Local reaction kinetics by imaging

Highlights

• An overview of the recent studies using the “kinetics by imaging” approach for CO oxidation on model systems is presented.

• The approach allows spatially-t-resolved kinetic studies with a spatial resolution of the used PEEM, e.g. on the μm-sized domains of polycrystalline samples.

• CO oxidation on Pd(hkl)-domains and on supported Pd-powder, role of defects and grain boundaries in the reaction kinetics are described as “case studies”.

Abstract

In the present contribution we present an overview of our recent studies using the “kinetics by imaging” approach for CO oxidation on heterogeneous model systems. The method is based on the correlation of the PEEM image intensity with catalytic activity: scaled down to the μm-sized surface regions, such correlation allows simultaneous local kinetic measurements on differently oriented individual domains of a polycrystalline metal-foil, including the construction of local kinetic phase diagrams. This allows spatially- and component-resolved kinetic studies and, e.g., a direct comparison of inherent catalytic properties of Pt(hkl)- and Pd(hkl)-domains or supported μm-sized Pd-powder agglomerates, studies of the local catalytic ignition and the role of defects and grain boundaries in the local reaction kinetics.