UTN- FRC -Producción Académica de Investigación y Desarrollo - Artículos
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Item Ga-SBA-3 A novel nanostructured material: synthesis, characterization and application(IOP Publishing, 2019) Martínez, María Laura; Gómez Costa , Marcos Bruno; Anunziata, Oscar AlfredoThis paper reports for the first time the incorporation of gallium into the structure of the mesoporous SBA-3 material in order to modify the intrinsic acidity of the material. The study indicates the effective incorporation of Ga into a network in tetrahedral form, with most in the interior of the lodging and a low proportion on the external surface. Gallium was introduced via post-synthesis using Ga-nitrate in appropriate conditions. The nanostructured material was characterized by ICP, x-ray diffraction, nuclear magnetic resonance-MAS, x-ray photoelectron spectra, FTIR, SEM, transmission electron microscopy and UV–vis. Pyridine was used as a probe molecule for the determination of its acidity following the amount and type of acidic sites by FTIR. In addition, aniline adsorption/desorption studies and subsequent in situ polymerization, polyaniline (PANI)/Ga-SBA-3, were carried out with the aim of producing a nanocomposite with conductive properties. The original material had good structural regularity and acidity of Brønsted and Lewis; the PANI/Ga-SBA-3 composite also showed a conductivity of 2.5 × 10−3 S cm−1, higher than that of its homologs Al-SBA-3 and Al-MCM- 41.Item Direct synthesis of ordered mesoporous carbon applied in hydrogen storage(Springer Science+Business Media, 2018) Juárez, Juliana María; Gómez Costa , Marcos Bruno; Anunziata, Oscar AlfredoIn this work, we present a direct, novel and low cost method for the preparation of an ordered mesoporous carbon (OMC). OMC was successfully synthesized by the carbonization of the silica/triblock copolymer/sucrose composite in the presence of sulfuric acid. The resulting material was characterized by XRD, N2 sorption analysis and TEM techniques. The novel synthesis technique improved significantly the H2 storage properties (3.78 wt%) compared with that of CMK-3 synthesized using the nanocasting strategy (2.2 wt%) at 77 K and 10 bar.Item Influence of vanadium nanoclusters in hydrogen uptake using hybrid nanostructured materials(Springer Science+Business Media, 2018) Juárez, Juliana María; Gómez Costa , Marcos Bruno; Martínez, María Laura; Anunziata, Oscar AlfredoIn this work, we report the synthesis and characterization of vanadium oxide nanoclusters (V2O5) supported in silica nano- structured material (SBA-15) and nanostructured carbon (CMK-3). This material is promising in hydrogen adsorption and storage application for energy harvesting. The materials with vanadium oxide nanoclusters (VxOy-SBA-15 and VxOy-CMK-3) were successfully synthesized and characterized by X-ray diffraction, textural properties, UV–Vis-DRS, X-ray photoelec- tron spectroscopy, temperature programmed reduction and transmission electron microscopy analyses. VxOy-SBA-15 and VxOy-CMK-3 improved significantly the H2 storage behavior (1.33 wt% and 3.43 wt% at 77 K and 10 bar) compared with their respective supports SBA-15 and CMK-3. The materials synthesized are promising in hydrogen uptake by weak link forces (physisorption). A mechanism of hydrogen adsorption was proposed and V5+ cation roll in hydrogen uptake was discussedItem Síntesis y caracterización del material nanoestructurado Fe-CMK-3 utilizado en almacenamiento de hidrógeno(Sociedad Argentina de Catálisis, 2019) Venosta, Lisandro F.; Juárez, Juliana María; Gómez Costa , Marcos Bruno; Anunziata, Oscar AlfredoEn este trabajo, informamos la síntesis y caracterización de nanoclusters de óxido de hierro soportados en el carbón nanoestructurado (CMK-3). Este material es prometedor en la aplicación de almacenamiento y adsorción de hidrógeno para almacenamiento de energía. Los materiales con nanoclusters de óxido de hierro (Fe-CMK-3) se sintetizaron exitosamente y se caracterizaron mediante difracción de rayos X, propiedades texturales y análisis de microscopía electrónica de transmisión. La incorporación de oxidos de hierro mejoró significativamente el comportamiento de almacenamiento de H2 (4,45% en peso a 77K y 10 bar) en comparación con su respectivo soporte (CMK-3). El material sintetizado es prometedor en la adsorción de hidrógeno por fuerzas de enlace débil (fisisorción). Se propuso un mecanismo de adsorción de hidrógeno y los nanoclusters de óxido de Fe en fase de magnetita tienen un rol importante en la absorción de hidrógeno.Item Tetralin hydrogenation and ring opening of decalin over Ir-Pt-SBA-15(CICat, 2014) Vallés, Verónica Alejandra; Rivoira, Lorena Paola; Ledesma, Brenda Cecilia; Cussa, Jorgelina; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelA series of Ir and Pt modified SBA-15 were prepared by the consecutive wet impregnation method, with different content of each metal. The final catalysts were characterized by XRD, TEM and H2 chemisorption to study the effect of content of metal on the dispersion of iridium/platinum. The catalysts synthesized with similar percentage of both metals showed the best activity measured in tetralin hydrogenation and ring opening of decalin at mild conditions.Item Fe-CMK-3 nanostructured material applied in hydrogen uptake J.(Catalysis Society of Australia, 2019) Juárez, Juliana María; Gómez Costa , Marcos Bruno; Anunziata, Oscar AlfredoAll over the world in the past decades, one of the most concerning subjects has been fossil fuel reduction, along with the global warming issue. These concerns have made hydrogen an ideal alternative to conventional fossil-fuel resources. Nevertheless, it has serious disadvantages, such as low volumetric and gravimetric densities that limit its storage [1]. One kind of OMC involves the carbon mesostructured from Korea (CMK). CMK-3 was chosen as a support material for hydrogen storage due to its large surface area, high chemical stability, uniform pore diameter, accessible porosity and three-dimensional conducting network [2]. Metal particles dispersed in the porosity of active carbons are largely contributing to enhanced storage abilities. In this work we studied the influence of the incorporation of iron nanoparticles inside the channels of CMK-3. This could help and make it possible storing hydrogen in carbon and silica matrix but with another mechanism, with a better reversibility improving hydrogen adsorption/desorption behavior.Item Nanoclusters of iron oxice included in CMK-3mesoporous carbon use as hydrogen storage material(Materials Research Society, 2019) Juárez, Juliana María; Venosta, Lisandro F.; Gómez Costa , Marcos Bruno; Anunziata, Oscar AlfredoIn this work we studied the influence of the incorporation of iron oxide nanoparticles inside the channels of the nanostructured mesoporous carbon CMK-3. This research includes synthesis of the mesoporous silicate and synthesis of CMK-3 by nanocasting strategy, incorporation of the iron oxide nanoclusters by wetness impregnation, characterization of these nanomaterials by XRD, N2 adsorption, XPS, and TEM, and study of the improvement in hydrogen adsorption. This material is promising in hydrogen adsorption and storage application for energy harvesting. According to XRD studies, the incorporation of oxide nanoclusters does not compromise the overall structure of the mesoporous carbon CMK-3. In the wide angle region it has been found typical reflections of iron oxide corresponding to the magnetite phase (Fe2+Fe3+ 2 O4). The modified sample Fe-CMK-3 reveal a reduced specific surface area and smaller pore diameter compared to pristine CMK-3 which involves the formation of magnetite nanoparticles within the mesoporous channels of CMK-3. TEM images of Fe-CMK-3 presents metallic oxide nanoparticles well dispersed. The incorporation of iron oxide nanoparticles improved significantly the H2 storage behavior (4.45% wt at 77K and 10 bar) compared to its respective support (CMK-3). Magnetite nanoclusters increased the capacity of hydrogen adsorption in pristine materials. Supposing that weakly orbital interactions occur between H2 and the metal nanocluster, physisorption is the main interaction, all cases have the potential to uptake H2 weakly as physisorption process and the last interaction achieves sufficiently strong energies to store more hydrogen to reach the level adsorption in Fe-CMK-3. In addition, no hydrogen chemisorption was detected. The materials synthesized are promising in hydrogen uptake by weak link forces (physisorption).Item Ordered mesoporous carbons (OMC) type CMK-3 modified with Vandium for improvement H2 storage(Diamond and Carbon Conference Organization, 2018) Juárez, Juliana María; Gómez Costa , Marcos Bruno; Martínez, María Laura; Anunziata, Oscar Alfredo; Martínez, María LauraSome previous studies probed that H2 adsorption can be improved for mesoporous carbons introducing into the framework of the nanomaterial some metals or oxides, like platinum, Zn, ZnO, Ni, NiO, or TiO2. Some other authors have made several efforts in the same direction, for instance, incorporated iron and copper nanoparticles into multiwalled carbon nanotubes and studied their hydrogen adsorption. In this work we studied the influence of the incorporation of vanadium nanoparticles inside the channels of mesoporous carbon CMK-3. This research includes the synthesis of the mesoporous silicate, (hard Template) and the synthesis of the CMK-3 by nanocasting strategy and the incorporation of the vanadium nanoclusters by wetness impregnation. This kind of materials are synthesize by nanocasting strategy using mesoporous silicates as templates and have high surface area (from 1000 to 2000 m2/g) and pore volumes in the range of 0.5 to 1 ml.g-1. Accordingly, CMK-3 was chosen as a support material for hydrogen storage due to its large surface area, high chemical stability, uniform pore diameter, accessible porosity and threedimensional conducting network. The characterization of these nanomaterials was obtained by XRD, N2 adsorption, XPS, TPR and Uv-Vis, TEM, and finally the study of the improvement in the hydrogen adsorption. V5+ cation in V2O5 is an active species to uptake and store hydrogen by a physisorption process and the support plays an important role in metal cluster dispersion and size.Item Novel hybrid Ga-SBA-3 nanostructured material: Synthesis, Characterization and Applications(., 2018) Martínez, María Laura; Gómez Costa , Marcos Bruno; Beltramone, Andrea Raquel; Anunziata, Oscar AlfredoIn this work we study the incorporation of gallium in the structure of the SBA-3 mesoporous material, with the purpose of modifying the intrinsic acidity of the material using pyridine in order to determine the acidic sites that this material possesses. In addition, studies of adsorption / desorption of aniline and its subsequent polymerization on the mesoporous Ga-SBA-3, that gives the unique hybrids compound, with conductive characteristics similar to those of an inorganic semiconductor. Si-SBA-3 was prepared using CTABr and TEOS, as surfactant and Si source respectively. To obtain Ga-SBA-3 post-synthesis incorporation was employed. Ga-SBA-3 were dehydrated at 400 ° C under vacuum and then were exposed to vapors of pyridine / liquid aniline depending on the studies to be performed (pyridine to determine the acid sites of the material and aniline for subsequent polymerization) at vacumm. The in-situ polymerization of aniline was carried out to produce PANI/Ga-SBA-3. The final PANI/Ga-SBA-3 material was characterized by XRD, ICP, SEM-EDX, FTIR, BET. Direct current electrical conductivity measurements were performed using pellets and a four-probe technique, improving the contacts with a gold layer. Higher amount of polyaniline in conductive emeraldine salt form was found in PANI/Ga-SBA-3 composite, with respect to other composites reported in the literature. At room temperature (273 K), the electrical conductivity of PANI/Ga-SBA-3 was 2.5x10-3 S/cm, higher than its of Al-SBA-3 and Al-MCM- 41 homologs. To explain the conductivity of the composite (nanowire of PANI within Ga-SBA-3), we must consider the configuration of the nanostructured material and the type of PANI anchoring.Item Aniline alkylation with methanol: relationship nature and strength of active sites - catalytic activity(Materials Chemistry, 2019) Juárez, Juliana María; Anunziata, Oscar AlfredoThe products of the alkylation of aniline (A) with methanol (M), both carbon alkylate and N-derivatives are important intermediaries in the organic synthesis. Thus, toluidine (To), N-methylaniline (NMA) and N-dimethylaniline (NNDMA), the main products of this reaction are used as intermediates in the manufacture of dyes, plastics and explosives. The preparation of these products in liquid phase has been widely studied. Naturally, this process in the presence of strong acids generates problems of corrosion and contaminating residues. A comparative analysis between all the reaction products obtained indicates that NMA is the initial product of aniline alkylation with methanol with the highest formation rate. The NNDMA would come from the alkylation of the NMA following a relatively similar behavior. NNDMT follows a particular behavior. It is always secondarily unstable except in SBS-SLS (Strong Bonsted - Strong Lewis site pairs), where it is stable at high conversion levels. To is always an unstable secondary product, except for the SBS-SBS (stable) group, with a maximum formation rate in SBS-SLS between 15-20% of aniline conversion and more than 20% in the neighboring SBS-SBS.