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Author: search.filters.author.Anunziata, Oscar AlfredoSubject: search.filters.subject.Ga-SBA-3

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    Ga-SBA-3 A novel nanostructured material: synthesis, characterization and application
    (IOP Publishing, 2019) Martínez, María Laura; Gómez Costa , Marcos Bruno; Anunziata, Oscar Alfredo
    This 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.
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    Novel hybrid Ga-SBA-3 nanostructured material: Synthesis, Characterization and Applications
    (., 2018) Martínez, María Laura; Gómez Costa , Marcos Bruno; Beltramone, Andrea Raquel; Anunziata, Oscar Alfredo
    In 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.
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    Aniline adsorption and polymerization over gallium modified mesoporous material.
    (Universidad Tecnológica Nacional., 2018) Martínez , María Laura; Rivoira , Lorena Paola; Beltramone, Andrea Raquel; Anunziata, Oscar Alfredo; Anunziata, Oscar Alfredo; Rivoira , Lorena Paola
    In this work we study aniline polymerization over a mesoporous Ga-SBA-3 synthesized in our laboratory. In order to modify the intrinsic acidity of the mesoporous material gallium was incorporated into the structure by post synthesis wet impregnation method using gallium nitrate. Structural and textural characterization of the materials was performed by X-ray diffraction (XRD), ICP and EDX analysis, N2 adsorption-desorption and BET area analysis, FTIR and scanning electron microscopy (SEM). The catalytic material presented a ratio Si/Ga=32. Aniline is a weak organic base and an amphiprotic compound, so it can accept or donate protons. The polyaniline (PANI) exists in diverse ways presenting different chemical and physical properties. The protonated polyaniline feature the conductivity of a semiconductor material, over 100 S/cm. Toward achieve aniline adsorption, the solid gallium silicate was exposed to aniline vapours. The aniline adsorption was studied by infrared spectroscopy and the results obtained were evaluated so as to been able to polymerize it over the mesoporous material generating a unique polyaniline-host composite with new properties. Those polyaniline/hosts composites obtained by a polymerization in-situ technique were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Comparing to previous results FTIR analysis of the polyaniline/Ga SBA-3 composite (PANI/Ga-SBA-3) showed characteristics bands attributed to the quinoidal stretching (N=Q=N) and C-C stretching of the benzene ring. The low angle XRD analysis showed that the mesoporous structure was maintained in spite of the gallium incorporation. The absence of PANI peaks and G2O3 in the wide angle XRD pattern confirms that the polyaniline is adsorbed over the gallium silicate mesoporous surface and the gallium is well dispersed over the support.