Person: Cabañas Poveda, Albertina
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First Name
Albertina
Last Name
Cabañas Poveda
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
8 results
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Now showing 1 - 8 of 8
Item 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 García-Pumarino, Concepción; Rodríguez Renuncio, José Antonio; Cabañas Poveda, AlbertinaThe 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.Item Polymorphism in the co-crystallization of the anticonvulsant drug carbamazepine and saccharin using supercritical CO2 as an anti-solvent(The Journal of Supercritical Fluids, 2018) Cuadra Mendoza, Isaac Alfonso; Cabañas Poveda, Albertina; Rodríguez Cheda, José Antonio; Pando García-Pumarino, Concepción1:1 Co-crystals of carbamazepine (CBZ) and saccharin (SAC) were obtained for the first time through the supercritical anti-solvent (SAS) technique based on using supercritical CO2 as anti-solvent. The capability of SAS to produce the desired polymorphic form (two polymorphs are known) was assessed. Operational conditions investigated were temperature (40.0 and 60.0 °C), pressure (10.0 and 15.0 MPa), solvent choice and coformer concentration in the organic solution (CBZ: 30 and 15 mg/mL; SAC: stoichiometric ratio). Co-crystals were characterized in terms of crystallinity and coformers interactions. No homocrystals were present. Using methanol, at 40.0 °C polymorph I was obtained with yields up to 65%; whilst at 60.0 °C a mixture of polymorphs was obtained. Mixtures of polymorphs were also obtained in the ethanol and dichloromethane experiments at the studied conditions while the dimethylsulfoxide experiments failed to produce any co-crystal polymorph. For comparison purposes, pure CBZ and SAC were also processed by SAS.Item 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 Rodríguez, Eduardo; Pando García-Pumarino, Concepción; Cabañas Poveda, AlbertinaThe 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.Item 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 García-Pumarino, Concepción; Cabañas Poveda, AlbertinaA 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.Item Thiol group functionalization of mesoporous SiO2 SBA-15 using supercritical CO2(Microporous and Mesoporous Materials, 2018) Tenorio, M.J.; Carnerero, C.; Torralvo Fernández, María Josefa; Pando García-Pumarino, Concepción; Cabañas Poveda, AlbertinaChemical modification of mesoporous SiO2 SBA-15 with thiol groups was performed using mercaptopropyltrimethoxysilane (MPTMS) dissolved in supercritical CO2 (scCO2). Thiol groups serve as adsorbents for the selective removal of contaminant metal cations and in catalysis. Functionalization was carried out in scCO2 at temperatures ranging from 40 to 150 °C and pressures from 15.0 to 29.0 MPa. For comparison purposes, the reaction was also performed in toluene at 80 and 110 °C. As opposed to toluene, scCO2 is considered a green solvent. Grafting of the thiol groups was confirmed by FTIR spectroscopy, thermogravimetric analysis (TGA) and elemental analysis. Grafting density and surface coverage of the materials modified using scCO2increased with temperature, CO2 density, time and stirring and varied from 1.3 to 4.4 mmol g−1 and from 1.3 to 4.0 molecules nm−2, respectively. On the other hand, surface area and pore size decreased as grafting density increased. At temperatures of 80 °C or higher, the pore size remained constant, suggesting the formation of a compact monolayer. Modification at higher temperatures led to larger grafting densities but very low surface areas. Assuming total hydrolysis and condensation of the precursor, the optimum grafting density and surface coverage of 2.3 mmol g−1 and 2.4 molecules nm−2, respectively, were obtained in scCO2 at 80 °C and 25.0 MPa for 4 h. Grafting densities of the samples prepared in toluene were by far much lower than those obtained using scCO2 at lower temperatures and shorter times, which demonstrates the advantages of CO2 as a green functionalization medium.- Project number: 242
Item Laboratorio integrado de prácticas de simulación de fundamentos y procesos químicos con fluidos supercríticos(2019) Calvo Garrido, María Lourdes; Cabañas Poveda, Albertina; Pando García-Pumarino, Concepción; García Baonza, Valentín; González Mac-Dowell, Luis; Tirado Armesto, Diego Felipe; Cuadra Mendoza, Isaac Alfonso; Menéndez Carbajosa, Alicia MartaEl objetivo del proyecto ha sido crear un laboratorio integrado de prácticas de simulación relacionadas con fundamentos termodinámicos y procesos con fluidos supercríticos, destinado a los alumnos de Química e Ingeniería Química. Item 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 Josefa; Pando García-Pumarino, Concepción; Rodríguez Renuncio, Juan Antonio; Cabañas Poveda, AlbertinaRu 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.Item Cocrystallization of the anticancer drug 5-fluorouracil and coformers urea, thiourea or pyrazinamide using supercritical CO2 as an antisolvent (SAS) and as a solvent (CSS)(The Journal of Supercritical Fluids, 2020) Cuadra Mendoza, Isaac Alfonso; Cabañas Poveda, Albertina; Rodríguez Cheda, José Antonio; Türk, MIchael; Pando García-Pumarino, ConcepciónCo-crystals of 5-fluorouracil (5-Fu) and the coformers urea, thiourea and pyrazinamide (PZA) were attempted for the first time through the supercritical antisolvent (SAS) and the cocrystallization with supercritical solvent (CSS) techniques. SAS operational conditions were temperature (313 K), pressure (7.0–15.0 MPa) and 5-Fu concentration in methanol (5 and 2.5 mg/mL). Coformer concentration was always in the desired stoichiometric ratio. Co-crystals were characterized using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Pure 5-Fu-urea cocrystals were obtained via SAS at 313 K and 8.0 MPa using a 5 mg/mL 5-Fu solution. All other SAS conditions studied led to 5-Fu homocrystal impurities. For comparison purposes 5-Fu, urea and thiourea were also processed by SAS. CSS produced a mixture of co-crystals and homocrystals only when supercritical CO2 was modified with methanol. Advantages and disadvantages of the two supercritical cocrystallization techniques are discussed.