Talk by Professor Jan-Dierk Grunwaldt
Institute for Chemical Technology and Polymer Chemistry and Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology (KIT), Engesserstr. 20, 76131 Karlsruhe, Germany
Abstract
Supported metal particles, clusters and single site catalysts play a tremendous role in various catalytic applications such as synthesis of methanol or hydrocarbons, hydrogenation reactions, emission control or power-to-X processes. As the structure of the catalytically active motifs is decisive, advanced preparation methods have been developed to prepare such species on various supports. Analogously, the support matrix is carefully selected to improve the catalytic performance but also to stabilize specific active sites. However, often their atomic structure and the electronic state change, e.g., during activation or under reaction conditions [1, 2]. Selected structural changes that may occur are summarized in Figure 1. To track and understand such dynamic changes in structure, in situ and operando techniques are crucial.
Various setups have been developed, but the identification of the active site still remains a challenge as complementary characterization tools need to be used, structural changes under transient conditions are challenging and only few studies under real operating conditions particularly high pressure or high temperature have been reported. The importance, potential and present limitations of such studies will be discussed using recent examples from environmental catalysis [4,5], syngas production [2], methanol/DME synthesis/CO2-hydrogenation [2,6-8], and direct H2O2 synthesis [9]. The importance of synchrotron X-rays will be highlighted including the need for beamlines like CAT-ACT which allow to conduct unique catalytic experiments with synchrotron radiation. Together with the advanced preparation and theoretical modelling this will allow a more targeted design of future catalysts [10].