Catalytic wet peroxide oxidation of phenol over Fe2O3/MCM-41 in a fixed bed reactor

•TOC conversion reached 72.5% and Fe leaching concentration was 0.01 mg/L over Fe2O3/MCM-41 in the CPWO of phenol.•The reaction mechanism of the CWPO for the phenol in fixed bed reactor was investigated.•The intermediates were nearly 0 mg/L when the catalyst bed height was over 2 cm.

Iron-containing (10 w/w%) MCM-41 catalysts were prepared and tested for catalytic wet peroxide oxidation (CWPO) of phenol aqueous solutions in a fixed bed reactor. First, Fe2O3/MCM-41 catalysts were prepared by incipient wetness impregnation and characterized by using X-ray diffraction (XRD), N2 adsorption-desorption and X-ray photoelectron spectra (XPS), respectively. Second, the effect of temperature, catalyst bed height and feed flow rate on phenol mineralization, hydrogen peroxide and total organic carbon (TOC) conversions were studied to determine the optimum condition. Moreover, Fe leaching concentration was detected to study the stability of the Fe2O3/MCM-41 catalyst. Finally, the evolution of intermediates was monitored to investigate the probable reaction mechanism of phenol oxidation over Fe2O3/MCM-41 catalyst in the fixed bed reactor. The experimental results showed that the conversion of TOC reached 72.5% and few Fe (0.01 mg/L) was detected under optimum condition (namely, feed flow rate of 2.0 ml/min, temperature of 80 °C, catalyst bed height of 4 cm). The probable multistep reaction route for oxidative destruction of phenol over Fe2O3/MCM-41 catalyst in a fixed bed reactor is based on hydroxyl radical reacting with phenol, resulted in aromatics such as catechol and hydroquinone, and p-benzoquinone, followed by evolution to carboxylic acids and finally completing oxidation to carbon dioxide and water. Few intermediate products were detected in the treated effluent when the catalyst bed height was higher than 2 cm.

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