Abstract
Structural characterization of zeolite and mesoporous silica in the forms of film and membrane as well as their incorporated nano-sized metals were performed by X-ray diffraction (GIXD and PXRD), reflectivity (XRR) and X-ray absorption spectroscopy (XAS) using synchrotron X-ray source.In the first chapter, an introduction of porous materials, nano-sized metals in porous materials and structural characterization methods employed in this thesis are described.In Chapter 2, on-substrate mesoporous silica films were investigated by GIXD, XRR and TEM. The better structured thin films were proved to have better mechanical properties. A thin layer of zeolite coated on the inner wall of an asymmetric ceramic tube was detected non-destructively by reducing the contribution of the crystalline support using GIXD.In the third chapter, the sizes of nano-Au and Pt were evaluated by both PXRD and XAS. It is interesting that sizes and morphologies were observed to be controlled through manipulating preparation and reduction conditions. In-situ PXRD was performed to detect the size increase of Au nanoparticles in reduced samples during thermal treatment.In Chapter 4, the local structure of gallium species in zeolites studied by computation simulation and XAS including XANES and EXAFS techniques is given. The simulation results of Ga/beta zeolites are in good agreement with previous EXAFS and FTIR results and can be used to predict the possible locations of gallium species in beta zeolites. The chemical state of Ga in as-synthesized TMG/ZSM-5 was monitored by in-situ XANES during reduction process. The reduced form sample was found to be oxidized fast at 773 K under oxygen atmosphere. Two kinds of oxidized gallium species, generated by direct oxidation and oxidation after reduction, respectively, were found to possess different catalytic activities.