Department of Chemistry
Humboldt University, Berlin, Germany
Thursday 17th May 2018
10:00 AM in 1003 Kemper Hall
Two classes of solid catalysts are considered, zeolites as solid acids used in hydrocarbon synthesis and conversion processes, and supported transition metal oxides as selective oxidation catalysts. With their well-defined crystalline structure zeolites are a perfect example of the active site concept. Ab initio calculations that yield free energies for elementary steps with chemical accuracy (4 kJ/mol)1 allows discriminating between different mechanisms. We look at proton exchange reactions and provide an accurate value for the proton exchange barrier of isobutane on H-ZSM-5 which is crucial in the discussion of whether alkane activation happens directly via carbonium type transition structures or indirectly via hydride transfer involving alkoxides or carbenium ions. Based on a detailed mechanism of the oxidative dehydrogenation of light alkanes and the oxidation of methanol to formaldehyde,2 the effect of different supporting oxides such as SiO2, Al2O3, ZrO2, and CeO2 on the activity of supported vanadium oxides is analyzed. The remarkably high activity observed for vanadia catalysts supported on ceria directly relates to a special synergy between the ceria support and the supported oxide (vanadia). Experimental model catalysts such as thin films and gas phase clusters have been crucial in reaching these conclusions.
1) Piccini, G.; Alessio, M.; Sauer, J. Angew. Chem., Int. Ed. 2016, 55, 5235.
(2) Kropp, T.; Paier, J.; Sauer, J. J. Am. Chem. Soc. 2014, 136, 14616.
(3) Sauer, J.; Freund, H.-J. Catal. Lett. 2015, 145, 109.
Joachim Sauer received the Dr. rer. nat. degree in Chemistry from Humboldt University in Berlin in 1974, and the Dr. sc. nat. degree from the Academy of Sciences in (East-)Berlin in 1985. Since 1993 he is Professor of Theoretical Chemistry at the Humboldt University in Berlin, and since 2006 external member of the Fritz Haber Institute (Max Planck Society). He is member of the Berlin-Brandenburg (formerly Prussian) Academy of Sciences, the German National Academy Leopoldina, and the Academia Europea. His research has explored the application of quantum chemical methods in chemistry, with emphasis on surface science, particularly adsorption and catalysis. He has published more than 370 research papers, notably in the area of modeling the structure and reactivity of transition metal oxide catalysts and zeolites, and he has given more than 450 invited lectures. From 1999 to 2011 he was chairman of the Collaborative Research Center of the German Research Foundation (DFG) “Aggregates of transition metal oxides – Structure, dynamics, reactivity” and he is co-founder and principal investigator of the DFG-funded Cluster of Excellence “Unifying concepts in catalysis” in Berlin. He is one of the editors of the Journal of Catalysis.