Surface reaction pathways are explored on model single crystal catalyst surfaces using a combination of surface science experiments in ultrahigh vacuum, in-situ monitoring of the surface intermediates during reaction, and by using density functional theory (DFT)  calculations.  This approach enables detailed reaction pathways to be obtained and is illustrated using palladium- and palladium-gold alloy catalyzed synthesis of vinyl acetate monomer (VAM).  It is shown that vinyl acetate is formed on a Pd(111) model catalyst via the so-called Samanos pathway, where reaction is initiated by coupling between ethylene and surface acetate species to form an acetoxyethyl intermediate that decomposes by �-hydride elimination to form VAM.  The way in which adsorbate coverage affects both reactivity and selectivity is discussed.  Gold-palladium alloys are found to improve the selectivity of the commercial catalyst.  The origins of the catalytic selectivity and activity of the alloys are also investigated by exploring reactions on well-characterized Au/Pd(111) and Au/Pd(100) model alloys.

Vinyl acetate formation pathways and selectivity on model metal and alloy catalyst surfaces

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.