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Chen X.,Ingenieria Metalurgica y Quimica Inorganica | Delgado J.J.,Ingenieria Metalurgica y Quimica Inorganica | Gatica J.M.,Ingenieria Metalurgica y Quimica Inorganica | Zerrad S.,Ingenieria Metalurgica y Quimica Inorganica | And 2 more authors.
Journal of Catalysis | Year: 2013

The promoting effect of a Ce0.80Tb0.20O 2-x mixed oxide on the catalytic behavior of a Ru supported on a commercial alumina catalyst for preferential CO oxidation in the presence of excess hydrogen reaction (PROX) has been investigated. Ru supported on this alumina and ceria-terbia mixed oxide has also been studied as reference systems. N2 physisorption, X-ray diffraction, high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), CO and H 2 chemisorption, and diffuse reflectance infrared Fourier transform have been used to characterize these Ru catalysts. The Ru/Ce 0.80Tb0.20O2-x-Al2O 3 catalyst resulting from the modification of the Ru/Al 2O3 sample with the ceria-terbia mixed oxide exhibits higher activity for PROX reaction and wider working temperature window than Ru/Al2O3 and Ru/Ce0.80Tb0.20O 2-x samples. This remarkable behavior is due to the simultaneous occurrence of CO oxidation and CO hydrogenation to methane on the former catalyst. Moreover, Ru/Ce0.80Tb0.20O 2-x-Al2O3 catalyst is the most active catalyst under the ideal PROX feed. It also shows high activity in presence of CO2 and H2O. The CO methanation also has been performed over Ru/Ce0.80Tb0.20O2- x-Al2O3 catalyst. The hydrogen concentration in the PROX feed has been varied in order to study the effect of hydrogen on PROX activity. The PROX reaction and transient experiment have been carried out using in situ diffuse reflectance infrared Fourier transform technique. The combination of Ru nanoparticles and the promotion effect of ceria-terbia are attributed to the unique performance of PROX reaction over Ru/Ce 0.80Tb0.20O2-x-Al2O 3 catalyst. © 2012 Elsevier Inc. All rights reserved. Source


Del Rio E.,Ingenieria Metalurgica y Quimica Inorganica | Gaona D.,Ingenieria Metalurgica y Quimica Inorganica | Hernandez-Garrido J.C.,Ingenieria Metalurgica y Quimica Inorganica | Calvino J.J.,Ingenieria Metalurgica y Quimica Inorganica | And 4 more authors.
Journal of Catalysis | Year: 2014

On the basis of calculated thermodynamic species distribution diagrams and by appropriately controlling the pH of aqueous HAuCl4 solutions, it has been possible to prepare, using a Speciation-controlled Incipient Wetness Impregnation (ScIWI) approach, Au catalysts supported on ceria-zirconia mixed oxides featuring both high gold loadings and excellent metal dispersions. This rational synthesis method is carried out at room temperature. It is both much simpler, in equipment terms, and less expensive than widely used Deposition-Precipitation (DP). Moreover, the use of ScIWI allows overcoming the severe limitations of previously assayed impregnation methods. With this procedure it is possible to prepare active catalysts in CO oxidation with high efficiency in terms of gold precursor usage, i.e. minimizing Au losses during synthesis. Therefore this, quite amenable, novel strategy for the facile preparation of highly dispersed supported gold catalysts gathers the necessary requirements for both its use at lab scale and an easy scaling-up to industrial levels. © 2014 Elsevier Inc. All rights reserved. Source

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