In this talk I’ll be presenting some recent results on the oxidation and reduction of ruthenium respectively its oxide under various reaction conditions. We studied in-situ the oxidation process of Ru in the pressure range from 10-5mbar to 10mbar of oxygen, applying the technique of surface x-ray diffraction (SXRD) [1]. Subsequently, the reduction behaviour of the produced oxide layers by hydrogen- and CO exposure was characterized by in-situ SXRD.
With FTIR spectroscopy we followed the CO oxidation reaction over RuO2(110) in a wide pressure range from 10-8mbar to 10-2mbar. We compare the FTIR results with corresponding DRIFT results on supported RuO2catalysts [2]. These experiments show clearly that both pressure and materials gaps have successfully been bridged for the catalysed CO oxidation reaction over RuO2 [3]. This knowledge has been utilized to improve the structural stability of RuO2 based catalysts [4].
[1] Y.B. He, M. Knapp, E. Lundgren, H. Over: Ru(0001) model catalyst under oxidizing and reducing reaction conditions: In-situ high-pressure surface x-ray diffraction study; J. Phys. Chem. B 109 (2005) 21825-21830.
[2] a) J. Aßmann, E. Löffler, A. Birkner, M. Muhler, Catal. Today, 85 (2003). 235. b) J. Aßmann, V. Narkhede, L. Khodeir, E. Löffler, O. Hinrichsen, A. Birkner, H. Over, M. Muhler, J. Phys. Chem. B, 108 (38)(2004). 14634. c) V. Narkhede, J. Aßmann, M. Muhler, Z. Phys. Chem, 219 (2005). 979.
[3] H. OVer, M. Muhler, Progress Highlight in Prog. Surf. Sci. 72 (2003) 3-17.
[4] J. Aßmann, D. Crihan, M. Knapp, E. Lundgren, E. Löffler, M. Muhler, V. Narkhede, H. Over, M. Schmid, A.P. Seitsonen, P. Varga, Angew. Chem. Int. Ed. 44 (2005) 917.
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