| Titanium dioxide as a kind of multi-functional n-type semiconductor materials, has a very important applications in many fields, such as sewage treatment, the solar cell, and light catalysis, etc. In recent years, there are many researches and applications of one-dimensional titanium dioxide nanomaterials which is prepared by the hydrothermal method. TiO2 nanobelts, not only keep the original special performance of titanium dioxide, but also have high specific surface and smooth surface, is a good carrier, supported Au catalysts has been widely studied due to their high catalytic performance. Monometallic Au catalysts frequently suffer from agglomeration of Au nanoparticles in the process of reaction, and cause deactivation. The addition of the second metal make bimetallic nanoparticles form a powerful synergy effect, improving the activity and stability of the catalysts.The main content of this thesis are as follows:Firstly, the one-dimensional TiO2 nanobelts which have a high specific surface area, and homogeneous defect site were prepared by hydrothermal method. Then, we adopted the depositional precipitation method to load size uniform and highly controllable bimetallic nanoparticles on the surface of TiO2 nanobelts, forming Au-M(M=Ag, Cu)/TiO2-NB heterogeneous nanostructures. Afterwards, we obtained the membrane assembled by Au-M(M=Ag, Cu)/TiO2-NB through a vacuum filter. The catalysts were characterized using XRD, ICP, HR-TEM and XPS techniques. The bimetallic catalysts showed excellent activity in the selective catalytic ethanol oxidation system. The optimal ratio of bimetallic atom is 1:1, Ethanol conversion rate of Au1Ag1/TiO2-NB and Au1Cu1/TiO2-NB are 45% and 55% respectively, acetaldehyde is the main product. Moreover, the catalytic activity has no significant decline in repeated use test. The size of nanoparticles in the bimetallic catalysts is less then 3 nm, and their ability of resistance to sintering is strong, almost no change after the reaction of the 30 hours. This is because bimetallic nanoparticles can form Au (nuclear)-MOx (shell) heterostructure by high temperature treatment in the aerobic environment, which maximize the contact interface, to form a strong synergy between metal-metal oxide, greatly improving the catalyst activity and stability. Preoxidation treatment has greater improvement on the performance of the Au1Ag1/TiO2-NB than Au1Cu1/TiO2, because Cu is more active than Ag, Au1Cu1/TiO2-NB has the ability to activate independently at the beginning of the reaction. The rise of reaction temperature is beneficial to the activation of O2 molecules, so that, ethanol conversion rate can be improved, however, the selectivity of product reduce, and even cause the excessive oxidation of ethanol, receiving CO and CO2. The increase of the oxygen-ethanol ratio is beneficial to improvement of the reaction conversion rate, but high oxygen-ethanol ratio change selectivity of the main product. The flexibility of Na2Ti3O7 nanopaper is wonderful, the paper can be arbitrary bended and folded, but its catalytic performance is poor.The other part, We prepared AuxAgy/Ti02-NB nanostructures by photodeposition-replacement method, through a simple assembly technology, nanopaper catalysts was obtained. To study the catalytic activity, these bimetallic catalysts were applied in benzyl alcohol gas phase catalysis system. The catalytic performance of Au7Ag1/TiO2-NB is the best, conversion rate is above 90%, and has been on the rise trend. The selectivity of benzaldehyde were all above 98%. Au-Ag bimetallic nanoparticles has good performance to resist sintering under high temperature. Compared with powder catalyst Au7Ag1/P25, Au7Ag1/TiO2-NB nanopaper has obvious advantages in the gas phase catalytic oxidation of benzyl alcohol. |
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