Facultad Regional Córdoba
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Item HDN of indole over Ir-modified Ti-SBA-15.(Univesidsad Tecnológica Nacional., 2015) Ledesma , Brenda Cecilia; Anunziata , Oscar Alfredo; Beltramone, Andrea RaquelThe 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 Tetraethyl Orthotitanate. Iridium was added by wetness impregnation. The acidity of Ti-SBA-15 was modified adding F or Al in order to improve the catalytic activity. The catalysts pre pared were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV–vis-DRS, Raman spectroscopy, 27 Al-MAS-NMR spectroscopy, XPS, TEM-EDS, Py-FTIR, H2-Chemisorption 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 F or Al incorporation. 27 Al-MAS-NMR spectroscopy indicated that aluminum was incorporated mainly in Td positions. The results showed that Ti incorporation helps to reduce significantly the size of iridium crystallites and improves its dispersion considerably. Ir/Ti-SBA-15 modified with Al, with Bronsted acid ity, was the most active catalyst for indole HDN, in mild conditions in a Batch reactor. The experimental data for indole hydrodenitrogenation was quantitatively represented by a Langmuir–Hinshelwood type rate equationItem 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 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 Indole HDN using iridium nanoparticles supported on titanium nanotubes(2022) Ledesma, Brenda Cecilia; Martínez, María Laura; Gómez Costa, Marcos Bruno; Beltramone, Andrea RaquelThe HDN of indole was studied over iridium modified titanate nanotube catalyst. Titanium nanotube was prepared by the alkaline hydrothermal method. Iridium was added by wetness impregnation. The activity was compared with Ir–TiO2 and commercial NiMo/Al2O3 catalysts. The catalysts prepared were characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV–Vis-DRS, FTIR, XPS, TEM, Py-FTIR and H2-Chemisorption. XRD, N2 isotherms and UV–vis-DRS con- firmed the nanotube structure. The analysis showed that the mesoporous structure was maintained after Ir incorporation. The results showed that titanate nanotube as support significantly reduce the size of iridium crystallites and improves its dispersion considerably. Iridium titanate nanotube presented abundant and strong Brönsted acidity compared with TiO2 iridium catalyst. According a kinetic study, Ir–TNT was the most active catalyst for indole HDN, in mild conditions in a Batch reactor. The Brönsted acidity in synergic effect with Lewis acidity and hydrogenolysis capacity of iridium species were the responsible for the good activity.Item Influence of ti incorporation to bimetallic mesoporous carbon in the production of 2,5‑dimethylfuran from biomass derivatives(2021) Ledesma, Brenda Cecilia; Juárez, Juliana María; Domine, Marcelo E.; Beltramone, Andrea RaquelMonometallic and bimetallic supported catalysts were developed to produce 2,5-dimethylfuran (DMF) trough hydrogenolysis of 5-(hydroxymethyl)furfural (HMF). Detailed physicochemical characterization was done to understand structure–activity correlation. Through a series of experiments and comparatives tests, the synergistic effect among Pt, Ir, and Ti incorporated in the support was investigated. Results revealed that using the titanium contained ordered mesoporous carbon, synthesized by a novel technique, high selectivity to DMF was achieved. In the case of the best catalyst PtIr-TiC, the good activity and excellent selectivity to the desired product DMF (98% yield) was related to the high hydrogenating capacity of the bimetal- lic sites, the acid support characteristics and the high metal nanoparticles dispersion achieved on the mesoporous titanium modified carbon support.Item Biofuel production using ordered mesoporous carbons with modified carbonaceous structure(2021) Ledesma, Brenda C.; Beltramone, Andrea R.Monometallic and bimetallic supported catalysts were developed to produce 2,5-dimethylfuran (DMF) trough hydrogenolysis of 5-(hydroxymethyl)furfural (HMF). Detailed physicochemical characterization was done in order to understand structure-activity correlation. Through a series of experiments and comparatives tests, the synergistic effect among Pt, Ir, and Ti incorporated in the support was investigated. Results revealed that using the titanium contained ordered mesoporous carbon, synthesized by a novel technique, high selectivity to DMF was achieved. In the case of the best catalyst PtIr-TiC, the good activity and excellent selectivity to the desired product DMF (98% yield) was related to the high hydrogenating capacity of the bimetallic sites, the acid support characteristics and the high metal nanoparticles dispersion achieved on the mesoporous titanium modified carbon support.