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No Access Submitted: 04 February 2002 Accepted: 06 August 2002 Published Online: 14 October 2002

  • Effect of surface phosphorus on the oxidative dehydrogenation of ethane: A first-principles investigation

J. Chem. Phys. 117, 8080 (2002); https://doi.org/10.1063/1.1510122
Amitesh Maiti, Niranjan Govind, Paul Kung, and Dominic King-Smith
  • Accelrys Inc., San Diego, California 92121
    • James E. Miller
  • Sandia National Laboratory, Albuquerque, New Mexico 87185
    • Conrad Zhang and George Whitwell
  • Akzo Nobel Chemicals Research, Dobbs Ferry, New York 10522
    • more...View Contributors
    • Amitesh Maiti
    • Niranjan Govind
    • Paul Kung
    • Dominic King-Smith
    • James E. Miller
    • Conrad Zhang
    • George Whitwell
    ABSTRACT
    Oxidative dehydrogenation (ODH) of small-chain alkanes has the potential to displace thermal cracking as the preferred method of light olefin production. Many heterogeneous catalysts for the ODH reaction have been discussed in the literature, including oxides, vanadates, and phosphates of rare earth and transition metals. Our experiments and the literature indicate that for most of these catalysts, including silica gel and alumina, a phosphorus-enriched surface enhances the ODH yield of ethane to ethylene. To understand the role of P, the ODH reactions were simulated on a silica surface, with and without P, using the density functional theory code DMol3 in a periodic supercell. Optimized structures for all intermediates as well as transition states were obtained for full catalytic cycles. The simulations reveal that activation barriers for the rate-limiting steps are lowered by ∼10 kcal/mol in the presence of P. The decrease results from a transition state in which the P atom remains quasi-5-valent and fourfold coordinated.

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