Ethylene hydrogenation mechanism on the Pt(111) surface. Theoretical determination

Journal Article · Thu Aug 10 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100353a039· OSTI ID:7197308

Anderson, A B; Choe, S J ^[1]

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1. Case Western Reserve Univ., Cleveland, OH (USA)

A (2 {times} 2) ethylidyne overlayer has been observed before and after ethylene hydrogenation to ethane over Pt(111) by Somorjai and co-workers. The role of ethylidyne in this catalytic process has been a topic of uncertainty. In his ASED-MO study it is shown that steric interactions prevent ethylene from approaching the ethylidyne-covered surface but ethylidyne can readily shift laterally to new sites and open up space for ethylene to approach and be hydrogenated by the surface platinum hydride. Hydrogenation by the {alpha}-H of surface ethylidene, which has been postulated to be a hydrogenation intermediate, is found to proceed with a higher activation energy, forming nonadsorbed ethyl radicals. The higher activation energy and the formation of ethyl radicals are inconsistent with experimental results. Furthermore, ethylidene is predicted to have insufficient stability to be present in substantial concentrations on the surface. It is shown that ethylidene can readily exchange {beta}-H with the surface, but {beta}-H exchange is very slow in the experimental studies. From these results it is concluded that ethylidene plays no substantial role in ethylene hydrogenation.

• OSTI ID: 7197308
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:16; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
100300 -- Synthetic Fuels-- Properties & Composition-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000* -- Chemistry
400201 -- Chemical & Physicochemical Properties
ALKANES
ALKENES
CALCULATION METHODS
CATALYSTS
CHEMICAL REACTIONS
DATA
ELEMENTS
ETHANE
ETHYLENE
HYDROCARBONS
HYDROGENATION
INFORMATION
MATHEMATICAL MODELS
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM
PLATINUM METALS
THEORETICAL DATA
TRANSITION ELEMENTS