Artículos, informes y presentaciones en Congresos



Envíos recientes

Mostrando 1 - 5 de 22
  • Producción de bioaditivos y biosurfactantes con aplicación en la industria de los combustibles
    ( 2020) Casella, Mónica Laura
    El interés de este proyecto es generar aditivos oxigenados a base de glicerol y furfural, los cuales son biodegradables, no tóxicos y renovables. Los aditivos para combustibles son sustancias que se agregan o mezclan con combustibles, especialmente gasolina, diesel o biodiesel, para mejorar sus propiedades combustibles y lograr un mejor rendimiento. El agotamiento de los combustibles fósiles ha intensificado la investigación y la utilización de combustibles renovables, entre ellos el biodiesel. En el proceso de producción de biodiesel, por cada 100 kg de biodiesel producido, se generan 10 kg de glicerol. En vista de las características y potenciales del glicerol, se están incrementando los esfuerzos para convertirlo en productos de mayor valor, lo que a su vez mejorará la economía general de la producción de biodiesel. Por otra parte, la renovabilidad y abundancia de biomasa lignocelulósica la convierten en un recurso viable para la producción de plataformas químicas como el furfural. Actualmente, el furfural se produce industrialmente mediante la hidrólisis ácida de biomasa de origen agrícola. Se propone el acoplamiento de furfural con glicerol para producir el 1,3-dioxolano en condiciones catalíticas y sin solventes. Los 1,3-dioxolanos pueden ser utilizados como aditivos de combustible.
  • Ultrasound Assisted Electrodeposition of Cu-SiO2 Composite Coatings: Effect of Particle Surface Chemistry
    ( 2019) Bengoa, Leandro N. ; Ispas, A. ; Bengoa, José Fernando ; Bund, A. ; Egli, Walter Alfredo
    Electrodeposition of Cu-SiO2 composite coatings from an alkaline non-cyanide electrolyte containing glutamate as complexing agent was studied. Silica mesoporous particles were synthesized using a modified Stöber methodology, and later their surface chemistry was changed by functionalizing them with 3-aminopropyltriethoxysilane. Particles microstructure and morphology were characterized (SEM, TEM, XRD) and their charging behavior in several electrolytes was studied through ζ -potential measurements. Galvanostatic deposition was performed in electrolytes containing both as-prepared and functionalized SiO2 at various current densities, and the influence of ultrasonic irradiation (37 Hz) was evaluated. For some experiments, 1.5 g L− of Polyquaternium 7 were added to the solution. SEM and XRD were used to characterized coatings morphology and microstructure, whereas EDS was used to estimate SiO2 wt%. The results showed that the effect of ultrasound on the codeposition process depends on current density and particle surface chemistry. All the trends observed in this study could be explained taking into account ζ -potential values recorded and previously reported theories. Adjusting the experimental conditions, it was possible to obtain deposits with SiO2 contents of ≈5 wt%. Finally, it was found that both ultrasonic irradiation and Polyquaternium 7 affect the morphology and crystal orientation of the deposits.
  • Preparation and characterization of a supported system of Ni2P/Ni12P5 nanoparticles and their use as the active phase in chemoselective hydrogenation of acetophenone
    ( 2018) Costa, Dolly Carolina ; Soldati, Analía L. ; Pecchi, Gina ; Bengoa, José Fernando ; Marchetti, Sergio Gustavo ; Vetere, Virginia
    Ni2P/Ni12P5 nanoparticles were obtained by thermal decomposition of nickel organometallic salt at low temperature. The use of different characterization techniques allowed us to determine that this process produced a mixture of two nickel phosphide phases: Ni2P and Ni12P5. These nickel phosphides nanoparticles, supported on mesoporous silica, showed activity and high selectivity for producing the hydrogenation of the acetophenone carbonyl group to obtain 1-phenylethanol. This is a first report that demonstrates the ability of supported Ni2P/Ni12P5 nanoparticles to produce the chemoselective hydrogenation of acetophenone. We attribute these special catalytic properties to the particular geometry of the Ni–P sites on the surface of the nanoparticles. This is an interesting result because the nickel phosphides have a wide composition range (from Ni3P to NiP3), with different crystallographic structures, therefore we think that different phases could be active and selective to hydrogenate many important molecules with more than one functional group.
  • Phosphorus as a promoter of a nickel catalyst to obtain 1-phenylethanol from chemoselective hydrogenation of acetophenone
    ( 2019) Costa, Dolly Carolina ; Soldati, Analía Leticia ; Bengoa, José Fernando ; Marchetti, Sergio Gustavo ; Vetere, Vicente
    Two catalysts were prepared using monodisperse pre-synthetized nanoparticles of metallic nickel and nickel phosphides with the same average diameter. Both nanoparticles species were deposited on the same support: mesoporous silica nano-spheres of MCM-41. This support is suitable to inhibit agglomeration and sintering processes during preparation steps. Therefore, two supported and activated catalysts with the same average nanoparticles diameter were obtained. They differ only in the nature of the active species: metallic nickel and nickel phosphides. The effect of the presence of a second element (phosphorus), more electronegative than nickel, on the activity and selectivity in the chemoselective hydrogenation of acetophenone was studied. The reaction conditions were: H2 pressure of 1 MPa, 80°C using n-heptane as solvent. With the aim to understand the catalytic results, nanoparticles, support and catalysts were carefully characterized by X-ray diffraction, diffuse light scattering, transmission electron microcopy, high resolution transmission electron microcopy, selected area electron diffraction, scanning electron microcopy, Fourier transformer infrared spectroscopy, N2 adsorption at -196 °C, atomic absorption, H2 and CO chemisorption and volumetric oxidation. Considering these results and geometric and electronic characteristics of the surface of both active species, a change in the adsorption intermediate state of acetophenone in presence of phosphorus is proposed to explain the hydrogenation chemoselectivity of nickel phospides
  • Zirconia-Supported Silver Nanoparticles for the Catalytic Combustion of Pollutants Originating from Mobile Sources
    ( 2019) Montaña, Maia ; Leguizamón Aparicio, María Silvia del Valle ; Ocsachoque, Marco ; Navas, Marisa B. ; Barros, Ivoneide de C. L. ; Rodríguez-Castellón, Enrique ; Casella, Mónica Laura ; Lick, Ileana D.
    This work presents the physicochemical characterization and activity of zirconia-supported silver catalysts for the oxidation of pollutants present in diesel engine exhaust (propane, propene, naphthalene and soot). A series of silver-supported catalysts AgxZ (x = 1, 5 and 10 wt.%, Z = zirconia) were prepared, which were studied by various characterization techniques. The results show that silver is mainly found under the form of small metal nanoparticles (<10 nm) dispersed over the support. The metallic phase coexists with the AgOx oxidic phases. Silver is introduced onto the zirconia, generating Ag–ZrO2 catalysts with high activity for the oxidation of propene and naphthalene. These catalysts also show some activity for soot combustion. Silver species can contribute with zirconia in the catalytic redox cycle, through a synergistic effect, providing sites that facilitate the migration and availability of oxygen, which is favored by the presence of structural defects. This is a novel application of the AgOx–Ag/ZrO2 system in the combustion reaction of propene and naphthalene. The results are highly promising, given that the T50 values found for both model molecules are quite low.