Abstract:

Fe2O3, heteropoly salt and Fe/ZrO2 exhibited high catalytic activity toward phenol hydroxylation using H2O2 as oxidant. A rapid hydroxylation of phenol was observed after an induction period in the hydroxylation of phenol catalyzed by Fe2O3; however, a slow hydroxylation of phenol was observed and the induction period disappeared in the same system catalyzed by heteropoly salt or Fe/ZrO2. The results suggest that, first, an induction period in hydroxylation of phenol is related to the formation of active species Fe3+ and Fe2+ from Fe2O3; and second, the slow hydroxylation is related to the surface catalysis reaction on heteropoly salt or Fe/ZrO2, leading to the disappearance of the induction period.

Key words: phenol hydroxylation, Fe2O3, induction period, heteropoly acidic salt, ·OH free radical