Application toward Confocal Full-Field Microscopic X-ray Absorption Near Edge Structure Spectroscopy.

Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples. Here, a fluorescence method is displayed using an energy-dispersive pnCCD detector, the SLcam, characterized by measurement times far superior to what is generally applicable. Additionally, this method operates in confocal mode, thus providing direct 3D spatially resolved chemical state information from a selected subvolume of a sample, without the need of rotating a sample. The method is applied to two samples: a gold-supported magnesia catalyst (Au/MgO) and a natural diamond containing Fe-rich inclusions. Both samples provide XANES spectra that can be overlapped with reference XANES spectra, allowing this method to be used for fingerprinting and linear combination analysis of known XANES reference compounds.

Ni-Cu Hydrotalcite-Derived Mixed Oxides as Highly Selective and Stable Catalysts for the Synthesis of ß-Branched Bioalcohols by the Guerbet Reaction.

A series of Ni-Cu hydrotalcite-derived mixed oxides have been synthesized and evaluated as heterogeneous catalysts for the dimerization of linear aliphatic alcohols to afford ß-branched Guerbet alcohols. The use of the hydrotalcite-structured catalyst precursor highly favors the catalyst stability. This Cu/Ni catalyst has an enhanced reducibility of Ni2+ species under reaction conditions, favoring the hydrogen transfer and hydrogenation capacity of the catalyst system. Catalytic results are reported for C8 , mixed C8 /C10 , and C18 alcohol feeds, with full conversions and Guerbet product purities of 72.5-96 %.

Modificación y aaracterización de una vermiculia Colombiana con especies de tiitanio, zirconio y sulfato / Modifiction and characterization of a Colombian vermiclite with titannium, zirconium and sulfat / Modificção e carracterização do vermiculite Colombian com titânio, zirconiõ e sulfato

El presente trabajo reporta los resultados de la caracterización química, estructural y textural de una vermiculita de origen colombiano modificada con especies simples de Zr y Ti, y el sistema mixto Ti-Zr en relaciones atómicas nominales Zr/(Ti + Zr) = 0,1 y 0,5. Adicionalmente, se evaluó la incidencia de la presencia de sulfato sobre los sistemas mencionados bajo las relaciones nominales sulfato/metal 0; 0,25 y 0,35, incorporando el sulfato ya sea en la solución intercalante, o por impregnación vía húmeda sobre los sólidos modificados y calcinados. Los resultados indican que cuando la sulfatación se lleva a cabo por intercalación, la naturaleza química de la solución intercalante afecta notoriamente la cantidad de metal incorporado, dependiendo de la relación sulfato/metal empleada. De otro lado se estableció que, cuando se lleva a cabo la sulfatación por impregnación, las propiedades texturales, estructurales y morfológicas de los sólidos obtenidos se ven fuertemente afectadas y estan acompañadas de una fijación de azufre significativamente mayor que para los sólidos sulfatados por intercalación.

The present work reports the results of chemical, structural and textural characterization of a Colombian vermiculite modified with simple species of Zr and Ti, and the mixed system of Ti-Zr in nominal atomic relations Zr/(Ti + Zr) = 0,1 and 0,5. Additionally, the incidence of sulfate presence was evaluated under the nominal relations sulfate/metal 0; 0,25 and 0,35, incorporating sulfate either in the intercalation solution, or by impregnation on modified and calcined solids. The results indicate that when the sulfation is carried out by intercalation, the chemical nature of the intercalation solution affects the amount of incorporated metal, depending on the relation used sulfate/metal. When the sulfation by impregnating is carried out, the textural, structural and morphologic properties of the obtained solids are strongly affected and are accompanied of a sulfur fixation significantly greater than for solids sulfated by intercalation.

O trabalho atual relata os resultados do produto químico, caracterização estrutural e textural de um vermiculite Colombian modificado com espécie simples do Zr e o Ti, e o sistema misturado do Ti-Zr no Zr/atômico nominal das relações (Ti + Zr) = 0.1 e 0.5. Adicionalmente, a incidência da presença do sulfato foi avaliada sobre o sulfato das relações/metal nominais 0; 0.25 e 0.35, incorporando sulfato já seja na solução ou do intercalação, ou pelo impregnação em sólidos modificados e calcinados. Os resultados indicam que quando o sulfatação é realizado pelo intercalação, a natureza química da solução do intercalação afeta a quantidade de metal incorporado, dependendo do sulfato/metal usados na relação. Quando o sulfação impregnando é realizado, as propriedades texturaes, as estruturais e as morfologicas de sólidos obtidos fortemente estão afetadas e acompanhadas de uma fixation de enxôfre significativamente mais grande do que para os sólidos sulfatados pelo intercalação.