Continuous Treatment of Phenol over an Fe2O3/γ-Al2O3 Catalyst in a Fixed-Bed Reactor

Abstract

Fe2O3/γ-Al2O3 catalysts were prepared using the wet impregnation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption. The continuous catalytic wet hydrogen peroxide oxidation of an aqueous phenol solution over Fe2O3/γ-Al2O3 was studied in a fixed-bed reactor. The effects of several factors, such as the weight hourly space velocity (WHSV), particle size, reaction temperature, H2O2 concentration, and initial pH, were studied to optimize the operation conditions for phenol mineralization. For a 1 g L−1 phenolic aqueous solution, the phenol was nearly completely removed and chemical oxygen demand (COD) removal was approximately 92 % at steady-state conditions with a WHSV of 2.4 × 10−2 gPhOH h−1 gcat −1 at 80 °C with 5.1 g L−1 H2O2. The long-term stability of the Fe2O3/γ-Al2O3 catalyst was also investigated for the continuous treatment of phenolic water. The removal of phenol and COD exhibited a slowly decreasing trend, which was primarily due to the complexation of active sites with acid organic compounds and the adsorption of intermediate products. The deposition of organic carbon and Fe leached from the catalyst had a small role in the partial deactivation of the catalyst. The Fe leached from the catalyst partially contributed to the phenol removal during a short run. However, this contribution could be neglected after 36 h because the Fe leached from the catalyst decreased to approximately 5 mg L−1.