Suchergebnisse

Acknowledgements The support of the Spanish Government (projects CTQ2014-52956-C3-2-R and CTQ2014-52956-C3-3-R) is recognized. ; Peer reviewed ; Postprint ; Postprint

Graphene oxide and multiwall carbon nanotubes (CNTs) were chemically modified by treatment with urea and subsequent annealing at different temperatures. These materials were used as supports for gold nanoparticles and the resulting samples have been applied as catalysts in the 1,3-butadiene partial hydrogenation reaction. The supports and catalysts were exhaustively characterized. It was shown that urea treatments modified the graphene surfaces and the morphology of CNTs, in both cases with incorporation of significant amounts of different nitrogen surface groups. The presence of these groups on few layered graphene or on CNT surfaces modifies the gold precipitation–deposition process during catalyst preparation, giving place to different amounts of incorporated gold on the various supports. The obtained catalytic results suggested that the partial hydrogenation requires limited availability of hydrogen, and for this the migration through adsorbed species between the metal and support to initiate the hydrogenation, probably by a spillover mechanism, seems to be a required step. In general intramolecular selectivity is structure-sensitive meanwhile catalytic activity is not structure-sensitive, as evidenced when the gold nanoparticle sizes are decreased. ; E C gratefully acknowledges nancial support from the Spanish Ministry of Science and Technology and from the UNED postdoc programme. This work was supported by the Spanish Government (project CTQ 2011-29272-C04-01and 03). ; Peer Reviewed

© Almohalla et al.; Licensee Bentham Open ; Catalytic bioethanol transformations over carbon nanomaterials (nanofibers and nanotubes) have been evaluated at atmospheric pressure and in the temperature range of 473-773 K. The pristine carbon materials were compared with these samples after surface modification by introducing sulfonic groups. The specific activity for ethanol dehydrogenation, yielding acetaldehyde, increases with the surface graphitization degree for these materials. This suggests that some basic sites can be related with specific surface graphitic structures or with the conjugated basic sites produced after removing acidic oxygen surface groups. Concerning the dehydration reaction over sulfonated samples, it is observed that catalytic activities are related with the amount of incorporated sulfur species, as detected by the evolution of SO2 in the Temperature programmed Desorption (TPD) as well as by the analysis of sulfur by X-Ray Photoelectron Spectroscopy (XPS). ; The financial support of the Spanish government by Projects CTQ2011-29272-C04-01 and 03 is recognized. ; Peer Reviewed