Dora Solís | Universidad Autónoma del Estado de México (original) (raw)

Papers by Dora Solís

Catalysis Today

Abstract In the current study, SnO2(5, 10 and 15 wt%)/MgAl-HT hydrotalcite-type materials were sy... more Abstract In the current study, SnO2(5, 10 and 15 wt%)/MgAl-HT hydrotalcite-type materials were synthesized by co-precipitation method. Besides, the photocatalytic activity of the materials was evaluated in the degradation of Rhodamine B under simulated sunlight. The characterization of the materials by X-ray diffraction (XRD), Raman spectroscopy, physisorption of nitrogen and X-ray photoelectron spectroscopy (XPS) showed the formation of the (003) and (110) characteristic plans of lamellar materials, vibrational modes typical of layered double hydroxides and tin, specific surface areas, pore size distribution and chemical composition, respectively. The photocatalytic activity showed that the SnO2(10 %)/MgAl-HT catalyst has the best degradation of the dye reaching a 75 % of degradation after 210 min under simulated solar light irradiation. The route of action of charge carriers was evaluated using scavengers for photogenerated holes, hydroxyl and superoxide radicals, such as triethanolamine, isopropanol and benzoquinone, respectively, when benzoquinone was used it was confirmed that superoxide radicals play an important role in degradation of Rhodamine B.

Radiochimica Acta, 2012

In the field of nuclear waste management, prediction of radionuclide migration through the geosph... more In the field of nuclear waste management, prediction of radionuclide migration through the geosphere has to take into account the effects of organic matter. This work deals with the effects of organic acids (citric and oxalic acid) on speciation of uranium(VI) sorbed onto zirconium diphosphate (ZrP2O7). Surface properties of zirconium diphosphate and its uranium(VI) sorption capability in the presence and absence of organic acids were previously studied. The preliminary study suggested that organic acids take part in the sorption equilibria. In order to understand the interactions between organic ligands (citrate or oxalate), uranium(VI) and zirconium diphosphate, a luminescence spectroscopy study was carried out. Luminescence measurements indicated that only one uranium(VI) surface complex is formed when citric or oxalic acid is present. Moreover, the total carbon content in the studied samples indicated that organic ligands remain on the surface when uranium(VI) sorption is carrie...

The climate change and its impact to the environment is a topic of general importance which in th... more The climate change and its impact to the environment is a topic of general importance which in the last years has raised a growing interest, to such a degree that many groups have been created worldwide to analyze it. The use of structured packing materials in an absorption column for washing sour gases proceeding from brick kilns is a suitable way to determine the material of more mechanical and chemical resistant and efficient in the treatment of these gases. In this work, three materials were characterized, a ceramic, a polymer and a metal by means of hardness test and electron microscopy (morphology). These materials are used as gas-liquid contactors, or packing beds in the absorption column for the sour gases treatment. The hardness results indicated that the ceramic material is the hardest one and therefore the most weak mechanically, the polymeric one is the most ductile, and the mechanical behavior of the metal material is intermediate. This study focuses on the first experimental stage, which is before the contact with the gases and particles from the kilns. The initial properties of the above materials were studied before being introduced the absorption column. The resistance to corrosion or the deposition, from the treatment of the gases in real conditions will be evaluated in a second phase on the research. The hydrodynamic behaviors were determined in the absorption column in order to determine the ideal conditions of operation, usually in the turbulence or load region. It was found that the polymeric material can work with a wide range of liquid load: from 0 to 30.03 m3 /m2 h, while with the metallic material it is better to work with a liquid load of 27.16 m3 /m2 h, Also, a standard test of corrosion (TAFEL), was performed using a solution of sulphuric acid 1N.. This was done in agreement to the ASTM G5-1999 standard procedure and the methods ININ No. P, SC (LC)-05. It found that the polymeric material is the most resistance to corrosion.Copyright © 2010 by ASME

Revista Internacional De Contaminacion Ambiental, Mar 21, 2013

Volume 3: Design and Manufacturing, Parts A and B, 2010

The climate change and its impact to the environment is a topic of general importance which in th... more The climate change and its impact to the environment is a topic of general importance which in the last years has raised a growing interest, to such a degree that many groups have been created worldwide to analyze it. The use of structured packing materials in an absorption column for washing sour gases proceeding from brick kilns is a suitable way to determine the material of more mechanical and chemical resistant and efficient in the treatment of these gases. In this work, three materials were characterized, a ceramic, a polymer and a metal by means of hardness test and electron microscopy (morphology). These materials are used as gas-liquid contactors, or packing beds in the absorption column for the sour gases treatment. The hardness results indicated that the ceramic material is the hardest one and therefore the most weak mechanically, the polymeric one is the most ductile, and the mechanical behavior of the metal material is intermediate. This study focuses on the first experimental stage, which is before the contact with the gases and particles from the kilns. The initial properties of the above materials were studied before being introduced the absorption column. The resistance to corrosion or the deposition, from the treatment of the gases in real conditions will be evaluated in a second phase on the research. The hydrodynamic behaviors were determined in the absorption column in order to determine the ideal conditions of operation, usually in the turbulence or load region. It was found that the polymeric material can work with a wide range of liquid load: from 0 to 30.03 m3 /m2 h, while with the metallic material it is better to work with a liquid load of 27.16 m3 /m2 h, Also, a standard test of corrosion (TAFEL), was performed using a solution of sulphuric acid 1N.. This was done in agreement to the ASTM G5-1999 standard procedure and the methods ININ No. P, SC (LC)-05. It found that the polymeric material is the most resistance to corrosion.Copyright © 2010 by ASME

CoMo catalysts were prepared using Al 2 O 3-MgO-(X) hybrid supports, where X = K 2 O or Li 2 O. T... more CoMo catalysts were prepared using Al 2 O 3-MgO-(X) hybrid supports, where X = K 2 O or Li 2 O. The textural, structural and acid-base properties of these materials were characterized by several techniques. The catalysts were preliminarily evaluated in the hydrodesulfurization (HDS), hydrogenation (HYD) and hydrocracking (HCK) model reactions. The aims of this work are to identify the effect of the addition of an alkaline oxide (either K 2 O or Li 2 O) to the Lewis acid sites in the CoMo/Al 2 O 3-MgO formulation; and on the other hand, to establish a relationship between the acidity and the catalytic performance (hydrogenation function). The results obtained from the pyridine thermodesorption analysis and the n-butyl amine titration techniques show that the incorporation of an alkaline oxide to the CoMo/Al 2 O 3-MgO formulation causes a slight decrease in the total number of acid sites (TNAS) with respect to Al 2 O 3 and the Al 2 O 3-MgO hybrid supports. Both the enhanced textural and structural stability of the CoMo/Al 2 O 3-MgO-(X) catalytic formulations, which could be probably attributed to the incorporation of Li or K cations to the MgO framework, stabilizing it, can also be observed. As for the catalytic performance, the CoMo/Al 2 O 3-MgO-(X) catalysts containing either Li 2 O or K 2 O, show a decrease in both the HYD and HYC conversions; however, the formulation containing Li 2 O shows the best catalytic behavior due to both the low n-octane yield and the low hydrocracking activity.

Studies in Surface Science and Catalysis, 2000

Three NiMo-HNaY-alumina catalysts with similar composition were prepared by different methods and... more Three NiMo-HNaY-alumina catalysts with similar composition were prepared by different methods and tested in the hydrodesulfurization of dibenzothiophene (DBT) and 4,6-dimethyl-DBT. It was found that the catalyst preparation method induces some changes of the characteristics of the deposited metallic species as well as of the acidic properties of the zeolite component. These changes affect the catalytic behavior in the hydrodesulfurization

Catalysis Today, 2004

In the search to obtain stable catalysts for selective elimination of sulfur from gasoline, maint... more In the search to obtain stable catalysts for selective elimination of sulfur from gasoline, maintaining octane number, NiMo catalysts supported on Al–Mg mixed oxides were prepared by the sol–gel method and evaluated after 6-month storage in contact with ambient air, the results were compared with the freshly prepared samples. Both, freshly prepared and aged samples were characterized by nitrogen physisorption measurements (SBET), infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) and high-resolution electron microscopy (HREM), they were tested in the thiophene hydrodesulfurization reaction.The results indicate that the incorporation of small amounts of magnesia (5mol%) into the alumina support, leads to the catalyst with low hydrogenation function and appropriate stability during prolonged contact with ambient conditions.

Catalysis Today, 2004

A series of hybrid catalysts constituted by NiMo/Al2O3 mixed with HNaY or Ni(1.45)NaY zeolite wer... more A series of hybrid catalysts constituted by NiMo/Al2O3 mixed with HNaY or Ni(1.45)NaY zeolite were prepared, and their activities in the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of an untreated gasoil and a commercially prehydrotreated gasoil were compared to those of conventional NiMo/Al2O3. The influence of HNaY zeolite loading on the activity of the hybrid catalysts was investigated with both untreated

Studies in Surface Science and Catalysis, 1999

A series of HNaY-Al2O3 supports with different amounts of HNaY zeolite was prepared by peptizatio... more A series of HNaY-Al2O3 supports with different amounts of HNaY zeolite was prepared by peptization method. It was found that the process of zeolite incorporation, as well as the procedure of aqueous impregnation of molybdenum species cause some dealuminization of HNaY zeolite framework and loss of its crystallinity as a result of Al2(MoO4)3 formation.

This work reports on the synthesis of photocatalysts in thin film form of TiO 2 modified with Sn,... more This work reports on the synthesis of photocatalysts in thin film form of TiO 2 modified with Sn, Eu as well as Sn and Eu simultaneously. The obtained films were characterized by X-Ray Photoelectron Spectroscopy, Raman Spectroscopy and Ultraviolet-Visible Spectroscopy, in order to obtain information on their chemical composition, vibrational features and optical properties respectively. Chemical composition reveal that the tin content was close to 4 at.%, whereas the europium content was approximately 1 at.%. Raman results show that the unmodified material is crystalline TiO 2 in the anatase phase; the Sn addition promotes the formation of the rutile crystalline phase. Europium incorporation as a novel modifier produces TiO 2 in which a mixture of both crystalline phases coexists. Optical measurements reveal that the band gap energy for all samples remains close to 3.4 eV. The photocatalytic activity was evaluated in the degradation reaction of the Malachite Green dye under simulated solar light. The most relevant result is that photocatalysts containing Sn and Eu show higher photocatalytic activity (60% of MG conversion) than the TiO 2 thin film (28% of MG conversion). The main objective of this work was to investigate the changes produced in the resulting material due to Sn and Eu incorporation as well as try to correlate such changes with the corresponding catalytic activity in terms of the Malachite Green dye conversion degree.

J. Phys.: Conf. Ser. 2307 012024, 2022

TiO2 thin films modified with MoO3 nanostructures were obtained by the spin coating technique. Th... more TiO2 thin films modified with MoO3 nanostructures were obtained by the spin coating technique. The precursors solutions were prepared by the sol-gel technique adding colloids of Mo-based nanostructures prepared by laser irradiation of powders suspended in liquid media. It was found that MoO3 layered nanostructures form the prepared colloidal solutions. The obtained films were characterized by X-Ray Photoelectron, Raman, Ultraviolet-Visible and PL Spectroscopies, and Scanning Electron Microscopy. XPS reveal the presence of TiO2 and MoO3 in the films. Raman results show that crystalline TiO2 in its anatase phase is obtained. These results indicate that the films are forming composites in which nanostructures of molybdenum trioxide are incorporated in the titania film. Optical measurements show that the band gap energy for all samples vary from 3.3 to 3.5 eV.

TiO 2 is used in a wide variety of applications, including photocatalysis in the environmental ar... more TiO 2 is used in a wide variety of applications, including photocatalysis in the environmental area for surface self-cleaning as well as air and water purification. In order to develop new materials with better photocatalytic response, it has been proposed the modification of TiO 2 following different strategies. In this work, the basics of photocatalysis are summarized discussing the advantages of using photocatalysts in thin film form. The results of the preparation and characterization of zinc-modified TiO 2 thin films using a novel synthesis route are presented; these indicate that depending on the Zn load incorporated into the film mixtures of TiO 2 with Zn titanates are formed. The obtained results in the photocatalytic evaluation of the films in the degradation of the malachite green dye are shown, it was found that the films containing Zn have a better response practically doubling the degradation degree obtained with the sample without Zn.

MRS Proceedings, 2016

ABSTRACTIn this work, the deposition and photocatalytic response of V2O5thin films modified with ... more ABSTRACTIn this work, the deposition and photocatalytic response of V2O5thin films modified with different amounts of Ag (Ag:V2O5) is reported. Films were deposited on glass and silicon substrates (100), using the pulsed laser deposition (PLD) technique. A high purity vanadium target, with a different number of silver pellets attached on it were used. Thin films were characterized by energy dispersive spectroscopy (EDS) to determine the elemental chemical composition; structural changes due to the addition of Ag were monitored by Raman spectroscopy; Optical microscopy was used to observe the surface morphology and UV-Vis spectroscopy was employed to determine optical properties. Photocatalytic response of the prepared films was studied through the degradation of a malachite green solution using a solar irradiation source.

Catalysis Today, 2016

Abstract In this work, it is reported the catalytic performance of low acidity catalysts in the h... more Abstract In this work, it is reported the catalytic performance of low acidity catalysts in the hydrodesulfurization reaction of dibenzothiophene. Catalytic CoMo formulations supported on materials based on Al2O3-MgO modified with several amounts of lithium oxide (x = 1, 5 and 10 wt.% of Li2O) were used. It was correlated the effect of the atomic lithium content on the dispersion of the Mo and Co phases in their oxidized and sulfided forms, in order to explain their catalytic performance. Elemental chemical composition on the catalyst surface as well as sulfurization degree and the interaction of sulfided Co and Mo phases with the support were determined by X-ray photoelectron spectroscopy (XPS). Textural properties were measured by N2 physisorption technique; the identification of the crystalline phases was studied by X-ray powder diffraction (XRD) and Raman spectroscopy (RS). The chemical coordination state was determined from diffuse reflectance spectroscopy (DRS) measurements. Reducibility was determined by temperature programmed desorption (TPR). Dispersion of MoS2 crystallites was revealed by high resolution transmission electron microscopy (HRTEM). Catalytic activity of the formulations was evaluated using a pressurized batch reaction system through the hydrodesulfurization reaction of dibenzothiophene as a model molecule, selectivity toward direct desulfurization reaction route was studied following the biphenyl and cyclohexylbenzene reaction products identified by using gas chromatography; results show that there is an optimal amount of 3.7 at.% of Li, which maintains hydrodesulfurization function and decrease the hydrogenation function compared to the conventional CoMo catalyst.

Applied Catalysis B: Environmental, 2009

The effect of Ti addition in alumina carriers on the catalytic properties of corresponding suppor... more The effect of Ti addition in alumina carriers on the catalytic properties of corresponding supported-PdPt materials, as tested in liquid-phase dibenzothiophene (DBT) hydrodesulfurization (HDS) was studied. To that end, Al 2 O 3 eTiO 2 materials (at Al/Ti ¼ 25, 10, and 2, mol ratio) were synthesized by low-temperature solegel method. Point of zero charge decreased by augmenting titania concentration in binary oxides, as to that of Al 2 O 3. On the other hand, textural properties and Lewis acidity (as determined by FTIR of adsorbed pyridine) increased with TiO 2 content in mixed supports. Noble metals were impregnated (nominal 1 wt%, Pd:Pt 4:1 mol ratio) on mixed supports and on reference alumina single oxide. Textural and surface modifications of alumina substrate provoked by titania addition resulted in improved metallic particles dispersion, as observed by High Resolution-TEM. Enhanced catalytic performance of noble metals-based materials with carriers of higher Ti-content was registered when tested in HDS reaction. In those cases, higher selectivity to products from hydrogenation reaction pathway was observed as well. Augmented medium and strong surface acidity and improved textural properties of carriers of enhanced TiO 2 concentration seemed to play a major role in obtaining noble metals catalysts of improved hydrogenating properties.

Materials, 2020

Water pollution by heavy metals represents several health risks. Conventional technologies employ... more Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infr...

Materials

Water pollution by heavy metals represents several health risks. Conventional technologies employ... more Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infr...

Science and Technology of Advanced Materials, 2008

The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and... more The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and the non-ionic polyoxyethylene-lauryl ether Brij 35 as surfactants on the textural, structural and electrical properties of nanosized TiO2 is analyzed in this work. The as-obtained samples were thermally treated at 400 °C to eliminate the surfactant, promote dehydroxylation and crystallize the sample. The TiO2 samples were characterized by thermal analysis, N2 physisorption, x-ray diffraction analysis, micro-Raman spectroscopy and scanning electron microscopy. To evaluate the TiO2 electrical features, I–V data were obtained. The x-ray diffraction results show that in the chemical synthesis using surfactants, the crystallite size is smaller than that of the commercial sample. The Raman spectroscopy results clearly indicate that, when P123 is used, the anatase phase of TiO2 is obtained, whereas when Brij 35 is used a mixture of the anatase and brookite phases is obtained. The specific surf...

Catalysis Today

Abstract In the current study, SnO2(5, 10 and 15 wt%)/MgAl-HT hydrotalcite-type materials were sy... more Abstract In the current study, SnO2(5, 10 and 15 wt%)/MgAl-HT hydrotalcite-type materials were synthesized by co-precipitation method. Besides, the photocatalytic activity of the materials was evaluated in the degradation of Rhodamine B under simulated sunlight. The characterization of the materials by X-ray diffraction (XRD), Raman spectroscopy, physisorption of nitrogen and X-ray photoelectron spectroscopy (XPS) showed the formation of the (003) and (110) characteristic plans of lamellar materials, vibrational modes typical of layered double hydroxides and tin, specific surface areas, pore size distribution and chemical composition, respectively. The photocatalytic activity showed that the SnO2(10 %)/MgAl-HT catalyst has the best degradation of the dye reaching a 75 % of degradation after 210 min under simulated solar light irradiation. The route of action of charge carriers was evaluated using scavengers for photogenerated holes, hydroxyl and superoxide radicals, such as triethanolamine, isopropanol and benzoquinone, respectively, when benzoquinone was used it was confirmed that superoxide radicals play an important role in degradation of Rhodamine B.

Radiochimica Acta, 2012

In the field of nuclear waste management, prediction of radionuclide migration through the geosph... more In the field of nuclear waste management, prediction of radionuclide migration through the geosphere has to take into account the effects of organic matter. This work deals with the effects of organic acids (citric and oxalic acid) on speciation of uranium(VI) sorbed onto zirconium diphosphate (ZrP2O7). Surface properties of zirconium diphosphate and its uranium(VI) sorption capability in the presence and absence of organic acids were previously studied. The preliminary study suggested that organic acids take part in the sorption equilibria. In order to understand the interactions between organic ligands (citrate or oxalate), uranium(VI) and zirconium diphosphate, a luminescence spectroscopy study was carried out. Luminescence measurements indicated that only one uranium(VI) surface complex is formed when citric or oxalic acid is present. Moreover, the total carbon content in the studied samples indicated that organic ligands remain on the surface when uranium(VI) sorption is carrie...

The climate change and its impact to the environment is a topic of general importance which in th... more The climate change and its impact to the environment is a topic of general importance which in the last years has raised a growing interest, to such a degree that many groups have been created worldwide to analyze it. The use of structured packing materials in an absorption column for washing sour gases proceeding from brick kilns is a suitable way to determine the material of more mechanical and chemical resistant and efficient in the treatment of these gases. In this work, three materials were characterized, a ceramic, a polymer and a metal by means of hardness test and electron microscopy (morphology). These materials are used as gas-liquid contactors, or packing beds in the absorption column for the sour gases treatment. The hardness results indicated that the ceramic material is the hardest one and therefore the most weak mechanically, the polymeric one is the most ductile, and the mechanical behavior of the metal material is intermediate. This study focuses on the first experimental stage, which is before the contact with the gases and particles from the kilns. The initial properties of the above materials were studied before being introduced the absorption column. The resistance to corrosion or the deposition, from the treatment of the gases in real conditions will be evaluated in a second phase on the research. The hydrodynamic behaviors were determined in the absorption column in order to determine the ideal conditions of operation, usually in the turbulence or load region. It was found that the polymeric material can work with a wide range of liquid load: from 0 to 30.03 m3 /m2 h, while with the metallic material it is better to work with a liquid load of 27.16 m3 /m2 h, Also, a standard test of corrosion (TAFEL), was performed using a solution of sulphuric acid 1N.. This was done in agreement to the ASTM G5-1999 standard procedure and the methods ININ No. P, SC (LC)-05. It found that the polymeric material is the most resistance to corrosion.Copyright © 2010 by ASME

Revista Internacional De Contaminacion Ambiental, Mar 21, 2013

Volume 3: Design and Manufacturing, Parts A and B, 2010

The climate change and its impact to the environment is a topic of general importance which in th... more The climate change and its impact to the environment is a topic of general importance which in the last years has raised a growing interest, to such a degree that many groups have been created worldwide to analyze it. The use of structured packing materials in an absorption column for washing sour gases proceeding from brick kilns is a suitable way to determine the material of more mechanical and chemical resistant and efficient in the treatment of these gases. In this work, three materials were characterized, a ceramic, a polymer and a metal by means of hardness test and electron microscopy (morphology). These materials are used as gas-liquid contactors, or packing beds in the absorption column for the sour gases treatment. The hardness results indicated that the ceramic material is the hardest one and therefore the most weak mechanically, the polymeric one is the most ductile, and the mechanical behavior of the metal material is intermediate. This study focuses on the first experimental stage, which is before the contact with the gases and particles from the kilns. The initial properties of the above materials were studied before being introduced the absorption column. The resistance to corrosion or the deposition, from the treatment of the gases in real conditions will be evaluated in a second phase on the research. The hydrodynamic behaviors were determined in the absorption column in order to determine the ideal conditions of operation, usually in the turbulence or load region. It was found that the polymeric material can work with a wide range of liquid load: from 0 to 30.03 m3 /m2 h, while with the metallic material it is better to work with a liquid load of 27.16 m3 /m2 h, Also, a standard test of corrosion (TAFEL), was performed using a solution of sulphuric acid 1N.. This was done in agreement to the ASTM G5-1999 standard procedure and the methods ININ No. P, SC (LC)-05. It found that the polymeric material is the most resistance to corrosion.Copyright © 2010 by ASME

CoMo catalysts were prepared using Al 2 O 3-MgO-(X) hybrid supports, where X = K 2 O or Li 2 O. T... more CoMo catalysts were prepared using Al 2 O 3-MgO-(X) hybrid supports, where X = K 2 O or Li 2 O. The textural, structural and acid-base properties of these materials were characterized by several techniques. The catalysts were preliminarily evaluated in the hydrodesulfurization (HDS), hydrogenation (HYD) and hydrocracking (HCK) model reactions. The aims of this work are to identify the effect of the addition of an alkaline oxide (either K 2 O or Li 2 O) to the Lewis acid sites in the CoMo/Al 2 O 3-MgO formulation; and on the other hand, to establish a relationship between the acidity and the catalytic performance (hydrogenation function). The results obtained from the pyridine thermodesorption analysis and the n-butyl amine titration techniques show that the incorporation of an alkaline oxide to the CoMo/Al 2 O 3-MgO formulation causes a slight decrease in the total number of acid sites (TNAS) with respect to Al 2 O 3 and the Al 2 O 3-MgO hybrid supports. Both the enhanced textural and structural stability of the CoMo/Al 2 O 3-MgO-(X) catalytic formulations, which could be probably attributed to the incorporation of Li or K cations to the MgO framework, stabilizing it, can also be observed. As for the catalytic performance, the CoMo/Al 2 O 3-MgO-(X) catalysts containing either Li 2 O or K 2 O, show a decrease in both the HYD and HYC conversions; however, the formulation containing Li 2 O shows the best catalytic behavior due to both the low n-octane yield and the low hydrocracking activity.

Studies in Surface Science and Catalysis, 2000

Three NiMo-HNaY-alumina catalysts with similar composition were prepared by different methods and... more Three NiMo-HNaY-alumina catalysts with similar composition were prepared by different methods and tested in the hydrodesulfurization of dibenzothiophene (DBT) and 4,6-dimethyl-DBT. It was found that the catalyst preparation method induces some changes of the characteristics of the deposited metallic species as well as of the acidic properties of the zeolite component. These changes affect the catalytic behavior in the hydrodesulfurization

Catalysis Today, 2004

In the search to obtain stable catalysts for selective elimination of sulfur from gasoline, maint... more In the search to obtain stable catalysts for selective elimination of sulfur from gasoline, maintaining octane number, NiMo catalysts supported on Al–Mg mixed oxides were prepared by the sol–gel method and evaluated after 6-month storage in contact with ambient air, the results were compared with the freshly prepared samples. Both, freshly prepared and aged samples were characterized by nitrogen physisorption measurements (SBET), infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) and high-resolution electron microscopy (HREM), they were tested in the thiophene hydrodesulfurization reaction.The results indicate that the incorporation of small amounts of magnesia (5mol%) into the alumina support, leads to the catalyst with low hydrogenation function and appropriate stability during prolonged contact with ambient conditions.

Catalysis Today, 2004

A series of hybrid catalysts constituted by NiMo/Al2O3 mixed with HNaY or Ni(1.45)NaY zeolite wer... more A series of hybrid catalysts constituted by NiMo/Al2O3 mixed with HNaY or Ni(1.45)NaY zeolite were prepared, and their activities in the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of an untreated gasoil and a commercially prehydrotreated gasoil were compared to those of conventional NiMo/Al2O3. The influence of HNaY zeolite loading on the activity of the hybrid catalysts was investigated with both untreated

Studies in Surface Science and Catalysis, 1999

A series of HNaY-Al2O3 supports with different amounts of HNaY zeolite was prepared by peptizatio... more A series of HNaY-Al2O3 supports with different amounts of HNaY zeolite was prepared by peptization method. It was found that the process of zeolite incorporation, as well as the procedure of aqueous impregnation of molybdenum species cause some dealuminization of HNaY zeolite framework and loss of its crystallinity as a result of Al2(MoO4)3 formation.

This work reports on the synthesis of photocatalysts in thin film form of TiO 2 modified with Sn,... more This work reports on the synthesis of photocatalysts in thin film form of TiO 2 modified with Sn, Eu as well as Sn and Eu simultaneously. The obtained films were characterized by X-Ray Photoelectron Spectroscopy, Raman Spectroscopy and Ultraviolet-Visible Spectroscopy, in order to obtain information on their chemical composition, vibrational features and optical properties respectively. Chemical composition reveal that the tin content was close to 4 at.%, whereas the europium content was approximately 1 at.%. Raman results show that the unmodified material is crystalline TiO 2 in the anatase phase; the Sn addition promotes the formation of the rutile crystalline phase. Europium incorporation as a novel modifier produces TiO 2 in which a mixture of both crystalline phases coexists. Optical measurements reveal that the band gap energy for all samples remains close to 3.4 eV. The photocatalytic activity was evaluated in the degradation reaction of the Malachite Green dye under simulated solar light. The most relevant result is that photocatalysts containing Sn and Eu show higher photocatalytic activity (60% of MG conversion) than the TiO 2 thin film (28% of MG conversion). The main objective of this work was to investigate the changes produced in the resulting material due to Sn and Eu incorporation as well as try to correlate such changes with the corresponding catalytic activity in terms of the Malachite Green dye conversion degree.

J. Phys.: Conf. Ser. 2307 012024, 2022

TiO2 thin films modified with MoO3 nanostructures were obtained by the spin coating technique. Th... more TiO2 thin films modified with MoO3 nanostructures were obtained by the spin coating technique. The precursors solutions were prepared by the sol-gel technique adding colloids of Mo-based nanostructures prepared by laser irradiation of powders suspended in liquid media. It was found that MoO3 layered nanostructures form the prepared colloidal solutions. The obtained films were characterized by X-Ray Photoelectron, Raman, Ultraviolet-Visible and PL Spectroscopies, and Scanning Electron Microscopy. XPS reveal the presence of TiO2 and MoO3 in the films. Raman results show that crystalline TiO2 in its anatase phase is obtained. These results indicate that the films are forming composites in which nanostructures of molybdenum trioxide are incorporated in the titania film. Optical measurements show that the band gap energy for all samples vary from 3.3 to 3.5 eV.

TiO 2 is used in a wide variety of applications, including photocatalysis in the environmental ar... more TiO 2 is used in a wide variety of applications, including photocatalysis in the environmental area for surface self-cleaning as well as air and water purification. In order to develop new materials with better photocatalytic response, it has been proposed the modification of TiO 2 following different strategies. In this work, the basics of photocatalysis are summarized discussing the advantages of using photocatalysts in thin film form. The results of the preparation and characterization of zinc-modified TiO 2 thin films using a novel synthesis route are presented; these indicate that depending on the Zn load incorporated into the film mixtures of TiO 2 with Zn titanates are formed. The obtained results in the photocatalytic evaluation of the films in the degradation of the malachite green dye are shown, it was found that the films containing Zn have a better response practically doubling the degradation degree obtained with the sample without Zn.

MRS Proceedings, 2016

ABSTRACTIn this work, the deposition and photocatalytic response of V2O5thin films modified with ... more ABSTRACTIn this work, the deposition and photocatalytic response of V2O5thin films modified with different amounts of Ag (Ag:V2O5) is reported. Films were deposited on glass and silicon substrates (100), using the pulsed laser deposition (PLD) technique. A high purity vanadium target, with a different number of silver pellets attached on it were used. Thin films were characterized by energy dispersive spectroscopy (EDS) to determine the elemental chemical composition; structural changes due to the addition of Ag were monitored by Raman spectroscopy; Optical microscopy was used to observe the surface morphology and UV-Vis spectroscopy was employed to determine optical properties. Photocatalytic response of the prepared films was studied through the degradation of a malachite green solution using a solar irradiation source.

Catalysis Today, 2016

Abstract In this work, it is reported the catalytic performance of low acidity catalysts in the h... more Abstract In this work, it is reported the catalytic performance of low acidity catalysts in the hydrodesulfurization reaction of dibenzothiophene. Catalytic CoMo formulations supported on materials based on Al2O3-MgO modified with several amounts of lithium oxide (x = 1, 5 and 10 wt.% of Li2O) were used. It was correlated the effect of the atomic lithium content on the dispersion of the Mo and Co phases in their oxidized and sulfided forms, in order to explain their catalytic performance. Elemental chemical composition on the catalyst surface as well as sulfurization degree and the interaction of sulfided Co and Mo phases with the support were determined by X-ray photoelectron spectroscopy (XPS). Textural properties were measured by N2 physisorption technique; the identification of the crystalline phases was studied by X-ray powder diffraction (XRD) and Raman spectroscopy (RS). The chemical coordination state was determined from diffuse reflectance spectroscopy (DRS) measurements. Reducibility was determined by temperature programmed desorption (TPR). Dispersion of MoS2 crystallites was revealed by high resolution transmission electron microscopy (HRTEM). Catalytic activity of the formulations was evaluated using a pressurized batch reaction system through the hydrodesulfurization reaction of dibenzothiophene as a model molecule, selectivity toward direct desulfurization reaction route was studied following the biphenyl and cyclohexylbenzene reaction products identified by using gas chromatography; results show that there is an optimal amount of 3.7 at.% of Li, which maintains hydrodesulfurization function and decrease the hydrogenation function compared to the conventional CoMo catalyst.

Applied Catalysis B: Environmental, 2009

The effect of Ti addition in alumina carriers on the catalytic properties of corresponding suppor... more The effect of Ti addition in alumina carriers on the catalytic properties of corresponding supported-PdPt materials, as tested in liquid-phase dibenzothiophene (DBT) hydrodesulfurization (HDS) was studied. To that end, Al 2 O 3 eTiO 2 materials (at Al/Ti ¼ 25, 10, and 2, mol ratio) were synthesized by low-temperature solegel method. Point of zero charge decreased by augmenting titania concentration in binary oxides, as to that of Al 2 O 3. On the other hand, textural properties and Lewis acidity (as determined by FTIR of adsorbed pyridine) increased with TiO 2 content in mixed supports. Noble metals were impregnated (nominal 1 wt%, Pd:Pt 4:1 mol ratio) on mixed supports and on reference alumina single oxide. Textural and surface modifications of alumina substrate provoked by titania addition resulted in improved metallic particles dispersion, as observed by High Resolution-TEM. Enhanced catalytic performance of noble metals-based materials with carriers of higher Ti-content was registered when tested in HDS reaction. In those cases, higher selectivity to products from hydrogenation reaction pathway was observed as well. Augmented medium and strong surface acidity and improved textural properties of carriers of enhanced TiO 2 concentration seemed to play a major role in obtaining noble metals catalysts of improved hydrogenating properties.

Materials, 2020

Water pollution by heavy metals represents several health risks. Conventional technologies employ... more Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infr...

Materials

Water pollution by heavy metals represents several health risks. Conventional technologies employ... more Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infr...

Science and Technology of Advanced Materials, 2008

The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and... more The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and the non-ionic polyoxyethylene-lauryl ether Brij 35 as surfactants on the textural, structural and electrical properties of nanosized TiO2 is analyzed in this work. The as-obtained samples were thermally treated at 400 °C to eliminate the surfactant, promote dehydroxylation and crystallize the sample. The TiO2 samples were characterized by thermal analysis, N2 physisorption, x-ray diffraction analysis, micro-Raman spectroscopy and scanning electron microscopy. To evaluate the TiO2 electrical features, I–V data were obtained. The x-ray diffraction results show that in the chemical synthesis using surfactants, the crystallite size is smaller than that of the commercial sample. The Raman spectroscopy results clearly indicate that, when P123 is used, the anatase phase of TiO2 is obtained, whereas when Brij 35 is used a mixture of the anatase and brookite phases is obtained. The specific surf...

In this work, the deposition and photocatalytic response of V 2 O 5 thin films modified with diff... more In this work, the deposition and photocatalytic response of V 2 O 5 thin films modified with different amounts of Ag (Ag:V 2 O 5) is reported. Films were deposited on glass and silicon substrates (100), using the pulsed laser deposition (PLD) technique. A high purity vanadium target, with a different number of silver pellets attached on it were used. Thin films were characterized by energy dispersive spectroscopy (EDS) to determine the elemental chemical composition; structural changes due to the addition of Ag were monitored by Raman spectroscopy; Optical microscopy was used to observe the surface morphology and UV-Vis spectroscopy was employed to determine optical properties. Photocatalytic response of the prepared films was studied through the degradation of a malachite green solution using a solar irradiation source.