Facultad Regional Córdoba
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Item Sulfur elimination by ODSwith titanium-modified SBA-16.(Univesidsad Tecnológica Nacional., 2015) Rivoira , Lorena Paola; Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Martínez , María Laura; Anunziata , Oscar Alfredo; Beltramone, Andrea RaquelOver 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 attractive properties, including lower temperature and pressure conditions and lower operating cost than conventional hydrodesulfurization (HDS) process. Oxidation of organosulfur compounds 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, dibenzothiophene 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. In this work, we describe the preparation and characterization 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 temperature, nature of the substrate and reuse of catalysts). 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 activityItem Aniline adsorption and polymerization over gallium modified mesoporous material.(Univesidsad Tecnológica Nacional., 2018) Martínez , María Laura; Rivoira , Lorena Paola; Beltramone, Andrea Raquel; Anunziata , Oscar Alfredo; Anunziata , Oscar Alfredo; Rivoira , Lorena PaolaIn 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.Item VOx-SBA-15 modified with AI and Ga in ODS of DBT.(Univesidsad Tecnológica Nacional., 2018) Rivoira , Lorena Paola; Martínez , María Laura; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Martínez , María LauraIn order to adapt current processes to the strict regulatory requirements, several technologies have been developed for deep desulfurization of diesel fuel. The major portion of sulfur compounds in light cycle oils (LCO) are dibenzothiophene (DBT) and alkyl-dibenzothiophenes, which are not easily removable by hydrotreating. Vanadium oxides supported on mesoporous SBA-15 catalysts with different vanadium loadings were studied in the oxidative desulfurization (ODS) of dibenzothiophene. The catalytic activity was improved when SBA-15 framework was modified with Al and Ga as heteroatom substituting Si. Structural and textural characterization of the catalysts were performed by means of XRD, N2 adsorption, UV–Vis–DRS, XPS, NMR, TEM, Raman, TPR and Py-FTIR. UV–Vis–DRS and Raman demonstrated that highly dispersed vanadium VO4-3 species are responsible for the high activity in the sulfur removal. The Ga modified support with an intermediate V/Si ratio was the most active catalyst, using hydrogen peroxide as oxidant and acetonitrile as solvent. 100% of DBT elimination was attained at a short time in mild conditions. Gallium and aluminum incorporation modified successfully the nature of the SBA-15 surface by generating Bronsted and Lewis acidity. The interaction between the acid sites with the vanadium active sites improved the activity of the catalysts. The more acidic support allowed better dispersion of the vanadium species due to stronger interaction metal-support. The reusability of the catalysts indicates that vanadium oxide supported on mesoporous SBA-15 modified with Ga and Al are potential catalysts for the ODS of dibenzothiophene.Item Sulfur elimination by ODSwith titanium-modified SBA-16.(Univesidsad Tecnológica Nacional., 2015) Rivoira , Lorena Paola; Vallés , Verónica Alejandra; Ledesma, Brenda Cecilia; Martínez , María Laura; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Martínez , María Laura; Ledesma, Brenda; Vallés , Verónica AlejandraNanostructured carbon CMK-3 and mesoporous silica SBA-15 modified with Fe by using different sources of Fe, were used in the oxidative desulfurization (ODS) of dibenzothiophene (DBT) as a model sulfur compound. Fe-CMK-3 and Fe-SBA-15 were prepared by wetness impregnation using FeCl3.6H2O and FeNO3.9H2O as different sources of Fe. A solution of FeCl3.6H2O/ FeNO3.9H2O in ethanol was mixed with the corresponding material solution (CMK-3 or SBA-15) at room temperature. The solution was placed in a rotary evaporator to remove excess of ethanol at about 333 K and 60 rpm. Afterwards, the sample was dried at 373 K for 18 h and was thermally treated in a dynamic inert (N2) atmosphere. The percentage of Fe has been 2 wt.% with respect to carbon in the final FeCl3-CMK-3 and FeNO3-CMK-3 material. Four samples modified with Fe have been prepared and were characterized by XRD, FTIR, XPS, BET, TEM and SEM. These studies indicated that it was possible to obtain a CMK-3 replica successfully from SBA-15, using sucrose as a carbon precursor. Wide angle XRD pattern of the sample modified with FeCl3.6H2O implies the formation of the magnetite phase in the silica channels. The nanomaterial area is significantly smaller with the incorporation of the metal, SBA-15 and CMK-3`s characteristic structure is maintained after the metal is within the host, in agreement with the XRD studies. The catalytic activity was improved when the nanoporous materials were modified with Fe. The nanoporous carbon modified with FeCl3.6H2O was the most active catalyst for ODS of DBT, using hydrogen peroxide (H2O2) as oxidant and acetonitrile as solvent. 100% of DBT elimination was attained at a short time in mild conditions.Item RSM in the analysis of conversion of DBT in oxidative desulfurization using vanadium-SBA-15 catalysts modified with AI and Ga.(Univesidsad Tecnológica Nacional., 2018) Rivoira , Lorena Paola; Cussa , jorgelina; Martínez , María Laura; Beltramone, Andrea Raquel; Martínez , María Laura; Cussa , jorgelinaExperiment design-response surface methodology (RSM) was used to model and optimize one response in the oxidative desulfurization of dibenzothiophene with hydrogen peroxide using VOx-Ga-SBA-15 catalysts with different Ga/Si and V/Si ratios. In this study, we analyze the influence of the nature of the catalyst (metal/Si ratio), the substrate/catalyst mass ratio and the oxidant/substrate ratio. Conversion at 15 min is the analyzed response. 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 objective function were obtained employing the catalyst with 4 wt.% of gallium and 6 wt.% of vanadium; optimal ratio between g DBT/g of catalyst was 4 and molar ratio H2O2/DBT was 5. The incorporation of gallium as heteroatom in tetrahedral position allows the better anchorage of the active species of vanadium generating a very well dispersed catalyst. Structural and textural characterization of the catalysts were performed by means of XRD, N2 adsorption, UV–Vis–DRS, XPS, NMR, TEM, Raman, TPR and Py-FTIR. UV–Vis–DRS and Raman demonstrated that highly dispersed vanadium pentoxide crystallites are responsible for the high activity in the sulfur removal. The high dispersion depended on the vanadium loading and on the nature of the support. The experiment design was able to find the best combination between the heteroatom and the vanadium active site in order to find the most active catalyst for ODS of DBT at the optimized experimental conditions.Item Iron modified mesoporous materials as catalysts for ODS of sulfur compounds.(Univesidsad Tecnológica Nacional., 2018) Rivoira , Lorena Paola; Juárez , Juliana María; Martínez , María Laura; Beltramone, Andrea Raquel; Martínez , María; Juárez , Juliana MaríaSe aplicaron catalizadores mesoporosos modificados con Fe en la reacción de ODS de DBTs, utilizando H2O2 como oxidante y acetonitrilo como solvente. Los soportes utilizados fueron SBA-15, MCM-48, CMK-3 y CMK-1.El hierro se incorporó mediante impregnación húmeda utilizando nitrato de hierro. Los catalizadores se caracterizaron por XRD, isotermas de N2, TEM, XPS e ICP. Hemos desarrollado catalizadores con gran área específica y volumen de poro, distribución estrecha del tamaño de mesoporos y especies de hierro altamente dispersas. Se probaron los catalizadores en desulfuración oxidativa de diferentes compuestos de azufre tales como benzotiofeno (BT), dibenzotiofeno (DBT) y 4,6-dimetil dibenzotiofeno 4,6-DMDBT). El catalizador preparado con CMK-3 como soporte fue el más activo para la reacción de ODS. La buena actividad se relacionó con la elevada dispersión de óxidos de hierro, principalmente en la fase magnetita. En la oxidación de DBT y utilizando Fe-CMK-3 se estudiaron la temperatura, peróxido de hidrogeno y concentración inicial de azufre. Se determinaron las condiciones óptimas de operación. Fe-CMK-3 es un catalizador activo y estable para ser aplicado en el proceso industrial de ODS. Palabras clave: SBA-15, MCM-48, CMK-3, CMK-1, Fe.Item Experimental desing optimization of the ODS of DBT using vanadium oxide supported on mesoporous GA-SBA-15.(Univesidsad Tecnológica Nacional ., 2018) Rivoira , Lorena Paola; Cussa , jorgelina; Vallés , Verónica Alejandra; Martínez , María Laura; Beltramone , Andrea Raquel; Martínez , María Laura; Vallés , Verónica Alejandra; Cussa , jorgelinaEn el presente trabajo se utiliza el diseño experimental de superficies de respuesta (RSM) para modelar y optimizar la oxidación de dibenzotiofeno (DBT) utilizando VOx-Ga-SBA-15 como catalizador. Analizamos como influye la naturaleza del catalizador (carga de V y Ga), la relación másica substrato/catalizador y la relación molar oxidante/substrato como variables para el diseño. La respuesta analizada fue la conversión a los 15 min de reacción. Las superficies de respuesta fueron obtenidas mediante el Diseño de Box-Behnken, encontrando así la mejor combinación entre los parámetros de reacción que permita optimizar el proceso. Los mayores valores de función objetivo se obtuvieron mediante el uso de la estadística, empleando el catalizador con 4 % p/p de galio y 6 % p/p de vanadio, la relación óptima entre g DBT/g de catalizador fue 4 y la relación molar H2O2/DBT fue 5. La incorporación de galio como heteroátomo en posición tetraédrica permite el mejor anclaje de las especies activas de vanadio generando un catalizador con muy buena dispersión. El diseño de experimento sirvió para encontrar la mejor combinación entre el heteroátomo y las especies activas de vanadio con el fin de hallar el catalizador mas activo para la oxidación de DBT en las condiciones experimentales óptimas.Item Material catalítico con estructura mesoporosa conteniendo galio, adsorción y polimerización de anilina.(Univesidsad Tecnológica Nacional., 2018) Martínez , María Laura; Rivoira , Lorena Paola; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Anunziata , Oscar Alfredo; Rivoira , Lorena PaolaEn este trabajo estudiamos la polimerización de anilina sobre el galosilicato mesoporoso del tipo Ga-SBA-3. Este material fue expuesto a vapores de anilina en equilibrio para obtener hospedajes saturados. La adsorción de anilina sobre estos materiales, sintetizados en nuestro laboratorio se estudió por espectroscopia infrarroja. La adsorción de anilina fue evaluada para luego polimerizar la anilina adsorbida para generar un composite de polianilina-hospedaje y obtener composites con propiedades únicas. Composites de polianilina, obtenidos por técnicas de polimerización in-situ, fueron caracterizados por espectroscopia infrarroja (FTIR), y difracción de rayos X (XRD). Los análisis FTIR del composite polianilina/Ga-SBA-3 (PANI/Ga-SBA-3) muestra bandas características de acuerdo a datos obtenidos en trabajos previos atribuidas al stretching quinoidal (N=Q=N) y al stretching C-C de anillo bencénico. Los análisis de XRD muestran que la polianilina está dentro de los canales del hospedaje. Palabras clave: Galosilicato, Ga-SBA-3, anilina, polianilina, PANI/Ga-SBA-3Item Iron-modified mesoporous materials as catalysts for ODS of sulfur compounds.(Univesidsad Tecnológica Nacional, 2018) Rivoira , Lorena Paola; Juárez , Juliana María; Martínez , María Laura; Beltramone , Andrea Raquel; Juárez , Juliana MaríaMandatory environmental regulations have been legislated all over the world so the top permitted content of sulfur in diesel is 15 ppm. ODS is the oxidation of sulfur compounds present in diesel to form sulfoxides and sulfones. These substances are highly polar and hence easily removed by extraction with solvent. Oxidant agent commonly used are peroxides such as hydrogen peroxide and tert-butylhydroperoxide (Di Giusepe et al., 2009). Since Diesel is a non-polar liquid while H2O2 is a polar liquid, a polar solvent is needed. The formed polar products can be easily removed from the operation unit by liquid liquid extraction. Mesoporous materials have been tried showing potential catalytic applications. Transition metals are commonly used as catalyst in ODS such as Mo, Mn, Sn, Fe, Zn, V and Ti (Cedeño-Caero et al., 2011). In this work, we propose the application of different supports as SBA-15, MCM-48, CMK-1 and CMK-3 for the preparation of Fe-catalysts.Item Material catalítico con estructura mesoporosa conteniendo galio, adsorción y polimerización de anilina del trabajo.(Univesidsad Tecnológica Nacional., 2018) Martínez , María Laura; Rivoira , Lorena Paola; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Anunziata , Oscar Alfredo; Rivoira , Lorena PaolaLa anilina (AN) es una base orgánica aromática débil y anfiprótica, que puede actuar como aceptor o donor de protones. La polianilina (PANI) existe en una variedad de formas. La forma de sal emeraldina (conductora, de color verde) o forma protonada de la polianilina tiene una conductividad en un nivel semiconductor de 100 S/cm, muchos órdenes de magnitud mayor que los polímeros comunes (aislantes, <10-9 S/cm), pero menor que los metales (conductores típicos, >104 S/cm). El material mesoporos SBA-3 ofrece oportunidades únicas para la preparación de nuevos materiales híbridos nanoestructurados En este sentido, el estudio de adsorción de anilina y su posterior polimerización sobre hospedajes tal como SBA-3 es de suma importancia (Anunziata et al., 2005, 2008). En este trabajo estudiamos la incorporación de galio en la estructura del material mesoporoso, con el fin de modificar la acidez intrínseca del material (Berrichi et al., 2006) y la adsorción de piridina en la superficie del mismo con el objetivo de determinar los sitios ácidos que posee este material. En adición se realizara estudios de adsorción/desorción de anilina y su posterior polimerización sobre el galosilicato mesoporoso Ga-SBA-3 que le confiere características únicas al compuesto, obteniéndose híbridos con características conductoras similares a las de un semiconductor inorgánico.