Facultad Regional Córdoba

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Author: search.filters.author.Vallés , Verónica Alejandra

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    Hydrogenation of tetralin in presence of nitrogen using a noble-bimetallic couple over a Ti-modified SBA-15.
    (Univesidsad Tecnológica Nacional., 2016) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Pecchi, Gina; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Ledesma , Brenda Cecilia
    Monometallic Pt- and bimetallic Pt-Ir-modified Ti-SBA-15 were used in the hydrogenation of tetralin to decalin in the presence of 150 ppm of N as quinoline and indole at 250 ◦C and 15 atm of pressure of hydrogen, using a Parr reactor. The catalyst was synthesized using sol-gel method and Ti was added during the synthesis using Tetraethyl Orthotitanate. Pt/Ir was added by wetness impregnation. The catalysts prepared were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV–vis DRS, Raman spectroscopy, XPS, TEM-EDS and TPR. UV–vis-DRS and Raman spectroscopy confirmed that Ti was incorporated in tetrahedral coordination in the framework of the SBA-15. The analysis showed that the mesoporous structure was maintained after metal incorporation and Ti incorporation helps to reduce significantly the size of the metals clusters and improves its dispersion considerably. Pt-Ir/Ti-SBA 15 was the most active catalyst. The experimental data were quantitatively represented by a modified Langmuir-Hinshelwood type rate equation. The preliminary results show these materials as a promising catalyst for HDT reactions.
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    Experimental desing optimization of the tetralin hydrogenation over Ir-Pt-SBA-15.
    (Univesidsad Tecnológica Nacional., 2015) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Rivoira , Lorena Paola; Cussa , jorgelina; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Cussa , jorgelina; Rivoira , Lorena Paola; Ledesma , Brenda Cecilia
    Experiment design-response surface methodology (RSM) is used in this work to model and optimize two responses in the hydrogenation of tetralin to decalin using bimetallic Ir–Pt-SBA-15 catalyst. In this study, we analyze the influence of the nature of the catalyst (metal molar fraction and metal loading), the catalyst/substrate ratio and the temperature of the reaction as factors for the design. The responses analyzed were conversion at 3 h and at 5 h of reaction time. The response surfaces were obtained with the Box– Behnken design, finding the best combination between the reaction parameters that allowed optimizing the process. By applying the statistic methodology, the higher levels of the two objective functions were obtained employing the catalyst with 1 wt.% of iridium and 0.7–0.8 wt.% of platinum; the optimal ratio between mass of catalyst and mole of tetralin was 17–19 g/mol and temperature between 200 and 220 ◦C
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    Sulfur elimination by oxidative desulfurization with titanium-modified SBA-16.
    (Univesidsad Tecnológica Nacional., 2015) Rivoira , Lorena Paola; Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Ponte , María Virginia; Martínez , María Laura; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Martínez , María Laura; Ponte , María Virginia; Ledesma , Brenda Cecilia; Vallés , Verónica Alejandra
    TiO2-modified mesoporous SBA-16 and titanium-substituted mesoporous SBA-16 were developed and tested in the oxidative desulfurization (ODS) of dibenzothiophene prevailing in liquid fuel. Pure TiO2 was used as reference. The titania-based catalysts were characterized by chemical analysis, XRD, EDX and TEM. The titanium state as tetrahedral (in Ti-SBA-16 sample) or octahedral (in TiO2/SBA-16 sample) coordination surrounding in the silicate matrix was determined by XPS, UV–vis DRS, FTIR, Raman and XANES. We assessed the impact exerted on performance of different reaction variables, including (nature and amount of the active catalytic species, phase system, molar ratio of oxidant H2O2 and DBT, reaction temperature, nature of the substrate and reuse of catalysts). In addition, we carried out a kinetic study and the activation energy was determined. We achieved 90% of S removal from a 0.2 wt.% dibenzothiophene solution at 60 ◦C in less than 1 h of reaction. The best catalytic results are obtained with high exposed surface of nanometric TiO2 species of TiO2/SBA-16 sample. The activated catalyst is very active in ODS reaction and can be reused four times with no loss in activity.
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    Noble-bimetallic supported CMK-3 as a novel catalyst for hydrogenation of tetralin in the presence of sulfur and nitrogen.
    (Univesidsad Tecnológica Nacional., 2016) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Juárez , Juliana María; Gómez Costa, Marcos Bruno; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Juárez , Juliana María; Ledesma , Brenda Cecilia
    Carbon ordered mesoporous CMK-3 with high surface area and high pore volume promotes a very good dispersion of Pt or Ir monometallic and Pt-Ir-bimetallic crystallites in the carbon framework. High active and stable nanospecies are responsible for the good activity and selectivity found in the hydrogenation of tetralin to decalin in the presence of N as indole and S as dibenzothiophene under mild conditions in a Batch reactor. The catalysts prepared were extensively characterized by XRD, N2 adsorption isotherms, XPS, TEM, ICP, CO Chemisorption and TPR. The analysis showed that the carbon mesoporous structure was maintained after metal incorporation, and very high dispersed metal-supported catalyst was obtained. The activity was compared using the turnover number, Pt-Ir-CMK-3 being the most active cat alyst in the presence of the inhibitors. The bimetallic catalyst showed more resistance to inhibition than monometallic catalysts. The reusability of Pt-Ir-CMK-3 suggests that it is a potential catalyst for hydrotreating reactions.
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    Novel preparation of titania-modified CMK-3 nanostructured material as support for Ir catalyst applied in hydrodenitrogenation of indole.
    (Univesidsad Tecnológica Nacional., 2017) Ledesma , Brenda Cecilia; Juárez , Juliana María; Vallés , Verónica Alejandra; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel
    Abstract Iridium catalyst was prepared using a novel tita nium oxide-CMK-3 support synthesized as a replica of Ti SBA-15. The catalyst was applied in the hydrodenitrogena tion of indole. The activity was compared with an iridium catalyst supported over a grafted titanium-CMK-3. Struc tural and textural characterization of the catalysts was per formed by means of N2 adsorption, XRD, UV–Vis–DRS, Raman spectroscopy, XPS, TEM and H2 Chemisorption. Ir Ti-CMK-3 was the most active catalyst for the hydro denitrogenation reaction at mild conditions. Titanium oxide contained in carbon ordered mesoporous CMK-3 promotes a very good anchorage of iridium metallic clusters in the carbon framework reaching high active site distribution and more stable nanoclusters.
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    Study of Ir/Ti-SBA-15 acidity influence on the HDN of indole.
    (Univesidsad Tecnológica Nacional., 2015) Ledesma , Brenda Cecilia; Vallés , Verónica Alejandra; Rivoira , Lorena Paola; Balangero, Gerardo Simón; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Rivoira , Lorena Paola; Vallés , Verónica Alejandra
    The hydrodenitrogenation of Indole has been studied over a series of Ti-modified SBA-15 supports and their respective Ir-catalysts. Ti-SBA-15 was synthesized using sol-gel method and Ti was added during the synthesis using TEOT as Ti source. Ti was incorporated into the framework replacing the Si atoms in the mesoporous structure. Ir/Ti-SBA-15 with and without F and/or Al were prepared to improve the catalytic activity. F and Al have been incorporated by wetness impregnation method. The effect of the incorporation of F and Al in the mesoporous structure was tested in the hydrodenitrogenation reaction of indole. The catalysts were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, TEM, FTIR and UV-vis-DRS and Raman spectroscopy. The low angle X-ray analysis showed for all the materials intensive reflection, characteristic of SBA-15 structure. The mesoporous structure was maintained after F and Al incorporation. The results showed that Ti incorporation reduces significantly the cluster size and improves considerably the Ir cluster dispersion. The catalytic activity of Ir/Ti-SBA-15 modified with F and Al, with higher acidity, avoided the irreversible adsorption of indole. The catalytic activity was studied in a 4563 Parr reactor, at 250°C, 15 atm of pressure of hydrogen and 360 rpm. The catalysts synthesized had good activity measured in hydrodenitrogenation of indole at mild conditions. The preliminary results show these materials as promising catalysts for HDN reactions
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    Ir-Pt/SBA-15 applied in the optimization of tetralin hydrogenation.
    (Univesidsad Tecnológica Nacional., 2015) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Rivoira , Lorena Paola; Cussa , jorgelina; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Anunziata; Cussa , jorgelina; Rivoira , Lorena Paola; Ledesma , Brenda Cecilia
    Bimetallic catalysts have received considerable attention for hydrotreating (HDT) because they show high activity. The features of the catalysts here studied are going to be correlated with their catalytic performance in the hydrogenation of tetralin at mild conditions. The final goal is to find the optimal proportion of each metal in order to be more active and the best reaction conditions (temperature and amount of catalyst). The statistical experiments design is the process of planning an experiment to obtain appropriate data that can be analyzed by statistical methods, to produce concrete and valid conclusions. One of the main advantages in the response curve is to visualize the response for all levels of the experimental factors Experiment design response surface methodology (RSM) is used in this work to model and to optimize the process. Platinum and Iridium nanoparticles were incorporated into SBA-15 support by the wet co-impregnation method. Ir content was set as 1wt. % and Pt was varied from 0 to 1wt. %. The catalysts were characterized by XRD, BET, XPS, TEM, ICP and TPR. XRD profiles are characteristic of the two-dimensional p6mm hexagonal mesostructure with d100 spacing of 10.16 nm; where the d100 spacing upon Ir and Pt incorporation were quite similar to pristine SBA-15. The TEM images and XPS demonstrate that the metal particles were mainly present inside the porous and XPS and TPR corroborated the reduced state of the metals. The catalytic activity was measured in a 4563Parr reactor at 15 atm of hydrogen and 360 rpm. Feed consisted in 50 mL of tetralin in Dodecane, the amount of tetralin is set according to the ratio of catalyst mass/mass reagent corresponding to each reaction. The application of this methodology allows a better understanding of the influence of the different factors: content of metal on catalyst (A), relationship: mass of catalyst/reagent mass (B) and reaction temperature (C), on two responses: conversion at 3 h and at 5 h of reaction time. These factors were carefully selected taking account the influence of the parameters in the reaction. The design was analyzed by Statgraphics and Statistica Soft. We found that, the variable Catalyst has the best influence over the Conversion at the 95.0% confidence level, according to the Pareto.
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    Eliminación de azufre mediante desulfuración oxidativa con Ti-SBA-16. Parte I. Síntesis y caracterización.
    (Univesidsad Tecnológica Nacional., 2015) Rivoira , Lorena Paola; Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Ponte , María Virginia; Martínez , María Laura; Beltramone , Andrea Raquel; Martínez , María Laura; Ponte , María Virginia; Ledesma , Brenda Cecilia; Ledesma , Lorena Paola; Vallés , Verónica Alejandra
    Se desarrollaron catalizadores tipo SBA-16 modificados con Ti como TiO2 y como heteroatomo y se probaron en la desulfuración oxidativa (ODS) del dibenzotiofeno predominante en el combustible líquido. Se utilizó TiO2 puro como referencia para comparar la actividad catalitica. Los catalizadores fueron caracterizados mediante análisis químico, XRD, EDX y TEM. El estado de coordinación tetraédrico del titanio (en la muestra de Ti-SBA-16) u octaédrico (en la muestra de TiO2/SBA-16) en la matriz de sílice se determinó por XPS, UV-vis DRS, FTIR, Raman y XANES. La actividad catalítica se muestra en la Parte 2 de este trabajo.
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    Tetralin Hydrogenation over Ir-Pt/SBA-15. Optimization by experimental desing.
    (Univesidsad Tecnológica Nacional., 2015) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Rivoira , Lorena Paola; Cussa , jorgelina; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Cussa , jorgelina; Rivoira , Lorena Paola; Ledesma , Brenda Cecilia
    Bimetallic catalysts have received considerable attention for hydrotreating (HDT) because they show high activity. The features of the catalysts here studied are going to be correlated with their catalytic performance in the hydrogenation of tetralin at mild conditions. The final goal is to find the optimal proportion of each metal in order to be more active and the best reaction conditions (temperature and amount of catalyst). The statistical experiments design is the process of planning an experiment to obtain appropriate data that can be analyzed by statistical methods, to produce concrete and valid conclusions. One of the main advantages in the response curve is to visualize the response for all levels of the experimental factors Experiment design response surface methodology (RSM) is used in this work to model and to optimize the process. Platinum and Iridium nanoparticles were incorporated into SBA-15 support by the wet co impregnation method. Ir content was set as 1wt. % and Pt was varied from 0 to 1wt. %. The catalysts were characterized by XRD, BET, XPS, TEM, ICP and TPR. XRD profiles are characteristic of the two-dimensional p6mm hexagonal mesostructure with d100 spacing of 10.16 nm; where the d100 spacing upon Ir and Pt incorporation were quite similar to pristine SBA-15. The TEM images and XPS demonstrate that the metal particles were mainly present inside the porous and XPS and TPR corroborated the reduced state of the metals. The catalytic activity was measured in a 4563Parr reactor at 15 atm of hydrogen and 360 rpm. Feed consisted in 50 mL of tetralin in Dodecane, the amount of tetralin is set according to the ratio of catalyst mass/mass reagent corresponding to each reaction. The application of this methodology allows a better understanding of the influence of the different factors: content of metal on catalyst (A), relationship: mass of catalyst/reagent mass (B) and reaction temperature (C), on two responses: conversion at 3 h and at 5 h of reaction time. These factors were carefully selected taking account the influence of the parameters in the reaction. The design was analyzed by Statgraphics and Statistica Soft. We found that, the variable Catalyst has the best influence over the Conversion at the 95.0% confidence level, according to the Pareto.
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    Hydrodenitrogenation of over Ir supporteD Ti-SBA-15 modified with F AND AI.
    (Univesidsad Tecnológica Nacional., 2015) Ledesma , Brenda Cecilia; Vallés , Verónica Alejandra; Rivoira , Lorena Paola; Balangero, Gerardo Simón; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Rivoira , Lorena Paola; Vallés , Verónica Alejandra
    The hydrodenitrogenation of Indole has been studied over a series of Ti-modified SBA 15 supports and their respective Ir-catalysts. Ti-SBA-15 was synthesized using sol-gel method and Ti was added during the synthesis using TEOT as Ti source. Ti was incorporated into the framework replacing the Si atoms in the mesoporous structure. Ir/Ti-SBA-15 with and without F and/or Al were prepared to improve the catalytic activity. F and Al have been incorporated by wetness impregnation method. The effect of the incorporation of F and Al in the mesoporous structure was tested in the hydrodenitrogenation reaction of indole. The catalysts were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, TEM, FTIR and UV-vis-DRS and Raman spectroscopy. The low angle X-ray analysis showed for all the materials intensive reflection, characteristic of SBA-15 structure. The mesoporous structure was maintained after F and Al incorporation. The results showed that Ti incorporation reduces significantly the cluster size and improves considerably the Ir cluster dispersion. The catalytic activity of Ir/Ti-SBA-15 modified with F and Al, with higher acidity, avoided the irreversible adsorption of indole. The catalytic activity was studied in a 4563 Parr reactor, at 250°C, 15 atm of pressure of hydrogen and 360 rpm. The catalysts synthesized had good activity measured in hydrodenitrogenation of indole at mild conditions. The preliminary results show these materials as promising catalysts for HDN reactions.