Multiple-wall carbon nanotubes obtained with mesoporous material decorated with ceria-zirconia

In this work, Ceria-Zirconia on ordered Santa Barbara mesoporous silica (Ce-Zr-SBA-15), has been used directly as a catalyst for the synthesis of carbon nanotubes (CNTs) through Chemical Vapor Deposition (CVD). In addition to cerium oxide, it contains zirconium oxide nano crystallites, which act as catalysts for carbon nanostructures. The catalytic performance of this material was evaluated for the decomposition of ethanol at 900 °C, with N2 flow. The carbon decomposed from absolute ethanol diffuses through the surface of the nanostructured catalytic material and precipitates in the form of MWCNT structures, which could be identified by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), showing average diameters of 30–35 nm.Fil: Rodriguez, Miguel Angel. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Anunziata, Oscar Alfredo. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Martinez, Maria Laura. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Probing the catalytic activity of sulfate-derived Pristine and post-treated porous TiO2(101) anatase mesocrystals by the oxidative desulfurization of dibenzothiophenes

Mesocrystals (basically nanostructures showing alignment of nanocrystals well beyond crystal size) are attracting considerable attention for modeling and optimization of functionalities. However, for surface-driven applications (heterogeneous catalysis), only those mesocrystals with excellent textural properties are expected to fulfill their potential. This is especially true for oxidative desulfuration of dibenzothiophenes (hard to desulfurize organosulfur compounds found in fossil fuels). Here, we probe the catalytic activity of anatases for the oxidative desulfuration of dibenzothiophenes under atmospheric pressure and mild temperatures. Specifically, for this study, we have taken advantage of the high stability of the (101) anatase surface to obtain a variety of uniform colloidal mesocrystals (approximately 50 nm) with adequate orientational order and good textural properties (pores around 3-4 nm and surface areas around 200 m2/g). Ultimately, this stability has allowed us to compare the catalytic activity of anatases that expose a high number of aligned single crystal-like surfaces while differing in controllable surface characteristics. Thus, we have established that the type of tetrahedral coordination observed in these anatase mesocrystals is not essential for oxidative desulfuration and that both elimination of sulfates and good textural properties significantly improve the catalytic activity. Furthermore, the most active mesocrystals have been used to model the catalytic reaction in three-(oil-solvent-catalyst) and two-phase (solvent-catalyst) systems. Thus, we have been able to observe that the transfer of DBT from the oil to the solvent phase partially limits the oxidative process and to estimate an apparent activation energy for the oxidative desulfuration reaction of approximately 40 kJ/mol in the two-phase system to avoid mass transfer limitations. Our results clearly establish that (101) anatase mesocrystals with excellent textural properties show adequate stability to withstand several post-treatments without losing their initial mesocrystalline character and therefore could serve as models for catalytic processes different from the one studied here.Fil: Rivoira, Lorena Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Martinez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; ArgentinaFil: Falcon, Horacio. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; ArgentinaFil: Campos-Martin, Jose M.. Consejo Superior de Investigaciones Científicas; EspañaFil: García Fierro, José Luis. Instituto de Catalisis y Petroleoquimica-csic; EspañaFil: Tartaj, Pedro. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica; Españ

Hydrogenation of tetralin over Ir-containing mesoporous catalysts

A new series of catalysts based on noble metals have been prepared with the main aim of obtaining thiotolerant catalysts to be used in second-stage processes of mild hydrotreating. We studied the catalytic properties of 1 wt % Ir-containing mesoporous materials in the hydrogenation of tetralin to decalin, in the presence of 100 ppm of dibenzotiophene at 250 °C and 15 atm pressure of hydrogen, using a Parr reactor. Ir/mesoporous materials were prepared by wetness impregnation, using iridium acetylacetonate as the source of Ir. The Ir/SBA-3 catalyst synthesized by us had a high activity in tetralin hydrogenation under mild conditions. The experimental data were quantitatively represented by a modified Langmuir-Hinshelwood-type rate equation. The preliminary results reveal that these materials are promising catalyts for HDS/HDN reactions.Fil: Vallés, Verónica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Balangero Bottazzi, Gerardo Simon. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Martínez, María Laura. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Gómez Costa, Marcos Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Anunziata, Oscar Alfredo. Universidad Tecnológica Nacional. Facultad Regional Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Universidad Tecnológica Nacional. Facultad Regional Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Catalizadores de Ir soportados en materiales mesoporosos

Las emisiones generadas a partir de la combustión del diesel contribuyen a la contaminación ambiental vinculada a los SOx y NOx. Es por ello que muchos países ya cuentan con regulaciones que restringen el contenido de azufre y nitrógeno en productos derivados del petróleo e incluso se espera lograr emisión cero. Las fracciones de petróleo antes de su uso en combustibles requieren de un proceso de refinación que involucra el hidrotratamiento catalítico (HDT), el cual se define como el contacto de una fracción del crudo con el hidrógeno, en presencia de un catalizador y bajo condiciones de operación adecuadas (alta presión y temperaturas entre 200-350°C), con el fin de prepararla para una conversión posterior y mejorar su calidad. En el HDT tienen lugar principalmente reacciones de hidrogenación de compuestos insaturados y reacciones de hidrogenólisis de los enlaces carbono-heteroátomos (azufre, metales o metaloides, nitrógeno y oxígeno). El HDT comprende los procesos de hidrodesulfurización, hidrodesmetalización, hidrodenitrogenación, hidrodesoxigenación, hidrodesaromatización y reacciones de ruptura catalítica. La eliminación profunda de azufre y nitrógeno requiere condiciones más severas en los procesos de hidrodesulfuración (HDT) e hidrodenitrogenación (HDN), incrementando los costos de producción. La industria de refinación de combustibles se ve en los últimos años presionada para desarrollar nuevos catalizadores y procesos que logren el procesamiento de crudos cada vez más pesados con alto contenido de heteroátomos y poliaromáticos, a la vez que deben limitar el contenido de azufre, nitrógeno y aromáticos en gasoil y destilados medios. Por otro lado la mayor concentración de la demanda del mercado en el rango de gasoil obliga a los refinadores a considerar el redireccionamiento de cortes interno de refinería hacia nuevas unidades de hidrocraqueo para aumentar el aporte al pool de gasolinas y diesel. Estos requerimientos impulsan avances particularmente en las tecnologías de hidrotratamiento. Actualmente los trabajos en hidrotratamiento están orientados a modificar el soporte utilizado, tradicionalmente (Al2O3), o al reemplazo de los metales convencionales tipo Co(Ni)Mo(W) por metales nobles. Los catalizadores basados en metales nobles soportados del grupo VIII (Pt, Pd, Ir, Rh, etc.) se presentan como una buena alternativa para reemplazar los ya existentes. El mayor desafío consiste en desarrollar un catalizador activo para las reacciones de HDT y resistente al envenenamiento por azufre o nitrógeno.Fil: Ledesma, Brenda Cecilia Soledad. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Beltramone, Andrea Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentin

Revalorization of agro-industrial waste as a catalyst source for production of biofuels

This work evaluates the bio-waste valorization approach for catalyst development, the use of products derived from biomass as raw material and the production of biofuels. In this research activated carbons were synthesized from orange peel using different synthesis conditions. With the activated carbons obtained with the best structure and texture, PtIr bimetallic catalysts were prepared. Carbon activation was carried out through a chemical process with phosphoric acid as an activating agent, varying acid concentration, substrate/activating agent ratio and time of contact between them. The best support was obtained using carbonization time of 1 h, carbonization temperature of 470 C, phosphoric acid concentration of 50 wt % and with BET area of 1429 m2 /g. Subsequently, the metallic nanoparticles were deposited in the activated carbon to use the solid as a catalytic material for the hydrogenation of HMF to 2,5-DMF. The catalyst showed excellent performance for the generation of biofuels.Fil: Ledesma, Brenda Cecilia Soledad. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Short time synthesis of titania modified-CMK-3 carbon mesostructure as support for Ir-catalyst applied in catalytic hydrotreating

Ti-CMK-3 carbon mesoporous was prepared using a novel synthesis method. This new method avoids the hard template synthesis used commonly. The method developed here, allows to reduce time, energy consumptionand cost. Structural and textural characterization of the titanium modified-mesoporous carbonwas performed by N2 adsorption, XRD, UV–vis-DRS, 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 used as support of the iridium nanoparticles, in order to prepare a catalyst to be tested in model hydrotreating reactions. The catalyst obtained by wet impregnation with iridium acetylacetonate were characterized by ICP-AES, H2 chemisorption, TEM, XPS and FTIR of adsorbed pyridine. The high Ir dispersion and small particle size, along with the moderate Lewis acidity generated by the presence of titanium in the support, were responsible for the good performance and stability of the catalyst in the hydrogenation of tetralin in presence of nitrogen compounds. Main advantage of the present study is the reduction of time and cost in the synthesis of the new material and the applicability for HDT reactions.Fil: Ledesma, Brenda Cecilia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; ArgentinaFil: Juarez, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; ArgentinaFil: Beltramone, Andrea Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentin

Kinetic studies on diacetyl synthesis over V-containing zeolites

The gas-phase oxidation of methyl ethyl ketone (MEK) was studied on V-ZSM-5 zeolite in the presence of molecular oxygen. Two types of competitive partial oxidations, i.e., diacetyl formation and oxidative scission reaction leading to acetaldehyde and acetic acid, took place at 200–350 ◦C. A detailed kinetic study was realized for the oxidation reaction, a linear relationship was observed between the conversion and partial pressure of oxygen, and an activation energy of 16 kcal/mol was encountered. The content of vanadium in the catalyst was also analyzed.Fil: Anunziata, Oscar Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Pierella, Liliana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Beltramone, Andrea Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentin

Hydrodeoxygenation of guaiacol over Pt-Ga-mesoporous catalysts

The hydrodeoxygenation (HDO) of guaiacol as model compound has been studied in a batch reactor over SBA-15 and Ga-SBA-15 supported platinum catalysts at 12 atm of H2 and different temperatures. Gallium incorporation as heteroatom into the mesoporous siliceous framework modified the nature of the support generating Brønsted acidity. The catalysts were characterized by means of X-ray diffraction, N2 isotherms, XPS, TPR, CO chemisorptions, Py FTIR and TEM. Good structure, narrow pore size distribution and high platinum dispersion were achieved in the synthesized catalysts. The catalysts were very active in the conversion of guaiacol at 200 °C, almost complete conversion was obtained in 3 h of reaction. Mild acidity generated by gallium incorporation enhanced the dispersion of platinum active species and improve the HDO ratio.Fil: Rivoira, Lorena Paola. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Martinez, Maria Laura. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

HDN of Indole over Ir-modified Ti-SBA-15

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 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 prepared were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV-vis-DRS, Raman spectroscopy, 27Al-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. 27Al-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 acidity, 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 equation.Fil: Ledesma, Brenda Cecilia Soledad. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Anunziata, Oscar Alfredo. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Beltramone, Andrea Raquel. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Experimental design optimization of the ODS of DBT using vanadium oxide supported on mesoporous Ga-SBA-15

Experiment design-response surface methodology is applied in this work to model and optimize the oxidation of dibenzothiophene (DBT) using VOx-Ga-SBA-15 catalyst. The analyzed variables are the influence of the nature of the catalyst (V and Ga loading), the substrate/catalyst mass ratio (g DBT/g of catalyst) and the oxidant/substrate molar ratio (H2O2/DBT). The response analyzed is conversion of DBT at 15 min of reaction time. A set of response surfaces were obtained applying the Box-Behnken Design. Based on statistical methodology it was possible to find the best arrangement between the amounts of the gallium heteroatom and the vanadium active species. The higher levels of the objective function were obtained employing the catalyst with 4 wt.% of gallium and 6 wt.% of vanadium; the optimal ratio between g DBT/g of catalyst was 4 and the molar ratio between H2O2/DBT was 5. Gallium incorporation as heteroatom in tetrahedral position allowed the better anchorage of the active species of vanadium, generating a very well dispersed catalyst. The optimized catalyst minimized the mass transfer limitation and moreover, was active after several recycles. The best catalyst was likewise very active for the oxidation of the most refractory sulfur compounds as benzothiophene and 4,6-dimetyldibenzothiopene.Fil: Rivoira, Lorena Paola. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cussa, Jorgelina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martinez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; ArgentinaFil: Beltramone, Andrea Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentin