Browsing by Author "Ledesma , Brenda Cecilia"

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2,5-DMF production through hydrogenation of 5 HMF over noble metal catalysts supported on Ti modified SBA-15.
(Universidad Tecnológica Nacional., 2017) Ledesma , Brenda Cecilia; Beltramone , Andrea Raquel
Catalytic hydrogenolysis reaction of 5-hydroxymethylfurfural platform molecule to produce 2,5-dimethylfuran conversion was studied. For that purpose noble metal (Pt and Ir) catalysts supported on SBA-15 and Ti-SBA-15 supports were used. All of the tested catalysts were able to convert completely HMF. However, among the mentioned catalysts, the bimetallic Pt-Ir catalyst supported on Ti-SBA-15 showed the best behavior in terms of DMF selectivity, probably due to Ti incorporation and the synergic effect with the noble metals. Moreover, this catalyst was studied in order to know the influence of some reaction parameters on DMF selectivity. As results obtained, the increment of the pressure and the bimetallic formation improved the DMF selectivity. Keywords: Bimetallic, Hydrogenolysis, biomass, titanium
2,5-DMF production through hydrogenation of 5 HMF over noble metal catalysts supported on TI-MODIFIED SBA-15.
(Universidad Tecnológica Nacional., 2009) Ledesma , Brenda Cecilia; Beltramone , Andrea Raquel
Catalytic hydrogenolysis reaction of 5-hydroxymethylfurfural platform molecule to produce 2,5-dimethylfuran conversion was studied. For that purpose noble metal (Pt and Ir) catalysts supported on SBA-15 and Ti-SBA-15 supports were used. All of the tested catalysts were able to convert completely HMF. However, among the mentioned catalysts, the bimetallic Pt-Ir catalyst supported on Ti-SBA-15 showed the best behavior in terms of DMF selectivity, probably due to Ti incorporation and the synergic effect with the noble metals. Moreover, this catalyst was studied in order to know the influence of some reaction parameters on DMF selectivity. As results obtained, the increment of the pressure and the bimetallic formation improved the DMF selectivity.
Bimetallic platinum/iridium modified mesoporous catalysts applied in the hydrogenation of HMF.
(Universidad Tecnológica Nacional., 2021) Ledesma , Brenda Cecilia; Juárez , Juliana María; Mazario , Jaime; Domine, Marcelo; Beltramone , Andrea Raquel; Juárez , Juliana María
Catalytic transformation of 5-hydroxymethylfurfural (HMF) to produce 2,5-dimethylfuran (2,5-DMF) was stu- died over bimetallic (PtIr) and monometallic (Pt) catalysts supported on CMK-3 and SBA-15 mesoporous ma- terials. The optimum temperature and hydrogen pressure for the maximum production of 2,5-DMF were 120 °C and 15 atm, respectively. Increases in temperature and pressure decreased the selectivity to 2,5-DMF. The cat- alysts were broadly characterized by different techniques, such as XRD, N2-isotherms, XPS, TPR, TEM and NH3- TPD. It was found that the metallic particles were well reduced and highly dispersed on the surface of supports having large surface area and narrow pore size distribution. The PtIr alloy species catalytic sites were very active and selective towards the formation of the desired 2,5-DMF. PtIr-CMK-3 catalyst showed an excellent activity, selectivity and stability to be applied in this process.
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
Hidrodenitrogenación de Indol utilizando catalizadores de Ir soportado sobre SBA-15 modificada con Ti.
(Universidad Tecnológica Nacional., 2016) Ledesma , Brenda Cecilia; Vallés , Verónica Alejandra; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Vallés , Verónica Alejandra
La hidrodenitrogenación de indol se estudió utilizando una serie de catalizadores de Ir soportado sobre SBA 15 modificada con Ti. El mesoporoso modificado Ti-SBA-15 se sintetizó usando el método sol-gel. El iridio fue incorporado mediante la técnica de impregnación húmeda incipiente. Con el fin de mejorar la actividad catalítica se modificó la acidez del material mesoporoso añadiendo F o Al. Los catalizadores fueron caracterizados por difracción de rayos X (XRD), isotermas de adsorción de N2, UV-Vis-DRS, espectroscopía Raman, espectroscopía 27Al-MAS-RMN, XPS, TEM, Py-FTIR y TPR. Los análisis confirman que el Ti fue incorporado en coordinación tetraédrica dentro de la SBA-15 y que la estructura mesoporosa se mantuvo después de la incorporación de F o Al. La espectroscopía27Al-MAS-RMN indica que el aluminio se incorporó principalmente en posicion tetraédrica. Los resultados mostraron que la incorporación del Ti ayuda a reducir significativamente el tamaño de los clusters de Iridio y mejora considerablemente su dispersión. El catalizador Ir-Ti-SBA-15, modificado con Al, fue el catalizador más activo para la hidrodenitrogenación de indol, en condiciones suaves en un reactor discontinuo. Los datos experimentales para la hidrodenitrogenación de indol fueron cuantitativamente representados por una ecuación de velocidad del tipo Langmuir-Hinshelwood.
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.
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.
Novel and simple one-pot method for the synthesis of Ti02 modified-CMK-3 applied in oxidative desulfurization of refractory organosulfur compounds.
(Univesidsad Tecnológica Nacional., 2016) Rivoira , Lorena Paola; Ledesma , Brenda Cecilia; Juárez , Juliana María; Beltramone , Andrea Raquel; Juárez , Juliana María; Ledesma , Brenda Cecilia
Ti-CMK-3 carbon mesoporous was prepared using a novel synthesis method. This new method avoids the hard template synthesis used commonly. The precursors of silicon, carbon and titanium are incorporated together with the other components during the only step of the synthesis. The method developed here, allows reducing time and energy consumption by 60% and thus, the cost of the overall process of synthesis. Structural and textural characterization of the titanium modified-mesoporous carbon was performed by N2 adsorption, XRD, UV–Vis DRS, XPS, Raman spectroscopy and TEM. The characterization results indicated that the textural and structural properties of the material synthesized by the short time method are comparable with the properties of the material prepared by the hard template method. Ti modified-mesoporous carbon was synthesized by dif- ferent methods in order to prepare catalysts to be tested in the oxidative desulfurization (ODS) of sulfur com- pounds. The catalyst prepared by the one-pot method is capable to oxidize high amount of sulfur (2000 ppm) in only 30 min of reaction time at 60–80 °C. The good performance and stability of the catalyst prepared using a novel synthesis method was attributed to well dispersed anatase nanospecies over the high area mesoporous carbon. Main advantage of the present study is the reduction of time and cost in the synthesis of the new material and the applicability for ODS reactions.
Novel preparation of CMK-3 nanostructured material modified with titania applied in hydrogen uptake and storage.
(Univesidsad Tecnológica Nacional., 2016) Juárez , Juliana María; Ledesma , Brenda Cecilia; Gómez Costa, Marcos Bruno; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Anunziata , Oscar Alfredo; Ledesma , Brenda Cecilia
This work deals with the development of a novel procedure to synthesize titania-modified nano structured carbon employing Ti-SBA-15 as hard template. The new mesoporous carbon displays high specific surface area of 1044 m2/g and large pore volume of 0.7 cm3/g. XRD pattern of Ti-CMK-3 indicates that the ordered structure of this material is similar to the CMK-3. XRD, XPS and UVeVis-DRS analysis indicated that Ti is highly dispersed as anatase phase in Ti-CMK-3. The synthesized Ti-CMK-3 exhibited significantly enhanced H2 storage properties (2.6 wt%, equivalent to 13 mmol/g) compared with CMK-3 without Ti (2.2 wt%, 11 mmol/g) at 77 K and 10 bar.
Novel preparation of titania-modified CMK-3 nanostructured material as support for Ir catalyst applied in hydrodenitrogenation of indole.
(Universidad Tecnológica Nacional., 2017) Ledesma , Brenda Cecilia; Juárez , Juliana María; Vallés , Verónica Alejandra; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Vallés , Verónica Alejandra; Juárez , Juliana María
Iridium catalyst was prepared using a novel titanium oxide-CMK-3 support synthesized as a replica of Ti-SBA-15. The catalyst was applied in the hydrodenitrogenation of indole. The activity was compared with an iridium catalyst supported over a grafted titanium CMK-3. Structural and textural characterization of the catalysts was performed 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 hydrodenitrogenation 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.
ODS of dibenzothiopene with titanium-modified SBA-16.
(Universidad Tecnológica Nacional., 2015) Rivoira , Lorena Paola; Vallés , Verónica Alejandra; Beltramone , Andrea Raquel; Martínez , María Laura; Ledesma , Brenda Cecilia; Anunziata , Oscar Alfredo; Anunziata , Oscar Alfredo; Ledesma , Brenda Cecilia; Martínez , María Laura; Vallés , Verónica Alejandra
Over the past, oxidative desulfurization (ODS) has drawn considerable interest as a new alter native method for deep sulfur elimination from light oils. This can be attributed to its attrac tive properties, including lower temperature and pressure conditions and lower operating cost [1-3] than conventional hydrodesulfurization (HDS) process. Oxidation of organosulfur com pounds results in the formation of sulfoxides/sulfones, highly polar and hence easily removed by both extraction into polar solvents or by adsorption. Due to their low reactivity, diben zothiophene derivatives (DBTs) are the most refractory species to be eliminated from oils. Hence, the ODS process through which DBTs are converted to their corresponding sulfones involves great interest at present [4-6]. We recently reported a good performance of this sup port in hydrotreating processes [7]. In this work, we describe the preparation and characteriza tion of new mesoporous catalytic materials based on Ti-containing SBA-16. We study here, the effect of the preparation method of titania-modified SBA-16 (characteristics of the active Ti and/or TiO2 species) and the effect of the different operation conditions in ODS of DBT under mild conditions in order to find the best performance. 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. 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 tempe rature, nature of the substrate and reuse of catalysts).
Reservorio nanoscópico de hidrógeno a partie de biorresiduos de cáscara de naranjas.
(Universidad Tecnológica Nacional., 2022) Juárez , Juliana María; Ledesma , Brenda Cecilia; Anunziata , Oscar Alfredo; Gómez Costa , Marcos Bruno; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Ledesma , Brenda Cecilia
Este trabajo aborda el enfoque de valorización de biorresiduos para el desarrollo de un novedoso nanomaterial carbonoso para ser utilizado en la adsorción de hidrógeno como una alternativa en el uso de hidrógeno verde. En esta investigación, los carbones activados se sintetizaron a partir de cáscara de naranja utilizando diferentes condiciones de síntesis. Con los carbones activados obtenidos con la mejor estructura y textura se estudió la adsorción de hidrógeno y los efectos en la meso/microporosidad de estos. La activación del carbón se realizó mediante un proceso químico con ácido fosfórico como agente activador, variando la concentración de ácido, la relación sustrato / agente activador y el tiempo de contacto entre ellos. El mejor material se obtuvo utilizando tiempo de carbonización de 1 h, temperatura de carbonización de 470oC, concentración de ácido fosfórico de 50% en peso y con área BET de 1402 m2 / g. Dicho material mejoró significativamente el comportamiento de almacenamiento de H2 en comparación con el carbón nanoestructurado del tipo CMK-3 (3,1% en peso a -196,15 oC y 10 bar). El material sintetizado es prometedor en la absorción de hidrógeno por fuerzas de enlace débiles (fisisorción).
Reservorio nanoscópico de hidrógeno a partir de biorresiduos de casacara de naranjas.
(Universidad Tecnológica Nacional., 2022) Juárez , Juliana María; Ledesma , Brenda Cecilia; Anunziata , Oscar Alfredo; Gómez Costas , Marcos Bruno; Beltramone, Andrea Raquel; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Ledesma , Brenda Cecilia
Este trabajo aborda el enfoque de valorización de biorresiduos para el desarrollo de un novedoso nanomaterial carbonoso para ser utilizado en la adsorción de hidrógeno como una alternativa en el uso de hidrógeno verde. En esta investigación, los carbones activados se sintetizaron a partir de cáscara de naranja utilizando diferentes condiciones de síntesis. Con los carbones activados obtenidos con la mejor estructura y textura se estudió la adsorción de hidrógeno y los efectos en la meso/microporosidad de estos. La activación del carbón se realizó mediante un proceso químico con ácido fosfórico como agente activador, variando la concentración de ácido, la relación sustrato / agente activador y el tiempo de contacto entre ellos. El mejor material se obtuvo utilizando tiempo de carbonización de 1 h, temperatura de carbonización de 470oC, concentración de ácido fosfórico de 50% en peso y con área BET de 1402 m2 / g. Dicho material mejoró significativamente el comportamiento de almacenamiento de H2 en comparación con el carbón nanoestructurado del tipo CMK-3 (3,1% en peso a -196,15 oC y 10 bar). El material sintetizado es prometedor en la absorción de hidrógeno por fuerzas de enlace débiles (fisisorción).
SINTESIS DIRECTA DE CMK-3 MODIFICADA CON TI, COMO SOPORTE DE IR APLICADO A REACCIONES DE HIDRODENITROGENACION.
(Universidad Tecnológica Nacional., 2018) Ledesma , Brenda Cecilia; Juárez , Juliana María; Beltramone, Andrea Raquel; Juárez , Juliana María
En el presente trabajo se sintetizó Ti-CMK-3 mediante un nuevo método de síntesis, en el cual se evita la utilización de un molde, con el fin de reducir el tiempo, el consumo de energía y por ende el costo. La caracterización estructural y superficial del catalizador se realizó mediante adsorción de N2, XRD, UV-Vis DRS, espectroscopía Raman y TEM. Los resultados de la caracterización indicaron que las propiedades texturales y estructurales del material sintetizado son comparables con las propiedades del material preparado por el método tradicional. El catalizador Ir-Ti-CMK-3 obtenido fue activo y selectivo para la reacción de hidrodenitrogenación (HDN) del indol. La principal ventaja del presente estudio es la reducción de tiempo y costo de la síntesis, simultáneamente con la aplicabilidad en las reacciones de Hidrotratamiento (HDT)
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.

Browsing by Author "Ledesma , Brenda Cecilia"

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