Catalytic wet oxidation of phenol and its derivatives with Fe2O3 and MnO2

Wet oxidation of phenol, 2-chlorophenol, 4-chlorophenol and 2-nitrophenol over iron oxide and manganese dioxide catalysts was tested in this work with or without hydrogen peroxide in the reaction mixture. Influence of factors such as catalyst load, reactant-hydrogen peroxide mole ratio, and reaction time was monitored for all the phenols. Increase in the amount of hydrogen peroxide in the feed composition resulted in a better conversion in all the cases and by using 5 – 10 moles of hydrogen peroxide for each mole of the reactant, conversion was better than 80%. The oxidation reaction was sufficiently fast except in the case of 2-nitrophenol. The wet oxidation could be carried out in air by using either iron oxide or manganese dioxide catalyst without adding hydrogen peroxide to the reaction mixture. The direct oxidation is more effective for 2-chlorophenol and 4-chlorophenol with iron oxide while manganese dioxide was more effective for phenol, 2-chlorophenol and 4-chlorophenol. In both cases, 2-nitrophenol was found to be more resistant to oxidation.