Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)
O 36.64: Poster
Montag, 7. März 2005, 15:00–18:00, Poster TU F
Catalytic Oxidation of Ammonia on RuO2(110) Surfaces: Mechanism and Selectivity — •Yuemin Wang1,2, Karl Jacobi2, Wolf-Dieter Schöne2, and Gerhard Ertl2 — 1Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin
The selective oxidation of ammonia on RuO2(110) surfaces was studied by a combination of vibrational spectroscopy (HREELS), thermal desorption spectroscopy (TDS), and steady-state rate measurements. The stoichiometric RuO2(110) surface exposes coordinatively unsaturated (cus) Ru atoms onto which either adsorption of NH3 (NH3-cus) or dissociative adsorption of oxygen (O-cus) may occur [1]. In the absence of O-cus ammonia desorbs completely thermally without any reaction. However, interaction between NH3-cus and O-cus starts already at 90 K by hydrogen abstraction and hydrogenation to OH-cus, leading eventually to N-cus and H2O. The N-cus species either recombine with each other to N2 or with neighboring O-cus leading to strongly held NO-cus which desorbs around 500 K [2]. Under steady-state flow condition the product selectivity was found to depend on temperature and relative partial pressures of the reactants: Excess oxygen favors the production of NO and at 530 K almost 100 percent selectivity for NO formation is reached. [1] C.Y.Fan, J. Wang, K. Jacobi, G. Ertl, J. Chem. Phys. 114 (2001) 10058. [2] Y. Wang, K. Jacobi, G. Ertl, J. Phys. Chem. B, 107 (2003) 13918.