Nanosized iron crystallites for Fischer-Tropsch synthesis

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dc.contributor.advisorClaeys, Michaelen_ZA
dc.contributor.authorMabaso, Evans Itaien_ZA
dc.date.accessioned2014-10-23T07:11:30Z
dc.date.available2014-10-23T07:11:30Z
dc.date.issued2005en_ZA
dc.descriptionIncludes bibliographical references (p. 131-148).en_ZA
dc.description.abstractFischer-Tropsch synthesis is the production of hydrocarbons from CO and H2. The catalytically active metals for industrial application are cobalt and iron. In this work iron-based catalysts were studied. To ensure maximum metal utilisation and therefore a high weight specific catalytic activity, the metal crystallites should possess large specific surface areas and that is only achievable with small metal crystallites. However, a minimum crystallite size might exist below which catalyst activity drops. Consequently, in order to investigate the role of crystallite size on the stability, the activity and selectivity of iron based catalysts, supported catalysts with a known narrow metal crystallite size distribution were prepared via precipitation in water-in-oil microemulsions in which water-to-surfactant ratio was the main design parameter. The study was subdivided into firstly characterisation of a suitable water-in-oil microemulsion system. Secondly preparation of nanosized oxidic iron crystallites with controlled crystallite size via precipitation in water-in-oil microemulsion. Thirdly preparation of the supported catalyst using the same but selected microemulsion systems. Finally catalyst testing under Fischer-Tropsch reaction conditions in a fixed bed reactor. A strictly linear relationship between water-to-surfactant ratio and crystallite size was observed. The catalyst preparation technique for unsupported iron oxides resulted in uniform nanocrystallites tailored to a size range of 2-16 nm. The morphology of the crystallites on supports remained largely unchanged upon reductive pretreatment. This made catalysts prepared in microemulsions ideally suitable for investigating the effect of crystallite size during Fischer-Tropsch synthesis.en_ZA
dc.identifier.apacitationMabaso, E. I. (2005). <i>Nanosized iron crystallites for Fischer-Tropsch synthesis</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research. Retrieved from http://hdl.handle.net/11427/8736en_ZA
dc.identifier.chicagocitationMabaso, Evans Itai. <i>"Nanosized iron crystallites for Fischer-Tropsch synthesis."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research, 2005. http://hdl.handle.net/11427/8736en_ZA
dc.identifier.citationMabaso, E. 2005. Nanosized iron crystallites for Fischer-Tropsch synthesis. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Mabaso, Evans Itai AB - Fischer-Tropsch synthesis is the production of hydrocarbons from CO and H2. The catalytically active metals for industrial application are cobalt and iron. In this work iron-based catalysts were studied. To ensure maximum metal utilisation and therefore a high weight specific catalytic activity, the metal crystallites should possess large specific surface areas and that is only achievable with small metal crystallites. However, a minimum crystallite size might exist below which catalyst activity drops. Consequently, in order to investigate the role of crystallite size on the stability, the activity and selectivity of iron based catalysts, supported catalysts with a known narrow metal crystallite size distribution were prepared via precipitation in water-in-oil microemulsions in which water-to-surfactant ratio was the main design parameter. The study was subdivided into firstly characterisation of a suitable water-in-oil microemulsion system. Secondly preparation of nanosized oxidic iron crystallites with controlled crystallite size via precipitation in water-in-oil microemulsion. Thirdly preparation of the supported catalyst using the same but selected microemulsion systems. Finally catalyst testing under Fischer-Tropsch reaction conditions in a fixed bed reactor. A strictly linear relationship between water-to-surfactant ratio and crystallite size was observed. The catalyst preparation technique for unsupported iron oxides resulted in uniform nanocrystallites tailored to a size range of 2-16 nm. The morphology of the crystallites on supports remained largely unchanged upon reductive pretreatment. This made catalysts prepared in microemulsions ideally suitable for investigating the effect of crystallite size during Fischer-Tropsch synthesis. DA - 2005 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2005 T1 - Nanosized iron crystallites for Fischer-Tropsch synthesis TI - Nanosized iron crystallites for Fischer-Tropsch synthesis UR - http://hdl.handle.net/11427/8736 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8736
dc.identifier.vancouvercitationMabaso EI. Nanosized iron crystallites for Fischer-Tropsch synthesis. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Catalysis Research, 2005 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8736en_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.otherCivil Engineeringen_ZA
dc.titleNanosized iron crystallites for Fischer-Tropsch synthesisen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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