1,721,156 research outputs found
Co and Ni supported on CeO2 as selective bimetallic catalyst for dry reforming of methane
No full textCo/CeO2 (Co 7.5 wt.%), Ni/CeO2 (Ni 7.5 wt.%) and Co-Ni/CeO2 (Co 3.75 wt.%, Ni 3.75 wt.%) catalysts were prepared by surfactant assisted co-precipitation method. Samples were characterized by XRD, BET, TPR and tested for the dry reforming of methane CH4 + CO2 2CO
+ 2H2 in the temperature range 600-800 °C with a CH4:CO2:Ar 20:20:60 vol.% feed mixture and a total flow rate of 50 cm3 min-1 (GHSW = 30000 mL g-1 h-1). The bimetallic Co-Ni/CeO2 catalyst showed higher CH4 conversion in comparison with monometallic systems in the whole temperature range, being 50% at 600 °C and 97% at 800 °C. H2/CO selectivity decreased in the following order:
Co-Ni/CeO2 > Ni/CeO2 > Co/CeO2. Carbon deposition on spent catalysts was analyzed by TG-DTA analysis. After 20 hours under stream at 750 °C, cobalt-containing catalysts, Co/CeO2 and Co-
Ni/CeO2, showed a stable operation in presence of a deposited amorphous carbon of 6 wt.%, whereas Ni/CeO2 showed an 8% decrease of catalytic activity due to a massive presence of
amorphous and graphitic carbon (25 wt.%)
YSZ-based Electrochemical Sensors: from materials preparation to testing in the exhausts of an engine bench test
No full textPlanar sensors based on tape-cast YSZ layers with parallel Pt finger electrodes, one coated with WO3 thick film as sensing electrode, were
fabricated. The sensors were tested in the laboratory at various concentrations of NO2 and CO at different temperatures and oxygen partial
pressures. Field tests were also performed; planar sensors were located close to a commercial oxygen sensor, downstream the three-way
catalytic converter of a FIAT fire 1242 c.c. spark ignition engine coupled to a dynamometer. The performance of the gas sensors was measured
at the air/fuel ratio stoichiometric point (A/F∼14.3) at different engine regimes (RPM and torque) and thus at different operating temperatures.
The response of gas sensors was compared with the response of the commercial lambda probe and related to the exhaust gas concentrations
measured by spectroscopic analytical equipment at the engine exhaust end. Preliminary measurements showed promising results in terms of
sensitivity, stability and reproducibility
Novel composite fuel electrodce for CH4-SOFC and CO2-SOEC
No full textThe development of reversible solid oxide cells allows to use a single device to derive chemicals from power (power-to-fuel technology) and power from chemicals (fuel-to-power technology). We investigated a composite fuel electrode (60 wt.% La0.6Sr0.4Fe0.8Mn0.2O3-δ and 40 wt.% (5 wt.% Ni)-containing Ce0.58Sm0.15O2-δ) for dry methane oxidation in SOFC-mode and for CO2reduction in SOEC-mode. In reducing conditions, Fe exsolved from the LSFMn perovskite formed a Ni-Fe alloy with Ni present on SDC. When tested as SOFC anode, the composite was active towards dry methane oxidation at 800 °C and stable for over 40h; if tested as SOEC cathode, it showed remarkable activity for CO2reduction. EIS analysis was used to have a better understanding of the cell mechanisms in SOFC and SOEC mode
Ni and Ni-Co La0.8Sr0.2Ga0.8Mg0.2O3 Infiltrated Cells in H2 and CH4/CO2 mixture
No full textLa0.8Sr0.2Ga0.8Mg0.2O3- (LSGM) based fuel cells infiltrated with different metal catalysts were fabricated and tested both in H2 and CH4/CO2 mixture. Ni, Co, Ni-Cu, Ni-Co LSGM impregnated powders were investigated for the dry reforming of methane reaction (DRM) (CH4+CO22CO+2H2). The catalytic activity for CH4 and CO2 conversion followed the order NiNi-Co>Co>Ni-Cu. Both Ni and Ni-Co catalysts, investigated versus time (50 hours) on stream of CH4/CO2=1.5 at 800°C, did not show any sign of deactivation indicating their stability toward coke deposition. Anyway, evidence of few carbon filaments were revealed by SEM micrographs and the carbon amount evaluated by TG-DTA analysis. Ni-LSGM and Ni-Co LSGM cells showed regarding electrochemical performance both in H2 and CH4/CO2 mixture in the 650-750°C temperature range
From the Bundesbank’s stick to the ECB’s signal: consistency between labor market and monetary institutions
No full textElectrical stability during redox cycles promoted by Pd exsolution in LSFPd thin films
No full textExsolution of metallic nanoparticles (NPs) from oxide supports offers a novel approach to design high-performance materials in the field of heterogeneous catalysis and energy conversion and storage. Here, we report the homogenous exsolution of Pd NPs with an average size of 100 nm in compressive strained La0.6Sr0.4Fe0.9Pd0.1O3-δ (LSFPd) thin films. We systematically explored the electrical resistivity and the redox stability of LSFPd thin films upon exsolution of NPs. Compared to La0.6Sr0.4FeO3-δ (LSF) thin films, whose electrical response was controlled by oxygen stoichiometry, LSFPd films showed a more stable electrical response in redox cycling with similar resistivity values both in air and hydrogen. The improved stability was attributed to dynamic and exsolution of NPs. Our study showed that the control of exsolution of NPs can provide a new way to regulate the electrical response of perovskite oxide semiconductors under external stimuli (i.e., atmosphere), which could be beneficial for the rational design of high-performance functional materials for micro solid oxide fuel cells, nano-sensors, and nano-actuators applications
GDC-based infiltrated electrodes for solid oxide electrolyzer cells (SOECs)
Full text linkIn this work, porous complex and metal-free cathodes based on a (La0.6Sr0.4) (Cr0.5Mn0.5)
O3 (LSCM) screen-printed backbone infiltrated with Ce0.9Gd0.1O2 (GDC) were fabricated for solid
oxide electrolyzer cells. GDC infiltration has been optimized by structural and microstructural
investigation and tested by electrochemical measurements in CO/CO2 mixtures. Infiltrated electrodes
with a non-aqueous GDC solution showed the best electro-catalytic activity towards CO2 reduction,
exhibiting a much lower polarization resistance, i.e., Rpol = 0.3 Wcm2 at 900 C. The electrochemical
performance of LSCM/GDCE in terms of Rpol is comparable to the best-performing Ni-YSZ cathode
in the same operating conditions (Rpol = 0.23 Wcm2
The existence of Nash equilibria in n-player LQ-games, with applications to international monetary and trade agreements
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