Surface modification after ethanol wet milling: A comparison between pristine glasses produced from natural minerals and analytical grade raw materials

Four glass compositions were produced taking into account different theoretical Leucite (KAlSi2O6)/Bioglass 45S5 (45% SiO2, 24.5% Na2O, 24.5% CaO, 6% P2O5) ratios using analytical grade reagents only; and replacing some of the reagents by natural minerals, all that were found to be bioactive when they were transformed to glass ceramics. Glasses of particle size below 174 μm were wet milled using ethanol in a high energy planetary ball mill. After wet milling, samples with 25 and 30% of theoretical Leucite content using reagents grade raw materials showed a higher dissolution rate in comparison to the same glasses made from natural mineral, while no differences were found on glasses with 40 and 50% of Leucite theoretical content. Samples with higher dissolution showed a crystalline carbonate phase named Pirssonite on its surface, while on the rest of samples amorphous carbonates were present.Fil: Stábile, Franco Matías. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Rodríguez Aguado, Elena. Universidad de Málaga; EspañaFil: Rodríguez Castellón, Enrique. Universidad de Málaga; EspañaFil: Volzone, Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentin

Nanoporous Materials and Their Applications

This book is a special collection of articles dedicated to the preparation and characterization of nanoporous materials, such as zeolitic-type materials, mesoporous silica (SBA-15, MCM-41, and KIT-6), mesoporous metallic oxides, metal–organic framework structures (MOFs), and pillared clays, and their applications in adsorption, catalysis, and separation processes. This book presents a global vision of researchers from international universities, research centers, and industries working with nanoporous materials and shares the latest results on the synthesis and characterization of such materials, which have given rise to the special interest in their applications in basic and industrial processes

Partial oxidation of H2S to sulfur on V-Cu-O mixed oxides bronzes

[EN] The present paper shows the influence of Cu-content in Cu-promoted V2O5 catalysts on both the physicochemical characteristics of catalysts and their catalytic performance in the partial oxidation of hydrogen sulfide. Both, the catalytic activity for H2S conversion and the selectivity to sulfur increased when increasing the Cu/V ratio of catalysts. The best catalyst gives a selectivity to sulfur at ca. 98% at total conversion of H2S. According to the characterization results (XRD, FTIR), V2O5 is partially transformed into vanadium oxide bronze, i.e. beta-Cu0.261V2O5, up to Cu/V ratios of 0.25. For higher Cu/V ratios, CuV2O6 and beta-Cu0.261V2O5 are observed. In the same way, the reducibility of V-species increased when increasing the Cu/V ratio of catalysts. On the other hand, the characterization of used catalysts indicates the transformation of V2O5 into V4O9, whereas the vanadium oxide bronze is stable under the studied reaction. The catalytic results are explained on the basis of the nature of crystalline phases and the presence of V5+-O-V4+ pairs in the more selective catalysts.The authors would like to acknowledge the Spanish MINECO Projects (CTQ2015-68951-C3-1-R and CTQ2015-68951-C3-3-R) and Severo Ochoa Program (SEV-2016-0683), and FEDER funds, for financial support. LRR thanks the MINECO for a predoctoral contract.Ruiz-Rodríguez, L.; Blasco Lanzuela, T.; López Nieto, JM.; Rodríguez-Castellón, E. (2019). Partial oxidation of H2S to sulfur on V-Cu-O mixed oxides bronzes. Catalysis Today. 333:237-244. https://doi.org/10.1016/j.cattod.2018.07.050S23724433

Surface modification after ethanol wet milling: A comparison between pristine glasses produced from natural minerals and analytical grade raw materials

Four glass compositions were produced taking into account different theoretical Leucite (KAlSi2O6)/Bioglass 45S5 (45% SiO2, 24.5% Na2O, 24.5% CaO, 6% P2O5) ratios using analytical grade reagents only; and replacing some of the reagents by natural minerals, all that were found to be bioactive when they were transformed to glass ceramics. Glasses of particle size below 174 μm were wet milled using ethanol in a high energy planetary ball mill. After wet milling, samples with 25 and 30% of theoretical Leucite content using reagents grade raw materials showed a higher dissolution rate in comparison to the same glasses made from natural mineral, while no differences were found on glasses with 40 and 50% of Leucite theoretical content. Samples with higher dissolution showed a crystalline carbonate phase named Pirssonite on its surface, while on the rest of samples amorphous carbonates were present.Centro de Tecnología de Recursos Minerales y Cerámic

The influence of promoters (Zr, La, Tb, Pr) on the catalytic performance of CuO-CeO2 systems for the preferential oxidation of CO in the presence of CO2 and H2O

CuO supported on CeO2 and Ce0.9X0.1O2, where X is Zr, La, Tb or Pr, were synthesized using nitrate precursors, giving rise ceria based materials with a small particle size which interact with CuO species generating a high amount of interfacial sites. The incorporation of cations to the ceria framework modifies the CeO2 lattice parameter, improving the redox behavior of the catalytic system. The catalysts were characterized by X-ray fluorescence spectrometry (XRFS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, thermoprogrammed reduction with H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalysts were tested in the preferential oxidation of CO under a H2-rich stream (CO-PROX), reaching conversion values higher than 95% between 115 and 140 °C and being the catalyst with 6 wt.% of Cu supported on Ce0.9Zr0.1O2 (sample 6CUZRCE) the most active catalyst. The influence of the presence of CO2 and H2O was also studied simulating a PROX unit, taking place a decrease of the catalytic activity due to the inhibitor effect both CO2 and H2O.The projects CTQ2012-37925-C03-03 and CTQ2012-30703 of Ministerio de Economía y Competitividad (Spain), the project of Excellence P12 RNM 1565 (Junta de Andalucía, Spain), the project of Excellence PROMETEUII/2014/010 (Generalitat Valenciana) and the UE (FEDER funding) are acknowledged for the financial support

Physical activation of graphene: An effective, simple and clean procedure for obtaining microporous graphene for high-performance Li/S batteries

Graphene nanosheets are a promising scaffold to accommodate S for achieving high performanceLi/S battery. Nanosheet activation is used as a viable strategy to induce a micropore system and further improve the battery performance. Accordingly, chemical activation methods dominate despite the need of multiple stages, which slow down the process in addition to making them tiresome. Here, a three-dimensional (3D)N-doped graphene specimen was physically activated with CO2, a clean and single step process, and used for the preparation of a sulfur composite (A-3DNG/S). The A-3DNG/S composite exhibited outstanding electrochemical properties such as an excellent rate capability (1,000 mAh·g─1at 2C), high reversible capacity and cycling stability (average capacity ~ 800 mAh·g─1at 1C after 200cycles), values which exceed those measured in chemically activated graphene. Therefore, these results support the use of physical activation as a simple and efficient alternative to improve the performance of carbons as an S host for high-performance Li-S batteries

Boosting the electrochemical oxygen reduction activity of hemoglobin on fructose@graphene-oxide nanoplatforms

A metal-free oxygen reduction reaction (ORR) electrocatalyst with outstanding performance was obtained through an easy and one-pot synthesis of hemoglobin functionalized fructose@graphene-oxide (GO) nanocomposites. The active pyridinic nitrogen sites of the highly unfolded proteins together with the excellent electronic properties of GO appears to be the main factors causing the improved electrocatalytic activity

Synthesis, Characterization and Catalytic Activity of UiO-66-NH2 in the Esterification of Levulinic Acid

The massive use of petroleum and its possible exhaustion are driving the current researchtrend to study alternative raw materials from biomass for organic reactions. In this context, thepresent article presents a study of the catalytic esterification of levulinic acid, a platform molecule,with ethanol. Metal-organic framework (MOF) type compounds UiO-66-NH2 have been synthesized. Zirconium was incorporated, using zirconium chloride as a metal precursor, together with 2-aminoterephthalic acid as an organic binding agent. An alternative route of synthesis was proposed using more favorable conditions from an economic and environmental point of view, replacing dimethylformamide by 50 and 75% acetone as substitute solvent. The physicochemical properties of the materials were evaluated by X-ray diffraction (XRD), Infrared Spectrometry with Fourier Transform (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), microwave plasma atomic emission spectroscopy (MP-AES) and N2 adsorption to understand their morphology, crystalline, chemical and pore structure. The progress of the reaction was followed by gas chromatography and mass spectroscopy. The catalytic activity result of MOF25% in autoclave reactor, showed 100% of selectivity to ethyl levulinate and a turnover number (TON) of 66.18 moles of product/moles of Zr. This good catalytic performance obtained by partial solvent replacement in the synthetic material provides a more economical and eco-friendly process for ethyl levulinate generation.Fil: Bravo Fuchineco, Daiana Antonella. 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: Heredia, Angelica Constanza. 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: Mendoza, Sandra Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Reconquista; ArgentinaFil: Rodríguez Castellón, Enrique. Universidad de Málaga; EspañaFil: Crivello, Mónica Elsie. 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

Ferric sludge derived from the process of water purification as an efficient catalyst and/or support for the removal of volatile organic compounds

[EN] Ferric chloride solutions are used as coagulants or flocculants in water treatment operations for human consumption. This treatment produces large amounts of clay-type solids formed mainly of montmorillonite with iron oxides and humic substances. This ferric sludge can be used as an efficient catalyst for the removal of volatile organic compounds (VOCs) by total oxidation. This waste isolated in the purification process has been activated by calcinations in air, characterized by several physicochemical techniques and employed as a catalyst for the removal by total oxidation of representative VOCs: toluene, propane and mixtures of toluene/propane with or without water. This ferric sludge has shown a catalytic activity one order of magnitude higher than that of a commercial iron oxide. This high activity has been related to the composition of the sludge (as it contains active metal oxides such as oxides of iron and manganese) and to the porous structure (leading to a reasonably high surface area). Moreover, it can be also used as a support for platinum, showing comparable (or even higher) catalytic activity than a similar platinum catalyst supported on conventional gamma-alumina.The authors would like to acknowledge the DGICYT in Spain CTQ2012-37925-C03-2, CTQ2015-68951-C3-1-R and CTQ2015-68951-C3-3-R. Authors from UV thank the University of Valencia (UV-INV-AE16-484416 project) and MINECO (MAT2017-84118-C2-1-R project) for funding. Finally, authors thank the Electron Microscopy Service of SCSIE of Universitat de Valencia for their support.Sanchis, R.; Dejoz, A.; Vázquez, I.; Vilarrasa-García, E.; Jiménez-Jiménez, J.; Rodríguez-Castellón, E.; López Nieto, JM.... (2019). Ferric sludge derived from the process of water purification as an efficient catalyst and/or support for the removal of volatile organic compounds. Chemosphere. 219:286-295. https://doi.org/10.1016/j.chemosphere.2018.12.002S28629521

Mixed Ionic-Electronic Conductivity, Redox Behavior and Thermochemical Expansion of Mn-Substituted 5YSZ as an Interlayer Material for Reversible Solid Oxide Cells

Manganese-substituted 5 mol.% yttria-stabilized zirconia (5YSZ) was explored as a prospective material for protective interlayers between electrolyte and oxygen electrodes in reversible solid oxide fuel/electrolysis cells. [(ZrO2)0.95(Y2O3)0.05]1−x[MnOy]x (x = 0.05, 0.10 and 0.15) ceramics with cubic fluorite structure were sintered in air at 1600 °C. The characterization included X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetry and dilatometry in controlled atmospheres, electrical conductivity measurements, and determination of oxygen-ion transference numbers by the electromotive force (EMF) technique. Mn-substituted 5YSZ solid solutions exhibit variable oxygen nonstoichiometry with manganese cations in a mixed 2+/3+ oxidation state under oxidizing conditions. Substitution by manganese gradually increases the extent of oxygen content variation on thermal/redox cycling, chemical contribution to thermal expansion and dimensional changes on reduction. It also deteriorates oxygen-ionic conductivity and improves p-type electronic conductivity under oxidizing conditions, leading to a gradual transformation from predominantly ionic to prevailing electronic transport with increasing x. Mn2+/3+→Mn2+ transformation under reducing atmospheres is accompanied by the suppression of electronic transport and an increase in ionic conductivity. All Mn-substituted 5YSZ ceramics are solid electrolytes under reducing conditions. Prolonged treatments in reducing atmospheres, however, promote microstructural changes at the surface of bulk ceramics and Mn exsolution. Mn-substituted 5YSZ with 0.05 ≤ x < 0.10 is considered the most suitable for the interlayer application, due to the best combination of relevant factors, including oxygen content variations, levels of ionic/electronic conductivity and thermochemical expansion