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The adsorption and reaction of trans-1,2-dichloroethene on CuPd(110) have been studied using molecular beam adsorption reaction, temperature-programmed desorption, reflection absorption infrared, high-resolution electron energy loss, and X-ray photoelectron spectroscopies. Below 165 K, the molecules adsorb intact at all coverages with their molecular planes orientated largely parallel to the metal surface. Above 165 K, decomposition is observed initially on adsorption, but is limited by availability of surface sites and stablisation effects of coadsorbed Cl. Between 300 and 350 K the main desorbing decomposition products are H2 and C2H2, while only H2 is produced between 350 and 675 K. Above 675 K evolution of HCl is observed. The decomposition of the hydrocarbon skeleton occurs mainly at Pd sites, while dechlorination is catalysed at Cu sites with Cl preferentially binding to the Cu atoms. This leads to dynamic changes in surface composition of the alloy with segregation of underlying Cu atoms to the surface that scavenge the Cl atoms and thus help to keep the Pd sites Cl free. [Copyright &y& Elsevier]

The adsorption and reaction of trans-1,2-dichloroethene on Cu nanoclusters supported on a thin Al2O3 film grown on NiAl(110) have been studied as a function of temperature and Cu cluster size using molecular beams and temperature-programmed desorption. At 300 K, dechlorination is observed on clusters of all sizes; subsequent desorption yields benzene and acetylene as the main reaction products. The ratio of these is strongly dependent on cluster size; for small clusters only acetylene evolution is observed. With increasing cluster size the probability of trimerisation of acetylene to produce benzene increases, although the desorption of acetylene remains dominant. The adsorption and reaction are compared to previous work on a Cu(110) single crystal where benzene was the main desorption product after adsorption at 300 K. The cluster size-dependent yield of desorption products is attributed to the inability of small clusters to accommodate the dissociation products prior to the trimerisation reaction. [Copyright &y& Elsevier]