Nanopartículas de Au, Nano-Au, fueron preparadas sobre diversos soportes y usadas como catalizadores para oxidación de CO. La síntesis de Nano-Au, soportadas sobre TiO2, CeO2 y γ-Al2O3, se realizó por precipitación en medio no acuoso de HAuCl4/etilenglicol en una suspensión Li2S/óxido/etilenglicol y un mínimo volumen de HClO4. Todos los sistemas nanoestructurados fueron caracterizados por TEM, XPS, XRD, AE, ICP y UV-Visible. Las imágenes TEM confirmaron la formación de Nano-Au/óxido, para todos los soportes. El análisis de la distribución de tamaño de partícula sugiere distintas dispersiones, siendo Au/Al2O3 (~3,45 nm) la que mostró una menor dispersión. A través de XRD se determinó la presencia de Au/óxidos, comparando con un patron XRD y se estimó el tamaño de cristal con la ecuación de Debye-Scherrer. El análisis del espectro UV-Visible muestra una banda de absorción característica cerca de 520 nm, debido a la resonancia de plasmón en todos los sistemas sintetizados y no se observó una tendencia clara entre el tamaño de partícula y el dezplazamiento en la absorbancia de dichas bandas. El análisis de XPS mostró dos señales, con ligeros desplazamientos en la energía de enlace, debidas a las transiciones Au4f7/2 y Au4f5/2, que indica la presencia de Au(0) y Au3+ como Au2S3. La actividad catalítica de las Nano-Au en reacciones de oxidación de CO, se realizó en un reactor de lecho fijo a baja temperatura, observándose sólo conversión con Au/TiO2 de hasta un 36%.

Gold nanoparticles, Nano-Au, were prepared on different supports and used as CO oxidation catalysts. Synthesis of Nano-Au, supported on TiO2, CeO2 and γ-Al2O3 was done by precipitation in non-aqueous HAuCl4/ethylene-glycol in a Li2S/oxide/ethylene-glycol suspension in a minimum HClO4 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/Al2O3 (~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 Au4f7/2 y Au4f5/2 transitions due to Au(0) and Au3+ from Au2S3. The CO oxidation catalytic activity of Nano-Au was done in a static bed reactor at low temperature, obtaining a 36% conversion with Au/TiO2.

Con la vista puesta en la reducción de azufre en diesel, fueron sintetizados catalizadores bimetálicos NiMo novedosos, soportados y en bulk, usando agentes directores de estructura. Dichos materiales fueron modificados durante el protocolo de calcinación, con el fin de obtener sistemas nanoestructurados. Todos los catalizadores fueron caracterizados usando diversas técnicas análisis elemental, análisis químico, microscopía de transmisión, microscopía de barrido, isotermas adsorción-desorción de N2, difracción de rayos-X, espectroscopía de fotoelectrones, dinamic light scatering y RAMAN. La presencia de CTAB, como agente director de estructura, permitió obtener materiales nanoestructurados, con tamaños de partículas entre 5 y 50 nm. Los materiales producidos son s NiMoSxCy de alta área superficial, que cuando son sujetos a una oxidación “suave” permite obtener nanoestructuras con un mínimo de sinterización. La actividad catalítica de todos los sustratos en la reacción de HDS, fue determinada en un reactor de lecho fijo a tres temperaturas 320, 360 y 400 °C, 40 bar de presión de H2, WHSV = 39 h-1 y 3h de reacción. El alimento para la reacción de HDS se preparó considerando el “efecto matriz”, de manera que estaba constituido por parafinas (60%), olefinas (30%), hidrocarburos aromáticos (10%) y sulfurados (470 ppm). Estos últimos constituidos por sulfuros muy refractarios presentes en el diesel tal como DBT (100 ppm) y 4,6-DMDBT (100 ppm).Todos los materiales sintetizados presentaron actividad en la reacción de HDS (400 °C, 3h), alcanzándose altas conversiones, pero favoreciendo al sustrato menos refractario DBT.

With a view to reducing the sulfur content in diesel fuels, were synthesized bimetallic catalysts novel NiMo catalysts, supported and unsupported, using structure-directing agents. The above mentioned materials were modified during the protocol of calcinations, in order to obtain nanostructured systems. All catalysts were characterized using several techniques CHNS-O, ICP-OES, TEM, SEM, EDX, N2 adsorption-desorption isotherms (BET), XRD, XPS, DLS and RAMAN. The presences of CTAB, as structure-directing agents, lead to nanostructured materials, with size of particle between 5 y 50 nm. The produced materials are hybrid NiMoSxCy the high surface area, which when they are subject to a “soft” oxydation leads to obtain nanostructured with minimum of sinterization. The catalytic activity of all substrates in HDS`s reaction, was determined in a flow fixed bed reactor at three temperatures 320, 360 y 400 °C, 40 bar of pressures of H2, WHSV = 39 h-1 and 3h for reaction time. The feedstock for HDS´s reaction was prepared considering “the matrix effect”, so that is was constituted by paraffin’s (60%), olefins (30%), and aromatic hydrocarbons (10%), and sulfur compounds (470 ppm). These last compounds constituted by very refractory species present in the fuel diesel as DBT (100 ppm) and 4,6-DMDBT (100 ppm). All the synthesized materials presented activity in the HDS reaction of (400 °C, 3h), conversions being reaching high conversions, favoring the least refractory DBT substrates.

The void structure of zeolites MCM-22, MCM-36 and ITQ-2 were discussed on the bases of catalytic reaction tests. The hydromerization of n-decane on bifunctional Pt/Zeolite Catalysts have been used as model reactions. Beta and ZSM-5 zeolites were used for comparison. It is concluded that all materials show features of 10MR zeolites and have also pores bigger than 12MR in this order MCM-22<MCM-36<ITQ-2.

The layered precursor of MCM-22 was prepared with different Si/Al ratios: 15, 25, 50, 100 and ¥. Upon heat treatment these precursors form MCM-22 zeolite. Both layered precursor and MCM-22 zeolite were characterized by several techniques: Chemical Analysis by Atomic Absorption Spectroscopy (AAS), X-Ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Pore Analysis by N2 and Ar adsorption, Scanning Electron Microscopy (SEM), Infrared Spectroscopy (IR) and Temperature Programmed Desorption of ammonium (TPD).

The structure of several types of layered materials will be described. These include clays, layered double hydroxides, group IV metal phosphates and other layered materials. The preparation of the pillared materials and pillaring agents will be presented along with a description of the properties and applications of the products.

Montmorillonite clay from Brazil was pillared with aluminium polyhydroxications. The influence of Al/Mont ratio and calcination temperature in the properties of the prepared materials was studied. Results showed that the pillarization process increases the basal spaces of the natural clay from 9,7 to 18,5Å and the superficial area from 41 to ~230m2/g. The calcination process at different temperatures showed that the pillared material was stable until 600oC but the adequate temperature for calcination was 450oC. Materials prepared with different Al/Mont ratios showed the maximum Al incorporation for ratios >10meq Al/g and a good distribution for rations >15meq Al/g.