1,720,969 research outputs found
Caratterizzazione di materiali porosi mediante adsorbimento di gas: evoluzione del composito di boro-grafite ottenuto mediante high energy ball milling
No full textI materiali porosi sono noti per le loro proprietà dovute alla capacità di adsorbimento di specie liquide o gassose. Lo
sviluppo di nuovi composti a elevatissima superficie specifica ha dato avvio a un rinnovato interesse scientifico e
tecnologico dovuto alla possibilità di utilizzare solidi porosi quali substrati per l'accumulo di gas in fase condensata. In
particolare, lo stoccaggio sicuro d’idrogeno in materiali adsorbenti in particolare, risulta cruciale per lo sviluppo delle
tecnologie per la sostenibilità energetica. Il presente rapporto tecnico è costituito da due parti: nella parte A si danno
alcuni cenni teorici di base sulle metodologie di caratterizzazione mediante adsorbimento di azoto; nella parte B è
riportato lo sviluppo mediante High Energy Ball Milling e la caratterizzazione di un materiale composito con porosità
di tipo a fenditura, costituito da nitruro di boro esagonale e grafite.Porous materials are well known for their capacity of adsorbing both liquid and gaseous species. The development of
new classes of materials with very high specific surface promoted the interest of the scientific community in their use as
solid substrates for gas storage. In particular, the safe hydrogen storage in adsorbing materials constitutes a crucial
issue in enabling the use of new technologies for energy sustainability. This technical report is divided in two parts: in
part A some theoretical basics are described on gas adsorption fundamentals for the characterization of porous
materials; in B on the synthesis by High Energy Ball Milling and the characterization of a boron nitride-graphite
composite with slit-like porosities are reported
NUOVO METODO PER LA PREPARAZIONE DI ANTIBIOTICI IN STATO AMORFO E PRODOTTI OTTENUTI UTILIZZANDO DETTO METODO
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The carbonatation reaction of layered Na(Mn1/3Fe2/3)O2: A high temperature study
No full textThe transformation of mixed sodium manganese ferrite into manganese ferrite induced by carbon dioxide was investigated. The reaction was performed in controlled conditions at different temperatures (600 °C and 800 °C). Transformation kinetics were followed in terms of powder composition evolution and weight gain by in-situ high temperature X-ray diffraction and thermogravimetric analysis respectively. Differently than expected by the reaction stoichiometry, the comparative analysis of the obtained experimental results reveals that sodium carbonate and manganese ferrite compounds formation is asynchronous.
A mechanism describing mixed sodium manganese oxide transformation into manganese ferrite following sodium extraction by carbon dioxide is proposed and discussed
SOFC Material and Stack Characterization Tests for Micro-CHP Application
No full textIn the present work preliminary characterization tests, finalized to application as a residential micro-CHP system, are reported. Through systematic, parallel testing under predetermined conditions, laboratories at ENEA and the University of Perugia aim at establishing the real lifetime expectancy and performance characteristic of 1 kW-class SOFC stacks fed with natural gas from the grid, downstream of a specifically developed desulphurizer for the abatement of odorants. Through the assessment of material response and delivered power also at single cell level, it will be possible to establish and improve the behaviour in time of a SOFC system operated under realistic conditions. There is continuous feedback with both the system optimization engineers as with powder development chemists, in order to bring the concept swiftly and efficiently to market maturity, as well as prepare the basis for second generation systems with improved stack performance and durability.</jats:p
Incorporation of Mg-Al hydrotalcite into a biodegradable poly (epsilon, caprolactone) by high energy ball milling
No full textThe technique of high energy ball milling (HEBM) was used to prepare nanocomposites of poly(epsilon-caprolactone) (PCL) and an organically modified Mg–Al layered double hydroxide. The amount of inorganic material was varied from 0 to 6 wt%, and the samples were melted and quenched in ice–water after milling. The molecular weight of PCL decreased and its distribution increased as a consequence of milling. The structural analysis of the milled samples, conducted by X-ray diffraction and infrared absorption techniques, showed that the 12-hydroxydodecanoates organic modifier was still attached to the inorganic lamellae even if a partial delamination of the layered compounds occurred. The mechanical parameters (modulus, stress at yield point, strain at break point and stress at break values) derived from the stress– strain curves, improved in the composite samples containing up to 2.8 wt% of inorganic filler, with respect to the pure polymer, in spite of the molecular weight decrease. The thermodynamic diffusion coefficient of water vapor in composite samples was lower than in pure PCL, indicating an improvement of the barrier effec
Chemical aspects of the water-splitting thermochemical cycle based on sodium manganese ferrite
No full textWater thermolysis by means of the sodium manganese ferrite cycle for sustainable
hydrogen production is reviewed, with particular focus on known elementary chemical
processes taking place on solid substrates in the 600e800 C temperature range. For the
purpose, in-situ high temperature x-ray diffraction technique has been utilized to observe
structural transformations produced by both temperature and reactive environment. The
water-splitting reaction and the regeneration of initial reactants are described as multistep
reactions, in which the role of carbon dioxide, through carbonation and decarbonation
reactions is highlighted. A thermodynamic phase stability diagram is reported
for the system MnFe2O4/Na2CO3/CO2
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