Oxidation mechanism of propylene on an Ag surface: Dipped adcluster model study

Zhen Ming Hu, Hiromi Nakai, Hiroshi Nakatsuji

    Research output: Contribution to journalArticle

    43 Citations (Scopus)

    Abstract

    The mechanisms of the epoxidation and complete oxidation of propylene over a silver surface are studied by the dipped adcluster model (DAM) combined with the ab initio HF and MP2 methods. Several postulated reaction pathways involving both molecularly and atomically adsorbed oxygens are investigated. The energy diagrams of the epoxidation and complete oxidation of propylene on the silver surface are presented, and the detailed electronic mechanisms for the oxidation of propylene are clarified. The calculations show that the mechanism involving the single precursor intermediate common to both epoxidation and complete oxidation proposed in some literatures can be ruled out. Instead, the two competitive mechanisms are suggested: the epoxide formation is initiated by the reaction of the olefinic carbon with the adsorbed oxygen, while the combustion is initiated by the abstraction of the allylic hydrogen by the adsorbed oxygen. The former mechanism is essentially the same as that in the epoxidation of ethylene reported previously. The latter mechanism is energetically more favorable for propylene, which is a reason for the low selectivity of the epoxidation of propylene. The adsorbed allyl species, which is an intermediate in the latter mechanism, is demonstrated to exist in the form of chemisorbed anion. The mechanisms presented in this paper seem to be useful for explaining the epoxidation and complete oxidation of other olefins. A comparison with the previous studies is also presented.

    Original languageEnglish
    Pages (from-to)371-391
    Number of pages21
    JournalSurface Science
    Volume401
    Issue number3
    Publication statusPublished - 1998 Apr 10

    Fingerprint

    Epoxidation
    propylene
    Propylene
    epoxidation
    Oxidation
    oxidation
    Oxygen
    Silver
    oxygen
    Epoxy Compounds
    silver
    Alkenes
    Olefins
    Anions
    epoxy compounds
    Hydrogen
    Ethylene
    Negative ions
    Carbon
    alkenes

    Keywords

    • Ab initio Hartree-Fock (HF) and second-order Møller-Plesset (MP2) methods
    • Atomic oxygen
    • Catalytic activity of silver
    • Dipped adcluster model (DAM)
    • Epoxidation vs. complete oxidation
    • Olefins
    • Propylene
    • Superoxide

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Condensed Matter Physics
    • Surfaces and Interfaces

    Cite this

    Oxidation mechanism of propylene on an Ag surface : Dipped adcluster model study. / Hu, Zhen Ming; Nakai, Hiromi; Nakatsuji, Hiroshi.

    In: Surface Science, Vol. 401, No. 3, 10.04.1998, p. 371-391.

    Research output: Contribution to journalArticle

    Hu, Zhen Ming ; Nakai, Hiromi ; Nakatsuji, Hiroshi. / Oxidation mechanism of propylene on an Ag surface : Dipped adcluster model study. In: Surface Science. 1998 ; Vol. 401, No. 3. pp. 371-391.
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