Probing reaction pathways on model catalyst curfaces: Vinyl acetate synthesis and olefin metathesis

TYSOE, WILFRED T.; GAO, FENG; WANG, YILIN; CALAZA, FLORENCIA C.; STACCHIOLA, DARIO J.

San Francisco, CA

Conferencia; 232nd ACS National Meeting; 2006

American Chemical Society

Surface science strategies are used to understand catalytic reaction pathways on model single crystal catalysts. The pathway for the synthesis of vinyl acetate from ethylene acetic and oxygen is explored on a Pd(111) single crystal, where it is shown that vinyl acetate is synthesized by reaction between ethylene and an acetate species to form a acetoxyethyl intermediate, which decomposes via a ¦Â-hydride elimination reaction to form vinyl acetate. The olefin metathesis pathway is studied on a MoAl alloy grown on a planar alumina substrate in ultrahigh vacuum, where carbene species grafted onto the surface from methylene iodide react with adsorbed ethylene to yield a cross metathesis products via a metallacyclic intermediate, in accord with the H¨¦risson-Chauvin mechanism.