About active sites and spectators in heterogeneous catalysis
Event details
| Date | 06.10.2016 |
| Hour | 16:00 › 17:00 |
| Speaker |
Prof. van Bokhoven Jeroen Institute for Chemical and Bioengineering, ETH Zurich and Head of Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Switzerland |
| Location | |
| Category | Conferences - Seminars |
The focus of my talk will address the difficulty to measure the structure of catalytically active sites in heterogeneous catalysis. Most catalysts have large
structural heterogeneity and the identification of what constitutes the active site is very complex. In supported metal catalysts, the support cannot be assumed to be an inactive component. Ceria is a well-known support that is able to store and release oxygen. For that reason, it finds application in reactions that involve redox reactions. Upon oxygen release, part of CeIV reduces to CeIII. The ceria oxygen-storage capacity and the presence of CeIII are often related to catalytic performance, however quantitative descriptions are lacking. By building on recently developed spectroscopic tools based on x-ray absorption and emission spectroscopy on the one hand and electron spectroscopy on the other, we have been able to quantify the role of CeIII in the oxidation of carbon monoxide over Pt/CeO2. Transient measurements with high time resolved x-ray emission spectroscopy showed the existence of CeIII as spectator and as active intermediate in the reaction. The consequences of these observations on the relationshhip between oxygen storage capacity and the presence of CeIII on catalytic performanve will be discussed.
structural heterogeneity and the identification of what constitutes the active site is very complex. In supported metal catalysts, the support cannot be assumed to be an inactive component. Ceria is a well-known support that is able to store and release oxygen. For that reason, it finds application in reactions that involve redox reactions. Upon oxygen release, part of CeIV reduces to CeIII. The ceria oxygen-storage capacity and the presence of CeIII are often related to catalytic performance, however quantitative descriptions are lacking. By building on recently developed spectroscopic tools based on x-ray absorption and emission spectroscopy on the one hand and electron spectroscopy on the other, we have been able to quantify the role of CeIII in the oxidation of carbon monoxide over Pt/CeO2. Transient measurements with high time resolved x-ray emission spectroscopy showed the existence of CeIII as spectator and as active intermediate in the reaction. The consequences of these observations on the relationshhip between oxygen storage capacity and the presence of CeIII on catalytic performanve will be discussed.
Practical information
- General public
- Free
Organizer
- Prof. Berend Smit
Contact
- Evelyn Ludi