Svnthesis Of Noble Metal Nanoparticles And Reparation And Catalytic Exploration Of RuO₂-Au Composite Materials Formed Within The Mesopores

Noble metal nano-materials are attractive for many applications due to their unique properties. However some inherent disadvantage such as complicated preparation process and poor thermal stability of nano-materials greatly limit their application as catalyst especially in hetercatalysis area.In this thesis, we explore new and catalysis application-oriented strategies for the synthesis of nano and composite nano-materials. Three research topics are included in this dissertation. Firstly, we explored simple approach for the synthesis of some noble metal nanoparticles (such as Au, Pt, Rh, Ru) in the polyol and oleylamine systems. We also investigated catalytic performance of Ru catalyst supported on mesoporous silica EP-FDU-12in the ammonia decomposition reaction at normal pressure. In the second part, we report a simple method for the synthesis of RuO2-Au composite nanoparticles through calcining Ru nanoparticles and Au nanoparticles encapsulated within extra-large mesocages of mesoporous silica. Thirdly, we also explore the properties of RuO2-Au composite materials as well as their catalytic activity in the selective gas oxidation of cyclohexanol. The main points are succinctly summarized as followed.1. Synthesis and preparation of noble metal nanoparticles under the polyol and oleylamine systems1) We explore a general method for the synthesis of noble nanoparticles in the solution system such as polyol and oleylamine. By using the chloride as the precursor, monodispersed and uniformed particle size can be produced. The existence of some small molecule like H2O in the oleylamine system can lead to the formation of dendritic Pt nanoparticles.2) Ruthenium nanoparticles are supported on silica support by colloid deposition in non-aqueous solution. We explore a simple method in determining the loading content of supported Ru catalysts by using the UV-Vis spetra as the detection tools. Ammonia decomposition was selected as the probe reaction to investigate the reactivity of supported Ru catalysts with different particle size at low loading level (<2wt%).2. RuO2-Au composite nanoparticles formed by one-step synthesis within the Mesopores.1) In this part we report a simple method for the synthesis of RuO2-Au CNPs through calcining RuNPs and AuNPs encapsulated within extra-large mesocages of mesoporous silica (EP-FDU-12). AuNPs and RuNPs were loaded into EP-FDU-12supports by a colloid deposition method. The RuO2-Au CNPs formed after the calcination at elevated temperature in air.2) By a series of characterization analysis, we found the nano-contact between Au and RuO2modifies the electronic and chemical properties of Au and RuO2, respectively.3. Exploration of the properties of RuO2-Au composite nanoparticles and their catalytic performance in gas-phase cyclo-hexanol selective oxidation.1) Due to the interaction between RuO2and Au composite, composite nanoparticles show enhanced thermal stability. Ru/Au ratio and the mesoporous supports are investigated for the enhanced thermal stability of composite nanoparticle.2) The composite nanoparticles show enhanced catalytic performance with better activities and reduced coking-deposition content in gas-phase cyclohexanol selective oxidation. Detailed discussion was been made about the mechanism of the anti-sintering and anti-coking of RuO2-Au CNPs.