건국대학교 융합신소재공학 교수 김 화 중 1

What is Zeolite ? 3-D intracrystalline microporous alumino-silicate materials 2

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Primary Building Units 4

Secondary Building Units 5

Framework Structure of Zeolite 6

Applications of Zeolite  Catalyst and Catalyst Support  Ion-Exchange Medium  Separation Process  Electrode and Electrolyte in Fuel Cell  Others 7

Structures of Commercial Zeolites  Zeolite A  Zeolites X and Y 8

Structures of Commercial Zeolites  Zeolite β  ZSM-5 9

Structures of commercial Zeolites  Mordenite  ETS-10 10

왜 연료전지인가 ? Nano-scale catalyst & application Lab. / Dep. of Materials Chemistry & Engineering 기존 화력발전 연료 열 에너지 기계적 에너지 전기 에너지 연료전지 연료 전기에너지 VS

고분자전해질연료전지 고분자전해질연료전지PEMFC Nano-scale catalyst & application Lab. / Dep. of Materials Chemistry & Engineering

Basic Structure of Fuel Cell  Basic Concept of Fuel Cell 15  Electrochemical Reaction  At Anode, H 2 → 2H + + 2e - At Cathode, 1/2O 2 + 2e - + 2H + → 2H 2 O Through Electrolyte, H + passes

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Different Types of Fuel Cell Type Mobile Ion Operating Applications Type Mobile Ion Operating Applications Temperature( o C) Temperature( o C) Alkaline-AFC OH - 50 – 100 Used in space vehicle Proton-Ex H + 50 – 100 Suitable for Vehicles and Membrane(PEM) Mobile but also for CHP Phophoric Acid H + ∼ kW CHP systems in use (PAFC) (PAFC) Molten carbonate CO 3 2- ∼ 650 Suitable for medium to large (MCFC) scale CHP systems, up to (MCFC) scale CHP systems, up to MW capacity MW capacity Solid Oxide(SOFC) O – 1000 Suitable for CHP, 2 kW to MW 17

Polymer Electrolyte Membrane Fuel Cell (PEMFC)  First developed in the 1960s (GM)  During late 1980s and early 1990s, PEMFC, Renaissance of interest 18

Fuel Cell  Be operated under hygroscopic condition  Notwithstanding the good electrical conductivity of carbon, Carbon is relatively hydrophobic 19. High Electrical Contact Resistance. High Ohmic Power Loss

Polymer Electrolyte  Polyethylene is modified by substituting fluorine for the hydrogen (Per-fluorination)  Poly-fluoroethylene or PTFE (Teflon). Resistant to chemical attack and durable. Highly hydrophobic : Expel water molecules out of the electrode 20

Nafion Type Membrane  Structure 21 Hydrophilic site

Electrodes  Comprises a catalyst to facilitate the reaction ● Catalyst : Platinum - Dispersed and supported on a high surface area support material ● Support Material : exclusively Carbon material - Good electrical conductivity : Facilitate the passage of the protons through membrane formed on catalyst while facilitates the flow of electrons to the external circuit from the electrode 22

Electrodes and Its Structure  Carbon supported Pt Catalyst 23 Carbon Support Pt Particle

Zeolite-Carbon hybrid type electrode 24 Zeolite (ETS-10, ZSM-5…) Carbon black Catalyst particle ELECTROLYTE = Polymer + = Polymer +Zeolite

Pt-Zeolite Nano-scale catalyst & application Lab. / Dep. of Materials Chemistry & Engineering Zeolite (ETS-10, ZSM-5…) Carbon black Catalyst particle

Characteristics of Zeolite in Fuel Cell  Excellent water retention ability (Hydrophilic)  Excellent proton ponductivity  High Surface area  High Pt dispersion 26

Fuel Cell Electrode with Conductive Zeolite Support Material  Conventional PEMFC(Polymer-Electrolyte Membrane Fuel Cell) ● Structure of Fuel Cell - Exclusively Carbon particles as a support material 27 Cathode (Pt over carbon) Membrane Anode (Pt over carbon) e-e-

Zeolite-Carbon Hybrid type MEA(Membrane-Electrode Assembly) 28

29 XRD results Pt(111) Pt(200) Pt(220) Pt(311) Pt-ZSM-5

30 Pt-ZSM-5 TEM images 2~5nm Pt Particle size

Fabrication of MEA(Membrane Electrode Assembly) Electrode Membrane Electrode

32 Electrode Mapping results Case Ⅰ Case Ⅱ Commercial ■ : Nafion, ■ : Zeolite or Carbon(Commercial), ■ : Pt

33 Cell performance

Potential Application of Zeolite to Fuel Cell  Advantages over Carbon Materials ● Provides Electrodes with lower Ohmic power loss because of its High Surface Area and Channel structure - Reduces the Cost of Catalyst - Creates the Higher Dispersion - Prevents the catalyst particles from agglomeration - More hydrophilic than carbon - Relatively higher gas permeability - High water retention ability 34

Synthesis of Nano-Pt particles using zeolite templating method 35 Furfuryl alcoholPolymerization Pyrolysis at 800 o C Reduction under H 2 Pt Nano Particles Advantages of Zeolite Templating method Steric effect prevent Pt cluster from the growth Pt(NH 3 ) 4 - Y Ion exchange of Pt(NH 3 ) 4 Cl 2 with zeolite Y

36 Polymerization Carbon Molecular Sieve ( 탄소 분자체 ) Furfuryl alcohol is added to zeolite for polymerization [Carbonprecursor for Pt/C] Breakage of C-H bonds leads to Carbon only Polymer fills vacant sites HF Pt nanoparticles are formed within the pores of carbon molecular sieve

37 c c a a b b Transmission Electron Micrograph (TEM) of Pt nanoparticles formed within Zeolite Y pore channels

38 a a b b c c Transmission Electron Micrograph (TEM) of Pt nanoparticles after removing Zeolite Y: a) 0.1 o C, (b) 0.2 o C and (c) 2.0 o C of heating rate for the decomposition of Pt(NH 3 ) 4 2+

TEM images of Carbon Molecular Sieve(CMS) 39

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TEM images of Pt-CMS and Pt-CB 41

Cell Performance 42

Zeolite-Polymer Composite Electrolyte  Problems of Conventional Nafion Electrolyte in DMFC (Direct Methanol Fuel Cell)  High Methanol Cross-Over  Low Proton Conductivity 43

44 Methanol Oxidation at anode CH 3 OH + H 2 O CO 2 + 6H + + 6e - E o anode = V Oxygen reduction at cathode 3/2 O 2 + 6H + + 6e - 3H 2 O E o cathode = 1.23 V Overall reaction in DMFC CH 3 OH + 3/2 O 2 2H 2 O + CO 2 E o cell = 1.18 cell voltage

45 2. 연구내용 및 결과 Study Concepts Nafion ® Zeolites Pore Size : 5.6 ⅹ 5.3 Å ZSM-5 Pore Size : 7.0 ⅹ 6.5 Å Mordenite MCM Å  Microporous crystalline aluminosilicates  Regular pore size - Shape selectivity  Selective sorption, Ion exchange, Catalytic activity  High thermal stability  High surface area  High Chemical stability  Water retention at high temperature Poor conductivity  Methanol crossover  High material cost

46 2. 연구내용 및 결과 Study Concepts H+H+ MeOH Zeolite Polymer matrix Sulfonation (PETMS) Organic Functionalize Ion Exchange

47 Samsung Note PC DMFCToshiba DMFC(1W) MTI DMFC Smart Fuel Cell Fujitsu note PC

48 Thank you for your attention !!!