Research objectives and content
The major objective is to investigate the impact of the surface morphology on the surface chemical composition at a submicron level of the industrially important supported Mo-oxide catalysts in order to identify the active catalyst phases. Preliminary experiments have shown that model samples can be investigated that use thin oxide films on conductive support foils. We could show that the topographic and compositional characterization using the recently developed photoelectron microscopy with lateral resolution of 0.1 um contributes useful information to the understanding of model catalysts. By combination of laterally resolved topographic and chemical maps with a small spot (0.01 um2) core level spectra in selected catalyst areas the chemical difference between the Mo-oxide phases will be identified. In particular, the unknown changes in the local chemistry of the catalyst induced by spreading and wetting of the support after heat treatment will be addressed. As a second part of the experiments we will focus of encapsulation processes known for the system Rh-TiO2 as a prototype process for the technical important Strong Metal-Support Interaction (SMSI) effects that may be responsible for catalysts deactivation.
Training content (objective, benefit and expected impact)
? The charging under the highly intensive and focused photon beam which is still an unresolved problem will be faced and tried to be solved. Testing suitable techniques for discharging the illuminated surface will make synchrotron radiation spectromicroscopy applicable to study insulating materials.
? Insight in differential charging phenomena can be achieved which has become important recently with developing new techniques for spectromicroscopy.
? Making use of the spatial resolution of the spectromicroscope will help to understand where or how reaction centers are formed on a real catalyst. We expect this will have positive impact on the design of catalysts with desired properties.
Links with industry / industrial relevance (22)
Supported MoO3 catalysts are widely used in the petrochemical industry. They are in use even in a more broader field whenever sulphur containing reaction participants occur. Rh-catalysts are used especially in car catalysts to reduce the amount of NOx. The project will be carried out in collaboration with ENI, an industrial center, which is a partner in construction of the Escamicroscopy beamline at ELETTRA.