Preparation of a CeO2/γ-Al2O3 composite and its catalytic degradation performance

Abstract

CeO₂/γ-Al₂O₃ composite catalyst has been prepared using CeO₂ as an active component and γ-Al₂O₃ as a support to remove dye from wastewater by catalytic degradation. The catalytic performance of the CeO₂/γ-Al₂O₃ sample for the degradation of methylene blue is studied under visible light irradiation. The results show the presence of <em>γ</em>-Al₂O₃ and CeO₂ with a cubic fluorite structure in the CeO₂/γ-Al₂O₃ samples synthesized at 550°C. Small CeO₂/γ-Al₂O₃ particle and a good dispersion of CeO₂ are achieved with loading of CeO₂. The loading of CeO₂ on γ-Al₂O₃ also increases the total pore volume and pore diameter, which results in a high specific surface area of 132.03 m²/g, a total pore volume of 0.74 cm³/g, and a mean pore diameter of 22.54 nm. The photocatalytic degradation efficiency of methylene blue by the CeO₂/γ-Al₂O₃ catalyst is higher than those of CeO₂ and γ-Al₂O₃. Under the same conditions the CeO₂/γ-Al₂O₃ catalyst achieves 98.36% degradation at 80 min, higher 5.0% and 11.9% degradation than CeO₂and γ-Al₂O₃, respectively. The high efficiency is attributed to promotion of the structural and textural performance of the CeO₂/γ-Al₂O₃ catalyst by synergistic interaction between CeO₂ and γ-Al₂O₃. These performances promote a larger surface area, higher content of acid sites, more •OH radicals and higher redox properties of the catalyst. The catalytic reaction kinetics could be fitted by the heterogeneous Langmuir-Hinshelwood model and the pseudo-first order rated constant for <em>k_app</em> is 17.5×10⁻², which is 1.33 and 2.5 times as big as those of CeO₂ and γ-Al₂O₃, respectively. CeO₂/γ-Al₂O₃ catalyst suggests promising application for practical dye pollutant treatment.