Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Heterogeneous catalysis II
O 35.3: Vortrag
Dienstag, 23. März 2010, 15:30–15:45, H33
The role of surface oxides in NOx storage reduction (NSR) catalysts — •Jelena Jelic1,2, Randall Meyer1, and Karsten Reuter2,3 — 1Univ. of Illinois at Chicago (USA) — 2Fritz-Haber-Institut Berlin (Germany) — 3TU München (Germany)
In the NSR approach to lean burn automotive emissions a longer O-rich mode in the cyclic operation first oxidizes and stores the excess NO before a short O-poor mode reduces the stored NOx. Bulk oxide formation in the oxidizing environment is commonly perceived as detrimental to the catalytic activity of the employed platinum metals. To qualify this notion we perform first-principles atomistic thermodynamics and kinetic Monte Carlo simulations determining the surface structure and composition, as well as catalytic performance of Pd(100) under gas-phase conditions typical for the NO oxidation. With bulk oxide formation prevented on the time scale of the O-rich mode, we identify an ultrathin PdO(101)/Pd(100) surface oxide film as the stable surface termination. Moreover, its turnover frequencies are similar to those measured for platinum metal, demonstrating that a surface oxide may be a viable catalyst for NO oxidation.