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Novel electrocatalytic membrane for ammonia synthesis
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dc.contributor.advisor | Irvine, John T. S. | |
dc.contributor.author | Klinsrisuk, Sujitra | |
dc.coverage.spatial | 231 | en_US |
dc.date.accessioned | 2010-11-12T12:38:14Z | |
dc.date.available | 2010-11-12T12:38:14Z | |
dc.date.issued | 2010 | |
dc.identifier | uk.bl.ethos.552477 | |
dc.identifier.uri | https://hdl.handle.net/10023/1294 | |
dc.description | Electronic version does not contain associated previously published material | en_US |
dc.description.abstract | Novel ceramic membrane cells of BaCe₀.₅Zr₀.₃Y₀.₁₆Zn₀.₀₄O[subscript(3-δ)] (BCZYZ), a proton-conducting oxide, have been developed for electrocatalytic ammonia synthesis. Unlike the industrial Haber-Bosch process, in this work an attempt to synthesise ammonia at atmospheric pressure has been made. The membrane cell fabricated by tape casting and solution impregnation comprises of a 200 μm-thick BCZYZ electrolyte and impregnated electrode composites. Electrocatalysts for anode and cathode were investigated. For the anode, the co-impregnation of Ni and CeO₂ provided excellent electrode performance including high catalytic activity, sintering stability and compatibility with the BCZYZ electrolyte. The best composition was the mixture of 25 wt% NiO and 10 wt% CeO₂. A symmetrical cell prepared with this electrode composition revealed low polarisation resistances of 1.0 and 0.45 Ωcm² in humidified 5% H₂/Ar at 400 and 500 °C, respectively. For the cathode, 25 wt% of impregnated Fe oxide provided a satisfactory performance in non-humidified N₂ atmosphere. Significant amounts of ammonia were produced from the single cell with Ni-CeO₂ anode and Fe oxide cathode at 400-500 °C under atmospheric pressure. Ammonia formation rate was enhanced by Pd catalyst addition and electrochemical performance was improved by Ru addition. The highest ammonia formation rate of 4 x 10⁻⁹ mols⁻¹cm⁻² was attained using the cell with a Pd-modified Fe cathode at 450 °C. The formation reaction of ammonia typically consumed around 1-2.5 % of total applied current while most of the applied current was employed in H⁺ reduction. The total current efficiency of around 90-100 % could be obtained from the membrane cells. | en_US |
dc.language.iso | en | en_US |
dc.publisher | University of St Andrews | |
dc.rights | Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported | |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | |
dc.subject | Ammonia synthesis | en_US |
dc.subject | Proton conducting oxide membrane | en_US |
dc.subject | Tape casting | en_US |
dc.subject | Ion impregnation | en_US |
dc.subject | BCZYZ | en_US |
dc.subject.lcc | TP223.K6 | |
dc.subject.lcsh | Ammonia--Synthesis | en_US |
dc.subject.lcsh | Electrocatalysis | en_US |
dc.subject.lcsh | Slip casting | en_US |
dc.subject.lcsh | Oxide ceramics | en_US |
dc.subject.lcsh | Fuel cells | en_US |
dc.title | Novel electrocatalytic membrane for ammonia synthesis | en_US |
dc.type | Thesis | en_US |
dc.accrualMethod | Scholarship from the Royal Thai Government | |
dc.contributor.sponsor | Royal Thai Government | en_US |
dc.type.qualificationlevel | Doctoral | en_US |
dc.type.qualificationname | PhD Doctor of Philosophy | en_US |
dc.publisher.institution | The University of St Andrews | en_US |
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