A series of Pt x -Sn y /C catalysts with different atomic ratios (x:y = 1:1, 2:1, 3:1) and diameters (~4 nm) were easily synthesized by a deposition process using formic acid as the reducing agent.Catalyst structure and chemical composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). XRD and SEM showed that the geometric environment was changed with Sn addition to the fcc Pt crystallites by forming a solid solution of Pt-Sn alloy phase for Pt 1 -Sn 1 /C catalyst, while for Pt 3 -Sn 1 /C and Pt 2 -Sn 1 /C, a decrease in Pt 4f binding energy was observed, and from the XPS results was attributed to charge transfer from Sn to Pt.From TEM results, it could be seen that Pt nanoparticles could be easily synthesized, even at a high metal load, without the use of expensive surfactants. The electrochemical behavior of catalysts during ethanol oxidation in acidic media was characterized and monitored in a half-cell test at room temperature by cyclic voltammetry, chronoamperometry, and anode potentiostatic polarization. The amount of Sn added affected the physical-chemical characteristics of the bimetallic catalysts; however, these catalysts did not show differences in the electrocatalytic activity towards ethanol oxidation. The presence or absence of alloy was a function of the Sn content on catalysts for the preparation method used. The behavior presented for Pt x -Sn y /C catalysts can be attributed to the so-called bifunctional mechanism, and to the electronic interaction between Pt and Sn.

A new single-phase copper chromate compound was successfully synthesized by a hydrothermal method and characterized by XRD, SEM, TGA, and XRF analysis. The experimental XRD pattern was analyzed by automatic indexing and the compound was found to be monoclinic with space group P2 1 / a and unit-cell parameters of a = 10.1829͑11͒ Å, b = 4.9516͑6͒ Å, c = 7.2899͑7͒ Å, and ␤ = 103.64͑1͒°. The chemical formula of the copper chromate compound determined by XRF and TGA was determined to be ͑NH 4 ͒ 1.5 Cu 2 Cr 2 O 8 ͑OH͒ 1.5 ·H 2 O. XRD results also showed that the synthesized compound decomposed into CuCr 2 O 4 and CuO after being calcined at 600°C. © 2009 International Centre for Diffraction Data.

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En el presente trabajo se sintetizaron dos materiales trimetálicos tipo hidrotalcita usando Ni, Zn, Mg yFe. Posteriormente, dichos materiales se modificaron con especies de V y Cr. Los materiales obtenidos secaracterizaron por espectroscopía de absorción atómica, difracción de rayos X, análisis termogravimétrico(ATG) y análisis térmico-diferencial (ATD). Mediante ATG se determinó una temperatura de calcinaciónde 500ºC para la obtención de los óxidos mixtos los cuales se evaluaron en la reacción de deshidrogenaciónoxidativa de propano (DHOP) usando una velocidad espacial de 50 ml/g.min , obteniéndose el mejor resultadopara el sistema NiMgFe con un rendimiento del 5.13% y una selectividad hacia el propeno del 34.35%, a unatemperatura de 400ºC