Theoretical Investigation of H2 Combustion on alphaAl2O3 Support

Abstract

Based on Density Functional Theory Generalized Gradient Approximation (DFT-GGA) calculations, we provide a theoretical model for the effect of the catalytic support (alpha alumina oxide (alphaAl2O3)) on the dissociation of molecular hydrogen (H2), molecular oxygen (O2), hydroxyl (OH), water (H2O), and the surface diffusion of oxygen and hydrogen species along the Al2O3 (0001) surface. These processes are key to understanding the inverse spillover effect that occurs during hydrogen combustion on alumina surfaces. Our results indicate the dissociation of O2 is not thermodynamically favored on the Al2O3 surface. However, both H2 and H2O can dissociate, forming hydroxyls with oxygen atoms in the second atomic layer. Once dissociated, oxygen species can diffuse locally but encounter a large barrier to long-range surface diffusion in the absence of defects or other species. In contrast, the barrier to the long-range surface diffusion of hydrogen is modest under ideal conditions.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 2008
Accession Number
ADA491360

Entities

People

  • D. G. Vlachos
  • Jan Andzelm
  • Jennifer Synowczynski

Organizations

  • United States Army Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Adsorption
  • Atoms
  • Carbon Monoxide
  • Chemistry
  • Combustion
  • Density Functional Theory
  • Dielectric Gases
  • Diffusion
  • Dissociation
  • Elements
  • Hydrogen
  • Measurement
  • Military Research
  • Molecular Dynamics
  • Potential Energy
  • Simulations
  • Spin States

Readers

  • Combustion science or combustion engineering.
  • Materials Science and Engineering.