In this work, zeolite Beta was synthesized experimentally in order to be used as filler
in fuel cell membranes in order to assess the proton conductivity of composite
membranes. Effects of the Si/Al ratio, and synthesis time on yield, relative
crystallinity, crystal size, and proton conductivity were investigated.
Zeolite Beta with Si/Al ratio between 10 and 30 was synthesized with a batch
formulation of 2.2Na2O:1Al2O3:ySiO2:4.6(TEA)2O:tH2O (where TEA& / #8801 / tetraethylammonium)
at 150° / C for 5-15 days of synthesis time. Sodium aluminate,
tetraethylammonium hydroxide (TEAOH) solution, sodium hydroxide pellets
(NaOH), and deionized water were used for the preparation of the batch solution.
Zeolite Na-Beta was calcined and treated with sulfuric acid solution at different
concentrations in order to have zeolite H-Beta. Polyetherether ketone (PEEK) was
sulfonated in order to have a proton conductive membrane and than zeolite H-Beta
was incorporated resulting in a composite or nanocomposite membrane. X-ray diffraction (XRD) analysis helped to understand whether the synthesized
material was zeolite Beta or not. The morphology and the crystal size of the crystals
were observed as a result of the scanning electron microscopy (SEM) analysis. In
order to see the effect of sulfuric acid treatment on the sodium (Na) content of the
zeolite Beta, inductively coupled plasma (ICP) analysis was performed. Synthesis
results indicate that as Si/Al ratio and synthesis time increased the yield of zeolite
Beta increased. It was observed that Si/Al ratio from 10 to 30, and synthesis time
between 5 to 15 days did not affect the crystal size significantly.
For the sulfonation of PEEK, sulfuric acid was used. Sulfonated polyetherether
ketone (SPEEK) was dissolved in a solvent that was dimethyl acetamide (DMAC),
incorporated with zeolite Beta, and then solvent was removed in the vacuum oven.
The proton conductivity was measured with a 2-probe impedance spectrometer.
Initial results indicate that zeolite Beta at 10 and 20 wt % loadings did not affect the
proton conductivity of the SPEEK membrane at 100 % relative humidity and room
temperature.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12607571/index.pdf |
| Date | 01 September 2006 |
| Creators | Gur, Nadiye |
| Contributors | Bac, Nurcan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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