Stability and deactivation of Fe-ZSM-5 zeolite catalyst for catalytic wet peroxide oxidation of phenol in a membrane reactor

Abstract

Stability and deactivation of Fe-ZSM-5 zeolite catalyst for catalytic wet peroxide oxidation (CWPO) of phenol were studied in a membrane reactor. Firstly, the Fe-ZSM-5 zeolite membrane catalyst was prepared by a paper-making/sintering process, secondary growth process and incipient wetness impregnation method. And the influence of residence time on the CWPO of phenol was evaluated by modifying the catalyst bed height. Then, stability of the Fe-ZSM-5 zeolite membrane catalyst was studied by the long-term experiment (40 hours). Finally, the deactivation mechanisms of the Fe-ZSM-5 zeolite membrane catalyst were investigated by N₂ adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermal gravimetric (TG) analysis, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, respectively. The results of CWPO of phenol showed that complete phenol conversion with a high TOC conversion (about 60%) was obtained at the catalyst bed height of 4 cm. Meanwhile, good stability with low Fe leaching concentration (about 0.5 mg L⁻¹) and high phenol conversion (above 85%) were obtained after continuously running for 40 hours. Furthermore, the loss of active component, the partial phase change of Fe₂O₃, the crystallinity change of the ZSM-5 zeolite membrane and the coke formation on the surface of the catalyst were found to be responsible for the deactivation of the catalyst.