Mechanism of catalytic decomposition of CH3I on the Cu(111) surface: A UBI-QEP approach

Azizian, S ; Sharif University of Technology | 2000

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  1. Type of Document: Article
  2. DOI: 10.1021/la0003847
  3. Publisher: ACS , 2000
  4. Abstract:
  5. The method of unity bond index-quadratic exponential potential (UBI-QEP) and the computer simulation of the temperature programmed desorption (TPD) patterns are employed to derive the kinetic and thermodynamic parameters associated with the steps of the pathway we propose for the catalytic decomposition of methyl iodide on the Cu(111) surface. Assuming a highly reactive `hot methyl' surface intermediate and on the basis of our calculations it is concluded that the desorption of a part of this species is responsible for the reported methyl radical TPD peak at 140 K, while a part of this surface species is trapped in the three-fold sites of the Cu(111) surface and desorbs to form the reported TPD peak at 470 K. It is also concluded that the rate-determining step of the formation of CH4, C2H4, C2H6, and C3H6, which are the products of the interaction of methyl iodide with the Cu(111) surface and all desorb at 470 K in a TPD experiment, is the surface dissociation of the adsorbed methyl groups. The effect of the surface coverage on the kinetic parameters of the reactions, appearing as changes of the products' distributions, is quantitatively accounted for
  6. Keywords:
  7. Computational methods ; Thermodynamic stability ; Temperature programmed desorption ; Surface phenomena ; Reaction kinetics ; Dissociation ; Iodine compounds ; Interfaces (materials) ; Decomposition ; Computer simulation ; Copper
  8. Source: Langmuir, Washington, DC, United States ; Volume 16, Issue 21 , 2000 , Pages 8095-8099 ; 07437463 (ISSN)
  9. URL: https://pubs.acs.org/doi/10.1021/la0003847