Study On The Supported Nano Ruthenium Catalyst And ZnS Luminescence Nanomaterials

Ruthenium catalyst has come to be used as the second-generation ammonia synthesis catalyst after the iron catalyst. It has a high activity even under low-temperature and low-pressure. The preparation, characterization and catalytic properties of supported metal nanoparticle catalysts have attracted considerable scientific attention because of the unique catalytic properties of metal nanoparticles and supported metal catalysts in heterogeneous catalysis. Therefore, investigation of supported nano ruthenium catalysts is of scientific and technological significance.The first part of this thesis attempted to study the supported nano ruthenium catalyst. We have done studies in the following several aspects.(1) Ruthenium nanoparticles were prepared by alcohol-thermal reduction process at 198°C with RuCl₃·nH₂O and HOCH₂CH₂OH as reactants. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible spectrophotometer (Uv-vis) was used to characterize and investigate the products. The results indicate that average size of Ru nanoparticles is 28nm when not using PVP as disperser. Morphology of the particle is spherical approximately. The products are agglomerated to some extent. When using PVP as surfactant, the Ru nanoparticles have narrow size distribution and little agglomeration occurs. Particle size is 5.6nm. During heat treatment, the UV-Vis absorption spectra were recorded to investigate the variation of reaction system. Absorption spectra show that different colors of solvent represent different intermediates in reduction process.(2) Alumina-supported nano ruthenium catalysts were prepared using alcohol-thermal reduction process. Ruthenium nanoparticles dispersed uniformly on the Alumina. Measured results show that its load is about 5.3wt%. We also used an impregnant method to prepared activated carbon-supported nano ruthenium catalysts, whose load is about 1.36wt%. This lower load has two reasons. The first reason is the low concentration of reaction solution. A fraction of supports could not be soaked with full access. Second, the metal precursors are easy to move out from the hole and lose during calcination and reduction process.Nanoscience has drawn considerable fundamental and technological attention over the world. Having the quantum size effect, surface effect, the dielectric confinement, nanoparticles have different physical properties compared with bulk materials. The optical properties of semiconductor nanoparticles doped with activator elements have been widely studied.In the second part of this thesis, we attempted to study on the ZnS luminescence nanomaterials. The main results are as follow.(1) ZnS nanomaterials and ZnS:Mn²⁺ luminescence nanomaterials were prepared by precipitation process at room temperature with Zn(CH₃COO)₂·2H₂O and Na₂S·9H₂O as reactants. X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence Spectroscopy (PL) were used to characterize and study the products. The results show that average size of the product is about 34nm. An excitation band centered is observed and the peak of emission is at 300 ran. The excitation spectrum shows a blue shift and the emission wavelength shows a red shift which can be attributed to the quantum size effect. The emission band centered at 420nm can be caused by S defects of ZnS nanocrystals. At about 590nm, there is a very weak emission band, which can be attributed to the ⁴T₁-⁶A₁ transition of Mn²⁺ ion.(2) ZnS:Mn²⁺ luminescence nanomaterials were prepared by solid-phase synthesis at low temperature with Zn(CH₃COO)₂·2H₂O and Na₂S·9H₂O as reactants. Nanomaterials of strong fluorescence can be produced by annealing at low temperature. XRD, SEM and PL were used to study the products. The average size of the products, which agglomerate seriously, is about 36nm. The emission bands of luminescence materials center at 600nm, while the excitation band is at 347nm. The emission of ZnS:Mn can be attributed to the ⁴T₁→⁶A₁ transition of Mn²⁺ ion. The most suitable annealing temperature is 110℃and a higher annealing temperature will bring impurities.