Preparation of Cu-ZSM-5 catalysts by chemical vapour deposition for catalytic wet peroxide oxidation of phenol in a fixed bed reactor

Abstract

Cu-ZSM-5 catalysts were prepared by chemical vapour deposition for catalytic wet peroxide oxidation (CWPO) of phenol in a fixed bed reactor. Firstly, Cu-ZSM-5 catalysts with Cu loading of 0.5, 2, and 6 wt% were prepared and characterized by X-ray diffraction (XRD), N2 adsorption– desorption and X-ray photoelectron spectra (XPS). The characterization results demonstrated that CuO was uniformly dispersed on ZSM-5 with slight effect on the structure properties of the support. Then, several variables, such as the copper loading, reaction temperature, catalyst bed height and feed flow rate were investigated in the CWPO of phenol in aqueous solution at high concentration (1000 ppm). Compared with the catalyst prepared by the impregnation method, the Cu-ZSM-5 prepared by chemical vapour deposition has a better capacity of further oxidizing the intermediate organic products into carbon dioxide and water with less metal loading. Based on the Cu-ZSM-5 catalyst with Cu loading of 6 wt%, complete removal of phenol and a high TOC reduction (around 70%) have been achieved at the temperature of 80°C feed flow rate of 2 ml min−1 and catalyst bed height of 3 cm. Moreover, this catalyst maintained high catalytic activity after three runs with high phenol conversion (94%) under this optimum operating condition. Finally, the reaction mechanism was studied based on the intermediates detected by high-performance liquid chromatography (HPLC).