Catalytic wet peroxide oxidation of phenol on Fe-ZSM-5/PSSF membrane catalysts: Effect of framework Fe by hydrothermal synthesis

Two kinds of zeolite membrane catalysts, Fe-ZSM-5/PSSF and Fe2O3/ZSM-5/PSSF, were synthesized by hydrothermal method and incipient wetness impregnation method respectively, and tested for catalytic wet peroxide oxidation (CWPO) of phenol in the fixed bed reactor. The paper-like stainless steel fiber (PSSF) were prepared by a combined papermaking and sintering process. Then hydrothermal and impregnation methods were applied to coat Fe-ZSM-5 as well as Fe2O3/ZSM-5 membrane catalyst on PSSF respectively. Framework Fe3+ species on the Fe-ZSM-5/PSSF zeolite membrane catalysts were characterized and tested for phenol oxidation in the fixed bed reactor. In addition, the effects of Si/Fe, temperature and residence time on catalyst performance were investigated. Results showed that Fe-ZSM-5/PSSF with Si/Fe = 120 showed highest activity. Higher temperature and longer residence time can improve the catalytic performance and the existence of the framework Fe3+ species over Fe-ZSM-5/PSSF can enhance the catalytic efficiency of phenol, with phenol conversion of over 99.0% and TOC conversion of 55.6% under condition of 4 cm bed height, 2 mL/min feed flow rate and 80 degrees C. Catalytic activity of Fe-ZSM-5/PSSF was dramatically increased compared to the Fe2O3/ZSM-5/PSSF, indicating the key role of framework Fe3+ played in the CWPO process. Finally, the stability test results showed that a relatively low decrease in activity of Fe-ZSM-5/PSSF (Si/Fe = 120) can be found after three consecutive runs (21 h).