Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

Malki, A.; Mekhalif, Zineb; Detriche, Simon; Fonder, Gregory J.; Boumaza, A.; Djelloul, A.

doi:10.1016/j.jssc.2014.03.019

Cited by 59 publications

(43 citation statements)

References 22 publications

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“…The qualitative changes in the chemistry of alumina nanoparticles and the surrounding disordered hydration layer were evaluated by monitoring the evolution of this peak. Several types of surface complexation models have been reported by various groups in an attempt to adequately describe the surface properties of alumina nanoparticles and their interaction with the solvent293435363738394041424344. It is worth noting, however, that the majority of reports pertained to the data acquired ex situ by employing the combination of thermal analysis (DTA, TGA) and conventional spectroscopic techniques, such as infrared spectroscopy (IR) and XPS.…”

Section: Discussionmentioning

confidence: 99%

Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

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Çınar

Kashyap

et al. 2015

Sci Rep

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Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles.

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Section: Discussionmentioning

confidence: 99%

Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

Firlar

Çınar

Kashyap

et al. 2015

Sci Rep

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“…The peaks at 460.0, 459.1 and 460.1 eV are all ascribed to Ti(IV) species (charge corrected to C 1s¼ 284.6 eV) (Fig. 7a-c) [42]. All fitting parameters of the grafting species were listed in Table 1, which suggested that titanium atoms are bonded to nitrogen atoms by a ratio of 1:1.…”

Section: Resultsmentioning

confidence: 94%

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

et al. 2015

Journal of Solid State Chemistry

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“…Para la muestra Fe2O3 se presentan picos a valores de 2 de 24,1º, 33,1º, 35,6º, 40,8º, 49,4º, 59,0º, 62,3º y 63,9º, característicos de la fase hematita [20]. Para la muestra RA se observan además de las señales de hematita, señales características de cuarzo estando ubicada la principal a 26,8º y de gibbsita a 20,9º y 21,9º [21].…”

Section: Caracterización De Los Precursores Catalíticosunclassified

Utilización de un residuo mineral industrial como catalizador en la hidroconversión de dibenciléter y de un carbón subbituminoso colombiano

Sánchez-Castañeda

Moreno-Lopera

Ruiz-Machado

2016

TecnoL.

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Un residuo mineral industrial, proveniente de la producción de sulfato de aluminio, se utilizó como precursor para la preparación de un catalizador de bajo costo, activo en reacciones de hidroconversión de dibenciléter, como compuesto modelo de las uniones C-O en el carbón, y de un carbón subbtituminoso colombiano. El residuo mineral y un óxido de hierro comercial (material de referencia) se sometieron a un proceso de sulfuración con el propósito de generar un sulfuro de hierro tipo pirrotita (Fe1-xS), el cual es la fase activa del hierro en reacciones de hidroconversión. Los sólidos se caracterizaron por difracción de rayos X, fluorescencia de rayos X, espectroscopía Raman y microscopía electrónica de barrido. Las pruebas de actividad catalítica, con el compuesto modelo y el carbón, se realizaron a 5 MPa H2, a temperaturas entre 240 °C y 400 °C y tiempos de reacción de 0,5 h y 1 h. Los resultados mostraron que el residuo mineral industrial fue más activo que el material de referencia y que presentó alta actividad hacia la ruptura de los enlaces C-O en el dibenciléter, siendo estos los enlaces responsables del ensamble de asfaltenos y preasfaltenos en la estructura molecular del carbón. Adicionalmente, la conversión del carbón incrementó significativamente en presencia del residuo mineral sulfurado alcanzando un valor de 83,9 %, valor 1,8 veces mayor que para la reacción sin catalizador, evidenciando el potencial del residuo mineral para ser usado como catalizador en la hidroconversión del carbón, debido a su buena actividad y bajo costo.

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Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

Cited by 59 publications

References 22 publications

Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

Utilización de un residuo mineral industrial como catalizador en la hidroconversión de dibenciléter y de un carbón subbituminoso colombiano

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