Origin of vinylic C-H bond activation in the combustion of alkenes on palladium: an HREELS study of propene on Pd(100)-p(2x2)-O

SURFACE SCIENCE

卷:391

Letter

Guo, XC ; Madix, RJ

关键词: combustion;    electron energy-loss spectroscopy;    oxidation;    oxygen;    palladium;    propene;    reaction mechanism;    single crystal surface;   

DOI  :  10.1016/S0039-6028(97)00574-8

来源: Elsevier

【 摘 要 】

While the mechanism of many reactions with oxygen on Ag(110) can be successfully predicted according to the gas-phase acidity of the reacting molecule, recent temperature-programmed reaction spectroscopic study of propene reactions with oxygen on Pd(100) reveals that the most reactive C-H bond is the vinylic rather than the most acidic, allylic, C-H bond. Using vibrational spectroscopy it is found that two forms of propene species exist on the surface al 130 K: a pi-bonded stale and a di-sigma-bonded state. The former desorbs molecularly upon heating, while the latter undergoes combustion. In the di-sigma-bonded state, the sp(3) rehybridization strongly reduces the acidity from its gas-phase value, rendering the methyl hydrogens unreactive. The mechanism for the combustion of propene is proposed. (C) 1997 Elsevier Science B.V.

【 授权许可】

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