Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell

Interest in the use of fuel cell as highly efficient, clean energy conversion device has been rapidly increasing over the past twenty years. Currently, proton exchange membrane fuel cells (PEMFC) are regarded as the paramount type of fuel cell due to their wide range of applicability. Perfluorosulfo...

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Main Author:	Md. Ajeman, Siti Nadiah
Format:	Thesis
Language:	English
Published:	2014
Subjects:	QD Chemistry
Online Access:	http://eprints.utm.my/id/eprint/48865/1/SitiNadiahMdAjemanMFS2014.pdf
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spelling	my-utm-ep.488652020-07-01T07:50:02Z Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell 2014-06 Md. Ajeman, Siti Nadiah QD Chemistry Interest in the use of fuel cell as highly efficient, clean energy conversion device has been rapidly increasing over the past twenty years. Currently, proton exchange membrane fuel cells (PEMFC) are regarded as the paramount type of fuel cell due to their wide range of applicability. Perfluorosulfonic acid (PFSA) ionomer Nafion® by DuPont remains the typical membrane in PEMFC under development today, despite well recognized drawbacks which include limitations in thermal stability. Recent studies have found that although the polymer-zeolite composite membranes have lower value of proton conductivity than Nafion®, polymer-zeolite composites show a more stable performance at high temperature. In this study, the proton transfer mechanism of zeolite functionalized sulfonic acid with water molecules is investigated using density functional theory (DFT) calculation at PM3/ONIOM(B3LYP/6-311G(d,p):PM3) level of theory. The systems were constructively built up by modifying the crystal structure of Linde Type A (LTA) zeolite functionalized sulfonic acid side chains, by varying the degree of separation of sulfonic acid side chains (2T, 3T and 4T) as well as the alkyl chain length (n=3, 5, 7) in order to study the effect of proton transfer at different distance and different chain length. Extensive searches for minimum energy conformations from 1 to 6 explicit water molecules revealed that 2T distance gives the best results for propyl sulfonic acid side chain, meanwhile 4T distance gives the best result for pentyl and heptyl sulfonic acid side chains, indicated by the minimum water molecules required to initiate second proton dissociation. The results have shown several agreements with previous calculation regarding polymeric fragments where partial dissociation of the protons in the fragments occurs at water contents of less than 3 H2Os/SO3H. Furthermore, we found that water distributions that facilitate a higher degree of dissociation and separation of the protons are important factors in stabilizing the fragments. 2014-06 Thesis http://eprints.utm.my/id/eprint/48865/ http://eprints.utm.my/id/eprint/48865/1/SitiNadiahMdAjemanMFS2014.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:86719 masters Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QD Chemistry
spellingShingle	QD Chemistry Md. Ajeman, Siti Nadiah Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
description	Interest in the use of fuel cell as highly efficient, clean energy conversion device has been rapidly increasing over the past twenty years. Currently, proton exchange membrane fuel cells (PEMFC) are regarded as the paramount type of fuel cell due to their wide range of applicability. Perfluorosulfonic acid (PFSA) ionomer Nafion® by DuPont remains the typical membrane in PEMFC under development today, despite well recognized drawbacks which include limitations in thermal stability. Recent studies have found that although the polymer-zeolite composite membranes have lower value of proton conductivity than Nafion®, polymer-zeolite composites show a more stable performance at high temperature. In this study, the proton transfer mechanism of zeolite functionalized sulfonic acid with water molecules is investigated using density functional theory (DFT) calculation at PM3/ONIOM(B3LYP/6-311G(d,p):PM3) level of theory. The systems were constructively built up by modifying the crystal structure of Linde Type A (LTA) zeolite functionalized sulfonic acid side chains, by varying the degree of separation of sulfonic acid side chains (2T, 3T and 4T) as well as the alkyl chain length (n=3, 5, 7) in order to study the effect of proton transfer at different distance and different chain length. Extensive searches for minimum energy conformations from 1 to 6 explicit water molecules revealed that 2T distance gives the best results for propyl sulfonic acid side chain, meanwhile 4T distance gives the best result for pentyl and heptyl sulfonic acid side chains, indicated by the minimum water molecules required to initiate second proton dissociation. The results have shown several agreements with previous calculation regarding polymeric fragments where partial dissociation of the protons in the fragments occurs at water contents of less than 3 H2Os/SO3H. Furthermore, we found that water distributions that facilitate a higher degree of dissociation and separation of the protons are important factors in stabilizing the fragments.
format	Thesis
qualification_level	Master's degree
author	Md. Ajeman, Siti Nadiah
author_facet	Md. Ajeman, Siti Nadiah
author_sort	Md. Ajeman, Siti Nadiah
title	Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
title_short	Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
title_full	Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
title_fullStr	Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
title_full_unstemmed	Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
title_sort	computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2014
url	http://eprints.utm.my/id/eprint/48865/1/SitiNadiahMdAjemanMFS2014.pdf
_version_	1747817490637914112

Computational study of proton transfer in restricted sulfonic acid for proton exchange membrane fuel cell

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