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Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts
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, red...
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| Format: | Thesis |
| Language: | English |
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Centre for Catalysis Research
2016
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| _version_ | 1867613322455547904 |
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| access_status_str | Open Access |
| author | Nyathi, Thulani Mvelo |
| author2 | Claeys, Michael |
| author_browse | Claeys, Michael Nyathi, Thulani Mvelo |
| author_facet | Claeys, Michael Nyathi, Thulani Mvelo |
| author_sort | Nyathi, Thulani Mvelo |
| collection | Thesis |
| description | 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. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/20547 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:17.944Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Centre for Catalysis Research |
| publisherStr | Centre for Catalysis Research |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/20547 Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts Nyathi, Thulani Mvelo Claeys, Michael Fischer, Nico Chemical Engineering Catalysis Research 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. 2016-07-20T12:36:40Z 2016-07-20T12:36:40Z 2016 Master Thesis Masters MSc http://hdl.handle.net/11427/20547 eng application/pdf Centre for Catalysis Research Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Chemical Engineering Catalysis Research Nyathi, Thulani Mvelo Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| thesis_degree_str | Master's |
| title | Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| title_full | Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| title_fullStr | Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| title_full_unstemmed | Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| title_short | Preferential oxidation of carbon monoxide in hydrogen-rich gases over supported cobalt oxide catalysts |
| title_sort | preferential oxidation of carbon monoxide in hydrogen rich gases over supported cobalt oxide catalysts |
| topic | Chemical Engineering Catalysis Research |
| url | http://hdl.handle.net/11427/20547 |
| work_keys_str_mv | AT nyathithulanimvelo preferentialoxidationofcarbonmonoxideinhydrogenrichgasesoversupportedcobaltoxidecatalysts |