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Garcia-Sancho C.,University of Malaga | Sadaba I.,Institute Catalisis y Petroleoqumica | Moreno-Tost R.,University of Malaga | Merida-Robles J.,University of Malaga | And 3 more authors.
ChemSusChem | Year: 2013

A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by using XRD, N2 adsorption-desorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of d-xylose to furfural. Under the operating conditions used all materials are active in the dehydration of xylose to furfural (excluding the MCM-41 silica support). The xylose conversion increases with increasing Nb2O5 content. At a loading of 16 wt% Nb2O5, 74.5% conversion and a furfural yield of 36.5% is achieved at 170°C, after 180 min reaction time. Moreover, xylose conversion and furfural yield increase with the reaction time and temperature, attaining 82.8 and 46.2 %, respectively, at 190°C and after 100 min reaction time. Notably, the presence of NaCl in the reaction medium further increases the furfural yield (59.9% at 170°C after 180 min reaction time). Moreover, catalyst reutilization is demonstrated by performing at least three runs with no loss of catalytic activity and without the requirement for an intermediate regeneration step. No significant niobium leaching is observed, and a relationship between the structure of the catalyst and the activity is proposed. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Newton M.A.,European Synchrotron Radiation Facility | Newton M.A.,Argonne National Laboratory | Newton M.A.,Institute Catalisis y Petroleoqumica | Michiel M.D.,European Synchrotron Radiation Facility | And 11 more authors.
ACS National Meeting Book of Abstracts | Year: 2010

Starting from a synchronous combination of EXAFS with Diffuse reflectance infrared spectroscopy (DRIFTS), a novel combination of very hard (86 keV) X-ray diffraction with DRIFTS will be outlined. The potential for combining these techniques for the in situ study of the dynamic structural-reactive behaviour of working catalysts with high (≪1 second) time resolution will be demonstrated using the examples of nanoparticulate Pd/Al2O3 and Pd/CeZrO4/Al2O3 catalysts during CO/NO cycling. Lastly, recent results, obtained from 1 wt% Pt/Al2O3 catalysts during stoichiometric - lean CO/O2 cycling, using a time resolved Pair distribution function (PDF) approach to analysis of hard (60 keV) X-ray scattering data will be presented and discussed.

Soares O.S.G.P.,University of Porto | Orfo J.J.M.,University of Porto | Gallegos-Suarez E.,Institute Catalisis y Petroleoqumica | Castillejos E.,Institute Catalisis y Petroleoqumica | And 2 more authors.
Environmental Technology (United Kingdom) | Year: 2012

The influence of the presence of inorganic and organic matter during the catalytic reduction of nitrate in a local groundwater over a Pd-Cu catalyst supported on carbon nanotubes was investigated. It was observed that the catalyst performance was affected by the groundwater composition. The nitrate conversion attained was higher in the experiment using only deionized water as solvent than in the case of simulated or real groundwater. With exception of sulphate ions, all the other solutes evaluated (chloride and phosphate ions and natural organic matter) had a negative influence on the catalytic activity and selectivity to nitrogen. © 2012 Taylor & Francis.

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