Study On Preparation And Hydrogenation Performance Of Au-Pd Bimetallic Catalysts

Due to the strong interaction and synergistic effect, bimetallic nanocatalysts have attracted widespread attention. It is known that the catalytic performance of supported bimetallic nanocatalysts is related to the preparation method, the size of nanoparticles and the nature of the support. So, how to prepare highly dispersed and stable bimetallic nanocatalyst still faces great challenges. This thesis explores a new method to prepare highly dispersed bimetallic nanoparticles, and investigate its catalytic properties. The main results have been summarized as follows:(1) Highly dispersed Au-Pd nanoparticles supported on SiO2have been successfully prepared by in-situ reduction method.3-aminopropyltriethoxysilane (APTES) was hydrolyzed in HCHO solution to prepare SiO2with reducing functional groups(-CH2CH2CH2NHCH2OH), the reducing functional groups could simultaneous reduction of HAuCl4and PdCl2in aqueous solution. IR and NMR results indicated that the reducing functional groups formed through the reaction between-NH2and HCHO. The TEM, STEM-EDX, XRD, XPS results indicated that high homogeneity of the two components have been formed in all the bimetallic catalysts metallic and the particles size were3-4nm.(2) The as-obtained Au-Pd/SiO2exhibited good catalytic activity and stability for hydrodechlorination of chlorobenzene under mild conditions. The significantly improved catalytic performance of the bimetallic catalyst can be ascribed to the high dispersion and modified electronic properties of Pd. The entirely conversion of chlorobenzene could be achieved within2h at normal temperatures and pressures. The organic functional groups on the surface of the carrier could stabilize Au-Pd NPs; Alkali and proton solvents promote the HDC of CB over Au-Pd/SiO2.(3) The as-obtained Au-Pd/SiO2exhibited good catalytic activity for hydrogenation of aromatic nitro-compounds in aqueous solution. Au-Pd/SiO2in water show better catalytic performance than in ethanol, acetone and n-hexane. Due to the presence of other reducing functional groups on the nitro-compounds, the substrate is simultaneously dechlorinated and hydrogenated to form mainly aniline together with both nitrobenzene and dechlorination products as by-products.