8 research outputs found
Effects of impregnation solvent and reduction temperature on the catalytic performance of Pd/Al2O3 in the selective hydrogenation of 1,3-butadiene
Influence of the Support on the Catalytic Characteristics of the Deposited Palladium in the Liquid-Phase Hydrogenation of Diphenylacetylene
Improvement of propane oxidation activity over Pt/Al2O3 by the use of MIXED γ- and χ-Al2O3 supports
Influence of calcination temperature on the structure and properties of Al2O3 as support for Pd catalyst
Effect of the distribution and dispersion of palladium nanoparticles on the reducibility and performance of Pd/Al2O3 catalyst in liquid-phase hydrogenation of olefins
Promotion of Ceria Catalysts by Precious Metals: Changes in Nature of the Interaction under Reducing and Oxidizing Conditions
By depositing ceria over supported precious metal (PM) catalysts and characterizing them with in situ diffuse reflectance UV (DR UV) and in situ Raman spectroscopy, we have been able to prove a direct correlation between a decrease in ceria band gap and the work function of the metal under reducing conditions. The PM–ceria interaction results in changes on the ceria side of the metal–ceria interface, such that the degree of oxygen vacancy formation on the ceria surface also correlates with the precious metal work function. Nevertheless, conclusive evidence for a purely electronic interaction could not be provided by X-ray photoelectron spectroscopy (XPS) analysis. On the contrary, the results highlight the complexity of the PM–ceria interaction by supporting a spillover mechanism resulting from the electronic interaction under reducing conditions. Under oxidizing conditions, another effect has been observed, namely, a structural modification of ceria induced by the presence of PM cations. In particular, we have been able to demonstrate by in situ Raman spectroscopy that, depending on the PM ionic radius, it is possible to create PM–ceria solid solutions. We observed that this structural modification prevails under an oxidizing atmosphere, whereas electronic and chemical interactions take place under reducing conditions