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Preparation, Characterization and Photothermo-catalytic Property of Nanostructured CeO2

Author: SunQian
Tutor: LiYuanZhi；WanChaoHui
School: Wuhan University of Technology
Course: Inorganic non-metallic materials
Keywords: CeO2 The light heat collaborative catalytic Lattice oxygen Oxygen ion conductivity
CLC: O643.36
Type: Master's thesis
Year: 2011
Downloads: 91
Quote: 0
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Abstract


Currently, volatile organic compounds has caused serious environmental pollution. Governance of volatile organic compounds has become a hot research, they are not only great harm to human health, but also caused serious environmental pollution, Ce02 beginning to receive attention as a new photocatalytic materials. This article was prepared by a nano Ce02 catalyst, analysis and characterization using XRD, XPS, BET, TEM, UV-visible absorption, photocurrent and AC impedance test means to study the performance of the catalyst nano Ce02 catalytic degradation of VOCs, The main contents and conclusions are as follows: urea and Ce (NO3) 3.6 H2O as raw materials, prepared mesoporous nanorods Ce02 microwave hydrolysis, the specific surface area of ??up to 121 m2 / g, an average pore size of 3nm; XRD shows nano-Ce02 pure fluorite cubic structures, the average grain size of 7nm. Compared with massive Ce02, the absorption band edge of the nano rod-like mesoporous Ce02 significantly redshift, its band gap is reduced to 2.75 eV, the reason is the presence of Ce3 the nanorods mesoporous Ce02. , The nanorods mesoporous the the Ce02 exhibit significant synergistic catalysis photothermal purification performance, benzene photothermal synergistic catalytic rate (240 ° C = Kptc 6.9 × 10-2min-1 is compared with the simple light catalytic and thermal catalytic hot catalytic (240 ° C, ktc = 1.1 × 10-2min-1) of 6-fold, is light catalytic (kpc = 7.5 × 10-3min-1) of 9 times, is thermo-catalytic and photocatalytic's and ktc Kpc = 1.85 × 10-2 min-1) 3.7 times. Nanorods mesoporous Ce02 is also efficient catalytic degradation of toluene, cyclohexane, acetone and other volatile organic contaminants; Meanwhile, the nano rod-like mesoporous the Ce02 having excellent thermal catalytic stability, after 30 cycles of use, still the ability to effectively degrade benzene. Nano photothermal synergistic catalytic reaction Ce02 follow Mars-van Krevelen redox cycle mechanism, namely: the lattice oxygen and benzene molecules in the nano-Ce02 the reaction C02 and Ce02-X, generated Ce02_X and oxidized to oxygen molecules in the air CE02, in order to achieve catalytic cycle of CeO2/CeO2-x. Photothermal synergistic catalytic reaction conditions under optical excitation nanometer CeO2 holes and electrons, the photo-generated electron and oxygen adsorption on the nano-Ce02 formation of reactive oxygen species (O2-), photogenerated holes nano Ce02 lattice oxygen bondage. Bound photogenerated holes of the oxygen ion migration, and to reduce the complex between the hole and electron. Because the oxygen ion conductivity increases with increasing temperature, so photogenerated holes and electrons between separation efficiency increased with increasing temperature, thereby improving the catalytic efficiency. In addition, different from the thermal catalytic photothermal synergistic catalysis under the reaction conditions, the high-pressure mercury light irradiation can improve the lattice with benzene molecule reactive nano Ce02, such as: in the high purity argon atmosphere and 240 ° C under the conditions of a high pressure mercury light irradiation, benzene is nano Ce02 lattice oxygen in the oxidation the C02 amount of light exposure of 4.16 mg / g-catalyst increased to 4.72 mg / g-catalyst; same time, nano Ce02 lattice oxygen reacts with benzene The oxygen in the air molecules and active oxygen generated Ce02_X simultaneously oxidized to Ce02, the accelerated CeO2/CeO2-x catalytic cycle, thereby further improving the catalytic efficiency of the nano-Ce02.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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