A density-functional study of the interaction of nitrogen with ruthenium clusters

David J. Dooling, Robert J. Nielsen, Linda J. Broadbelt*

*Corresponding author for this work

Research output: Contribution to journalConference article

24 Scopus citations

Abstract

Recently, the synthesis of ammonia over ruthenium-based catalysts has become an industrially viable process. Unfortunately, investigations of ammonia synthesis over ruthenium are scarce, particularly in comparison to the number of studies carried out over iron. To begin to fill this void, we have performed a series of electronic density-functional theory (DFT) calculations to investigate the effect of particle size and surface structure on ammonia synthesis over ruthenium. Our study has focused on the dissociative adsorption of dinitrogen, which is thought to be the rate-determining step in the synthesis, on both single-crystal surfaces and spherical clusters of ruthenium. The equilibrium adsorbate geometries were remarkably similar on both the single-crystal surfaces and the spherical clusters studied. The binding energy of dinitrogen in the end-on state exhibited a strong dependence on ruthenium surface atom coordination, being much stronger on atoms with low coordination. The main difference between the two single-crystal surfaces studied was the ability of the open Ru(1120) face to stabilize a low-energy side-on dinitrogen state, while the close-packed Ru(0001) face could not. It is likely that this stable side-on state provides a low-energy dissociation pathway.

Original languageEnglish (US)
Pages (from-to)3399-3409
Number of pages11
JournalChemical Engineering Science
Volume54
Issue number15-16
DOIs
StatePublished - Jul 1 1999
EventProceedings of the 1998 15th International Symposium on Chemical Reaction Engineering, ISCRE 15 - Newport Beach, CA, USA
Duration: Sep 13 1998Sep 16 1998

Keywords

  • Ammonia
  • Density-functional theory
  • Nitrogen
  • Promoter
  • Ruthenium
  • Single crystal

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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