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1 Development of Direct Methanol Fuel Cell and Special Proton Exchange Membranes Impervious to Methanol by Professor Anil Kumar Department of Chemical.

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Presentation on theme: "1 Development of Direct Methanol Fuel Cell and Special Proton Exchange Membranes Impervious to Methanol by Professor Anil Kumar Department of Chemical."— Presentation transcript:

1 1 Development of Direct Methanol Fuel Cell and Special Proton Exchange Membranes Impervious to Methanol by Professor Anil Kumar Department of Chemical Engineering Indian Institute of Technology Kanpur, Kanpur – (India)

2 2 Schematic Diagram of a Fuel Cell

3 3 Fuel Cell Stack

4 4 Electrosorption (forming Pt-CH 2 OH, Pt 2 -CHOH species) of methanol onto Platinum layer deposited on MEA Addition of oxygen to adsorbed carbon containing intermediates generating CO 2 Mechanism for Methanol Oxidation

5 5 Operation of Fuel Cell

6

7

8 Types of Fuel Cells Fuel CellOperating Conditions Alkaline FC (AFC)Operates at room temp. to 80 0 C Apollo fuel cell Proton Exchange Membrane FC (PEMFC) Operates best at C Hydrogen fuel Originally developed by GE for space Phosphoric Acid FC (PAFC)Operates best at ~200 0 C Hydrogen fuel Stationary energy storage device Molten Carbonate FC (MCFC)Operates best at C Nickel catalysts, ceramic separator membrane Hydrocarbon fuels reformed in situ Solid Oxide FC (SOFC)Operates at C Conducting ceramic oxide electrodes Hydrocarbon fuels reformed in situ Direct Methanol Fuel Cell (DMFC) Operates best at C Methanol Fuel For portable electronic devices

9 Summary of Reactions and Processes in Various Fuel Cells

10 Block Diagram of the Component Parts of a Fuel Cell

11 Depiction of Components of Complete Fuel Cell System

12 Polyelectrolyte Membrane Fuel Cell (PEMFC)

13 13 Technology Limitations with DMFC Poor Electrode Kinetics Large activation work potential mV Cell Voltage Loss Catalyst Development Mass Transport CO 2 Rejection Low MeOH concentration Electrode Structure mV Cell Voltage Loss Electrode Material Development

14 14 Technology Limitations with DMFC Cathode Electrode Material Development Poor Electrode Kinetics Methanol Crossover Mass Transport Large Activation Overpotential Mixed Cathode Potential Reduced Gas Permeability mV Cell Voltage Loss mV Loss Above 100mV Loss Catalyst Development

15 Electrode Material: Special conducting carbon Vulcan XE-72 available with Cabot Corporation, USA. Anodic Catalyst: Platinum-Ruthenium adsorbed on conducting carbon. Procedure of making it is well documented. Cathodic Catalyst: Platinum adsorbed on conducting carbon. Procedure of making it is well documented. Membrane: Nafion Membrane available with DuPont USA. They create lot of problems before supplying. Three components of the Fuel Cells

16 16 Polystyrene (PS) Membranes Dense membranes used for gas separation and pervaporation Sulfonated PS membrane used in methanol based fuel cells Sulfonated PS blended with Nafion® membrane High impact PS blended with polyaniline Anion exchange membranes prepared by chloromethylation of polystyrene Ion Exchange Membranes

17 17 Experimental Section Preparation of clay support Casting of prepolymer syrup on wet clay support Gas phase nitration of the membrane at C Amination of the membrane using hydrazine hydrate Quaternization by dichloroethane and triethylamine Styrene, AIBN, BPO, DMA, Bulk polymerization at 70 0 C 70 0 C, 12 h Membrane Preparation

18 18 Clay raw material Composition (wt. %) Kaolin10.15 Ball clay12.90 Feldspar4.08 Quartz18.85 Calcium carbonate Pyrophyllite11.50 Water20.00 Composition I Casting Clay mixture casted on a gypsum surface II Drying Ambient Temp : 24 h C : 12 h C : 12 h III Sintering C : h IV Dip Coating Dip coated in polymerized TEOS (tetraethyl orthosilicate) Drying, C : 24 h Sintering, C : 5 h Preparation of Clay Support Steps of Preparation

19 Solid Oxide Electrolyte Ceramics Overpotential η OP = η AOP – η COP – IR internal Perovskite Oxides: La 1-a A a M 1-b B b O 3-x A=Sr 2+, Ln 3+, Ce 4+ M=Fe, Co, Gaa=0.1 to 1mol B=Co, Fe, Mgb=0.1 to 0.5 mol High Temperature Superconductors YBa 2 Cu 3 O 7-x Piezoelectric material BaTiO 3 Semiconductor sensors SrTiO 3 Oxygen Ion Conductors LaGaO 3-x Proton Conductor doped BaCeO 3-x Cathode Material La 0.8 Sr 0.2 CoO 3-x Working Temperature range: C

20 Modification of the Support NO x Sup NO 2 Catalyst + NH 2 NH 2 Sup NH 2 Imidazole FeCl 3 Sup N CH 2 Cl - N N CH 2 Cl - N N Sup N CH 2 FeCl 4 - N N CH 2 FeCl 4 - N N

21 21 Experimental Section Nitration: 2NaNO 2 +H 2 SO 4  NO + NO 2 +H 2 O+Na 2 SO 4 Amination: Quaternization: Modification Reactions

22 22 Membrane Characterization Scanning electron microscopy (SEM) Crossectional view of the membrane Ceramic Support Membrane layer

23 23 Experimental Setup for Electrodialysis HCl Solution NaCl solution Pump O2O2 H2H2 DC Power Supply Catholyte Anolyte anode cathode

24 KWh/mol of NaOH produced Current efficiency Energy consumption Operating parameters Salt concentrations, flow rate, current density Performance of the Membrane

25 Overall performance of Anion Exchange Membrane Flow rate (ml/min) Current Density (A/m 2 ) NaCl (N) Cell Voltage (V) Current Efficiency (%) Energy Consumption kWh/mol

26 26 Results and Discussion Effect of number of runs

27 Physical pore Region I r CbCb C1C1 x = l x = 0 x Region II Domain of EDL Effective pore diameter (a) C Domain of EDL Effective pore Schematic Diagram of a Flat Membrane Schematic Diagram of a Single Pore Space Charge Model

28 28 Space Charge Model Assumptions 1.  Re<10 -6 as a ~ Pores are long and narrow (l >>a) radial and axial variation of u r neglected neglected Axial variation of potential neglected 4. All external forces (for example, gravity etc.) assumed to be negligible.

29 29 (a) Nernst Planck equation: (b) Navier Stokes equation: Governing Equations Convection Diffusion Migration (c) Poisson equation

30 30 (d) Poisson-Boltzmann equation (PBE) Boundary conditions: Space Charge Model, Volumetric flow rate Electrical Current Solute Flux

31 31 Space Charge Model where

32 32 Series Solution of PBE Space Charge Model Calculate a 1 =0 Step I Step II Step III Step IV Step V Assume Calculate a i Calculate a 0 Calculate k 0 – k 9

33 33 Integral expressionsAnalytical expressions Space Charge Model

34 34 Start Input Js*, I*, c II Assume wall potential Assume c I Solve PBE equation 5, Calculate J s_cal eqn 11 Cal I*_cal using eqn 10 Is (J s_cal - J s * ) < tol Is (I * – I * cal ) 2 is min Stop No Yes Solution Scheme Space Charge Model No

35 35 S parameter Vs pore diameter at different time interval Results and Discussion

36 36


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