1 EUROMEMBRANE 2009 Preparation and characterization of composite PBI membranes for high temperature PEMFC applications E.C. van de Ven, Z. Borneman, M. Wessling European Membrane Institute Twente 07/09/2009 Title: to modify choose 'View' then 3 'Heater and footer'
2 Contents - ZEOCELL project, theme Energy, FP7 - PBI membrane preparation - Membrane characterization - Conclusions
3 EU Project, theme Energy, FP7
4 Aim of the ZEOCELL project Traditional Proton Exchange Membrane Fuel Cell : • expensive catalyst (noble metal) • sensitive to impurities in fuel High temperature PEMFC (130-200°C) : • reaction rate and CO-tolerance increase, • reduction of operating voltage, • cogeneration is possible Challenges: corrosion, electrolyte evaporation, fuel cross over
5 Introduction: approach - Composite membrane made by synergic combination of Polymers Ionic liquids Zeolites
6 Membrane requirements - chemically, mechanically and thermally stable up to 200°C - porosity between 15-75% - pore size of 60 – 500 nm - proton conductivity ≥ 100 mS/cm at 100°C - thickness between 15-150µm
7 PBI polymer Membranes based on: Polybenzimidazole (PBI) poly(1,4-phenylene-5,5 (6 )-bisbenzimidazole-2,2 -diyl) A high temperature resistant material (Tg = 327°C) Applied in gas separation and solvent resistant nano filtration
8 PBI membrane Phase separation is needed to prepare porous membranes
9 PBI membrane Preventing of macro-void formation in PBI membranes by delayed phase inversion Macro-voids H 2 O No Macro-voids H 2 O/NMP
10 Porosity 65% Membrane morphology results
11 Proton conductivity - pretreatment of the PBI membrane Immersed in ethanol during 1 hour Immersed in hexane during 24 hrs Vacuum oven at 50°C 4 hrs Immersed in IL at 20°C, 24 hrs, atmospheric Vacuum during 15 min. Wiping off excess of IL Measurement with 3 preselected imidazole based ionic liquids
12 Proton conductivity – Impedance spectroscopy BNC connect or s St eel Far adai c cage Ther m ocoupl e PTFE St ai nl ess M em br ane st eel el ect r odes sam pl e BNC connect or s
13 Proton conductivity – Fitting procedure T= 20°C
14 Proton conductivity- Measurements Measurements are usually performed at 20°C but we need data in the range of 130-190°C. Solution: measurements done at 60, 50, 40 and 20°C and determine if the proton conductivity shows Arrhenius behavior.
15 Proton Conductivity - Results 60°C 50°C 40°C 20°C 10 IL C Ln proton cond. [mS/cm] 1 IL B 0.1 IL A 0.01 2.9 3.1 3.3 3.5 1000/T [1/K]
16 Proton Conductivity – Results 130 100 60 50 40 [°C] 0,01 p ro to n c o n d u c tiv ity [m S /c m ] Ionic Liquid C 0,001 2,4 2,5 2,6 2,7 2,8 2,9 3 3,1 3,2 1000/T [1/K]
17 Status Membrane requirements - chemically, mechanically and thermally stable up to 200°C - porosity between 15-75% - pore size of 60 – 500 nm - proton conductivity ≥ 100 mS/cm at 100°C onwards to - thickness between 15-150µm
18 Conclusions - Porous PBI membranes have been prepared by delayed phase separation • No macro-voids • Regular porous structure • Becomes proton conductive by addition of Ionic Liquid - Proton conductivity shows Arrhenius behavior confirmed by high temperature measurements - PBI membranes with Ionic Liquids are a promising candidate for applications in PEMFC
19 Acknowledgements The Zeocell project was funded by the European Commission under the 7 th Framework Program. It was a response on the EC call: Energy Topic 2007.1.1.1: Basic research for materials and processes for PEMFC’s. Grant Agreement nº: 209481.
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