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Functional Carbonaceous Materials Combined with Photocatalysis/Thermal Catalysis for VOCs Removal Obtained Via Sol-Gel Method

Author: SunJian
Tutor: LiuShouXin
School: Northeast Forestry University
Course: Forest Chemical Process Engineering
Keywords: Titanium dioxide Activated carbon fiber Rare earth doped Toluene Removal
CLC: TB34
Type: Master's thesis
Year: 2010
Downloads: 86
Quote: 1
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Abstract

With economic development and social progress, the indoor air pollution caused by volatile organic compounds VOCs (Volatile organic compounds) has caused widespread concern. Most indoor volatile organic compounds are toxic, environmental protection organizations have confirmed that the quality of indoor air quality is one of the important factors that affect human health. These VOCs include formaldehyde, benzene, toluene, lower alcohols, ketones, chlorinated organics, mainly from paints, coatings, solvents, preservatives, air fresheners and disinfectants. More than 20 species of which can directly damage and even cancer, such as formaldehyde, benzene and BTEX and organic peroxides. Catalytic heterogeneous photocatalytic TiO2 in the field of environmental protection, water and gas phase organic and inorganic pollutants photocatalytic removal has made great progress, and is considered a highly promising deep purification technology for environmental pollution. Adsorption material such as activated carbon adsorption purification technology is widely used, but due to the advantages and disadvantages of each combination of the two will be one of the most promising technologies in indoor air purification. In recent years people more and more emphasis on precious metals thermal catalysis, precious metals in cryogenic thermal catalytic oxidation of CO and VOCs and other pollutants have great potential, and the adsorption, photocatalytic and thermal catalytic precious metals combined with undoubtedly clean indoor VOCs have a lot of new ideas. In this paper, the sol - gel synthesis of rare earth La doped TiO2 catalyst, to design a set of reaction device, toluene simulated pollutants, systematic study of the doping amount of heat treatment temperature and other parameters of the catalyst to remove toluene performance, and on this basis to introduction of noble metal, effects of noble metal doping amount, and the reaction temperature and other factors affect the catalyst degradation of toluene, and then the composite catalyst load on ACF prepared Pt/LaTiO2/ACF composite catalyst, and investigated adsorption, photocatalysis and thermal catalytic synergy. And characterization methods combined with SEM, XRD and XPS analysis of the appearance of the surface of the composite and crystalline structure. By GC-MS technique to detect the type and distribution of the composite material of the intermediate product of toluene place. The experimental results are as follows: 1. Tetrabutyl titanate and lanthanum nitrate as raw material, the use of sol-gel method, preparation of rare earth La doped TiO2 photocatalyst film. The study showed that: La doping can improve the visible light catalytic activity of the catalyst, 2.8% La/TiO2-500 ℃ in 60min to completely remove 6110.18mg · m-3 Gas toluene; doped La in La2O3 the form distributed in TiO2 surface, and the formation of the Ti-O-La key; La doping inhibit TiO2 anatase to rutile phase transition, increase the phase transition temperature, reduce the grain size and to increase the catalyst surface area; smooth surface of La/TiO2 film, dense La introduction can effectively inhibit the generation of TiO2 film stomatal; La doping can increase the absorption of TiO2 in the visible region, the catalyst to the long-wave absorption edge mobile; the La f orbital electron transition catalyst for visible light activity increased. 2 of Pt is deposited on the catalyst surface in order to adsorb oxygen and elemental form, mainly the form of adsorbed oxygen. Photodeposition PT the prepared Pt-La2O3/TiO2 composite catalyst, the catalyst surface hydroxyl functional groups OH-stretching significantly enhanced. Pt incorporation did not cause changes in the structure of the TiO2 phase, the Pt incorporation of the grain size is reduced, and increases the ratio of surface area of ??the catalyst. Circular Nano Pt uniformly distributed in La2O3/TiO2 on, no agglomeration occurs and relatively uniform size distribution of about 5nm but less 10 nm. The increase in the deposition of the Pt catalyst on the absorption of visible light. The the preparation of Pt-La2O3/TiO2 catalyst by light deposition Pt than TiO2 and La2O3/TiO2 has higher photocatalytic activity. 3 in different systems (LaTiO2, Pt/LaTiO2, Pt/LaTiO2/ACF) on the initial concentration of the degradation of toluene 13872.3 mg/m3 load of ACF Pt/LaTiO2/ACF with respect to the other two catalyst for toluene adsorption improve, Pt/LaTiO2/ACF completely degraded within 60min the initial concentration 13872.3 mg/m3 toluene. Combination of adsorption, Photocatalytic and thermal catalytic greatly enhanced the ability of the supported catalyst for the degradation of toluene. The intermediate product generated in the process of toluene TiO2/ACF, and Pt/La0.28Ti10O2/ACF Degradation having a large difference in the type and content. TiO2/ACF intermediate product of from 9, the intermediate product mainly of alcohols, ethers, phenols, acids, ketones, etc., also contain a small amount of long-chain alkanes, relatively broad types of intermediate content. From 8 Pt/La0.28Ti10O2/ACF intermediate, all for the long chain alkane, visible toluene in the role of a catalyst, toluene containing a benzene ring is completely open, showed Pt/La0.28Ti10O2/ACF respect TiO2 / ACF catalytic activity is very high.

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