Accession Number:

ADA184237

Title:

Surface Chemistry of Transition Metal Carbides: A Theoretical Analysis.

Descriptive Note:

Technical rept.,

Corporate Author:

CORNELL UNIV ITHACA NY LAB OF ATOMIC AND SOLID STATE PHYSICS

Personal Author(s):

Report Date:

1987-07-01

Pagination or Media Count:

61.0

Abstract:

Extended Huckel tight binding calculations have been employed to analyze the interactions of oxygen, carbon monoxide and methanol with the 100 and 111 faces of a representative rocksalt carbide, TiC. The 111 face have been experimentally shown to be the most active toward the adsorption, dissociation or decomposition of adsorbates, whereas the 100 face demonstrates very little activity. Calculations suggest that the differential reactivity of the two faces is the result of the coordination of the atom in the active site and the presence of surface carbon. For CO on the 100 the population of the 2Pi level increases if carbon vacancies are included in the calculations and dissociated occurs. For the 111 metal-terminated face of TiC the population of the 2Pi level is nearly identical to that calculated for Ti0001. Methanol dissociates into methoxy and a protic species on the 111 face but remains molecular on the 100. The calculations suggest that the molecular species is stabilized by interaction of the methanolic proton with the surface carbon.

Subject Categories:

  • Physical Chemistry
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE