Synthesis and Characterization of Gold and Copper Nanoparticles in Mesoporous Frameworks
MetadataVis full innførsel
- Institutt for kjemi 
In this thesis, the mesoporous materials SBA-15 and Al-SBA-15 have been synthesized and characterized. In addition, syntheses of mesoporous AlPO and SAPO have been investigated. SAPO was successfully synthesized, while mesoporous AlPO was only stable as-synthesized and collapsed during calcination. The SAPO synthesized does not appear to have mesopores. However, the sample shows a high surface area of 520 m2/g without exhibiting an ordered pattern on regular XRD. The similarities and differences between SBA-15 and SAPO have been examined, mainly by X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and N2 adsorption (BET).Solutions containing both gold and copper cations were introduced to a sample of SBA-15, and X-ray Absorption Spectroscopy (XAS) was used to examine whether bimetallic clusters where gold and copper are in close proximity of each other were formed, or whether gold and copper formed separate clusters. Results indicate that bimetallic clusters are formed. This is based on an interaction between gold and copper, leading to a partial reoxidation of gold during propene oxidation. This is evidenced by a distinct change in the XANES of gold when copper is reduced. EXAFS data indicate a bimetallic core-shell configuration of the particles with copper in the center with a layer of gold on the surface. The size of the particles was estimated to be small enough to fit inside the pores of SBA-15.