Efficient catalytic wet peroxide oxidation of phenol at moderate temperature using a high-load supported copper catalyst

The use of hydrogen peroxide as the oxidizing agent in the presence of a catalyst (Catalytic Wet Peroxide Oxidation, CWPO) has emerged as a clean and effective alternative among other catalytic oxidation processes. The objective of this study is to evaluate the CWPO of phenol solutions using a high-load CuO/Al2O3 catalyst, which allows maintaining a high activity and efficiency compared to homogeneous copper, also overcoming secondary effluent contamination.The catalytic oxidation of aqueous phenol solutions using H2O2 as oxidizing agent and a home-made CuO/Al2O3 catalyst was studied in a batchwise slurry reactor. The applied H2O2:phenol molar ratio was only nearly 30% higher than the stoichiometric ratio. Experiments were performed at temperatures between 303 and 343 K using different catalyst loads. Phenol disappearance and TOC reduction were monitored throughout the reaction time.Both phenol and TOC conversions were larger as temperature and catalyst load increased, following the higher hydrogen peroxide decomposition rates achieved. At the highest catalyst load and temperature, complete phenol conversion and ca. 80% TOC removal was achieved. Catalyst performance in terms of phenol and TOC disappearance was maintained after 12 h of usage. Although there is evidence of some copper leaching from the catalyst, the homogeneous contribution to the overall activity is marginal.

► The CuO/γ-Al2O3 catalyst gave complete phenol conversion and 85% TOC reduction.
► High peroxide efficiency achieved with concentrations close to stoichiometric.
► Catalyst used in consecutive runs yields similar performance.