AVS 50th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM4
The Effect of Atomic Steps on the Adsorption and Desorption of CO on Ru(109)

Monday, November 3, 2003, 9:20 am, Room 327

Session: Catalysis I: Adsorption and Reactions of Small Molecules at Surfaces
Presenter: G.A. Morgan, Jr., University of Pittsburgh
Authors: G.A. Morgan, Jr., University of Pittsburgh
T. Zubkov, University of Pittsburgh
J.T. Yates, Jr., University of Pittsburgh
O. Kühlert, Philipps University, Germany
M. Lisowski, Philipps University, Germany
R. Schillinger, Philipps University, Germany
D. Fick, Philipps University, Germany
H.J. Jänsch, Philipps University, Germany
Correspondent: Click to Email
Ru is well known as an effective catalyst for the hydrogenation of CO to produce hydrocarbons. CO hydrogenation likely occurs after CO dissociation on Ru. We have shown that the dissociation of CO occurs preferentially on the atomic step sites of the Ru(109) surface, which exposes 9-atom wide terraces of (001) orientation, separated by double-atom height steps. This was demonstrated by isotopic mixing studies where @super 12@C@super 16@O and @super 13@C@super 18@O were shown to extensively mix above 480 K, a temperature where the C-O bond has just disappeared in the reflection IR spectrum. The isotopically mixed CO desorbs in a distinct recombination process at about 500 K, a kinetic process which is absent on the planar Ru(001) surface. Carbon atoms deposited from the decomposition of ethlylene can poison the step sites, which are responsible for CO dissociation. Thus the well known activity of Ru as a Fischer-Tropsch catalyst may be due to the special activity of defect sites with low Ru-Ru coordination numbers compared to Ru(001) sites.@footnote *@ @FootnoteText@ @footnote *@ Work Supported by DOE-BES.