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  • Today,I am talking about sofc that operate directly on hydrocarbons.I will discuss performace studies
  • Check voltage
  • H2 is good fuel for sofcHowever. It features several disadvantages such as production, storage and transportation. Direct electro-oxidation of hydrocarbon, anode should have
  • Although Ni-YSZ anodes have high catalytic activity
  • The specific objectives wereFabrication of defect free solid oxide fuel cells were one of the time consuming process during the research work. Further we preapared
  • please check about the poreformer (ps graphite nature why selected, ethano, dispersant, binders)SOFC WERE PREPARED BY TAPE CASTING METHOD.THIS CHART SHOWS THE PREPARATION PROCEDURE OF ANODE AND ELECTROLYTE SLURRY WHICH WERE USED FOR TAPE CASTINGIn the first stage, YSZ POWDER were mixed with binder and dispersant. Then they were magnetic stirred for 24 h. In second stage, binders were added and mixed for 24 h. The electrolyte slurry was first casted on the glass plate using doctor blade according to required thickness.After drying the tape, the anode layer were then casted on top of electrolyte Disk of required size and shape are then cut out from this bilayer and cosindered at 1450 ºC.Fabrication issues such as pinholes, delamination were observed in earlier stage of work. To avoid that, the additive composition A and tand it waThere were fabrication issuesf like pin holes, cracking, delamination etc . To avoid these, solvent, binder, poreformer to solid ratio was optimized we optimize the composition of solid, pore formers and binders. The optimized composition is given in this figure. Lot of Efforts have been made for facbrocation of cofc.
  • LSM WAS USED AS THE CATHODE CATALYST for oxygen reduction reactions and is good electronic conductOR.Give refrence. Discuss phase of LSM RHOMBOHYDREL PEROVSKITE STRUCTUREALL the time, cathode prepared by similar methodTake XRD, SEM AND HRTEM OF CATHODE FOR THESIS.
  • This slide showing the experimental setup and procedureThis is systematic represntation of cell testing unitQuartz tube was used for cell testing. This is inner and outer tube for inlet and outlet gases.Here SOFC was mounted on alumina tube and it was sealed with ceramic pasteFuel was supplied from anode side and cathode was exposed to air.Two silver wires were connected to anode and cathode sides and connected with autolab to measure of Current –voltage charcteristics and eis.whole setup was kept inside split furnace and heated at 800 ºC for 4h .After steady value of open circuit voltage (OCV) was obtained, i-V characteristics were recorded in H2, CH4 or n-C4H10 fuels using potentiostat-galvanostat (PGSTAT 30, Autolab) by applying normal linear sweep voltammetry
  • Cu-Fe/CeO2-YSZ anodes were prepared for three molar ratios of Cu-Fe [1:0, 3:1 and 1:1]. XRD were taken after reduction at 800 C in H2 for 2h[1:0] means 100% Cu and no Fe. It will be represented by Cu/CeO2-YSZ anodes. 3:1 and 1:1 means 75% Cu and …….will be represented by in my next slides
  • SEM OF Cu-Fe/CeO2-YSZ anodes reduced at 800 °C in H2. 10 WT% CeO2, 20 WT% Cu-Fe for three molar ratios were incorporated in porous YSZ and ANODES WERE reduced in H2 at 800C FOR 2H.This is for…..It was observed that
  • Performance of ………………were evaluated with YSZ electrolye and LSM /YSZ cathode.SEM of SOFC shows anode, electrolyte and cathode thickness is 90, 80 and 40 µm.Power density of ~ 78, 110 and 160 mW/cm-2 was observed for Cu-Fe/CeO2-YSZ anodes for Cu-Fe molar ratio of 1:0, 3:1 and 1:1. It can be concluded that performance increase with increase in Fe loading in Cu/CeO2-YSZ anodes
  • EIS was measured during cell operation in H2 near OCV conditions. The ohmic as well as polarization resistance was less in comparison to Cu-Ceria-YSZ anodes. We have calculated electrolyte resistance for 80 µm thick electrolyte which was ~0.38 Ω. cm2.Less additional ohmic resistance was observed for Cu-Fe [1:1] due to better dispersion between catalyst particles resulting better electronic conduction.EIS was measuredNumber of oxygen vacancies increases with more ceria substitution by fe3+ cations
  • Cu-Fe/CeO2-YSZ anodes were further characterized after exposure of methane fuel. Optical microscopy images showed no visible cell disintegration. No weight gain was observed.TGA of same was carried out which shows no significant weight loss due to oxidation of carbon to CO2.
  • Performance of Cu-Fe/CeO2-YSZ anodes were further investigated in methane.Cu-Fe/CeO2-YSZ anodes showed higher performance in comparison to Cu/CeO2-YSZ anodes.Performance of all the anodes are lower in CH4 than H2 might be due to less reactive nature of CH4 in comparison to H2.
  • The performance of Cu-Fe/CeO2-YSZ anodes were tested in CH4 for 46 h The degradation of 125 to 100 mW/cm2 was observed. Impedance spectra showed that increase in ohmic and polarization resistance of cell might be responsible for power loss.
  • AGGOLOMERATIONAFTER CELL OPERATION, Cu-Fe/CeO2-YSZ anodes were characterized by SEM and TGASEM shows the particle size increases from 1 to 1.5 µm. Some agglomeration was aslo observed.TGA SHOWS no significant weight loss

Transcript

  • 1. Performance Studies of Copper-Iron/CeriaYttria Stabilized Zirconia Anode for Electrooxidation of Hydrogen and Methane Fuels in Solid Oxide Fuel Cells Presented by Gurpreet Kaur Department of Chemical Engineering Indian Institute of Technology Delhi International Conference on December 10-11, 2013 Advances in Energy Research Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India
  • 2. Solid Oxide Fuel Cell Solid oxide fuel cell is a device that converts gaseous fuels (hydrogen, natural gas) via an electro-chemical process directly into electricity. Principle of SOFC Salient Features of SOFC  SOFCs are over 60 % efficient (conversion of fuel to electricity) Operating Temperature: 700-1000 C  Provides environment friendly power generation Conventional SOFC Components Anode Side Reactions Cathode Side Reactions 2 H 2 2O 2 CH 4 4O 2 C4 H10 13O 2 2 H 2 O 4e O2 4e 2O 2 CO2 2 H 2 O 8e O2 8e 4O 2 O2 26e 4CO2 5H 2O 26e 13O 2 Electrolyte – 8 % Yttria Stabilized Zirconia (YSZ) – a pure ionic conductor Anode – Ni provides electronic conductivity and enables electrochemical oxidation of fuel. Cathode - La0.8Sr0.2MnO3 (LSM) provides electronic conductivity and enables electrochemical reduction of O2. Applications Stationary electrical power generation Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 1
  • 3. Why Direct Hydrocarbons ? Production of hydrogen by steam reforming reactions of natural gas and higher hydrocarbons requires additional purification steps to satisfy fuel cell demands Direct hydrocarbon solid oxide fuel cell can operate in hydrocarbon fuels without the need for pre-reforming. Anode requirements for oxidation of hydrocarbons     High electro catalytic activity for oxidation of fuel Good electronic conductivity for transport of electrons from the TPB Good ionic conductivity for transport of oxide ions to the TPB Sufficient porosity for diffusion of fuel gases and exhaust gases to and from the TPB Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 2
  • 4. Literature Review nodes for Direct Hydrocarbon Solid Oxide Fuel C Nickel/Yttria-stabilized Zirconia based Anodes1 High catalytic activity for fuel oxidation and for steam reforming of methane Relatively inexpensive; chemically and physically compatible with YSZ electrolyte Problems in use with dry hydrocarbons; Tends to promote carbon deposition1 Copper/Ceria/Yttria Stabilized Zirconia2Alternative anode material for direct hydrocarbons CeO2 : Mixed ionic and electronic conductor in reducing medium. Good oxidation catalyst for hydrocarbons Poorer electronic conductor Cu: To increase the electronic conductivity, addition of Cu is necessary Cu/CeO2-YSZ anodes are stable in variety of hydrocarbons Limited by lower Van Dillen and (~ 100 mW/cm Today 2000; 76, 1. M .L.Toebes, J.H. Bitter, A.J.performanceK.P.de Jong, Catal. 2 at 800 C). 33 – 42 . 2. R. J. Gorte, S. Park, J. M. Vohs, C. Wang, Adv Mater. 2000; 12: 1465 -69 Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 3
  • 5. Objective of Research Work  Fabrication of complete solid oxide fuel cell in laboratory scale using tape casting technique of thickness of < 600 µm and anode porosity of 70 %. Additives composition is optimized to get defect free SOFC  Preparation of Cu/CeO2-YSZ and Cu-Fe/CeO2-YSZ anodes using wet impregnation method.  Characterization of prepared anodes using thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental dispersive X-ray (EDX) to investigate the thermal, structural, morphological properties and elemental analysis  Current-Voltage characterization of prepared anodes with YSZ electrolyte and LSM-YSZ cathodes in H2 and methane fuels.  Frequency response analysis of SOFC with prepared anodes to study various resistances e.g. ohmic resistance, polarization resistance.  Study the effect of temperature, bimetallic molar ratio and addition of precious metals on the performance of SOFC in H2 and methane fuels.  Investigation of carbon deposition using optical microscopy and thermal gravimetric analysis.  Longevity testing in methane fuel. Gurpreet Kaur and Suddhasatwa Basu, Journal of Power Sources, 241, 783-790, 2013 Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 4
  • 6. Preparation Procedure for Anode and Electrolyte Slurry for Tape Casting Solvent (Ethanol and MEK) + Dispersant (oleic acid) Stirring Magnetic Stirring, 24 h Yttria-Stabilized Zirconia Pore-formers i.e. Graphite and Polystyrene) for anode only SOFC Fabrication Binder (Polyethylene Glycol and Polyvinyl butryl) Stirring Homogeneous Slurry Magnetic Stirring, 24 h Composition of anode and electrolyte for tape casting slurry Homogeneous Slurry Component Electrolyte Tape Casting and Drying for 24 h Porous YSZ Anode Tape Casting and Drying for 24 h Co-sintering, 1450 C YSZ Graphite Polystyrene Ethanol (EtOH) Methylethyl ketone (MEK) Oleic acid Polyvinyl butyral (PVB) Polyethylene glycol (PEG) Quantity 24 gm 5 gm 3.8 gm Tape casted electrolyte layer Porous YSZ layer on dense YSZ electrolyte 16 ml 9 ml 1.0 ml 3.8 gm 3 ml No poreformers (graphite and polystrene) SEM of porous and dense added in electrolyte slurry Fabrication issues YSZ sintered at 1450 ºC Green tape – Pin holes Department of Chemical Engineering Sintered layers – cracking, delamination etc Indian Institute of Technology-Delhi, New Delhi 110 016, India SEM of porous YSZ Porosity 70 vol % 5
  • 7. Preparation Procedure of Anode for SOFC (Wet Impregnation Method) Porous YSZ Impregnation of 1M Ce(NO3)3, 6H2O Calcinations at 400 ºC for 2 h TGA of impregnated nitrate solution in porous YSZ Repeated impregnation to get desired loading Impregnation of 1M Cu(NO3), 3H2O and Fe(NO3)3, 9H2O solution Cu-Fe [1:1] Calcinations at 400 ºC for 2 h Anode Cu/CeO2-YSZ and CuFe/CeO2-YSZ  Data was collected from room temperature to 1000 ̊C at a rate of 10 ̊C/min. Zero air flow rate: 50 ml/min  Calcination temperature of 400 ºC is selected to get metal oxides Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 6
  • 8. Synthesis Procedure of Cathode (La0.8Sr0.2MnO3) La0.8Sr0.2MnO3 showed good chemical and thermal compatibility with YSZ electrolyte material 2500 2000 XRD spectra of La0.8Sr0.2MnO3 Calcination 1100 oC for 2 h Intensity (cps) Dissolve La(NO3)3, Sr(NO3)2, Mn(NO3)2 in stoichiometric ratio 1000 500  All peaks corresponds to perovskite phase  Particles size of LSM ~0.3 µm Mixing (Agate mortar) La0.8Sr0.2MnO3– 0.45 g YSZ – 0.45 g Graphite– 0.1 g 1500 0 20 30 40 50 60 70 80 2θ( ) SEM of La0.8Sr0.2MnO3 Slurry preparation Mixed powders with glycerol * R.J. Bell, G.J. Millar, J. Drennan, Solid State Ionics 2000; 131: 211–220. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 7
  • 9. Experimental set up and Procedure High Temperature SOFC Furnace Electrolyte YSZ Cathode LSM:YSZ PGSTAT 30, Autolab (i-V and impedance measurements) Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 8
  • 10. X-ray Diffraction of Cu-Fe/CeO2-YSZ Anodes ¤ • *,o • ɵ (c) ¤ɵ + (•) YSZ (*) Fe2O3 (o) CuFe2O4 (+) CuO (¤) Cu (ɵ) Fe + (b) 8000 • 6000 • * Intensity (a.u) • ( ) YSZ ( ) Cu ( ) Fe (*) CeO2 (ο) Fe3O4 (¤) Fe2O3 * (d) * * 4000 (c) ο 2000 ¤ ¤ ο ¤ ¤ (b) (a) (a) 0 25 35 45 55 65 75 2 Theta (Degree) XRD patterns of (a) YSZ, (b) Cu-Fe/YSZ calcined at 300 C (c) Cu-Fe/YSZ reduced at 800 C XRD patterns of (a) YSZ, (b) Fe/CeO2-YSZ, (c) Cu/CeO2YSZ and (d) Cu-Fe/CeO2-YSZ after reduction in H2 at 800 C  Cu-Fe/CeO2-YSZ anodes were prepared for three molar ratios of Cu-Fe [1:0, 3:1 and 1:1].  Peaks at 43.3º and 44.2 corresponds to Cu and Fe and in metals are present cubic structure.  Small shift in the peaks for Cu and Fe was observed in the spectra, according to phase diagram1, some Fe can be incorporated in Cu phase at 800 C. 1. Turchanin MA, Agraval PG, Nikolaenko IV, J Phase Equilibria 2003;24:307-19. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 9
  • 11. Scanning electron microscopy of Cu-Fe/CeO2-YSZ anodes after reduction in H2 at 800ºC 20 wt% Cu-Fe [3:1] 20 wt% Cu-Fe [3:1] 10 wt% CeO2, 20 wt% Cu-Fe [1:0, 3:1 and 1:1]  Addition of Fe in Cu based anodes improves the catalyst dispersion  Better interconnection between particles helps to improve the electrical conduction and provides more surface area for fuel oxidation reaction  Particle size was observed to be 1 µm 20 wt% Cu-Fe [1:1] Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 10
  • 12. Elemental dispersive analysis of Cu/CeO2-YSZ and Cu-Fe/CeO2YSZ anodes Presence of metals inside the pores with no significant impurity observed. Results indicate the success of fabrication of anodes by wet impregnation method. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 11
  • 13. Performance of SOFC in H2 at 800°C (Cu-Fe/CeO2/YSZ anodes for Cu-Fe molar ratio of 1:0, 3:1 and 1:1, YSZ as electrolyte, LSM/YSZ as cathode i-V (filled symbols) and power curves (open symbols) for different molar ratio of Cu-Fe SEM of SOFC Performance Curves 400 350 1 Voltage (V) 300 ~90 µm 80 µm 0.8 250 0.6 200 150 0.4 100 0.2 40 µm 50 0 Power Density (mW/cm2) 1.2 0 0 200 400 Current Density 600 800 (mA/cm2)  SEM of SOFC shows anode, electrolyte and cathode thickness of 90, 80 and 40 µm.  Power density of ~ 190, 260 and 330 mW/cm-2 was observed for Cu-Fe/CeO2-YSZ anodes for Cu-Fe molar ratio of 1:0, 3:1 and 1:1.  Performance increased with increase in Fe loading in Cu/CeO2-YSZ anodes Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 12
  • 14. XRD of Cu-Fe/CeO2-YSZ anode after reduction in H2 EIS of SOFC for different molar ratio of Cu-Fe of 1:0(∆), 3:1 (◊) and 1:1 (□) 0.3 -Zim (ohm cm2 ) -Zim (ohm cm2) 0.3 0.2 0.2 0.1 0 7 7.5 8 8.5 9 9.5 10 Zre (ohm cm2 ) 0.1 RΩ 0 0 0.3 0.6 Rp Zre 0.9 1.2 (ohm cm2) 1.5 1.8 Lattice parameter CeO2 calculated from XRD: 5.36Å Pure CeO2 lattice parameter- 5.41 Å  Calculated electrolyte resistance for 80 µm thick electrolyte is ~0.38 Ω. cm2.  Less additional ohmic resistance was observed for Cu-Fe [1:1] due to better dispersion between catalyst particles resulting better electronic conduction.  Total polarization resistance decreases with increase in Fe molar ratio suggest that prepared anodes have better electro-catalytic activity towards oxidation of H2.  Improvement in the performance of cell might also be due to incorporation of Cu and Fe ions in CeO 2 lattice Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 13
  • 15. Characterization of Cu-Fe/CeO2-YSZ anodes after exposure to CH4 at 800 C Optical microscopy images of Cu-Fe/CeO2-YSZ anodes for Cu-Fe molar ratio of (a) 1:0, (b) 3:1 (c) 1:1 after exposure to CH4 for 1h (a) Table - Weight changes after CH4 flow Metal wt% in Weight porous CeO2/YSZ change (%) Cu: Fe [1:0]- (20wt%) TGA of Cu-Fe/CeO2-YSZ anode after reduction in (a) H2 and (b) H2 followed by exposure of CH4 for 1 h -0.027 Cu: Fe [1:1]- (20wt%) (c) -0.030 Cu: Fe [3:1]- (20wt%) (b) -0.021  No significant weight gain was observed due to carbon deposition after CH4 flow Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 14
  • 16. Performance of Cu-Fe/CeO2-YSZ anodes in CH4 at 800 ºC 150 Cu-Fe [1:1] Voltage (V) 1 Cu-Fe [3:1] Cu-Fe [1:0] 0.8 100 0.6 0.4 50 0.2 0 Power Density (mW/cm2) 1.2 0 0 50 100 150 200 250 300 350 Current Density (mA/cm2)  Cu-Fe/CeO2/YSZ anodes for Cu-Fe molar ratio of 1:1 showed higher performance than 1:0 and 3:1.  Performance of all the anodes are lower in CH4 than H2 might be due to less reactive nature of CH4 in comparison to H2.  OCV was observed to be less than Nernst potential (> 1.05 V ) suggesting that complete oxidation of CH4 is not taking place.  Oxidation of hydrocarbon on surface may occur in multiple steps and equilibrium has been established between hydrocarbons and partial oxidation products. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 15
  • 17. Effect of addition of 1 wt% Pd on the performance of Cu-Fe/CeO2-YSZ anodes in H2 and CH4 Performance curves of Cu-Fe/CeO2-YSZ anodes with (□) and without (○) 1 wt% Pd 200 0.8 150 H2 0.6 100 0.4 50 0.2 Cu-Fe [1:1] 0 100 200 300 400 500 120 100 0.8 80 CH4 0.6 60 0.4 40 0.2 20 Cu-Fe [1:1] 0 0 140 1 Voltage (V) Voltage (V) 1 1.2 600 0 Power Density (mW/cm2) 250 Power Density (mW/cm2) 1.2 0 0 Current Density (mA/cm2) 100 200 300 400 Current Density (mA/cm2)  Significant improvement in the cell performance in CH4 was observed with addition of 1 wt% of Pd  Results suggest that resistance associated with surface reactions decreases with addition of 1 wt% Pd. Anode 160 µm, Electrolyte 100 µm Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 16
  • 18. Long term performance of Cu-Fe/CeO2/YSZ anodes in CH4 0.4 Cu-Fe [1:1] 150 100 0.5V 50 -Zim (ohm cm2) 0.2 -Zim (ohm cm2) Power Density (mW/cm2) 200 0.3 0.2 0.15 22 h 1h 0.1 30 h 0.05 46 h 0 0.3 0.4 0.5 0.6 Zre (ohm cm2) 0.1 CH4, 800 C 0 0 10 20 30 Time (h) 40 50 0 0 0.5 1 1.5 2 Zre (ohm cm2)  Power density decreased from 125 mW/cm2 to 100 mW/cm2 during 46 h testing  Increase in ohmic resistance may be due to increase in particle size of catalyst particles at 800 C during stability test. (repeated thrice).  Increase in ohmic resistance and polarization resistance might be responsible for this loss.  Cu-Fe/CeO2/YSZ anode showed much better stability than Ni/YSZ anodes in which complete performance degradation takes place within 5 h. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 17
  • 19. SEM and TGA of Cu-Fe/CeO2-YSZ anodes after cell testing in CH4 for 46 h  SEM shows catalyst particle size increased from 1.0 to 1.5 µm after cell operation at 800 °C for 46 h TGA shows no significant weight loss suggesting that carbon ,if present, is not in significant quantity. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 18
  • 20. Summary SOFC Fabrication and Electrochemical Characterization  Solid oxide fuel cells was fabricated by tape casting and wet impregnation method.  Additives (pore-formers, binder and solvent) composition was optimized to get defect free button cells. SOFC testing (i-V and EIS) was carried out for Cu/CeO2-YSZ and Cu-Fe/CeO2-YSZ anodes with YSZ as electrolyte and LSM/YSZ as cathode. Performance of Cu-Fe/CeO2-YSZ Anodes in H2 and Methane  XRD shows the formation of Cu and Fe phase. Addition of Cu to Fe enhances the reduction of Fe.  SEM shows that better dispersion between catalyst particles achieved with addition of Fe in Cu/CeO2-YSZ anodes  Addition of Fe in Cu/CeO2-YSZ anodes showed improved performance in H2 and CH4 fuels.  Electrochemical impedance spectra showed less ohmic as well as charge transfer resistance for CuFe/CeO2-YSZ anodes in comparison to Cu/CeO2-YSZ anodes.  SOFC performance increased with addition of 1 wt % Pd in Cu-Fe/CeO2-YSZ anodes.  No significant degradation in the performance observed during cell operation in CH4 suggesting that anodes are stable in comparison to conventional Ni/YSZ anodes. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 19
  • 21. References [1] Lashtabeg, A. and Skinner, S. J. (2006) Solid oxide fuel cells-a challenge for materials chemists, Journal of materials chemistry, 16, pp. 3161-70. [2] Baker, R. T. K. (1989) Catalytic growth of carbon filaments, Carbon, 27, pp.1315-23. [3] Gorte, R. J., Vohs, J. M. (2003) Novel SOFC anodes for direct electrochemical oxidation of hydrocarbons, Journal of catalysis, 216, pp. 477-86. [4] Gorte, R. J., Park, S., Vohs, J. M. and Wang, C. (2000) Anodes for direct oxidation of dry hydrocarbons in solid oxide fuel cells, Advanced Material, 12, pp.1465-69. [5] Zhu, H., Wang, W., Ran, R., Su, C., Shi, H. and Shao, Z. (2012) Iron incorporated Ni-ZrO2 catalysts for electric power generation from methane, International Journal of Hydrogen Energy, 37, pp. 9801-9808. [6] Gordes, P., Christiansen, N., Jensen, E. J. and Villadsen, J. (1995) Synthesis of perovskite-type compounds by drip Pyrolysis, Journal of Material Science, 30, pp.1053-58. [7] Mitterdorfer, A. and Gauckler, L.G. (1998) La2Zr2O7 formation and oxygen reduction kinetics of La0.85Sr0.15MnYO3,O2(g) YSZ system, Solid State Ionics, 111, pp. 185-218. [8] Turchanin, M. A., Agraval, P. G. and Nikolaenko I. V. (2003) Thermodynamics of alloys and phase equilibria in the copper iron system, Journal of Phase Equilibria, 24, pp. 307-309. [9] Kameoka, S., Tanabe, T. and Tsai, A. P. (2005) Spinel CuFe2O4: a precursor for copper catalyst with high thermal stability and activity, Catalysis Letters, 100, pp. 89-93. [10] Lv, H., Tu, H., Zhao, B., Wu, Y. and Hu, K. (2007) Synthesis and electrochemical behavior of Ce1-xFex02-δ as a possible SOFC anode materials, Solid State Ionics, 177, pp. 3467-3472. [11] Xing, Z., Hua, W., Honggang, W., Kongzhai, L. and Xianming C. (2010) Hydrogen and syngas production from two-step steam reforming of methane over CeO2-Fe2O3 oxygen carrier, Journal of Rare Earth, 28, pp. 907-913. [12] Buccheri, M. A., Singh, A. and Hill, J. M. (2011) Anode- versus electrolyte-supported Ni-YSZ/YSZ/Pt SOFCs: Effect of cell design on OCV, performance and carbon formation for the direct utilization of dry methane, Journal of Power Sources, 196, pp. 968-976 Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India 20
  • 22. Thank You Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India
  • 23. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India
  • 24. Nernst Potential calculation for multiple reactions E 1.15 G / nF 1.1 CH 4 OCV (V) 1.05 2O2 CO2  CH 4 3 / 2O2 1 C O2 CO 1/ 2O2 0.9 CO 2 H 2 O CO2 C 1/ 2O2 0.95 2 H 2O  CH 4 O2 CO CO2 C 2 H 2O Experimental 0.85 850 900 950 1000 1050 1100 Temperature ( K) An observed OCV is less than Nernst potential suggesting that complete oxidation of methane is not taking place. Multiple anode reactions may occur simultaneously with dominating contribution from one reaction. Department of Chemical Engineering Indian Institute of Technology-Delhi, New Delhi 110 016, India