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Influence of Hydrogen and Operation Conditions on CO2 Adsorption on Pt and PtRu Catalyst in a PEMFC
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.ORCID iD: 0000-0002-0452-0703
2013 (English)In: ECS Electrochemistry Letters, ISSN 2162-8726, Vol. 2, no 5, F41-F43 p.Article in journal (Refereed) Published
Abstract [en]

CO2 is a major component in reformate gas and can, as a source of CO, be a catalyst poison in polymer electrolyte membrane fuel cells. The effect of CO2 on cell performance is not fully understood in the presence of hydrogen. This paper addresses the influence of hydrogen on CO2 adsorption on Pt/C and PtRu/C catalysts. The results show that the reduction and adsorption of CO2 is slow but increases if hydrogen is present, especially on PtRu/C. Further, exposure to a CO2 and H-2 mixture at 0.15 V on PtRu/C results in current oscillations, which are dependent on operation conditions.

Place, publisher, year, edition, pages
2013. Vol. 2, no 5, F41-F43 p.
Keyword [en]
Membrane Fuel-Cells, Gas Shift Reaction, Carbon-Dioxide, Oxidation, Monoxide, Anode, Electrocatalysts, Oscillations, Spectroscopy, Performance
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-123638DOI: 10.1149/2.008305eelISI: 000318556600007ScopusID: 2-s2.0-84880445075OAI: diva2:630144

QC 20150626

Available from: 2013-06-18 Created: 2013-06-13 Last updated: 2016-10-07Bibliographically approved
In thesis
1. The Impact of Hydrocarbon and Carbon Oxide Impuritiesin the Hydrogen Feed of a PEM Fuel Cell
Open this publication in new window or tab >>The Impact of Hydrocarbon and Carbon Oxide Impuritiesin the Hydrogen Feed of a PEM Fuel Cell
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The proton exchange membrane fuel cell generates electricity from hydrogen and oxygen (from air) through electrocatalytic reactions in an electrochemical cell. The Pt/C catalyst, commonly used in PEM fuel cells, is very sensitive to impurities that can interact with the active catalyst sites and limit fuel cell performance. Unfortunately, most hydrogen is currently produced from fossil sources, and inevitably contains impurities.

The subject of this thesis is the effect of hydrogen impurities on the operation of a PEM fuel cell using a Pt/C anode. The impurities studied are carbon monoxide (CO), carbon dioxide (CO2), and selected hydrocarbons. Particular focus is given to the interaction between the impurities studied and the anode catalyst. The main method used in the study involved performing cyclic voltammetry and mass spectrometry, simultaneously. Other electrochemical techniques are also employed.

The results show that all the impurities studied adsorb to some extent on the Pt/C catalyst surface, and require potentials comparable to that of CO oxidation, i.e., about 0.6V, or higher to be removed by oxidation to CO2. For complete oxidation of propene, and toluene, potentials of above 0.8, and 1.0V, respectively, are required. The unsaturated hydrocarbons can be desorbed to some extent by reduction, but oxidation is required for complete removal. Adsorption of ethene, propene, and CO2 is dependent on the presence of adsorbed or gaseous hydrogen. Hydrogen inhibits ethene and propene adsorption, but facilitates CO2 adsorption. Adsorption of methane and propane is very limited and high concentrations of methane cause dilution effects only.

The adlayer formed on the Pt/C anode catalyst in the presence of CO2, or moderate amounts of hydrocarbons, is found to be insffuciently complete to notably interfere with the hydrogen oxidation reaction. Higher concentrations of toluene do, however, limit the reaction.

Abstract [sv]

Polymerelektrolytbränslecellen genererar elektricitet fran vätgas och syrgas (fran luft) genom elektrokatalytiska reaktioner i en elektrokemisk cell. Den platina-baserade katalysator som oftast används i dessa bränsleceller är känslig mot föroreningar, då dessa kan interagera med katalysatorns aktiva yta, och därmed begränsna bränslecellens prestanda. Tyvärr produceras dagens vätgas huvudsakligen fran fossila källor och innehåller därför oundvikligen föroreningar.

Denna avhandling behandlar hur olika vätgasföroreningar påverkar katalysatorns aktivitet och bränslecellens drift. De föroreningar som studeras är kolmonoxid (CO) och koldioxid (CO2), samt ett antal mindre kolväten. Störst fokus ligger på hur dessa föroreningar interagerar med anodens Pt/C katalysator. Den metod som huvudsakligen används är cyklisk voltammetri kombinerat med masspektrometri, men flera elektrokemiska metoder har använts.

Resultaten visar att alla undersökta föroreningar adsorberar på Pt/C katalysatorns yta i större eller mindre utstreckning. For att avlägsna det adsoberade skiktet genom oxidation till CO2 krävs potentialer jämförbara med CO oxidation, dvs ca 0,6V, eller högre. Fullständig oxidation av propen eller toluen kräver potentialer högre än 0,8V respektive 1,0V. De omättade kolvätena kan delvis avlägsnas genom reduktion, men fullständig avlägsning kräver oxidation. Närvaron av väte, i gasform eller adsorberat pa katalysatorn, hämmar adsorptionen av eten och propen, men främjar CO2 adsorption. Metan och propan adsorberar i mycket begränsad utstreckning på Pt/C katalysatorns yta. De prestandaförluster som uppstår av höga koncentrationer av metan förklaras av utspädning av vätgasen.

Det adsorberade skiktet som bildas när Pt/C katalysatorn exponeras för CO2 eller måttliga koncentrationer av studerade kolväten, är inte tillräckligt heltäckande for att märkbart påverka vätgasreduktionen. Däremot kan höga koncentrationer av toluen begränsa reaktionen.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 91 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:26
Fuel Cell, Hydrogen Impurities, Carbon Monoxide, Carbon Dioxide, Ethene, Propene, Methane, Propane, Toluene, Electrochemically Active Surface Area, Cyclic Voltammetry, Mass Spectrometry, bränslecell, vätgasföroreningar, kolmonoxid, koldioxid, eten, propen, metan, propan, toluen, elektrokemisk aktiv yta, cyklisk voltammetri, masspektrometri
National Category
Chemical Engineering
Research subject
Chemical Engineering
urn:nbn:se:kth:diva-193694 (URN)978-91-7729-008-7 (ISBN)
Public defence
2016-10-28, K2, Teknikringen 28, Stockholm, 10:00 (English)

QC 20161010

Available from: 2016-10-10 Created: 2016-10-07 Last updated: 2016-10-10Bibliographically approved

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