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Available online xxxKeywords: Hydrogen Carbon dioxide Methanation Ruthenium on alumina Activation of the catalyst Stability a b s t r a c tThe methanation of carbon dioxide has been studied over 3% Ru/Al 2 O 3 and 20% Ni/Al 2 O 3 commercial catalysts. Experiments have been performed in diluted conditions in a flow catalytic reactor with a continuous IR detection of products. The data, reported here, confirm that 3% Ru/Al 2 O 3 is an excellent catalyst for CO 2 methanation (96% methane yield with no CO coproduction at 573 K at 15,000 h À1 GHSV in excess hydrogen). The performance is better than that of Ni/Al 2 O 3 catalyst. The reaction orders over both catalysts with respect to both hydrogen and CO 2 were determined over conditioned catalysts. A conditioning of the Ru/Al 2 O 3 catalyst by reactant gas stream was found to be needed and more effective than conditioning in hydrogen, possibly because water vapour formed during methanation reaction will react to remove chlorine impurities from catalyst surface Conditioned Ru/Al 2 O 3 catalyst was found to retain stable high activity after different shutdown and start-up procedures, thus being possibly applicable in intermittent conditions.

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In this paper the results concerning the synthesis of magnetite (Fe3O4) nanoparticles (NPs), their functionalization using silane derivatives, such as (3-Aminopropyl)triethoxysilane (APTES) and (3-mercaptopropyl)trimethoxysilane (MPTMS), and their exhaustive morphological and physical characterization by field emission scanning electron microscopy (FE-SEM) with energy dispersion X-ray spectrometer (EDX) analysis, AC magnetic susceptibility, UV-VIS and IR spectroscopy, and thermogravimetric (TGA) analyses are reported. Two different paths were adopted to achieve the desired functionalization: (1) the direct reaction between the functionalized organo-silane molecule and the surface of the magnetite nanoparticle; and (2) the use of an intermediate silica coating. Finally, the occurrence of both the functionalization with amino and thiol groups has been demonstrated by the reaction with ninhydrin and the capture of Au NPs, respectively.