Effect of CeO_2 doping on catalytic activity of Fe_2O_3/γ-Al_2O_3 catalyst for catalytic wet peroxide oxidation of azo dyes

摘要

In order to find a catalyst with high activity and stability for catalytic wet peroxide oxidation (CWPO) process under normal condition, with Fe_2O_3/γ-Al_2O_3 and Fe_2O_3-CeO_2/γ-Al_2O_3 catalysts prepared by impregnation method, the effect of CeO_2 doping on the structure and catalytic activity of Fe_2O_3/γ-Al_2O_3 for catalytic wet peroxide oxidation of azo dyes at 25℃ and atmospheric pressure is evaluated using BET, SEM, XRF, XRD, XPS and chemical analysis techniques, and test results show that, better dispersion and smaller size of Fe_2O_3 crystal can be achieved by adding CeO_2, and the content of chemisorbed oxygen can also be increased on the surface of catalyst. CWPO experimental results indicate that azo dyes in simulated wastewater can be efficiently mineralized and the catalytic activity of Fe_2O_3-CeO_2/γ-Al_2O_3 can be increased by about 10% compared with that of Fe_2O_3/γ-Al_2O_3 because of the promotion of the structural and redox properties of the ferric oxide by ceria doped. Leaching tests indicate that Fe_2O_3/γ-Al_2O_3 and Fe_2O_3-CeO_2/γ-Al_2O_3 are stable with a negligible amount of irons found in the aqueous solution after reaction for 2h. It can therefore be concluded from results and discussion that in comparison with Fe_2O_3/γ-Al_2O_3, Fe_2O_3-CeO_2/γ-Al_2O_3 is a suitable catalyst, which can effectively degrade contaminants at normal temperature and atmospheric pressure.