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

摘要

CeO 2 /γ-Al 2 O 3 composite catalyst has been prepared using CeO 2 as an active component and γ-Al 2 O 3 as a support to remove dye from wastewater by catalytic degradation. The catalytic performance of the CeO 2 /γ-Al 2 O 3 sample for the degradation of methylene blue is studied under visible light irradiation. The results show the presence of γ -Al 2 O 3 and CeO 2 with a cubic fluorite structure in the CeO 2 /γ-Al 2 O 3 samples synthesized at 550°C. Small CeO 2 /γ-Al 2 O 3 particle and a good dispersion of CeO 2 are achieved with loading of CeO 2 . The loading of CeO 2 on γ-Al 2 O 3 also increases the total pore volume and pore diameter, which results in a high specific surface area of 132.03 m 2 /g, a total pore volume of 0.74 cm 3 /g, and a mean pore diameter of 22.54 nm. The photocatalytic degradation efficiency of methylene blue by the CeO 2 /γ-Al 2 O 3 catalyst is higher than those of CeO 2 and γ-Al 2 O 3 . Under the same conditions the CeO 2 /γ-Al 2 O 3 catalyst achieves 98.36% degradation at 80 min, higher 5.0% and 11.9% degradation than CeO 2 and γ-Al 2 O 3 , respectively. The high efficiency is attributed to promotion of the structural and textural performance of the CeO 2 /γ-Al 2 O 3 catalyst by synergistic interaction between CeO 2 and γ-Al 2 O 3 . 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 k app is 17.5×10 ?2 , which is 1.33 and 2.5 times as big as those of CeO 2 and γ-Al 2 O 3 , respectively. CeO 2 /γ-Al 2 O 3 catalyst suggests promising application for practical dye pollutant treatment.