| Nowadays, indoor air quality is paid more and more attention with improvement of our living standard. Indoor air purification also gradually becomes hot issue. However, there are so many kinds of air purification methods, which have advantages and disadvantages. Photocatalytic is a new technology for degradation of pollution gas. Its advantages are low energy consumption, simple operation, no secondary pollution; disadvantages are low efficiency, low reaction rate, easily lost activity of catalyst. Ozone oxidation is another technology for removal of air pollution. However, ozone can bring about secondary pollution though it has strong oxidation ability, and ozonation is not selective, can not target selective oxidation of pollutants. At the same time, the operational processes of ozone oxidation for removal of pollution are complicated, and need high initial investment and operating costs. Recently the photo-degradation of organic pollutants with the assist of ozone has also made some progress, but mostly confined to the effect of the reactant concentration, ozone concentration, air temperature and humidity and UV light intensity on the degradation. Howvever, the researchs about the effect of the catalyst loading, catalyst crystal, support material, pore structure, pore size distribution of support and the support modified by transition metal ions on the degradation were few, as well as the mechanism of degradation. But these researchs were very important for improving the degradation efficiency. Low concentration of pollutants in the air flow rate quickly, and pollutants are not easily oxidized on the catalyst surface. Therefore, the increasing of adsorption and condensation of pollutants on catalysts could promote the degradation rate. Molecular sieves were good adsorption materials, especially suitable for the adsorption of small organic molecules. Therefore, this dissertation mainly focus on the effect of titanium dioxide load, titanium dioxide crystal, molecular sieve material type, pore size distribution, pore size and molecular sieve modified by transition metal ions on photocatalytic degradation of pollutants with the assist of ozone, as well as the degradation mechanism. The contents and conclusions are as follows: In comparison with the performance of activated carbon activated bamboo carbon with titianium dioxide loading, the following facts were found. First, the conductive property of support had effect on the photocatalysis of it. The better electrical conductivity of support is, the worse the photocatalytic activity of catalyst is. Second, the orderly pore structure and narrow distribution of pore was favorable to the increasing of ozone usage. Last, Ozone plays a more important role than photocatalysis under the condition of Uv-ozone. As to activated carbon and activated bamboo carbon, the acetaldehyde degradation on the latter is higher because of its ozone usage.In the investigation of photo-degradation acetaldehyde on TiO2/MCM-41 composite catalysts assisted by ozone, it was found that distribution and crystal phase of TiO2 loading affected photocatalysis activity of catalysts. High photocatalysis activity of catalyst should be the result of high specific surface area, large amount of TiO2 loading and suitable phase of TiO2 loading. It also was found that TiO2 loading could enhance hydrophobic property of MCM-41, which was favorable to the adsorption of acetaldehyde on catalysts. The adsorption increment of acetaldehyde on catalyst could increase the contact time and probability between ozone with acetaldehyde molecular, which lead to the increasing of ozone usage.The degradation efficiency of acetaldehyde was also influenced by the concentration of ozone and the contact time between reactants with catalysts. The gas-solid contact time also affected the rate of degradation capacity. Then, the key to increasing the rate of degradation capacity is how to find out balance between the rates of mass transfer with the rate of surface reaction. Selective adsorption was relative to pore size of molecular sieve and the radius and shape of reactant molecular through the comparison of three molecular sieves. The selective adsorption can enhance remarkably adsorption amount of target reactant on support, leading to the increasing of reactant concentration on catalyst, which can increase the degradation rate of acetaldehyde under UV lamp, ozone or UV-ozone. The absorbance of support to ultra-violet can also affect the photocatalytic activity of catalysts. The activity of TiO2/BC was low under the condition of UV lamp or UV-ozone because of the strong adsorption of activated bamboo carbon to ultra-violet, on the contrary, the activity of TiO2/MCM-41 and TiO2/H-ZSM-5 was higher because of the weak adsorption of MCM-41 or H-ZSM-5 to ultra-violet M-ZSM-5 (M=Zn,Cu,Mn)were prepared by ion-exchange method. TiO2/M-ZSM-5 serials of catalysts were synthesized by impregnation method. The conclusions could be drawn in the investigation of the degradation of acetaldehyde on M-ZSM-5 or TiO2/M-ZSM-5 as follows: M-ZSM-5 have shown a certain degree of photocatalytic activity under the condition of UV lamp. The activity of the order: Cu-ZSM-5>Zn-ZSM-5>Mn-ZSM-5. But the photocatalytic activity of TiO2/M-ZSM-5 has not greatly improved, and some actually declined. All M-ZSM-5 and TiO2/M-ZSM-5 catalysts have activity to degrade a certain amount of acetaldehyde under the condition of ozone, especially Mn-ZSM-5 own the highest activity. But the degradation efficiency decreased slightly on TiO2/M-ZSM-5 catalysts. All the sample of acetaldehyde degradation efficiency was higher under the condition UV-ozone than those under UV or ozone. The activity of the order under the condition of Uv-ozone: TiO2/Mn-ZSM-5>Mn-ZSM-5>Cu-ZSM-5 >TiO2/Cu-ZSM-5>Zn-ZSM-5>TiO2/Zn-ZSM-5. Acetaldehyde molecules interact easily with Zn, Cu, Mn ion to form a stable state in M-ZSM-5 (M= Zn, Cu, Mn), making it difficult to transfer to the surface of titanium dioxide to be photodegraded. Therefore the photocatalytic activities of M-ZSM-5 with titianium dioxide loading are not improved compare to M-ZSM-5, TiO2/Zn-ZSM-5 and TiO2/Cu-ZSM-5 also declined. Mn-ZSM-5 own the highest activity than the other catalysts under the condition of ozone because Mn ions can catalyze ozone to produce maximum amount of reactive oxygen atoms among the three transition metal ion, which make it has the maximum utilization of ozone. However, the acetaldehyde degradation declined after loading titianium dioxide due to the decreasing of specific surface area, and then also may be due to titanium dioxide loading, which would cover the part of the transition metal ions leading to the decline of reaction active sites. The increasing of acetaldehyde conversion under the condition Uv-ozone may be contributed by following factors. First, The UV light or ozone can degrade the acetaldehyde on catalysts directly. Second, the reaction between photo-generated electron and ozone can produce large amount reactive oxygen atoms to decompose acetaldehyde. Therefore, the photodegradation efficiency of acetaldehyde increased greatly with the assistance of ozone, although the photocatalytic activity of M-ZSM-5 or TiO2/M-ZSM-5 is low.
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