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Catalytic CO2 reduction has been performed using carbon nanofibers or nitrogen doped carbon nanofibers as novel support for several Ru contents. The catalyst consisting of 5 wt% Ru on nitrogen doped carbon nanofiber exhibited the highest conversion at relatively low temperature, complete selectivity to CH4 and stable catalytic performance. The catalytic performance was substantially superior to catalysts supported on carbon nanotubes and akin to the best metal oxide supported catalyst in the literature. The characterisation of the prepared catalyst by transient experiments (CO2-TPD, TPSR and transient response to CO2 removal) revealed that the catalyst support participates actively in the reaction. The Ru content governed the selectivity, either favouring CO formation for lower Ru contents (0.5-2 wt%) or CH4 formation for 5 wt% Ru loading. The mean Ru particle size determined by TEM was similar for the several metal loadings. Therefore, the substantially different selectivity patterns cannot be attributed to structure sensitivity. The higher selectivity to CH4 can be explained by the enhanced supply of 4 Had to the activated COad intermediate, which was demonstrated to be the rate determining step. ; The financial support of European Commission (FREECATS project, FP7 Grant agreement nº 280658) from Spanish Ministry MINECO and the European Regional Development Fund (project ENE2013-48816-C5-5-R), and Regional Government of Aragon (DGA-ESF-T66 Grupo Consolidado) are gratefully acknowledged. ; Peer reviewed

Carbon materials have rarely been used as support for CO2 methanation, which is usually carried out using catalysts supported on metal oxides. Here, it is shown that Ru nanoparticles supported on nitrogen-doped carbon nanofibers (NCNF) provide competitive CH4 production rate and stability compared to Al2O3-supported catalysts. Contrary to the general belief about the inert nature of carbon supports, it is demonstrated that NCNF is a non-innocent spectator in CO2 methanation due to its ability to store a high amount of COad reaction intermediates. This explains the excellent catalytic behaviour afforded by this unconventional catalyst support. ; The financial support of European Commission (FREECATS project, FP7 Grant agreement nº 280658), from Spanish Ministry MINECO and the European Regional Development Fund (project ENE2013-48816-C5-5-R), and Regional Government of Aragon (DGA-ESF-T66 Grupo Consolidado) are gratefully acknowledged. ; Peer reviewed

El pdf del artículo es la versión post-print. ; Sulfonated hydrothermal carbons present high activity for esterification of palmitic acid with alcohols. However, the catalyst is significantly deactivated upon recovery. Leaching of sulfonated species does not account for this deactivation, which is observed even by pretreatment only with the alcohol under reflux. Solid state NMR shows the presence of chemically bound alkyl groups coming from the alcohol, clearly different from strongly physisorbed species obtained by pretreatment at room temperature. The formation of sulfonate esters accounts for the deactivation behavior in reactions taking place in alcohols as solvents, mainly with methanol due to its higher reactivity. © 2012 Elsevier Inc. All rights reserved. ; This work was made possible by the financial support of Aragón regional government (Project PI050/09), the Spanish Ministerio de Ciencia e Innovación (Projects MAT 2008-02365, CTQ2011-28124), and the European Commission (Grant agreement No. 226347). ; Peer Reviewed

AbstractZinc/air batteries are convenient energy storage devices for both small and massive applications. While future perspectives indicate the need for low‐cost components and sustainable fabrication processes, the battery performance is in part controlled by the kinetics of the oxygen reduction reaction (ORR), which typically involves transition metals as catalysts. In this context, we prepare a series of metal‐free water‐based carbon inks, which are tested for their catalytic performance, once deposited on a gas‐diffusion substrate, in the air cathode of a simple battery prototype. The inks contain a variety of well‐defined carbon nanomaterials and additives, exhibiting different physicochemical properties that critically influence the interaction with the gas diffusion hydrophobic substrate. The intrinsic ORR catalytic activity of the ink material is also analyzed on a glassy carbon electrode by the rotating ring‐disc electrode (RRDE) method and specific capacitance measurements. The discharge capacity on our zinc/air battery prototype correlates well with the intrinsic catalytic activity in the RRDE. However, only the activity in the RRDE does not actually assure the performance on the commercial cathode of the prototype, since other chemical compatibility issues play a role. Thus, we highlight the importance of catalyst testing, not only on the RRDE but also under realistic device conditions.