by TiO2: An Insight on the Effect of Surface Fluorination
To achieve better activity, TiO2 was modified through surface fluorination using hydrofluoric acid (denoted as HF-TiO2). The photocatalytic activities of the as-prepared HF-TiO2 and pure TiO2 photocatalysts were evaluated for selective aerobic oxidation of benzyl alcohol. Experimental results indicated that without any loss of selectivity (>98%), distinct rate enhancement can be observed on HF-TiO2 comparing to pure TiO2. To optimize the condition of pretreatment, different concentrations of hydrofluoric acid were also used and the optimal concentration was determined to be 2%. Moreover, the dynamics of benzyl alcohol oxidation followed pseudo-first-order kinetic. By ESR technique and experiments adding different captures, the active specie is determined to be O2 while O2.- and H2O2 were byproducts of the reaction. In a word, this study opens a new path to obtain both high selectivity and conversion yield by TiO2 photocatalysis.
Zhenyu Du and X.B Sun
Q. Wang "Selective Aerobic Oxidation of Aromatic Alcohols Catalyzed by TiO2: An Insight on the Effect of Surface Fluorination", Advanced Materials Research, Vols. 113-116, pp. 327-330, 2010