Microreactors for In Situ Single Catalyst Particle Characterization Using Advanced Imaging Techniques

Heterogeneous catalysts are characterized by a multi-length scale structure with a complex pore network that exhibits specific tortuosity and pore connectivity. This structure plays a crucial role in catalytic processes, defining the activity and selectivity towards specific reaction products. A spatial and time-resolved structure-activity relationship is fundamental to enhance and improve catalyst performance. Traditional characterization methods for solid catalysts typically provide averaged information across the analyzed batch of particles, overlooking the intra and interparticle heterogeneities inherent in these materials. Exploring solid catalysts at varying depths and during operations (in situ or operando) allows us to obtain complementary information, which is crucial for obtaining a comprehensive understanding of the underlying mechanisms governing catalytic reactions.

This thesis contributes to the advancement of innovative microfluidic devices for investigating heterogeneous catalysts at the single particle level in real reaction conditions. The microfluidic devices presented in the thesis allow for in situ imaging of compositional and structural changes of individual catalyst particles using 3D high-resolution X-ray microscopy and studying the influence of the particle porosity (pore size, surface area) on mass transport at the single particle level.