AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS1-TuM

Paper SS1-TuM7
Kinetics of Co Oxidation Catalyzed by Supported Iridium Particles in a Wide Pressure Range

Tuesday, November 16, 2004, 10:20 am, Room 210B

Session: Catalytic Reactions: The Role of Surface Steps and Structure
Presenter: M.M. Sushchikh, University of California, Santa Barbara
Authors: M.M. Sushchikh, University of California, Santa Barbara
E.W. McFarland, University of California, Santa Barbara
Correspondent: Click to Email
Recent work in ultra-high vacuum (UHV) has demonstrated kinetic hysteresis in the CO oxidation reaction on single crystal iridium surfaces@footnote 1@,@footnote 2@; the reaction rate variation in CO and O@sub 2@ partial pressures varied depending upon the initial partial pressure. The phenomena observed were explained using a Langmuir-Hinshelwood mechanism. We have investigated the phenomena at elevated pressures on a supported Ir catalyst to test the validity of the model scaled more than 9 orders of magnitude in pressure. It is expected that sticking coefficients at the high surface coverages are not equal to those at lower coverages and as the pressure approaches atmospheric, kinetic phase transitions are affected by changes in the gas composition. Furthermore, on the supported metal particulate catalyst heat transfer effects are more complex. The rate of CO@sub 2@ formation on Ir as a function of reactant pressures (up to 1 atm) was monitored and excellent agreement was found with the UHV experiments. @FootnoteText@ @footnote 1@ S.Wehner, F.Baumann, M.Ruckdeschel, J.Küppers, J.Chem.Phys., 119(13)(2003)6823.@footnote 2@ S.Wehner, F.Baumann, J.Küppers, Chem.Phys.Lett., 370(2003)126.