Size and pressure independent kinetics of CO oxidation on alumina-supported iridium nanoparticles

✍ Scribed by Michael Sushchikh; Lucas Cameron; Horia Metiu; Eric W. McFarland

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 117 KB
• Volume: 40
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20354

✦ Synopsis

Abstract

The gas‐phase oxidation of CO catalyzed by iridium was studied under CO‐rich reactant conditions over the pressure range 10^−4^–10^−2^ Pa to investigate the controversial size and pressure dependencies. The reactivity of iridium clusters with an average size of 3 nm was compared to macroscopic metal particles with extended single crystal facets over a range of temperatures (433–573 K), and the apparent activation energies for CO oxidation were consistent with the known activation energies for CO desorption from iridium surfaces. No size‐specific dependence of the reaction kinetics was measured, and no indication of the previously reported “pressure gap” was observed. Unlike many other transition metal catalysts, iridium may be used as a model catalyst for CO oxidation in different morphological forms over a range of pressures without invoking a change in the kinetic model. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 826–830, 2008