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• Copper dispersion on a rod-shaped ceria was examined with respect to copper loading. • Monolayer and bilayer copper clusters were dominate at copper loading of less than 15 mol.%. • Multi-layered copper clusters and faceted nanoparticles were formed at higher copper loadings. • The active copper-ceria interface was constructed by the positively-charged copper atoms with the oxygen vacancies on ceria. • The WGS activity increased linearly with copper loading up to 15 mol.%. Cu species in the forms of layers, clusters and particles were dispersed on a rod-shaped ceria by a deposition-precipitation method and the resulting Cu/CeO 2 catalysts were tested for the low-temperature water-gas shift reaction. The structural, chemical and surface properties of the Cu/CeO 2 catalysts were analyzed by spectroscopic and microscopic techniques. It was identified that dispersion of copper on the rod-shaped ceria strongly depended on the metal loading (1–28 mol%): lower contents resulted in copper monolayers and/or bilayers while higher loadings led to multi-layered clusters and faceted particles. The copper-ceria interface was constructed by an intimate bonding of positively-charged copper atoms with oxygen vacancies on ceria, in a form of Cu+-O v -Ce3+, involving the electronic and geometric interactions between the copper atoms in the metal species and the oxygen vacancies on ceria. The overall activity increased linearly with the copper content in the range of 1–15 mol%, contributed mainly by copper monolayers and/or bilayers. Further increasing Cu loading up to 28 mol% only slightly enhanced the activity because of the presence of multilayered and crystalline Cu particles. This finding demonstrates that the dispersion of copper on the rod-shaped ceria depends on the loading of copper in the Cu/CeO 2 catalysts, which is associated with the number and density of the active sites. [ABSTRACT FROM AUTHOR]

Abstract: The sorptive and catalytic properties of alumina supported Cu nanoparticles coated with a thin film of 1-butyl-2,3-dimethyl-imidazolium trifluoromethane sulfonate (BDiMIm) for low-temperature water–gas shift have been explored. For uncoated catalysts, the rate per gram catalyst passed through a maximum with increasing concentration of oxygen on the Cu surface. For reduced catalysts, the presence of oxygen facilitates the dissociation of water, while in excess it decreases the reaction rates due to limiting the reactant concentration. Catalysts coated with ionic liquid showed a higher turn over frequency for the water–gas shift reaction at low temperatures compared to uncoated catalysts and to the best commercial systems, which is attributed to a higher concentration of water in the proximity of the active sites and to the facile decomposition of carboxyl intermediates by the interaction with the ionic liquid. In addition, the presence of the ionic liquid reduces the sorption strength of CO leading to a better balance of the reactants at the surface. [Copyright &y& Elsevier]