Desarrollo, Producción e Innovación en la Investigación científica
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Item Multiple-wall carbon nanotubes obtained with mesoporous material decorated with caria-zirconia.(Univesidsad Tecnológica Nacional, 2020) Rodríguez , Miguel Angel; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Juárez , Juliana María; Juárez , Juliana María; Anunziata , Oscar AlfredoIn this work, Ceria-Zirconia on ordered Santa Barbara mesoporous silica (Ce-Zr-SBA-15), has been used directly as a catalyst for the synthesis of carbon nanotubes (CNTs) through Chemical Vapor Deposition (CVD). In addition to cerium oxide, it contains zirconium oxide nano crystallites, which act as catalysts for carbon nanostructures. The catalytic performance of this material was evaluated for the decomposi- tion of ethanol at 900 °C, with N2 flow. The carbon decomposed from absolute ethanol diffuses through the surface of the nanostructured catalytic material and precipitates in the form of MWCNT structures, which could be identified by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), showing average diameters of 30–35 nm.Item Multiple-wall carbon nanotubes obtained with mesoporous material decorated with ceria-zirconia(2020) Rodríguez, Miguel Angel; Anunziata, Oscar Alfredo; Beltramone, Andrea Raquel; Martínez, María LauraIn this work, Ceria-Zirconia on ordered Santa Barbara mesoporous silica (Ce-Zr-SBA-15), has been used directly as a catalyst for the synthesis of carbon nanotubes (CNTs) through Chemical Vapor Deposition (CVD). In addition to cerium oxide, it contains zirconium oxide nano crystallites, which act as catalysts for carbon nanostructures. The catalytic performance of this material was evaluated for the decomposition of ethanol at 900 °C, with N2 flow. The carbon decomposed from absolute ethanol diffuses through the surface of the nanostructured catalytic material and precipitates in the form of MWCNT structures, which could be identified by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), showing average diameters of 30–35 nm.Item Mesopore carbón starch with acid properties: synthesis and characterization(2020) Martínez, María Laura; Anunziata, Oscar A.We have shown that a promising material with acidic properties can be successfully prepared from starch mesoporous carbon (SMC), functionalized with sulfated zirconia. The process of assembling P123, starch, zirconia, and silicon synthesized Zr-modified ordered mesoporous carbon. SMC and Zr-SMC were characterized by BET for their texture properties and, using Scanning Electron Microscopy (SEM), their morphology. Acidic properties were acquired by programmed thermodesorption of ammonia (NH3 TPD). These studies show that the Zr-SMCs material is mainly composed of mesopores with an average pore size of approximately 3.5 nm, high surface area and pore volume, and has medium to strong acidity properties.Item Multiple-wall carbón nanotubes obtained with mesoporous material decorated with cerio-zirconium(2020) Martínez, María Laura; Anunziata, Oscar A.In this work, Ce-Zr-SBA-15 has been used directly as a catalyst for the synthesis of multi-vall carbon nanotubes (MWCNT) through Chemical Vapor Deposition (CVD). In addition to cerium oxide, it contains zirconium oxide Nano crystallites, which act as catalysts for carbon nanostructures. The catalytic performance of this material was evaluated for the decomposition of ethanol at 900 °C, with N2 flow. The structural characterization of the resulting catalyst was carried out by means of SEM and XRD. The decomposed carbon of absolute ethanol diffuses through the surface of the nanostructured material and precipitates in carbon structures called multiple-walled nanotubes, which could be visualized/detected/identified by TEM, showing diameters of the carbon nanotubes that range from 15 to 25 nm.Item Green hydrogen from catalytic ammonia decomposition(2021) Gómez Costa, Marcos B.; Juárez, Juliana M.; Anunziata, Oscar A.Ir/γ-alumina catalysts for decomposition of ammonia were prepared by Iridium ion exchange procedure, onto γ-alumina synthesized by sol-gel method. In order to determine the physical and chemical properties we used X ray diffraction (XRD) analysis, Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR-MAS). The samples displayed the characteristic band at 1620 cm-1 corresponds to a N-H bending of ammonia adsorbed on electron-acceptor sites, and the characterization by pyridine adsorption and desorption to determine the presence of Lewis acid sites, with absence of Brønsted sites, showing higher acid strength than commercial sample used as reference. The analysis of particle size and morphology reveal uniformity, with tendency to a spheroid aspect and smaller to 3 μm of diameter. The 27Al NMR-MAS test, allowed determining the tetrahedral and octahedral aluminum presence in both samples, where the higher proportion of octahedral Al in γ-alumina synthesized by us, is correlated toward the greater electron acceptor acid sites. The designed method was effective for Ir/γ-alumina catalysts synthesis. The surface area was 150 and 260 m2/g for the commercial sample and the alumina prepared by and us, and after the Ir incorporation (10-18% w/w in both samples), they surfaces were reduced approximately 5.4-8.8% and 4.3-7.2% respectively. XRD analyses show the absence of maximums at 28º and 34.7º 2 corresponding to iridium oxide, indicating a high efficiency of the reduction treatment, increasing the active sites for the specific reaction of ammonia decomposition. The distribution of the Ir crystallites determined by XRD and TEM indicated that, the samples prepared by ion exchange method produced smaller Iridium clusters than by impregnation procedure of alumina sample, with higher surface area and greater anchorage sites. According to preliminary catalytic tests, the Ir/γ-alumina catalysts prepared by a novel method showed higher activity to ammonia decomposition to N2 and green H2.Item Characterization and conditioning of zeolitic tuffs to improve their catalytic features(2018) Vinuesa, Ariel José; Bonetto, Luciana; Renzini, María Soledad; Saux, Clara; Pierella, Liliana BeatrizZeolites are usually employed as adsorbents of organic and inorganic compounds due to their high ion-exchange capacity and shape selective structure that act as molecular sieve. These crystalline hydrated aluminosilicates of Na, K and Ca consist of a three-dimensional framework, having a negatively charge lattice. This characteristic is responsible of the ion exchange capacity of these materials1. Because of their unique properties, such as tridimensional micropore structure, high surface area, high chemical stability, excellent absorption capacity, high thermal and mechanical stability and controllable acidity, zeolites have been widely used as catalysts and supports on heterogeneous catalysis applications. Nevertheless, the complicated and high expensive synthesis considerably restrict the application of the synthetic zeolites on remediation reactions. In this sense, natural zeolites could overcome these difficulties since their high abundance and low extraction cost make them cheap materials2. In this work, zeolitic tuffs from Compañía Minera Argentina (San Juan, Argentina), from now on named NZ, were characterized by means of XRD, FTIR, TG, N2 adsorption isotherms, ICP and BET. In order to improve these natural zeolites properties, a series of conditioning treatments were applied to the raw materials. Considering that the impurities that are present in the as received solids could affect the catalytic processes results, one of the applied treatments was the washing with deionized water all night (WZ). Also, NZ were treated with HNO3 (NAZ) and HCl (CAZ) aqueous solutions at 90 °C during 5 h under magnetic stirring. After the acidic treatment, the solids were washed with deionized water until neutral pH and further dried in oven overnight. Finally, different thermal treatments were applied under static oxidant atmosphere. The raw and modified zeolites were extensively characterized in order to determine the effect of the applied treatments. Surface area of these porous materials showed a noticeable increment after acidic treatments (higher than 50%). This effect could be assigned to the lixiviation of ionic species inside porous structure, since porous volume also showed an increment higher than 35%. This hypothesis was confirmed by ICP results. Nevertheless, it should be noted that acidic and thermal treatments also affected crystallinity of the samples. By XRD it was observed a reduction of Clinoptilolite signals intensities for NAZ and CAZ. When thermal treatments were applied, CAZ sample exhibited a collapse of the zeolitic structure and just quartz signals were observed. In this sense, nitric acid treatment is better in order to improve surface area, maintaining the zeolite phase of the material. Two temperatures were evaluated for the thermal treatment of NAZ samples, 350 and 500°C. According to XRD results, the highest temperature is not recommendable, since notorious crystallinity lost was obtained. Therefore, 350°C was adopted as calcination temperature. These materials were further tested as catalysts for different procedures, such as photocatalysis for colorant degradation and catalytic pyrolysis for polymer and biomass residues valorizations.