Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 4: Heterogeneous catalysis I
O 4.7: Vortrag
Montag, 22. März 2010, 12:45–13:00, H33
First-Principles Approach to Heat and Mass Transfer Effects in Model Catalyst Studies — •Sebastian Matera1 and Karsten Reuter1,2 — 1Fritz-Haber-Institut Berlin (Germany) — 2Technische Universität München (Germany)
We assess heat and mass transfer limitations in in situ studies of model catalysts with a first-principles based multiscale modeling approach that integrates a detailed description of the surface reaction chemistry and the macro-scale flow structures. Using RuO2(110) as a representative substrate for the frequently studied CO oxidation reaction we find corresponding limitations to significantly mask the intrinsic catalytic function at the high conversion rates reached at near-ambient gas-phase conditions [1]. Two crucial and hitherto largely unappreciated factors specific to the model catalyst reactor geometry are in this respect the degree of heat dissipation at the back of the thin sample and the propensity to build-up a product boundary layer above the flat-faced surface. A qualified discussion of a possibly different surface chemistry across the “pressure gap” requires accounting for resulting temperature and pressure gradients, both in experimental in-situ setups and through predictive-quality integrated models as the one presented here. Otherwise wrong mechanistic conclusions may be derived which hamper our progress towards an atomic-scale understanding of the function of heterogeneous catalysts at technologically relevant gas-phase conditions. [1] S. Matera and K. Reuter, Catal. Lett. 133, 156 (2009).