Síntesis de nano-Au soportados en óxidos metálicos y su actividad catalítica en reacciones de oxidación de CO

Gold nanoparticles, Nano-Au, were prepared on different supports and used as CO oxidation catalysts. Synthesis of Nano-Au, supported on TiO 2, CeO 2 and �-Al 2O3 was done by precipitation in non-aqueous HAuCl 4/ethylene-glycol in a Li 2S/oxide/ethylene-glycol suspension in a minimum HClO 4 volume. All the nano-structured systems were characterized by TEM, XPS, XRD, AE, ICP and UVVisible methods. The TEM images confirm Nano-Au/ oxide formation on all the supports. Particle size distribution analysis suggest different dispersions, being Au/Al 2O3 (~3,45 nm) the least dispersed system. XRD analysis shows the presence of Au/oxide, compared with the XRD standard, and crystal size was estimated using the Debye-Scherrer equation. UV-visible spectra shows a characteristic band near 520 nm, due to plasmon resonance in all the synthetized systems and there was no clear tendency between particle size and the absorption band displacement. XPS analysis shows two peaks with a slight displacement in bonding energy, assigned to the Au4 f7/2 y Au4 f5/2 transitions due to Au(0) and Au 3+ from Au 2S3. The CO oxidation catalytic activity of Nano-Au was done in a static bed reactor at low temperature, obtaining a 36% conversion with Au/TiO 2.