Artículos SCI

This work is devoted to the study of the role of both metals in the intermetallic PtxCuy/ γ Al2O3 catalysts commonly employed in CO-PROX reaction. Therefore, monometallic Pt and Cu based catalysts and PtCu intermetallic compound with different molar ratios (Pt3Cu1 and Pt1Cu3) supported catalysts were carefully synthesized and deeply characterized. Room temperature CO adsorptions by FTIR spectroscopy were carried out on the mono- and intermetallic catalysts being the monometallic catalyst determinant for the study. From the analysis of the nature of the platinum surface in Pt/ γ Al2O3, we have demonstrated that the role of Pt sites is based in the CO dissociation for the CO2 formation and also how the platinum surface is partially blocked by leftovers from the synthesis. Moreover, the study of the Cu/ γ Al2O3 and the bimetallic catalysts PtxCuy/ γ Al2O3 allowed elucidating the effect of the copper in the metallic site and support interphase as well as the role of copper in the hydrocarbon oxidation.

Usually, nanoparticle synthesis methodologies require the use of organic molecules (capping agent, solvent molecules, etc.), which results in carbon deposits on the nanoparticle surface. These residues modify the surface properties mainly affecting the catalytic behavior. In this work, unsupported poly(vinylpyrrolidone) (PVP)-stabilized PtCu (1:3 molar ratio) bimetallic alloy nanoparticles were synthetized and characterized. An alternative surface cleaning method has been designed, which successfully removes the presence of organic fragments. To address this key issue, we have combined a first nanoparticle washing step with a near ambient pressure X-ray photoelectron spectroscopy (NAPXPS) study in order to obtain a clean active site and the total understanding of the carbon elimination mechanism. The dynamic evolution of the surface organic species composition under different gas mixtures at 750 mTorr and 350 degrees C has been studied, and only under CO2 exposure, NAPXPS analysis revealed a total availability of the active site by the removal of the organic nanoparticle coating.