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H2 production by steam reforming of bioethanol
No full textDifferently supported Ni-based catalysts, with variable metal loading, have been synthesized by means of an innovative prepn. procedure. This technique, named Flame Spray Pyrolysis, allows the continuous one-step prodn. of nanosized particles, characterized by high thermal stability due to a flash calcination for a few milliseconds into a flame. The morphol. and structural features of the as prepd. supports and of activated catalysts are here summarized, together with catalyst performance for the steam reforming of bioethanol at 750°C, atm. pressure. Alumina, chosen for comparison with com. catalysts for this application, did not show a suitable support due to its high surface acidity, which leads to faster coking with respect to other supports. Increasing Ni loading allowed to increase H2 productivity and the best results were achieved with the sample 15 wt.% Ni/La2O
La pirolisi in fiamma come metodo di preparazione di nanomateriali per applicazioni ambientali ed energetiche
No full textCOGENERATION OF THERMAL AND ELECTRIC POWER FROM RENEWABLE SOURCES
No full textThis project deals with a different use of ethanol deriving from biomass. The aim is to produce hydrogen starting from 2nd generation bioethanol as raw material. H2 is then purified and fed to a PEM fuel-cell. The latter co-generates electrical and thermal energy with a 5kWelectric+ 5kWthermal power size, suitable for de-localized energy production. The goals of this work are different: efficient H2 production by bioethanol steam reforming (SR), H2 purification by high and low temperature water gas shift (HTWGS+LTWGS) and methanation of residue CO (<20ppmv), check of the overall plant efficiency and performance under widely different operating and load conditions.
This project is divided in two steps. The former consists in efficiency tests on the above mentioned semi-commercial device (GH2-5000 Energy System provided by Helbio S.A) composed by a PEM fuel-cell integrated in a steam reforming + H2 purification system. The latter step focuses on catalytic tests on new materials in order to find innovative catalysts for the SR of bioethanol. In particular, we aim at finding catalysts active at lowest reaction temperature, to promote the WGS reaction even in the SR step and to lower the energy input of the endothermic SR reaction, due to the exothermicity of the WGS one.
A series of Ni catalyst, differently supported, were synthesised and characterised. Three different series of Ni-based catalysts for the steam reforming reaction were synthesised by two different procedures. Al2O3, TiO2 and La2O3 were chosen as supports and the Ni loading was 5-10-15 wt% for each set of samples. Ni supported on Al2O3 was chosen at first, because it is the most common SR catalyst commercially available and it was assumed as reference material. The biggest problem when using alumina as support was coke formation during the SR reaction, depressing selectivity and deactivating the catalyst. For this reason binary supports, such as Al2O3/La2O3, are used to decrease support acidity . In the present work catalysts directly supported on pure La2O3 were also prepared. At last TiO2 - supported samples, rather new for this application, were prepared to achieve lower acidity than alumina, coupled with interesting redox properties of the support, which could enhance surface cleaning. The selected supports were prepared in nano-powder form by flame spray pyrolysis (FP,) and then Ni was added in proper amount by impregnation from a Ni(NO3)2 · 6H2O aqueous solution. A parallel, completely new, preparation procedure was developed by directly adding Ni during the FP synthesis.
Some of the catalysts prepared were included in a project financed by Regione Lombardia in collaboration with the Universities of Venice (UniVE) and Genoa (UniGE). This project was focused on catalytic materials for both ethanol (ESR) and glycerol (GSR) steam reforming. Catalysts with different active phases (Ni, Co, Cu) and different supports (TiO2, SiO2, ZrO2) were synthesised. Different strategies have been adopted for the preparation of the samples (UniMI-UniVe), namely flame pyrolysis and metal impregnation over traditionally prepared supports. All the catalysts were characterised by atomic absorption, XPS, XRD, O2-chemisorption, FT-IR,TPR-TPO (UniVE, UniGE, UniMI).
Finally, some tests were carried out on the integrated 5 kW plant to set up the analytical procedure. The first tests revealed a number of electrical and set up problems, which were partly solved. Preliminary experiments allowed to monitor the trend of CO concentration , confirming the H2 purity level required to feed the PEMFC (10 ppmv in the reformate). Currently the system was returned to the supplier to allow interfacing with a new type of HT-PEMFC that operates at 160° C and is therefore able to withstand a level of CO equal to 2 vol%
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
La-Ag-Co perovskites for the catalytic flameless combustion of methane
Full text linkAg represents an interesting dopant for the highly active LaCoO3 perovskites used for the catalytic flameless combustion (CFC) of methane, due to its ability to adsorb and activate oxygen and to the possibility of incorporation into the framework as Ag+ or Ag2+, with formation of oxygen vacancies. In the present work we compared the catalytic activity and resistance to sulphur poisoning of a series of LaCoO3, x%Ag/LaCoO3, La1-xAgxCoO3 samples (nominal composition), the latter two notations indicating post-synthesis Ag loading or direct incorporation during the synthesis, respectively. The samples were prepared by flame pyrolysis (FP) and by the sot-gel (SG) method, leading to different particle size and possibly to different incorporation degree of the dopant, quantified by Rietveld refinement of XRD patterns.
Higher activity was observed, in general, with fresh catalysts synthesised by FP. The SG samples demonstrated a slightly better resistance to sulphur poisoning when considering the conversion decrease between the fresh and the poisoned samples, due to lower surface exposure. However, interesting data have been obtained with some of the Ag-doped poisoned FP samples, performing even better than the fresh SG-prepared ones.
Ag addition led to a complex change of activity and resistance to poisoning. The activity of FP-prepared samples doped with a small amount of Ag (e.g. 5 mol%) was indeed lower than that of the undoped LaCoO3. By contrast, a further increase of Ag concentration led to increasing catalytic activity, mainly when big extra framework Ag particles were present. By contrast, for SG samples a low Ag amount was beneficial for activity, due to an increased reducibility of Co3+
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