1) The document describes research into using NdFeO3 as the anode material for sulfur-oxygen solid oxide fuel cells (S/O2-SOFCs).
2) NdFeO3 powder was prepared via a sol-gel method and was found to be stable when exposed to sulfur vapor or sulfur dioxide at 800°C based on XRD analysis.
3) A single cell with a NdFeO3-SDC/SDC/LSM-SDC structure achieved maximum power densities of 0.154 mW/cm2 at 620°C and 0.265 mW/cm2 at 650°C when using sulfur vapor and SO2 as fuels
ELECTROLYTIC SEPARATION OF LEAD AND ITS DIOXIDE FROM CARBONATE ORE RESIDIUUMAl Baha University
Electrowinning work is carried out on the roasted Eastern Desert complex carbonate ore residuum. Lead and its dioxide are electrodeposited from various electrolyte ore baths and the results showed a wide variety of ore electrolyte solutions, either in the form of soluble simple ore salts, or those containing complex ore anions. The optimum conditions and the efficiency of the electrolytic extraction are determined experimentally on the ore leach solutions.
Madkour 1986-journal of-chemical_technology_and_biotechnologyAl Baha University
Thermodynamic Studies on Sulphate Roasting for Zinc Electrowinning from Carbonate Ore
The bulk of the work consists of a theoretical study of the possibility of submitting Umm-Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolu- tion of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H2S04 (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Madkour 1985-journal of-chemical_technology_and_biotechnology._chemical_techn...Al Baha University
Recommended Flowsheets for the Electrolytic Extraction of Lead and Zinc from Red Sea Polymetal Ore
The polymetal complex ore Umm-Gheig considered in Egypt as a rather rich source of lead and zinc is subjected to mineralogical, chemical, spectral, X-ray and differential thermal analyses. Hydrometallurgical treatments based on leaching, precipitation and electrodeposition of metal from the ore are established. The influences of current density, temperature and metal ion concentration on the Faradic current efficiency are discussed. Advantages and disadvantages of flow- sheets and various approaches depending on convenient baths for the electro- deposition of metals are investigated. The results of electron microscopic investiga- tion confirmed by metal value data given in the A.S.T.M. cards coincide well with those given by chemical analysis.
ELECTROLYTIC SEPARATION OF LEAD AND ITS DIOXIDE FROM CARBONATE ORE RESIDIUUMAl Baha University
Electrowinning work is carried out on the roasted Eastern Desert complex carbonate ore residuum. Lead and its dioxide are electrodeposited from various electrolyte ore baths and the results showed a wide variety of ore electrolyte solutions, either in the form of soluble simple ore salts, or those containing complex ore anions. The optimum conditions and the efficiency of the electrolytic extraction are determined experimentally on the ore leach solutions.
Madkour 1986-journal of-chemical_technology_and_biotechnologyAl Baha University
Thermodynamic Studies on Sulphate Roasting for Zinc Electrowinning from Carbonate Ore
The bulk of the work consists of a theoretical study of the possibility of submitting Umm-Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolu- tion of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H2S04 (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Madkour 1985-journal of-chemical_technology_and_biotechnology._chemical_techn...Al Baha University
Recommended Flowsheets for the Electrolytic Extraction of Lead and Zinc from Red Sea Polymetal Ore
The polymetal complex ore Umm-Gheig considered in Egypt as a rather rich source of lead and zinc is subjected to mineralogical, chemical, spectral, X-ray and differential thermal analyses. Hydrometallurgical treatments based on leaching, precipitation and electrodeposition of metal from the ore are established. The influences of current density, temperature and metal ion concentration on the Faradic current efficiency are discussed. Advantages and disadvantages of flow- sheets and various approaches depending on convenient baths for the electro- deposition of metals are investigated. The results of electron microscopic investiga- tion confirmed by metal value data given in the A.S.T.M. cards coincide well with those given by chemical analysis.
Octahedral rhenium K4[Re6S8(CN)6] and Cu(OH)2cluster modifiedTiO2for the phot...Pawan Kumar
tOctahedral hexacyano rhenium K4[Re6S8(CN)6] cluster complexes were grafted onto photoactive Cu(OH)2cluster modified TiO2{Cu(OH)2/TiO2} support. The rhenium and copper cluster modified TiO2photocata-lyst combines the advantages of heterogeneous catalyst (facile recovery, recycling ability of the catalyst)with the reactivity, selectivity of the soluble molecular catalyst. The synthesized heterogeneous cata-lyst was found to be highly efficient photoredox catalyst for the reduction of CO2under visible lightirradiation. Methanol was found to be the major liquid product with the formation of hydrogen as a byproduct as determined with GC-FID and GC-TCD, respectively. The methanol yield after 24 h irradiationwas found to be 149 mol/0.1 g cat. for Re-cluster@Cu(OH)2/TiO2photocatalyst that is much higher than35 mol/0.1 g cat. for Cu(OH)2/TiO2and 75 mol/0.1 g cat. for equimolar rhenium cluster in the presenceof triethanolamine (TEOA) as a sacrificial donor. The quantum yields (MeOH) of Re-cluster@Cu(OH)2/TiO2and Cu(OH)2/TiO2were found to be 0.018 and 0.004 mol einstein−1, respectively. These values are muchhigher than those reported for other heterogeneous catalysts for six electron transfer reaction
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Study of the Influence of Nickel Content and Reaction Temperature on Glycerol...IJRESJOURNAL
ABSTRACT: La2O3-SiO2-supported nickel catalysts were evaluated in glycerol steam reforming. The samples (30wt% La and 5, 10 and 15wt% of Ni on 70wt% commercial SiO2), prepared by the simultaneous impregnation method, were characterized by EDX, nitrogen physisorption, XRD, in-situ XRD, XANES and TPR. The analyses revealed NiO species weakly interact with the support and the different metallic surface areas of the catalysts. Catalytic tests were performed in a fixed bed reactor at 600oC and 15Ni catalyst, which showed the best performance, was also evaluated at 500oC and 700oC. According to the results, the Ni content on the catalyst surface interferes in the distribution of gaseous products H2, CO, CO2 and CH4. The increase in the Ni content increases the carbon formation during reaction. The reaction temperature affected the catalytic performance and the best results were obtained with the 15Ni catalyst at 600oC, which was also tested for 20 hours for the analysis of its stability.
IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE)
electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved
by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the
electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and
x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by
chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised
for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this
study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis
duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active
IrO2 electrocatalyst was not favoured.
Development of Ni-doped Yttria stabilized Zirconia composite for SOFC applica...IOSRJAP
Ni-doped Yttria stabilized Zirconia (NiO/YSZ) has been synthesized using low cost combustion process from an aqueous solution containing ZrO(NO3)2.6H2O, Y(NO3)3.6H2O, Ni(NO3)2.6H2O and urea. Pellets were sintered at 13500C for 5 hours and its sintered density is estimated to be of 95%. Sintered pellets were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) & X-ray photoelectron spectroscopy (XPS) techniques. From the XRD analysis, as grown powder of NiO/YSZ showed nano-crystalline behavior with homogeneous mixture of YSZ and NiO phases. However sintered powder showed µ-size dense grain growth. Temperature and frequency dependent dielectric properties are corroborated with the conduction mechanism. Both dielectric constant (K) and loss (tan δ) are increased sharply at high temperature region, which is expected to be the onset of dipolar relaxation phenomena due to the presence of oxygen vacancies. A mixed conductivity involving ionic conduction in the high temperature range and electronic conduction in the low temperature range was observed. The decrease in K and tan δ with increase in frequency at a given temperature suggests the dynamic interaction of oxygen vacancies & oxide ion pairs.
Octahedral rhenium K4[Re6S8(CN)6] and Cu(OH)2cluster modifiedTiO2for the phot...Pawan Kumar
tOctahedral hexacyano rhenium K4[Re6S8(CN)6] cluster complexes were grafted onto photoactive Cu(OH)2cluster modified TiO2{Cu(OH)2/TiO2} support. The rhenium and copper cluster modified TiO2photocata-lyst combines the advantages of heterogeneous catalyst (facile recovery, recycling ability of the catalyst)with the reactivity, selectivity of the soluble molecular catalyst. The synthesized heterogeneous cata-lyst was found to be highly efficient photoredox catalyst for the reduction of CO2under visible lightirradiation. Methanol was found to be the major liquid product with the formation of hydrogen as a byproduct as determined with GC-FID and GC-TCD, respectively. The methanol yield after 24 h irradiationwas found to be 149 mol/0.1 g cat. for Re-cluster@Cu(OH)2/TiO2photocatalyst that is much higher than35 mol/0.1 g cat. for Cu(OH)2/TiO2and 75 mol/0.1 g cat. for equimolar rhenium cluster in the presenceof triethanolamine (TEOA) as a sacrificial donor. The quantum yields (MeOH) of Re-cluster@Cu(OH)2/TiO2and Cu(OH)2/TiO2were found to be 0.018 and 0.004 mol einstein−1, respectively. These values are muchhigher than those reported for other heterogeneous catalysts for six electron transfer reaction
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Study of the Influence of Nickel Content and Reaction Temperature on Glycerol...IJRESJOURNAL
ABSTRACT: La2O3-SiO2-supported nickel catalysts were evaluated in glycerol steam reforming. The samples (30wt% La and 5, 10 and 15wt% of Ni on 70wt% commercial SiO2), prepared by the simultaneous impregnation method, were characterized by EDX, nitrogen physisorption, XRD, in-situ XRD, XANES and TPR. The analyses revealed NiO species weakly interact with the support and the different metallic surface areas of the catalysts. Catalytic tests were performed in a fixed bed reactor at 600oC and 15Ni catalyst, which showed the best performance, was also evaluated at 500oC and 700oC. According to the results, the Ni content on the catalyst surface interferes in the distribution of gaseous products H2, CO, CO2 and CH4. The increase in the Ni content increases the carbon formation during reaction. The reaction temperature affected the catalytic performance and the best results were obtained with the 15Ni catalyst at 600oC, which was also tested for 20 hours for the analysis of its stability.
IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE)
electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved
by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the
electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and
x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by
chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised
for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this
study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis
duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active
IrO2 electrocatalyst was not favoured.
Development of Ni-doped Yttria stabilized Zirconia composite for SOFC applica...IOSRJAP
Ni-doped Yttria stabilized Zirconia (NiO/YSZ) has been synthesized using low cost combustion process from an aqueous solution containing ZrO(NO3)2.6H2O, Y(NO3)3.6H2O, Ni(NO3)2.6H2O and urea. Pellets were sintered at 13500C for 5 hours and its sintered density is estimated to be of 95%. Sintered pellets were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) & X-ray photoelectron spectroscopy (XPS) techniques. From the XRD analysis, as grown powder of NiO/YSZ showed nano-crystalline behavior with homogeneous mixture of YSZ and NiO phases. However sintered powder showed µ-size dense grain growth. Temperature and frequency dependent dielectric properties are corroborated with the conduction mechanism. Both dielectric constant (K) and loss (tan δ) are increased sharply at high temperature region, which is expected to be the onset of dipolar relaxation phenomena due to the presence of oxygen vacancies. A mixed conductivity involving ionic conduction in the high temperature range and electronic conduction in the low temperature range was observed. The decrease in K and tan δ with increase in frequency at a given temperature suggests the dynamic interaction of oxygen vacancies & oxide ion pairs.
Synthesis and Characterization Studies of Solvothermally Synthesized Undoped ...IJERA Editor
Nanocrystalline TiO2 was investigated by solvothermal synthetic method using toluene as a solvent. Titanium tetra isopropoxide (TTIP) was used as a precursor, which was decomposed at high temperature and precipitated in toluene. Subsequently, the solution was thermally treated at 250C for five hours in stainless steel autoclave. Amorphous Nano TiO2 was formed. When these amorphous Nano TiO2 was calcinated to 550 C anatase Nano TiO2 crystalline with particle size <20 nm was formed. These amorphous and anatase phase Nano TiO2 was characterized by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and Photoluminescence (PL) studies and the results were discussed.
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
A Simple Thermal Treatment Synthesis and Characterization of Ni-Zn Ferrite (N...IOSR Journals
Cubic structured nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) have been synthesized by thermal treatment method. This simple procedure employed an aqueous solution containing only metal nitrates as precursors, polyvinyl pyrrolidone as a capping agent, and deionized water as a solvent. The solution was thoroughly stirred for 2 hour, dried at 353 K for 3 hour, the dried material crushed into powder and calcined the powder at 873 K to remove organic substances and crystallize the particles. The microstructure properties of the prepared ferrite nanoparticles were measured using FTIR, XRD, TEM, and EDX and the magnetic properties were determined using VSM and EPR. The average particle size increased from 7 to 22 nm with the increase of calcination temperature from 723 to 873 K. The saturation magnetization, coercivity field, and g-factor increased respectively from 24 emu/g, 11 G, and 2.0673at 723 K to 38 emu/g, 60 G, and 2.1227 at 873 K. This method offers simplicity, a low cost, and an environmentally friendly operation since it produces no by-product effluents.
Jennifer Schaus and Associates hosts a complimentary webinar series on The FAR in 2024. Join the webinars on Wednesdays and Fridays at noon, eastern.
Recordings are on YouTube and the company website.
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This session provides a comprehensive overview of the latest updates to the Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards (commonly known as the Uniform Guidance) outlined in the 2 CFR 200.
With a focus on the 2024 revisions issued by the Office of Management and Budget (OMB), participants will gain insight into the key changes affecting federal grant recipients. The session will delve into critical regulatory updates, providing attendees with the knowledge and tools necessary to navigate and comply with the evolving landscape of federal grant management.
Learning Objectives:
- Understand the rationale behind the 2024 updates to the Uniform Guidance outlined in 2 CFR 200, and their implications for federal grant recipients.
- Identify the key changes and revisions introduced by the Office of Management and Budget (OMB) in the 2024 edition of 2 CFR 200.
- Gain proficiency in applying the updated regulations to ensure compliance with federal grant requirements and avoid potential audit findings.
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Canadian Immigration Tracker March 2024 - Key SlidesAndrew Griffith
Highlights
Permanent Residents decrease along with percentage of TR2PR decline to 52 percent of all Permanent Residents.
March asylum claim data not issued as of May 27 (unusually late). Irregular arrivals remain very small.
Study permit applications experiencing sharp decrease as a result of announced caps over 50 percent compared to February.
Citizenship numbers remain stable.
Slide 3 has the overall numbers and change.
Jennifer Schaus and Associates hosts a complimentary webinar series on The FAR in 2024. Join the webinars on Wednesdays and Fridays at noon, eastern.
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Presentation by Jared Jageler, David Adler, Noelia Duchovny, and Evan Herrnstadt, analysts in CBO’s Microeconomic Studies and Health Analysis Divisions, at the Association of Environmental and Resource Economists Summer Conference.
What is the point of small housing associations.pptxPaul Smith
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ZGB - The Role of Generative AI in Government transformation.pdfSaeed Al Dhaheri
This keynote was presented during the the 7th edition of the UAE Hackathon 2024. It highlights the role of AI and Generative AI in addressing government transformation to achieve zero government bureaucracy
A process server is a authorized person for delivering legal documents, such as summons, complaints, subpoenas, and other court papers, to peoples involved in legal proceedings.
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Up the Ratios Bylaws - a Comprehensive Process of Our Organizationuptheratios
Up the Ratios is a non-profit organization dedicated to bridging the gap in STEM education for underprivileged students by providing free, high-quality learning opportunities in robotics and other STEM fields. Our mission is to empower the next generation of innovators, thinkers, and problem-solvers by offering a range of educational programs that foster curiosity, creativity, and critical thinking.
At Up the Ratios, we believe that every student, regardless of their socio-economic background, should have access to the tools and knowledge needed to succeed in today's technology-driven world. To achieve this, we host a variety of free classes, workshops, summer camps, and live lectures tailored to students from underserved communities. Our programs are designed to be engaging and hands-on, allowing students to explore the exciting world of robotics and STEM through practical, real-world applications.
Our free classes cover fundamental concepts in robotics, coding, and engineering, providing students with a strong foundation in these critical areas. Through our interactive workshops, students can dive deeper into specific topics, working on projects that challenge them to apply what they've learned and think creatively. Our summer camps offer an immersive experience where students can collaborate on larger projects, develop their teamwork skills, and gain confidence in their abilities.
In addition to our local programs, Up the Ratios is committed to making a global impact. We take donations of new and gently used robotics parts, which we then distribute to students and educational institutions in other countries. These donations help ensure that young learners worldwide have the resources they need to explore and excel in STEM fields. By supporting education in this way, we aim to nurture a global community of future leaders and innovators.
Our live lectures feature guest speakers from various STEM disciplines, including engineers, scientists, and industry professionals who share their knowledge and experiences with our students. These lectures provide valuable insights into potential career paths and inspire students to pursue their passions in STEM.
Up the Ratios relies on the generosity of donors and volunteers to continue our work. Contributions of time, expertise, and financial support are crucial to sustaining our programs and expanding our reach. Whether you're an individual passionate about education, a professional in the STEM field, or a company looking to give back to the community, there are many ways to get involved and make a difference.
We are proud of the positive impact we've had on the lives of countless students, many of whom have gone on to pursue higher education and careers in STEM. By providing these young minds with the tools and opportunities they need to succeed, we are not only changing their futures but also contributing to the advancement of technology and innovation on a broader scale.
PPT Item # 9 - 2024 Street Maintenance Program(SMP) Amendment
Nd feo
1. JOURNAL OF RARE EARTHS, Vol. 30, No. 11, Nov. 2012, P. 1138
Foundation item: Project supported by National Natural Science Foundation of China (50975002, 90289008), Graduate Innovation Fund of Anhui University of
Technology (2011011), and Research Project for University Personnel Returning from Overseas sponsored by the Ministry of Education of China
(90289008)
Corresponding author: CHU Xiangfeng (E-mail: xfchu99@ahut.edu.cn; Tel.: +86-555-2311551)
DOI: 10.1016/S1002-0721(12)60194-X
NdFeO3 as anode material for S/O2 solid oxide fuel cells
CHEN Tongyun (䰜ৠѥ)1
, SHEN Liming (≜߽䫁)1
, LIU Feng (߬ዄ)1
, ZHU Weichang (ᴅӳ䭓)2
,
ZHANG Qianfeng (ᓴगዄ)3
, CHU Xiangfeng (ټዄ)1
(1. School of Chemistry and Chemical Engineering; 2.School of Materials Science and Engineering; 3. Institute of Molecule Engineering and Applied Chemistry, Anhui
University of Technology, Maanshan 243002, China)
Received 11 April 2012; revised 4 September 2012
Abstract: Sulfur-oxygen solid oxide fuel cells (S/O2-SOFCs) can improve the utilization ratio of energy via converting the combustion heat
of sulfur into electrical energy directly, and sulfur trioxide which is an intermediate in sulfuric acid industry can be obtained directly via
S/O2-SOFCs. The anode material NdFeO3 was prepared via sol-gel method, the phase stability of NdFeO3 in sulfur vapor or sulfur dioxide
atmosphere was investigated. The single cell, consisting of NdFeO3-SDC/SDC/LSM-SDC structure, was fabricated by the screen-printing
method and tested by the home-built equipment with sulfur vapor or sulfur dioxide as the fuel. As indicated by X-ray diffraction (XRD)
analysis, NdFeO3 was stable in sulfur vapor or sulfur dioxide atmosphere at 800 ºC, the phase composition of the mixture of NdFeO3 and SDC
(Sm doped CeO2) did not change after the mixture was calcined at 800 ºC for 4 h. The transmission electron microscope (TEM) photograph
revealed that the average grain size of NdFeO3 powder was about 80 nm. With sulfur vapor or SO2 as the fuel, the maximum open circuit
voltages (OCVs) of the single cell were 409 mV at 620 ºC and 474 mV at 650 ºC, respectively; the maximum power densities of single cell
were 0.154 mW/cm2
at 620 ºC and 0.265 mW/cm2
at 650 ºC, respectively.
Keywords: NdFeO3; anode; sulfur; solid oxide fuel cell; rare earths
Sulfuric acid is an important chemical raw material, and
the annual output of sulfuric acid in China reached 70 mil-
lions tons in 2010[1]
. Sulfur is a main raw material for the
production of sulfuric acid, about 50% of the sulfuric acid
output in China was produced by using sulfur as the raw
material in 2010. The preparation process of sulfuric acid
using sulfur as the raw material is closely related to the fol-
lowing two reactions:
1/nSn+O2=SO2 (1)
SO2+1/2O2=SO3 (2)
The two reactions can be written as one reaction:
S+3/2O2=SO3 rGm
(298 K)=–609.3 kJ/mol (3)
At present, the heat energy given by the reaction (3) can-
not be utilized totally, because most of the combustion heat
of sulfur is lost in the form of heat. Nowadays, solid oxide
fuel cells (SOFCs) are attracting more and more attention
due to their merits, such as high efficiency (60%) compared
with the traditional gas turbine power plants (30%–40%) and
little pollution[2,3]
. Although SOFCs can operate with any
fuel in theory, the present SOFCs operate with pure hydro-
gen as fuel. However, hydrogen is obtained by steam re-
forming of methane[4,5]
and water electrolysis. Compared
with the hydrogen price[6]
, the price of sulfur[7]
is cheap. If
S/O2-SOFC is developed, it can convert sulfur into sulfur
trioxide directly and transform the combustion heat of sulfur
into electricity energy. If 1 t of sulfur is used as the fuel,
about 53000 kWh of electricity energy can be generated by
S/O2-SOFC in theory and the resultant sulfur trioxide can be
used for producing sulfuric acid.
The structure of S/O2-SOFC is anode/SDC/LSM-SDC.
The main difference between the S/O2-SOFC and the other
kinds of SOFCs is the anode materials. Cowin et al.[8]
re-
ported that it is necessary for anode materials to have good
performance in fuel at working temperature, such as good
stability, catalytic activity for fuel oxidation, high ion
conductivity, good electronic conductivity, chemical stabil-
ity to contacting components and matched thermal expan-
sion coefficient (TEC) to contacting components. Al-
though the SOFCs have been developed for a long time, as
far as we known, the SOFCs using sulfur as the fuel and
its anode materials with good performance are rarely re-
ported. Zhu et al.[9,10]
studied preliminarily the perform-
ance of sulfur/oxygen SOFC using Ca or Mg doped La-
CrO3 as the anode material. Joseph et al.[11]
reported that
Fe-substituted LaCrO3 could be used as the anode material
for methane SOFC. Marti et al.[12]
reported that AMnO3+x
and AFeO3+x (A=La, Pr, Nd and Cd) perovskite-type ox-
ides have catalytic activity for methane combustion and
AFeO3+x perovskite are more stable than the manganites
thermally. In our present work, the performance of
2. CHEN Tongyun et al., NdFeO3 as anode material for S/O2 solid oxide fuel cells 1139
S/O2-SOFCs using NdFeO3 as anode catalyst was studied
preliminarily.
1 Experimental
1.1 Preparation of anode NdFeO3 powder and electrolyte
Ce0.8Sm0.2O1.9 (SDC) ceramic
The NdFeO3 powder was prepared via sol-gel method ac-
cording to the literatures[13,14]
. Stoichiometric Fe(NO3)3·9H2O
and Nd2O3 were weighed and dissolved in nitric acid solu-
tion. Citric acid (nnitric acid:nmetal ion=1:1) was added under stir-
ring. Ammonium hydroxide was used to adjust the pH to 7.
The resulting solution was heated slowly to evaporate water
until the viscous gel formed; the gel was then milled and
heated at 700 ºC for 2 h.
The SDC powder was prepared via co-precipitation method[15]
.
The powder was dry-pressed at 200 MPa into a cylinder of
25 mm diameter to form 1 mm thick SDC pellets, and sin-
tered at 1200 ºC for 6 h with a heating rate of 3 ºC/min[15]
.
The density of the sintered SDC pellet was measured by the
Archimedes method.
1.2 Characterization of anode material
The difference thermal analysis (DTA) and thermal ther-
mogravimetry (TG) of as-prepared gel were conducted in air
at a heating rate of 5 ºC/min. The NdFeO3 powder was char-
acterized by an X-ray diffractometer (XRD) (D/max-rA, Ri-
gaku) with Cu K radiation in the range of 20º–80º. The
chemical stability between NdFeO3 and SDC was tested by
calcining the mixture of NdFeO3 and SDC at 800 ºC for 4 h
and analyzing the phase composition of the mixture. The
microstructure of NdFeO3 powder was observed with a
transmission electron microscope (TEM) (JEM-100CX II).
The NdFeO3 powder was exposed to sulfur vapor or SO2 at
800 ºC for 2 h to study the stability of NdFeO3 anode mate-
rial in sulfur vapor or SO2.
1.3 Fabrication and testing of single cell
The electrode slurries were prepared according to the fol-
lowing procedure: the mixture of SDC powder, electrode
material and absolute ethanol was ball-milled for 3 h until
ethanol volatized. The electrode slurries was continually
ground for 2 h after ethyl cellulose terpineol solution (w=6%)
was added. The anode and cathode slurries were printed on
both sides of SDC electrolyte, respectively. Then the cells
were calcined at 1200 ºC for 2 h. The cathode area (1 cm–2
)
was used to calculate power density. The composition of the
electrode slurries is listed in Table 1.
The home-built equipment for testing the performances of
single cell is shown in Fig. 1. The temperature of tube fur-
nace I must be higher than the boiling point of sulfur (444 ºC)
if sulfur is used as fuel. N2 is the carrier gas of sulfur vapor.
SO2 gas could be introduced into the cell directly at a flow
rate of 100 ml/min. The temperature of tube furnace II is the
working temperature of cells.
Table 1 Composition of electrode slurries
Slurry component Anode slurry Cathode slurry
SDC 1 g 1 g
NdFeO3 1 g –
La0.8Sr0.2MnO3 (LSM) – 1 g
6% ethyl cellulose+94% terpineol 3 g 3 g
Ethanol 20 ml 20 ml
Fig. 1 Home-built equipment of single cell
2 Results and discussion
2.1 Thermoanalysis of dry gel
Fig. 2 presents the TG curve and DTA curve of the gel.
The mass loss occurring between 90 and 132ºC results from
the release of adsorbed water and hydrated water, and two
endothermic peaks appear in DTA curve at 90 and 132 ºC. A
sharp exothermic peak exists between 132 and 163 ºC,
which is due to the decomposition of citric acid
(C6H8O7H2O+ CO2). As shown in Fig. 2, the mass of the
sample decreases sharply between 132 and 163 ºC. A small
exothermic peak at 320 ºC is attributed to the decomposition
of nitrate[16]
. A tiny mass loss occurring between 640 and
660 ºC is due to the phase-crystallization step. No more mass
loss was observed in the temperature range from 660 to 700 ºC
corresponding to crystallization of NdFeO3.
2.2 Phase stability and microstructure of anode powder
The XRD patterns of the samples are shown in Fig. 3. The
XRD pattern of NdFeO3 before exposure to sulfur vapor or
SO2 (shown in Fig. 3 (1)) suggests that NdFeO3 was well
Fig. 2 TG and DTA curves for the gel
3. 1140 JOURNAL OF RARE EARTHS, Vol. 30, No. 11, Nov. 2012
Fig. 3 XRD patterns of NdFeO3 before exposure to S(g) or SO2 (1),
after exposure to S(g) at 800 ºC for 2 h (2) and after exposure
to SO2 at 800 ºC for 2 h (3)
crystallized. The chemical stability to fuel is of great impor-
tance for SOFC anode materials[17]
. Fig. 3 (2) and (3) show
the patterns of NdFeO3 powder after exposure to sulfur va-
por or SO2 at 800 ºC for 2 h, respectively. Compared with
the XRD pattern in Fig. 3 (1), there are no additional diffrac-
tion peaks besides the peaks of sulfur (shown in Fig. 3 (2)).
It indicates that the stability of NdFeO3 powder in sulfur va-
por or SO2 at 800 ºC is good. As shown in Fig. 4, the XRD
pattern of the mixture of NdFeO3 and SDC have hardly
changed after calcining at 800 ºC for 4 h. It reveals that there
is no chemical reaction between NdFeO3 and SDC at 800 ºC.
It can be observed from the TEM photographs of NdFeO3
powder (shown in Fig. 5) that the average grain size of
NdFeO3 powder is about 80 nm. The aggregation of grains
may be attributed to the high temperature of calcining[18]
.
2.3 Performance of a single cell
Fig. 6 shows the temperature dependence of the OCVs for
a single cell with sulfur vapor or SO2 as fuel. It is clear that
the OCVs increase with the increase of temperature and
reach the maximum value of 409 mV at 620 ºC and 474 mV
at 650 ºC using sulfur vapor or SO2 as fuel, respectively. The
OCVs decrease when the working temperature is higher than
the optimum temperature. When the operating temperature is
low, the OCVs are low because of low mobility of oxygen
ion in SDC electrolyte and low vapor pressure of sulfur va-
Fig. 4 XRD patterns of the mixture of NdFeO3 and SDC before cal-
cining (1) and after calcining at 800 ºC for 4 h (2)
Fig. 5 TEM micrographs of NdFeO3 powder
Fig. 6 Temperature dependence of the OCVs for single cells
por (sulfur as fuel)[19,20]
. The fall of OCVs at high tempera-
ture (higher than 650 ºC) may result from the following two
reasons: (1) Instability of Ag current collector in sulfur vapor
or SO2; (2) Theoretical reversible potential
˄E(t)˅
of the cell is
not determined by Nernst equation, but by entropy change
(E(t)=Eo+S*(T–To)). Hence, current collectors with good
stability for S/O2 SOFC are being studied in our group.
The performance of the single cell using sulfur vapor or
SO2 as fuel is shown in Fig. 7. The maximum power densi-
ties of the single cell using sulfur vapor or SO2 are 0.154
mW/cm2
at 620 ºC and 0.265 mW/cm2
at 650 ºC, respec-
tively. The low power density, which impedes application of
S/O2 or SO2/O2-SOFC, could be attributed to high ohm re-
sistance of electrolyte, low electrical conductivity (most of
electric energy is lost on the internal resistance of cell) and
non-porous microstructure of NdFeO3 (the sulfur vapor or
SO2 molecule is hard to diffuse into non-porous anode mate-
4. CHEN Tongyun et al., NdFeO3 as anode material for S/O2 solid oxide fuel cells 1141
Fig. 7 Cell performance of a single cell (NdFeO3-SDC/SDC/LSM-
SDC)
rial)[8]
. However, if anode material NdFeO3 is doped with
some other elements in A-site or B-site, porous anode material
is prepared and anode-supported single cell using doped-
NdFeO3 as anode is assembled, the performance of cell could
be improved[21]
. Hence, NdFeO3 will be a promising candidate
for S/O2-SOFC and SO2/O2-SOFC anode and further investi-
gation on this subject is now being done by our group.
3 Conclusions
NdFeO3 powder was prepared via sol-gel method at 700 ºC
for 2 h. A drastic decomposition reaction of citric acid
around 160ºC could be seen from the TG/DTA curves. The
pure phase was formed at the temperature of 660 ºC. The
average grain size of NdFeO3 powder was about 80 nm. The
NdFeO3 anode material exhibited good stability in sulfur va-
por or SO2 at 800 ºC. There was no chemical interaction be-
tween NdFeO3 and SDC at 800 ºC. With sulfur vapor or SO2
as fuel, the maximum open circuit voltages of single cell were
409 mV at 620 ºC and 474 mV at 650 ºC, respectively; the
maximum power densities of single cell were 0.154 mW/cm2
at 620 ºC and 0.265 mW/cm2
at 650 ºC, respectively. Al-
though the power densities were not ideal, further studies are
in progress, and the power density of the single cell can be
further improved. NdFeO3 is a possible candidate for S/O2 and
SO2/O2-SOFCs anode.
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