Cu-CeO2 anodes for solid oxide fuel cells: Determination of infiltration characteristics

In this work, the optimum compositions for a Cu-CeO2-YSZ anode were introduced as a solid oxide fuel cell anode structure. The minimum Cu content, a suitable infiltration technique and the optimum CeO2 amounts were determined. The continuum percolation limit of metallic Cu was demonstrated to be 30% by mass in the YSZ matrix. The simultaneous and sequential impregnation of Cu and CeO2 salt solutions was investigated using XRD and SEM techniques. It was concluded that the phase distribution in the YSZ scaffold was more efficient and that there was no chemical interaction between Cu and CeO2 during the co-calcination process with simultaneous infiltration. The OCV values of the cells increased greatly with 5%, 10% and 20% CeO2 content. On the other hand, over this loading, the OCV values were approximately 920 mV for increasing amounts of CeO2. The current-voltage measurements showed that up to Cu/CeO2 at 70/30, the electrochemical performance of the cell increased and then decreased for 60/40. The corresponding optimal Cu/CeO2 loading was investigated using single cell I-V characterization, and a 35% Cu-15% CeO2-50% YSZ cermet structure is the proposed ideal cell composition. (C) 2016 Elsevier B.V. All rights reserved

Effect of the calcination temperature on Ni/MgAl2O4 catalyst structure and catalytic properties for partial oxidation of methane

Effect of calcination temperature on Ni/MgAl2O4 catalyst was investigated in order to evaluate changes on structural and catalytic properties for catalytic partial oxidation of methane. The catalysts were calcined at different temperatures after impregnation of nickel salt solution on MgAl2O1 support. The prepared catalysts showed nearly 89% CH4 conversion and 99% H-2 selectivity under the flow of 157,000 (l kg(-1) h(-1)) with the ratio of CH4/air = 0.44 at 1 atm and 800 degrees C. However, turnover frequency values of the catalysts were between 8.2 and 42.3 s(-1) and increased according to Ni particle size. Lewis basicity/acidity ratio increased from 2.14 to 4.46 with increasing calcination temperature. It was found that coking rate on the catalysts depends on Ni particle size and surface basicity/acidity. The experimental results showed that calcination temperature and time have a significant influence on both structural and catalytic properties of the catalysts that show strong metal oxide support interaction. It could be claimed that high calcination temperatures could be beneficial to obtain highly active, selective and stable Ni/MgAl2O4 catalysts, which possess strong metal oxide support interaction, by maintaining Ni dispersion high after reduction, increasing surface basicity and enhancing the stability of Ni particles against sintering. (C) 2013 Elsevier Ltd. All rights reserved

Studies on oxidative coupling of methane using Sm2O3-based catalysts

The effects of Mn/Na2WO4, Li, and CaO loading on the monoclinic Sm2O3 catalyst were investigated for the oxidative coupling of methane using O-2 or N2O as an oxidant. The catalysts were prepared by wet impregnation method and characterized by XRD, BET, CO2-TPD, and XPS analysis. Impregnation of Mn/Na2WO4 on monoclinic Sm2O3 resulted in the formation of Sm2-xMnxO3 phase, decreasing the catalytic performance. Li impregnation increased the C-2 selectivity but decreased the catalytic activity. The SmLiO2 formation increased the catalytic activity and selectivity. High amounts of CaO impregnation increased the C-2 selectivity of monoclinic Sm2O3 without a loss in catalytic activity. 6Li/m-Sm2O3 were found unstable due to the Li loss from the catalyst. The 15CaO/m-Sm2O3 was quite stable and showed 8.2% ethylene yield with N2O use, much higher than that was obtained with the well-known 2Mn/5Na(2)WO(4)/SiO2 and 4Li/MgO catalysts. N2O was more selective than O-2 as an oxidant and enhanced ethylene formation

Preparation and characterization of Ni based catalysts for the catalytic partial oxidation of methane: Effect of support basicity on H-2/CO ratio and carbon deposition

The catalytic partial oxidation of methane (CPOM) was studied on Ni based catalysts Catalysts were prepared by wet impregnation method and characterized by using AAS BET XRD HRTEM TPR TPO Raman Spectroscopy and TPSR techniques The prepared catalysts showed nearly 95% CH4 conversion and nearly 96% H-2 selectivity under the flow of 157 500 (L kg(-1) h(-1)) with the ratio of CH4/O-2 = 2 by using air as an oxidant at 1 atm and 800 C Support basicity greatly influenced the H-2/CO ratio and carbon deposition It was found that the lowest carbon deposition occurred on Ni impregnated MgO catalyst Considering the results it was found that Ni/MgO catalyst with 10% Ni content would be the best catalyst amongst Ni/Al2O3 Ni/MgO/Al2O3 Ni/MgAl2O4 and Ni/Sorbacid for the CPOM only under more reductive conditions Under optimum conditions Ni/MgO showed poor performance and therefore Ni/Sorbacid would be the ideal catalyst because of its greater carbon resistance than the other catalysts (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserve

Er and Gd Co-Doped Ceria-Based Electrolyte Materials for IT-SOFCs Prepared by the Cellulose-Templating Method

Ce0.9-x Gd0.1Er (x) O1.9-x/2 (0 a parts per thousand currency sign x a parts per thousand currency sign 0.1) (EGDC) powders were successfully synthesized with a fast and facile cellulose-templating method for the first time and characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The samples were calcined at a relatively low calcination temperature of 773 K (500 A degrees C). The sintering behavior of the calcined EGDC powders was also investigated at 1673 K (1400 A degrees C) for 6 hours. Calcined Ce0.9-x Gd0.1Er (x) O1.9-x/2 (0 a parts per thousand currency sign x a parts per thousand currency sign 0.1) powders and sintered Ce0.9-x Gd0.1Er (x) O1.9-x/2 (0 a parts per thousand currency sign x a parts per thousand currency sign 0.1) pellets crystallized in the cubic fluorite structure. It was found that the relative densities of the sintered EGDC pellets were over 95 pct for all the Er contents studied. Moreover, the effect of Er content on the ionic conductivity of the gadolinium-doped ceria (GDC, Ce0.9Gd0.1O1.90) was investigated. The highest ionic conductivity value was found to be 3.57 x 10(-2) S cm(-1) at 1073 K (800 A degrees C) for the sintered Ce0.82Gd0.1Er0.08O1.91 at 1673 K (1400 A degrees C) for 6 hours

Preparation and characterization of Ca-Sm-Ce mixed oxides via cellulose templating method for solid oxide fuel cell applications

SmxCa0.2 xCe0.8Oy materials are synthesized by changing mol ratios of the composition as x ¼ 0, 0.05, 0.1, 0.15 and 0.2, respectively, with a fast and facile cellulose templating method for the ? rst time. Micro- structures of the calcined and sintered samples are characterized by XRD and SEM-EDX. Density measurements are actualized by using Archimedes method. The electrical conductivity of the samples is obtained from two-probe impedance spectroscopy. Maximum solubility limit of CaO in CeO2 is found to be 9.4 mol% from the XRD results. Incorporation of CaO slightly increases the sinterability of the samples. It is observed that Smþ 3 expands the CeO2 lattice more than Caþ 2. 10 mol% CaO incorporated sample show the highest total conductivity with the value of 0.032 S cm 1 at 800 C. Obtained results show that Sm0.1Ca0.1Ce0.8Oy can be an excellent candidate for intermediate temperature solid oxide fuel cell applications due to its lower cost and higher performance compared to Sm0.2Ce0.8Oy at 800 C. Addi- tionally, cellulose templating method can be used as an effective method in order to prepare mixed oxide structures since the performances of the samples are higher than the samples which are prepared by more complex or costly hydrothermal and co-precipitation methods in literature

Synthesis, Spectral Characterization and Antimicrobial Activity of Some Transition Metal Complexes of 1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane

1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane (L) complexes with Fe(NO3)(3), CoCl2, Co(NO3)(2), Ni(NO3)(2), CuCl2, Cu(ClO4)(2), PdCl2, CdI2, Hg(NO3)(2) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT-IR, NMR, ESI-MS, fluorescence spectroscopy. Also, the crystal structure of 1,3-bis(1H-benzimidazol-2-yl)-2- oxapropane] dichlorocobalt(II), [Co(L)Cl-2], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO3)(2) complex: it showed weak activity toward all of the microorganisms