The Polymerization of Acetylene on Pd Clusters

5 The Polymerization of Acetylene on Pd Clusters The Reactivity of Free Clusters 

Atomic metal ions are known to activate hydrocarbons as described, e.g., in the reviews by Schwarz and Schroder [471,472]. Cox and coworkers have also 

Although a lot of information on the stoichiometry of the intermediates has been obtained in the gas phase, the unambiguous assignment of neutral 

We now consider the influence of the support material on the reactivity of the three atoms. The experiments show that the coinage metal atom silver remains inert when deposited on the MgO surface and exposing this model system to 1 Langmuir of acetylene at 90 K and detecting benzene as function of temperature (Fig. 1.100). Thus, the electronic structure of Ag is not substantially changed even when trapped at an F center. Calculations 

the reaction on Pd/Fsc is rate limited in the last step, the conversion of (C4H4)(C2H2) into CeHe- This is different from the Pd(lll) surface where the rate determining step for the reaction is benzene desorption. The calculations are consistent with the experimental data. In fact, on Pdi/Fsc, the computed barrier of 0.98 eV corresponds to a desorption temperature of about 300K, as experimentally observed (Fig. 1.100). On Pd (111) surfaces, the bonding of benzene is estimated to be 1.9eV. This binding is consistent with a desorption temperature of 500 K as observed for a low coverage of CeHe on Pd(lll) [489], 

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