The effects of lanthanum addition in Ni/CeO 2 catalysts were investigated. The influence of synthetic procedures, namely, impregnation or coprecipitation of lanthanum and cerium oxide, were evaluated. Materials were analyzed by BET, AAS, DRIFT-MS, TPR, OSC, XRD, and SEM-EDX. Samples were tested in ethanol steam reforming (ESR). Both lanthanumpromoted samples exhibited a higher stability in time than nonpromoted catalyst. Nonetheless, catalytic behavior is strongly affected by the preparation method. TPR, OSC, and XRD analyses showed that the coprecipitation method allowed the best interaction between ceria and lanthana, leading to an increased redox ability and best catalytic performances as a result. A catalyst with a support prepared via the coprecipitation method showed ethanol conversion of 90% and hydrogen selectivity higher than 70% even after 60 h of reaction.

A series of monometallic and bimetallic metal catalysts (Pd, Cu, Fe, PdCu, PdFe) supported on ZrO 2 (6−8 nm) were synthesized and tested for the hydrogenation of bio-oil model compounds (furfural, vanillin, glucose) under 50 bar H 2 at 100°C. The catalysts were fully characterized and their properties related to their catalytic activity. The bimetallic PdFe and PdCu displayed enhanced catalytic performance compared to the monometallic catalysts for aldehyde hydrogenation (furfural, vanillin, glucose). For the best catalyst, 98% vanillin alcohol (VA) and 65.5% furfuryl alcohol (FA) conversion was obtained for 80 min batch-time. PdFe showed high selectivity toward sorbitol (74%) from glucose, though at low conversion (20%). Overall, we have demonstrated that bimetallic Fe-and Cu-based catalysts promoted by Pd show significantly better performance for the partial hydrogenation of bio-oil model compounds than the corresponding monometallic ones. The better performance of the Pd-doped Fe/Cu catalysts is linked to the presence of smaller and better dispersed Pd nanoparticles (STEM) and their lower acidity (∼90 μmol/g cat) than corresponding monometallic ones (∼167 μmol/g cat).

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ARTICLEThis journal is © The Royal Society of Chemistry 20xx J. Name., 2013, 00, 1-3 | 1 Nickel-based catalysts were investigated for hydrogen production by ethanol steam reforming. A suitable support was looked for among the metal oxides TiO2, ZrO2 and CeO2. Alongside catalytic testing with ethanol-water mixture, a series of characterization measurements were carried out: N2-physisorption, XRD, TPR, TPO, CO2-TPD, SEM, AAS and IC. Zirconium and cerium oxides proved to be suitable supports, even if both still suffer from coking phenomena. The effects of doping by both calcium oxide and gold nanoparticles were checked. Doping by calcium oxide prevented deactivation and highly increased the hydrogen yield. Moreover, the addition of gold nanoparticles greatly improved the hydrogen yield. The combination of the two dopants resulted in the best performing catalyst: the basic doping by CaO and the promotion of the water gas shift reaction by gold nanoparticles contributed to the highest hydrogen production.

Hydrogen is defined the future energy carrier, and ethanol steam reforming can be a sustainable process for its production. Promoting the addition of lanthanum on a Ni-zirconia catalyst was evaluated, with a focus on the lanthanum introduction method (incipient wetness impregnation and coprecipitation). The lanthanum addition strongly affected the morphological, structural, and chemical features of the catalysts. It particularly affected the stabilization of the zirconia phase and the surface basic properties. For the promoted materials, a higher ethanol conversion and hydrogen yield were obtained. The best catalytic results with the catalyst prepared via promoter impregnation, 81% of ethanol conversion and 25% of H 2 yield after 16 h of reaction, were obtained. By a CO 2 -TPD technique, it was estimated to be the most basic material. DRIFT analyses were used to understand the effect of basic sites in the reaction pathway. High numbers of medium and strong basic sites reduced the formation of unwanted intermediates such as ethylene. In this way, the formation of coke deposits is reduced. SEM, TG analyses, and Raman spectroscopy confirmed the results.

Methane dry reforming (MDR) allows the transformation of carbon dioxide and methane, the two main greenhouse gases, into syngas. Given the high endothermicity of the process, it is necessary to produce a catalytic system that is very active, selective and resistant to coking deactivation; this work focuses on the development of a heterogeneous catalyst based on nickel supported on cerium oxide. Several strategies of synthesis of the catalysts were studied with particular attention to the lanthanum addition methodology. Both supports and catalysts, fresh and used, were deeply characterized by different techniques (N2 physisorption, TPR, XRD, SEM). The effect of temperature on activity and selectivity of the different catalysts was also studied. A positive effect of lanthanum addition is strongly related to the synthetic methodology. Incipient wetness impregnation of lanthanum precursor on an already calcined ceria has led to the best catalytic activity. This behaviour is due to a more effective interaction between nickel and the support, which results in a higher dispersion of the active phase. The structural modifications have led to an improvement of the redox pump of the ceria, reducing the formation of coke during the reaction and improving the stability on time on stream.

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