Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts

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dc.contributor.advisorClaeys, Michaelen_ZA
dc.contributor.advisorFischer, Nicoen_ZA
dc.contributor.authorNyathi, Thulani Mveloen_ZA
dc.date.accessioned2016-07-20T12:36:40Z
dc.date.available2016-07-20T12:36:40Z
dc.date.issued2016en_ZA
dc.description.abstractThe preferential oxidation of CO (CO-PROX) has been identified as one route of further reducing the trace amounts of CO (approx. 0.5 - 1 vol%) in the H2-rich reformate gas after the high- and low-temperature water-gas shift reactions. CO-PROX makes use of air to preferentially oxidise CO to CO₂, reducing the CO content to below 10 ppm while minimising the loss of H₂ to H₂O. In this study, a Co₃O₄/γ-Al₂O₃ model catalyst was investigated as a cheaper alternative to the widely used noble metal-based ones. The CO oxidation reaction in the absence of hydrogen has been reported to be crystallite size-dependent when using Co₃O₄ as the catalyst. However, studies looking at the effect of crystallite size during the CO-PROX reaction are very few. Metal-support interactions also play a significant role on the catalyst's performance. Strong metal-support interactions (SMSI) in Co₃O₄/Al2o₃ catalysts give rise to irreducible cobalt aluminate-like species. Under CO oxidation and CO-PROX reaction conditions, such strong interactions in a similar catalyst can have a negative effect on the performance of Co₃O₄ but can keep its chemical phase intact i.e., help prevent the reduction of the Co₃O₄ phase. The catalysts used to investigate these two effects (i.e., crystallite size and metal-support interactions) were synthesised using the reverse micelle technique from which nanoparticles with a narrow size distribution were obtained. Certain properties of the microemulsions prepared were altered to obtain five catalysts with varying Co₃O₄ crystallite sizes averaging between 3.0 and 15.0 nm. Four other catalysts with different metal-support interactions were also synthesised by altering the method for contacting the support with the cobalt precursor. The crystallite size of Co₃O₄ in these four catalysts was kept in the 3.0 - 5.0 nm size range.en_ZA
dc.identifier.apacitationNyathi, T. M. (2016). <i>Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research. Retrieved from http://hdl.handle.net/11427/20547en_ZA
dc.identifier.chicagocitationNyathi, Thulani Mvelo. <i>"Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research, 2016. http://hdl.handle.net/11427/20547en_ZA
dc.identifier.citationNyathi, T. 2016. Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Nyathi, Thulani Mvelo AB - The preferential oxidation of CO (CO-PROX) has been identified as one route of further reducing the trace amounts of CO (approx. 0.5 - 1 vol%) in the H2-rich reformate gas after the high- and low-temperature water-gas shift reactions. CO-PROX makes use of air to preferentially oxidise CO to CO₂, reducing the CO content to below 10 ppm while minimising the loss of H₂ to H₂O. In this study, a Co₃O₄/γ-Al₂O₃ model catalyst was investigated as a cheaper alternative to the widely used noble metal-based ones. The CO oxidation reaction in the absence of hydrogen has been reported to be crystallite size-dependent when using Co₃O₄ as the catalyst. However, studies looking at the effect of crystallite size during the CO-PROX reaction are very few. Metal-support interactions also play a significant role on the catalyst's performance. Strong metal-support interactions (SMSI) in Co₃O₄/Al2o₃ catalysts give rise to irreducible cobalt aluminate-like species. Under CO oxidation and CO-PROX reaction conditions, such strong interactions in a similar catalyst can have a negative effect on the performance of Co₃O₄ but can keep its chemical phase intact i.e., help prevent the reduction of the Co₃O₄ phase. The catalysts used to investigate these two effects (i.e., crystallite size and metal-support interactions) were synthesised using the reverse micelle technique from which nanoparticles with a narrow size distribution were obtained. Certain properties of the microemulsions prepared were altered to obtain five catalysts with varying Co₃O₄ crystallite sizes averaging between 3.0 and 15.0 nm. Four other catalysts with different metal-support interactions were also synthesised by altering the method for contacting the support with the cobalt precursor. The crystallite size of Co₃O₄ in these four catalysts was kept in the 3.0 - 5.0 nm size range. DA - 2016 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts TI - Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts UR - http://hdl.handle.net/11427/20547 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/20547
dc.identifier.vancouvercitationNyathi TM. Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research, 2016 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/20547en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentCentre for Catalysis Researchen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemical Engineeringen_ZA
dc.subject.otherCatalysis Researchen_ZA
dc.titlePreferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalystsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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