Spin-coated La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolyte on Infiltrated Anodes for Direct Methane Fuel Cells

Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel and nickel/copper nitrate solutions, dried and fired at 700°C. Homogeneous metal coating with proper interconnection was observed by SEM, chemical stability was confirmed by XRD, and electrical characterization of anodic substrates was performed. Catalytic activity of different anodes was evaluated ex-situ in a quartz micro-reactor fed with CH4:CO2 mixtureat range 650 and 700°C. To investigate the redox properties of the metallic phases, the anodic substrates were subjected to redox ageing cycles and characterized by H2-TPR

Nickel-based structured catalysts for indirect internal reforming of methane

A structured catalyst for the dry reforming of methane (DRM) was investigated as a biogas pre-reformer for indirect internal reforming solid oxide fuel cell (IIR-SOFC). For this purpose, a NiCrAl open-cell foam was chosen as support and Ni-based samarium doped ceria (Ni-SmDC) as catalyst. Ni-SmDC powder is a highly performing catalyst showing a remarkable carbon resistance due to the presence of oxygen vacancies that promote coke gasification by CO2 activation. Ni-SmDC powder was deposited on the metallic support by wash-coating method. The metallic foam, the powder, and the structured catalyst were characterized by several techniques such as: N2 adsorption-desorption technique, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), focused ion beam (FIB), temperature programmed reduction (H2-TPR), and Raman spectroscopy. Catalytic tests were performed on structured catalysts to evaluate activity, selectivity, and stability at SOFC operating conditions

Horizontal permeable reactive barriers with zero-valent iron for preventing upward diffusion of chlorinated solvent vapors in the unsaturated zone

Chlorinated solvents are extensively used in many activities and hence in the past decades impacted a large number of sites. The presence of these contaminants in groundwater is challenging particularly for the management of the vapor intrusion pathway. In this work we examine the potential feasibility of using horizontal permeable reactive barriers (HPRBs) placed in the unsaturated zone to treat chlorinated solvent vapors emitted from groundwater. Zero-valent iron (ZVI) powders, partially saturated with water and characterized by different specific surface areas (SSA), were tested, alone or mixed with sand, in lab-scale batch reactors using TCE as model compound. Depending on the type of iron powder used, a reduction of TCE concentration in the vapor phase from approximately 35% up to 99% was observed after 3 weeks of treatment. The best performance in terms of TCE reduction was obtained using the ZVI characterized by the intermediated values of the specific surface area (SSA). This finding, which is in contrast with the results generally observed in in aqueous solutions, was tentatively attributed to a non-selective higher reactivity of the fine-grained iron samples with water and dissolved oxygen (with a consequent iron passivation) or to the occurrence of a diffusion-limited reaction kinetics. Based on the first-order kinetic degradation rate constants estimated from the experimental data, a horizontal barrier of 1 m containing ZVI or a mixture of ZVI and sand can potentially lead to an attenuation of TCE vapors over 99%

Co and Ni supported on CeO2 as selective bimetallic catalyst for dry reforming of methane

Co/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.%)

Co-exchanged mordenites: preparation, characterization and catalytic activity for the abatement of NO with CH4 in the presence of excess O2

INNSBRUCK (AUSTRIA), 31 AUGUST - 4 SEPTEMBER 200

Ni and Ni-Co La0.8Sr0.2Ga0.8Mg0.2O3 Infiltrated Cells in H2 and CH4/CO2 mixture

La0.8Sr0.2Ga0.8Mg0.2O3- (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+CO22CO+2H2). The catalytic activity for CH4 and CO2 conversion followed the order NiNi-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

Selective Oxidation of Benzyl Alcohol catalyzed by CeO2-Nanorods Supported Palladium”.

Selective oxidation of benzyl alcohol (BA) to benzaldehyde (BZ) is considered as a crucial functional group transformation, since the product is a key intermediate for the synthesis of fine chemicals, in the perfume, pharmaceutical and dyestuff industries. This oxidation reaction is conventionally performed by various stoichiometric oxygen donors such as chromates, permanganates, and peroxides which are expensive and highly toxic. Therefore, from environmental point of view, and to reduce the overall production cost, there is a great interest in the development of heterogeneous catalysts capable of utilizing air or O2 as greener oxidants. Supported noble-metal catalysts has been investigated in numerous studies and showed promising potential to carry out selective oxidation of BA to BZ; however, various issues such as catalyst deactivation and BZ selectivity must be overcome for the industrial implementation of this reaction. In this research work, the selective oxidation of BA to BZ was studied using Palladium supported on CeO2 Nanorods (NR) as catalyst, and atmospheric air as greener oxidant. CeO2-NR were prepared according to previously published hydrothermal method [10]. Palladium oxide was deposited by wet-impregnation on CeO2-NR using Pd(NO3)2 • 2H2O and calcination at 400 °C (PdO/CeO2-NR). The effect of oxidation state of palladium on the catalytic activity was also investigated by using the reduced form of the catalyst (Pd/CeO2-NR-H2). Structural, morphological and redox properties of the synthetized materials were studied by mean of XRD, TEM, SEM, TPR and BET methods. Catalytic oxidation of benzyl alcohol using PdO/CeO2-NR or Pd/ CeO2-NR-H2 was conducted in toluene and in ethanol solvents under air flow (20ml/min). Effect of temperature (60-110 °C), BA concentration and catalyst/BA ratio (1/1, 2/1, 3/1) on catalytic activity and BZ yield was studied. Reactant and products were analyzed by GC-MS. The results showed that in toluene, catalyst deactivation occurred and high BZ yield was not achieved. In ethanol as solvent, BZ was produced with up to 99% yield and considerable selectivity. The oxidation rate increased with the catalyst/substrate ratio and with the BA concentration

Novel composite fuel electrodce for CH4-SOFC and CO2-SOEC

The 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

The catalytic activity of cobalt-exchanged mordenites for the abatement of NO with CH4 in the presence of excess O2

The abatement of NO with methane in the presence of oxygen was studied on various commercial MOR in the Na-form (Na-MOR) and H-form (H-MOR), or exchanged to various extents with cobalt (Co-MOR). The sodium and cobalt contents were determined by atomic absorption. Samples were characterized by FTIR and volumetric measurements of CO adsorption. Chemical analysis indicated that one cobalt species replaced two Brønsted acid sites in H-MOR and two Na + ions in Na-MOR. The IR analysis of the OH stretching region, evidencing an unexpected presence of Brønsted acid sites (band at 3610 cm-1) in Co-MOR, indicated that the exchange process had a more complex stoichiometry. The adsorption of CO at RT on Co-MOR, in addition to the bands of the corresponding H-MOR and Na-MOR matrices, yielded two types of CoII-carbonyls, the first type occupied the mordenite main channels, and the second one the mordenite smaller channels. Brønsted acid sites in mordenites were active for the selective catalytic reduction of NO with CH4. Co-MOR samples were far more active than Na-MOR and H-MOR samples, showing that acid protons play a negligible role when Co is present. Co-MOR catalysts showing the highest activity had the largest amount of Co II-carbonyls in the main channels. This result strongly suggests that CoII in the main channels of MOR are the active sites for the CH4 + NO + O2 reaction. © 2003 Elsevier B.V. All rights reserved