Person:
Cabañas Poveda, Albertina

First Name

Albertina

Last Name

Cabañas Poveda

URI

https://hdl.handle.net/20.500.14352/76101

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Químicas

Department

Química Física

Area

Química Física

Identifiers

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Now showing 1 - 10 of 22

Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology
(Philosophical Transactions A, 2015) Morère, Jacobo; Royuela, Sergio; Asensio, Guillermo; Enciso, Eduardo; Pando, Concepción; Cabañas Poveda, Albertina
The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO2 (scCO2) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO2 allowed the efficient penetration of metal precursors dissolved in scCO2 within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO3)2⋅6H2O and NiCl2⋅6H2O were tried as precursors. Different methodologies were used: impregnation in scCO2 and reduction in H2/N2 at 400°C and low pressure, reactive deposition using H2 at 200–250°C in scCO2 and reactive deposition using ethanol at 150–200°C in scCO2. The effect of precursor and methodology on the nickel particle size and the material homogeneity (on the different substrates) was analysed. This technology offers many opportunities in the preparation of metal-nanostructured materials.
Project number: 172
Formación en Química Sostenible y su relación con los Objetivos de Desarrollo Sostenible
() Cabañas Poveda, Albertina; Pérez Velilla, Eduardo; Vázquez Villa, Henar; García Melo, Fátima; Calvo Garrido, Lourdes; González Mac-Dowell, Luis; Acción Salas, Fernando; Parrón Nieto, Andrea; Valero Herrero, Patricia; Calvo Garrido, María Lourdes
En el proyecto se propone la realización de trabajos en grupo dirigidos a los alumnos de Química General de 1º en los que se desarrollen los principios de la Química Sostenible y se relacionen con los Objetivos de Desarrollo Sostenible. Las mejores presentaciones serán grabadas en video para su difusión.
Production and Characterization of a new Copper(II) Propanoate-Isonicotinamide Adduct obtained via Slow Evaporation and using Supercritical CO2 as an Antisolvent
(Crystal Growth and Design, 2019) Cuadra Mendoza, Isaac Alfonso; Martínez Casado, Francisco Javier; Rodriguez Cheda, Jose A.; Redondo, M.I.; Pando, Concepción; Cabañas Poveda, Albertina
A new adduct of isonicotinamide (INA) with copper(II) propanoate [Cu(C3)2] was prepared [Cu2(C3)4(INA)4] using two different methods. This type of compound shows high fungicidal activity. Solvent evaporation from ethanol rendered crystals suitable for single-crystal X-ray diffraction. Furthermore, a new semicontinuous method capable of simultaneous crystallization and micronization of the adduct using supercritical CO2, the supercritical antisolvent technique (SAS), was also assessed. Crystals were characterized using powder X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis coupled with mass spectrometry, scanning electron microscopy, and microelemental analysis. In the adduct, two copper(II) ions are coordinated through two bridging and two chelating carboxylates to the propanoate anions forming approximately a plane. Each metal ion is then coordinated with the pyridine nitrogen of two different INA molecules that behave as monodentate ligands. The amide groups of the INA form H-bonds with other amide and carboxylate groups forming a molecular crystal with a three-dimensional H-bond arrangement of the binuclear units. With the SAS technique, crystals 100-fold smaller than those obtained by slow evaporation were obtained, proving SAS as a suitable method for mixed-ligand complexes preparation with reduced particle size and therefore expected bioavailability enhancement.
One-step Sustainable Preparation of Superparamagnetic Iron Oxide Nanoparticles Supported on Mesoporous SiO2
(Journal of Supercritical Fluids, 2020) Chamorro, Elena; Granados García Tenorio, María José; Calvo Garrido, María Lourdes; Torralvo Fernández, María José; Sáez Puche, Regino; Cabañas Poveda, Albertina
Superparamagnetic iron oxide nanoparticles (SPIONs) supported on high surface area mesoporous SiO2 are advanced materials of great interest in catalysis, adsorption and biomedicine. Here we present a new process to prepare SPION/SiO2 materials by the impregnation and insitu decomposition of Fe(NO3)3.9H2O on mesoporous SiO2 supports in a 25-50% mol ethanol + CO2 mixture at 523 K and 25.0 MPa. -Fe2O3 nanoparticles (NPs) of average size between 6-9 nm were distributed homogeneously on the supports. NPs deposited into the SBA-15 mesopores but mostly on the external surface of MCM-41. Materials prepared with the highest ethanol content were very homogeneous. Magnetic measurements confirmed the superparamagnetic nature of the materials at room temperature. The process proposed is sustainable and scalable, avoids tedious preparations and the additional high temperature treatment under a controlled atmosphere, as the metal decomposition is performed insitu in the CO2-expanded liquid mixture.
Designing nanocomposites using supercritical CO2 to insert Ni nanoparticles into the pores of nanopatterned BaTiO3 thin films
(Journal of Materials Chemistry C, 2016) Castro, Alichandra; Morère, Jacobo; Cabañas Poveda, Albertina; Ferreira, Liliana; Godinho, Margarita; Ferreira, Paula; Vilarinho, Paula
A new concept to prepare nanocomposite thin films is explored. Two chemical-based bottom-up steps are used to design functional films including: i) block copolymerassisted self-assembly of a porous matrix; and ii) impregnation of nanoparticles from a ferroic phase within the pores by supercritical CO2 deposition. Porous nanopatterned BaTiO3 thin films with ca. 17 nm of thickness are prepared using a cost-effective solgel solution containing a block copolymer and evaporation-induced self-assembly methodology. Hexagonal-arranged pores with diameter of ca. 95 nm, running perpendicularly to the substrate are filled with Ni nanoparticles using the supercritical fluid deposition technique from reduction of hydrated nickel nitrate in a supercritical CO2-ethanol mixture at 250 ºC. Small Ni nanoparticles with 21 ± 5 nm nm are selectively deposited inside the pores of the porous matrix. Structural and magnetic properties prove the coexistence of both phases.
Supercritical fluid deposition of Ru nanoparticles into SiO2 SBA-15 as a sustainable method to prepare selective hydrogenation catalysts
(RSC Advances, 2015) Morère Rodríguez, Jacobo; Torralvo Fernández, María José; Pando García-Pumarino, Concepción; Rodríguez Renuncio, Juan Antonio; Cabañas Poveda, Albertina
Ru nanoparticles were successfully deposited into mesoporous SiO2 SBA-15 using supercritical CO2 (scCO2). The use of scCO2 favoured the metal dispersion and Ru nanoparticles uniformly distributed throughout the support were obtained. Different precursors and methodologies were employed: impregnation with Ru(tmhd)2(COD) in scCO2 at 80 ºC and 13.5 and 19.3 MPa and further reduction in H2/N2 at 400 ºC at low pressure, reactive deposition of Ru(tmhd)2(COD) with H2 in scCO2 at 150 ºC and reactive deposition of RuCl3•xH2O with ethanol in scCO2 at 150 and 200 ºC. The size of the particles was limited in one dimension by the pore size of the support. The metal loading varied with the methodology and experimental conditions from 0.9 to 7.4% Ru mol. These materials exhibited remarkable catalytic activity. The Ru/SiO2 SBA-15 materials prepared by reactive deposition with H2 in scCO2 were selective catalysts for the hydrogenation reactions of benzene and limonene, allowing the production of partly hydrogenated hydrocarbons that may serve as building blocks for more complex chemicals. scCO2 is shown to be a green solvent that allows the preparation of efficient heterogeneous catalysts to design sustainable processes. Furthermore, in the hydrogenation of limonene, scCO2 was also used as the solvent.
Prediction of the best cosolvents to solubilise fatty acids in supercritical CO2 using the Hansen solubility theory
(Chemical Engineering Science, 2018) Tirado Armesto, Diego Felipe; Tenorio, María José; Cabañas Poveda, Albertina; Calvo Garrido, María Lourdes
Cosolvents are employed to improve the extraction efficiency and modify the selectivity of the main solvent. However, choosing a proper cosolvent in supercritical extraction is an arduous task. This study aimed to predict the best cosolvents for the supercritical CO2 extraction of oleic and linoleic acids using the Hansen solubility theory. Calculations were performed for eight organic cosolvents used in food and pharmaceutical production. The best cosolvents for the solubilization of both fatty acids were short-chain alcohols, ethanol and methanol. The predictions were validated with bubble pressures of the mixtures with a 0.003 fatty acid molar fraction at temperatures of 313.2 K and 323.2 K. The experimental results agreed with the predictions. The effect of pressure was well predicted via the direct relationship between pressure and the solvent density. However, the impact of temperature was not properly foreseen because the variation of solute vapour pressure was not considered. The Hansen theory predicted that the miscibility enhancement of the solute in the supercritical mixture is maximum at low pressures and low cosolvent concentrations, as was experimentally confirmed.
Modelling and Scaling-Up of a Supercritical Fluid Extraction of Emulsions Process
(Processes, 2023) Tirado, Diego ; Cabañas Poveda, Albertina; Calvo Garrido, María Lourdes
Supercritical CO2(scCO2) is utilized in the supercritical fluid extraction of emulsions (SFEE) to swiftly extract the organic phase (O) from an O/W emulsion. The dissolved substances in the organic phase precipitate into small particles and remain suspended in the water (W) with the aid of a surfactant. The process can be continuously conducted using a packed column in a counter-current flow of the emulsion and scCO2, at moderate pressure (8–10 MPa) and temperature (37–40 ◦C). To ensure the commercial viability of this technique, the organic solvent must be separated from the CO2 to facilitate the recirculation of both streams within the process while minimizing environmental impact. Thus, the aim of this work was to design a plant to produce submicron materials using SFEE, integrating the recovery of both solvents. First, experimental equilibrium data of the ternary system involved (CO2/ethyl acetate/water) were fitted with a proper thermodynamic model. Then, simulations of the whole integrated process at different scales were carried out using Aspen Plus®, along with economical evaluations. This work proposes the organic solvent separation with a distillation column. Thus, the two solvents can be recovered and recycled to the process in almost their entirety. Furthermore, the particles in the aqueous raffinate are produced free of solvents and sterilized for further safe use. The costs showed an important economy scale-up. This work could ease the transfer of the SFEE technology to the industry.
Solubility of the metal precursor Ni(NO3)2⋅6H2O in high-pressure CO2 + ethanol mixtures
(Journal of Chemical & Engineering Data, 2017) Tenorio, María José; Ginés, Sonia; Pando, Concepción; Rodríguez Renuncio, José Antonio; Cabañas Poveda, Albertina
The solubility of Ni(NO3)2⋅6H2O in high-pressure CO2 + ethanol mixtures was measured using a high-pressure variable-volume view cell from (308.2 to 353.2 K) and up to 25.0 MPa. This compound has been used previously as a Ni precursor in metal deposition experiments using supercritical CO2. Ni(NO3)2•6H2O was not soluble in pure CO2 but the addition of ethanol into the system allowed the solubilisation of the hydrated salt in the mixture. Mole fraction of Ni(NO3)2•6H2O varied from 1.67 10-4 to 1.97 10-3. At these salt concentrations, the phase diagram of the CO2 + EtOH + Ni(NO3)2⋅6H2O system resembled that of the CO2 + EtOH binary system and, at the studied conditions, a vapourliquid equilibrium was observed. For the higher ethanol concentrations, the bubble points closely matched those of the CO2 + EtOH system. For the lower EtOH concentrations, however, much higher solubilisation pressures were required, due to the release of water molecules from the salt into the solution. Ni(NO3)2⋅6H2O solutions were stable in highpressure CO2 + EtOH mixtures at the studied conditions.
Green Preparation of PtRu and PtCu/SBA-15 Catalysts using Supercritical CO2
(Journal of CO2 utilization, 2017) Sánchez Miguel, E.; Tenorio, María José; Morère, Jacobo; Cabañas Poveda, Albertina
Sustainability is emerging as design criteria in catalysts production. Hence, the preparation of Pt bimetallic catalysts using supercritical CO2 (scCO2) as a green solvent is proposed. PtRu and PtCu nanoparticles (NPs) were deposited on mesoporous SiO2 SBA-15 by the reduction of Pt, Ru and Cu metalorganic precursor in scCO2. The simultaneous and sequential deposition of both metals was attempted using different reduction methodologies. The materials were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray analysis (EDX). XRD patterns matched closely that of cubic Pt. TEM images showed small NPs homogeneously distributed throughout the SBA-15 mesopores. Smaller particles were obtained when the reduction was performed in H2/N2 at low pressure. Sequential deposition of Cu or Ru in the first place followed by Pt yielded equimolar metal ratios. Samples prepared by sequential deposition were studied by Scanning Transmission Electron Microscopy (STEM). Composition profiles of the PtRu samples suggested an alloy structure. These catalysts were used in the hydrogenation of the renewable furfural in scCO2 at 80ºC. PtRu materials presented a high activity and selectivity to furfuryl alcohol.