Browsing by Author "Vallés, Verónica"
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Item Desulfuración oxidativa utilizando material mesoporoso Ti-SBA-16(2014) Rivoira, Lorena Paola; Vallés, Verónica; Ledesma, Brenda; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelLa oxidación de compuestos organosulfurados conduce a la formación de los sulfóxidos/sulfonas correspondientes, lo que permite que sean fácilmente removidos mediante extracción en solventes polares o por adsorción. El proceso de ODS es llevado a cabo bajo condiciones muy suaves, comparado con el proceso convencional de HDS. El objetivo del presente trabajo es estudiar el efecto del método de preparación de SBA-16 modificada con titanio en el rendimiento de la ODS del DBT con H2O2 y acetonitrilo como solvente en condiciones suaves de reacción. Se estudiaron dos materiales TiO2-SBA-16 obtenido por impregnación húmeda y Ti-SBA-16 obtenido mediante síntesis directa. con una relación de Si/Ti=20. Para la actividad catalítica se lleva a cabo la reacción de oxidación a 70°C y presión atmosférica se utilizó un reactor batch. Se utilizó H2O2 como agente oxidante y acetonitrilo como solvente.Item Eliminación de azufre mediante desulfuración oxidativa con SBA-16 modificada con titanio(2014) Rivoira, Lorena Paola; Vallés, Verónica; Ledesma, Brenda; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelLa oxidación de compuestos organosulfurados conduce a la formación de los sulfóxidos/sulfonas correspondientes, los cuales son mucho más polares, lo que permite que sean fácilmente removidos mediante extracción en solventes polares o por adsorción. El proceso de ODS es llevado a cabo bajo condiciones muy suaves (presión atmosférica y 60-90ºC), comparado con el proceso convencional de HDS, donde comúnmente son usadas presiones mayores a los 30 bar y temperaturas desde los 300 a los 380ºC. Resultados recientes muestran que tamices moleculares que contienen Ti exhiben buena reactividad catalítica en la oxidación de sulfuro, mercaptano, tiofeno y derivados (1). El objetivo del presente trabajo es estudiar el efecto del método de preparación de SBA-16 modificada con titanio (características de las especies activas de Ti y/o TiO2) en el rendimiento de la ODS del DBT con H2O2 y acetonitrilo como solvente en condiciones suaves de reacción.Item Hidrogenación de tetralin en presencia de quinolina sobre Ir/SBA-16 modificada con titanio(2014) Ledesma, Brenda; Vallés, Verónica; Rivoira, Lorena Paola; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelEn el presente trabajo informamos resultados de la hidrogenación efectiva de tetralin en presencia de quinolina, en condiciones menos severas que las industriales; para lo cual desarrollamos un nuevo material catalítico mesoporoso Ir/SBA-16 modificado con titanio. La incorporación de Ti facilitó la mayor y mejor homogeneidad en la dispersión de partículas de Ir metálico (Ir0). Para conocer el efecto en la dispersión del metal de transición (1), el Ti fue incorporado vía post síntesis como TiO2 y en red empleando el método sol-gel obteniendo así los catalizadores Ir/TiO2-SBA-16 e Ir/Ti-SBA-16.Item Hidrogenación de tetralin utilizando un catalizador bifuncional de iridio/platino-SBA-15(2014) Vallés, Verónica; Ledesma, Brenda; Rivoira, Lorena Paola; Cussa, Jorgelina; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelLos catalizadores bimetálicos de Pt–Pd han recibido considerable atención debido a que demuestran tener una alta actividad en una amplia variedad de aplicaciones catalíticas (1). Con alta actividad, selectividad y estabilidad, comparada con catalizadores monometálicos de Pt y Pd. Por ejemplo, catalizadores bimetálicos Pt-Pd muestran tener mayor resistencia frente a envenenamientos en comparación con catalizadores de Pt (2-4). Las características estudiadas del catalizador serán correlacionadas con su performance catalítica en la hidrogenación del tetralin. El objetivo final es encontrar la proporción óptima de cada uno de los metales de forma de lograr la mayor actividad en dicho proceso.Item Hydrogenation of tetralin over Ir catalysts supported on titania-modified SBA-16(2014) Ledesma, Brenda; Vallés, Verónica; Rivoira, Lorena Paola; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelAbstract A series of Ti modified SBA-16 supports and their respective Ir-catalysts were prepared and character- ized to study the effect of support preparation method on the dispersion of iridium and on the characteristics of Ir surface species. Two methods of incorporation of titania were tested: the sol–gel method in order to obtain Ti as heteroatom and incipient wetness impregnation to obtain Ti as TiO2 (anatase phase). The results show that supports with different Ti species and dispersion can be obtained. The final catalyst was characterized at different preparation stages by XRD, elemental analysis and BET. The presence of Ti as Ti4? in the nanostructure of SBA and as TiO2 (anatase phase) was analyzed by UV–Vis–DRS and Raman spectroscopy. The iridium oxidation sate upon Ti-con- taining SBA-16 was studied by XPS, EDX, TEM and XRD, arriving at the good proportion of Ir0. H2 chemi- sorption and TEM characterization for Ti-SBA-16 indi- cated that Ir particle size was lower than anatase/SBA-16. The catalyst that we synthesized had good activity mea- sured in tetralin hydrogenation in presence of quinoline at mild conditions. The experimental data were quantitatively represented by a modified Langmuir–Hinshelwood-type rate equation. The preliminary results show these materials as promising catalysts for HDS/HDN reactions.Item Hydrogenation of tetralin over Ir-containing mesoporous catalysts(2012) Vallés, Verónica; Balangero, Gerardo Simón; Martínez, María Laura; Gómez Costa, Marcos Bruno; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelThe yield in fluid catalytic cracking (FCC) depends on the extent of aromatic hydrogenation in the gas oil hydrotreater. To optimize the gas oil hydrotreater, it is crucial to understand the aromatic hydrogenation reaction chemistry occurring in the gas oil hydrotreater. Gas oils, which consist of hydrocarbons in the boiling point range of 290−570 °C, contain several aromatic compounds (including three rings, two rings, and one ring). Light cycle oil (LCO), which contains large concentrations of aromatics, has a poor cetane value and, hence, by itself, is a very poor-quality diesel. Because the current regulations [on cetane and polynuclear aromatic (PNA) hydrocarbons] are not stringent, LCO is currently blended with diesel. However, it is anticipated (based on existing regulations in Europe and California) that diesel quality in the near future will be more stringently regulated in terms of cetane and aromatics. To find alternative processes, it is necessary to develop new and more active catalysts to replace the current ones. Optimal design and operation of such hydrogenation processes can be achieved through the use of reliable simulation tools; however, such tools require detailed knowledge of kinetic pathways and rates.1−3 Kinetic experiments on hydrogenation are typically performed in the gas phase under atmospheric pressure on group VIII metal catalysts. Previously, Beltramone et al.4,5 reported a detailed study and a quantitative network analysis of polynuclear aromatics aromatization at industrial conditions, and Korre and Klein6 reported an exhaustive study in a batch reactor at high pressure. Otherwise, the sulfur and nitrogen compounds found in synthetic feedstocks and heavy petroleum fractions can strongly inhibit hydroprocessing reactions through competitive adsorp- tion. The presence of these species even at low concentrations can limit the observed catalytic activity and necessitate the use Article Current processes for dearomatization use catalysts combin- ing the acidity of a support and the hydrogenation and hydrogenolysis/ring-opening activity of an incorporated metal. Hydrogenation/hydrocracking is most often practiced on cyclic molecules over primarily acidic zeolite, alumina, or silica- alumina-supported noble and other group VIII metal catalysts. Different processes have used catalysts such as NiMo, CoMo, NiW, Pt, and Pd on various supports.7−17 The dominance of the acid function can lead to cracking, and thus, a primary focus is the optimization of the acid function. In fact, it was shown recently that significant enhancements in hydrogenation can be made by focusing on the metal function. The metal function is usually provided by Pt and/or Pd, but it has been shown that Ir, Ru, and Rh also have exceptional activities and selectivities for the target reaction of hydrogenation and, depending on the reaction conditions, selective ring-opening.18−20 Some alumina- supported transition-metal catalysts have much higher hydro- denitrogenation (HDN) and hydrodesulfurization (HDS) activities than the conventional NiMo system.21−25 For example, Rh, Ir, Ru, and Pt supported on silica or alumina are known to effectively catalyze nitrogen removal from methylamine, quinoline, or pyridine also in the reduced state.26 Noble-metal sulfides, either unsupported as bulk compounds27 or supported on active carbon,28 have been studied extensively in hydrorefining. It has been shown that transition-metal sulfides of the second and third rows such as those containing Ru, Rh, Os, and Ir are especially active during HDS reactions.27 Similarly, sulfides of Ir, Os, and Re were found to be most active in the HDN of quinoline,28 and sulfides of Ir and Pt were found to be most active in the HDN of pyridine.29 However, catalytic properties of metal deposited on alumina or other supports have been studied less frequently, and moreover, the primary attention to date has been devoted only to Ru.30 It was shown by Cinibulk and Vit́31 that the HDN of higher pressures and temperatures to obtain desired conversions. Therefore, the need for more active catalysts is crucial in this process. The development of highly active and selective hydrotreating catalysts is one of the most pressing problems facing the petroleum induItem Material catalitico Ir/Ti-SBA-16 para la hidrogenación de tetralin(2014) Ledesma, Brenda; Vallés, Verónica; Rivoira, Lorena Paola; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelEn el presente trabajo informamos resultados de la hidrogenación efectiva de tetralín en presencia de quinolina, en condiciones menos severas que las industriales; para lo cual desarrollamos un nuevo material catalítico mesoporoso Ir/SBA-16 modificado con titanio. La incorporación de Ti facilitó la mayor y mejor homogeneidad en la dispersión de partículas de Ir metálico (Ir0). Para conocer el efecto en la dispersión del metal de transición, el Ti fue incorporado: 1) vía post síntesis como TiO2: Se realiza un secado previo del material SBA-16, luego, 0,5 g. de la muestra seca se dispersó en una solución que contenía 2ml de Tetrabutilortotitanato (TTBT) y 5 ml de etanol, y 2) en red empleando el método de síntesis sol-gel: se parte de una síntesis de SBA-16 ya publicada y luego de incorporar el TEOS, a continuación se gotea Tetraetilortotitanato (TEOT) disuelto previamente en etanol.Item Síntesis y caracterización de un catalizador soportado iridio/platino-SBA-15 para su aplicación(2014) Vallés, Verónica; Ledesma, Brenda; Rivoira, Lorena Paola; Cussa, Jorgelina; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelEn el presente trabajo se estudió el efecto de la dispersión de metales nobles Ir y Pt y la interacción con el soporte SBA-15, relacionándolos con la actividad catalítica del catalizador en la reacción de hidrogenación del Tetralin utilizando un reactor Parr a 250°C y 15 atm. Con este objetivo se sintetizaron catalizadores Ir/Pt-SBA-15 modificados con distintos % de Ir y Pt. La mesoestructura del soporte SBA-15 le confiere una estabilidad térmica relativamente alta y el diámetro apropiado de poro permite convertir moléculas voluminosas como las presentes en los cortes de combustibles líquidos. El soporte fue preparado por el método de sol-gel. Para la obtencion del sitio catalitico se utilizó l método de impregnación incipiente. Se disuelven el Acetil acetonato de Iridio (IrAcAc) y el Acido cloroplatinico hidratado (H2PtCl6.H2O) en 50 ml de etanol a 50ºC con reflujo. Luego se agrega a la SBA-15 previamente pesada la solución y se lo lleva a un evaporador rotatorio a 60 ºC y 70 rpm hasta lograr evaporar todo el solvente. Luego se deja secando en estufa a 110 ºC por 24 h. Posteriormente es calcinado en mufla a 500 ºC por 5 horas, seguido de reducción con hidrógeno. El material fue caracterizado mediante difracción de rayos X (XRD), se puede observar que conserva la estructura mesoporosa a bajo ángulo, mientras que a alto ángulo se observan los índices de refracción característicos de Ir y Pt metálicos. También fueron caracterizados por XPS y TEM. La dispersión del Me fue calculada mediante quimisorción de H2 se obtuvieron partículas de iridio/Platino (d= 4,0-2.0 nm) homogéneamente disperso, con una dispersión de más del 60%. Se obtuvo unaItem Syntesis, characterization and hydrotreating catalitic performance of Ir/Ti-SBA-16 and Ir/TIO2-SBA-16.(2014) Ledesma, Brenda; Vallés, Verónica; Rivoira, Lorena Paola; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelA series of Ti modified SBA-16 supports and their respective Ir-catalysts were prepared, and characterized to study the effect of support preparation method on the dispersion of iridium and on the characteristics of Ir surface species, with the main aim of obtaining Nitrogen-tolerant catalysts to be used in second stage processes of mild-hydrotreating. Two methods of titania incorporation were tested: the sol-gel method in order to obtain Ti as heteroatom and incipient wetness impregnation to obtain Ti as TiO2 (anatase phase). The final catalyst was characterized at different stage of preparation by XRD, EDX, TEM, elemental analysis and BET, arriving at the good proportion of Ir0. The presence of Ti as Ti+4 in the nanostructure of SBA and as TiO2 (anatase phase) was analyzed by UV-vis-DRS and Raman spectroscopy. The average metal particle size indicates that the Ir particle size is lower when we used Ti-SBA-16 than anatase/SBA-16. We study the catalytic properties of 1 wt% Ir-containing SBA-16 materials modified with Ti as heteroatom and impregnated with TiO2 (anatase phase), in the hydrogenation of tetralin to decalin in the presence of 100 ppm of N as quinoline at 250°C and 15 atm of pressure of hydrogen, using a Parr reactor. The catalysts synthesized by us had good activity measured in tetralin hydrogenation under mild conditions. The experimental data was quantitatively represented by a modified Langmuir-Hinshelwood type rate equation. The preliminary results show these materials as promising catalysts for HDT and HDN reactions.Item Synthesis, characterization and catalytic performance of bimetallic Ir-Pt catalysts for tetralin hydrogenation(2014) Vallés, Verónica; Ledesma, Brenda; Rivoira, Lorena Paola; Cussa, Jorgelina; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelBimetallic Pt–Pd catalysts have received considerable attention, because they show high activity in a variety of catalytic applications (1) and stability compared with monometallic Pt or Pd catalysts. For instance, the bimetallic Pt–Pd catalysts have been shown to have higher resistance toward poisonscompared to Pt catalysts (2-4). For supported bimetallic clusters, the surface and bulk composition strongly depend on a series of parameters, for example, preparation procedures, metal–metal and metal–support interactions. The final goal is to find the optimal proportion of each metal in order to be more active in these processes.In this case a 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 metal showed the best activity measured in tetralin hydrogenation. Platinum (Pt) and Iridium (Ir) nanoparticles were incorporated into SBA-15 support [1-4] by the wet co-impregnation method. The metal precursors were Iridium acetylacetonate and cloroplatinic acid. The samples were calcined at 500°C and previous to the catalytic test the samples were reduced by heating at 2°C/min to 450°C in a H2 stream for 5 h. Hereinafter this catalyst will be referred as Ir-Pt- SBA-15 (x), with x= 1-3. The catalytic activity was measured in a 4563Parr reactor, at 250°C, 15 atm of pressure of hydrogen and 360 rpm for tetralin hydrogenation (feed consisted in 50 mL of 5% v/v of tetralin (98.5% FLUKA) in Dodecane). The Pt-Ir-SBA-15 catalyst with 1 %wt. of each metals had the highest activity measured in tetralin hydrogenation at mild conditions. The good activity was correlated with higher Ir/Pt dispersion on SBA-15 mesostructured material used as support, as we seen by TEM and H2 Chemisorption, with higher active metal sites exposed to reactant. The Ir-Pt-SBA-15 activity is sufficiently high to envisage use in the final stages of a refinery process producing diesel fuel of high Cetane Number by hydrodearomatization.Item Synthesis, characterization and hydrotreating activity of Ir catalysts supported on titania-modified mesoporous material(2014) Ledesma, Brenda; Vallés, Verónica; Rivoira, Lorena Paola; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelA titanium modified catalyst based on noble metal has been prepared with the main aim of obtaining Nitrogen-tolerant catalysts to be used in second stage processes of mild-hydrotreating. We study the catalytic properties of 1 wt% Ir-containing SBA-16 materials modified with Ti as heteroatom and impregnated with TiO2 (anatase phase), in the hydrogenation of tetralin to decalin in the presence of 100 ppm of N as quinoline at 250°C and 15 atm of pressure of hydrogen, using a Parr reactor. The iridium oxidation sate upon Ti-containing SBA-16 was studied by XPS, EDX, TEM and XRD, arriving at the good proportion of Ir0. The average metal particle size indicate that the Ir particle size is lower when we used Ti-SBA-16 than anatase/SBA-16. The experimental data was quantitatively represented by a modified Langmuir-Hinshelwood type rate equation. The preliminary results show these materials as promising catalysts for HDS/HDN reactions.Item Tetralin hydrogenation and ring opening of decalin over Ir-Pt-SBA-15(2014) Vallés, Verónica; Rivoira, Lorena Paola; Ledesma, Brenda; 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 Titania-modifed SBA-16 applied to oxidative desulfuration of DBT(2014) Rivoira, Lorena Paola; Vallés, Verónica; Ledesma, Brenda; Martínez, María Laura; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelRecent results show that Ti-containing molecular sieves exhibit good catalytic reactivity in the oxidation of sulfide, mercaptan, thiophene and derivatives [1]. In this work, we describe the preparation and characterization of new mesoporous catalytic materials based on Ti-containing SBA-16. The aim of the present work is to study the effect of the preparation method of titania-modified SBA-16 (characteristics of the active species Ti and/or TiO2) on the performance in the ODS of DBT with H2O2 and acetonitrile as solvent at mild conditions.