Author:

Abstract:

Heterogeneous catalysts are commonly used to enhance the rate and the selectivity of chemical reactions. These materials are routinely characterized by analyzing a large amount (up to billions) of catalyst particles at once, thus providing averaged information about their properties. While this approach is widespread in catalysis research, it overlooks intrinsic variability within catalytic materials. Insights into these heterogeneities can be obtained by spatially resolving the properties of individual catalyst particles, enabling a more rational optimization of these materials ultimately. Therefore, several microscopy methodologies have found their way to catalysis research during the past decades, mostly focusing on resolving fine structural details and the elemental composition. Complementary molecular information on the smallest length scales is often less accessible. Stimulated Raman scattering (SRS) microscopy is a promising chemical imaging technique that offers fast, 3D, label-free vibrational imaging with a sub-micrometer resolution. While its power has been showcased in various biomedical studies, the development of this technique in materials and catalysis research is lagging behind. This PhD thesis aims to develop SRS microscopy assays to spatially resolve the fine chemical details of zeolite catalysts at the single-particle level. The impact of synthesis and post-synthetic treatment conditions on the structural and compositional properties of different zeolites were investigated using the Raman signature of molecules located in their porous structure. The results illustrate the capabilities of SRS microscopy as a tool for catalyst characterization in general. Furthermore, the insights gathered by advanced vibrational imaging enable a more rational material optimization.