La_2O_3/Fe_2O_3-CeO_2 Composite Oxide Catalyst and Its Performance

摘要

The La_2O_3/Fe_2O_3-CeO_2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties of La_2O_3/Fe_2O_3-CeO_2 samples was investigated. The results show that the cubic CeO_2 structure can be obtained at 600. The rod-shaped sample prepared by coprecipitation method, displays the highest crystalline and the strongest diffraction peak intensity. The spherical sample is acquired from sol-gel method, while the small granular sample prepared by hydrothermal method tends to aggregate. The maximum specific surface area of the sample prepared by coprecipitation method is 76.21 m~2/g, the minimum specific area of the sample from sol-gel method is 32.66 m~2/g and the maximum pore size is 13.84 nm, while the minimum pore volume and pore size of the sample by hydrothermal method are 0.038 cm~3/g and 3.95 nm respectively. The band gap energy of catalyst samples is in the following order: sample-CP sample-SG sample-HT. The sample obtained by coprecipitation method has the best catalytic degradation performance for methylene blue. Under the excitation of visible light, the degradation rate was 99.58% at 50 minutes, which was higher than those of sol-gel method and hydrothermal method by 5.58% and 9.54% respectively. The catalytic degradation reaction is a first-order kinetic model: ln (c_0/ct) = kt + q_e. The maximum k-value of the sample degradation process obtained by coprecipitation method is 0.074 min~(-1).