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Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process
Research on the co-feeding of ammonia into the Fischer-Tropsch (FTS) process over ironbased catalysts revealed that the presence of ammonia during the FTS leads to the formation of nitrogen-containing compounds (NCCs). Recent studies on the addition of ammonia to the FTS process, now known as the Ni...
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| Format: | Thesis |
| Language: | English |
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Department of Chemical Engineering
2021
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| _version_ | 1867613293138411520 |
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| access_status_str | Open Access |
| author | Goho, Danielle Sympathie |
| author2 | Claeys, Michael |
| author_browse | Claeys, Michael Goho, Danielle Sympathie |
| author_facet | Claeys, Michael Goho, Danielle Sympathie |
| author_sort | Goho, Danielle Sympathie |
| collection | Thesis |
| description | Research on the co-feeding of ammonia into the Fischer-Tropsch (FTS) process over ironbased catalysts revealed that the presence of ammonia during the FTS leads to the formation of nitrogen-containing compounds (NCCs). Recent studies on the addition of ammonia to the FTS process, now known as the Nitrogen Fischer-Tropsch (NFTS) process, reported that the production of NCCs during the NFTS process is enhanced by the presence of oxygenates. The studies, therefore, suggested that oxygenates are the primary precursors of NCCs. However, due to the gap in knowledge related to the NFTS reactions mechanisms, the validity of this assumption is still unknown. In this thesis, the aim was to investigate the correlation between the presence of oxygenates under the FTS conditions and the formation of NCCs under the NFTS conditions and check the suitability of various iron-based catalysts for the NFTS process. From literature, four ironbased catalysts, known for yielding a high percentage of oxygenates, were identified, synthesised, characterised and then tested under FTS conditions to determine the optimum reaction conditions for oxygenates formation. It was found that high oxygenates selectivity can be achieved at low temperature and high space velocity as at these operating conditions the occurrence of secondary reactions involving oxygenates are limited. Furthermore, the catalysts were tested under NFTS conditions to determine their catalytic performance and their selectivity towards NCCs. During the NFTS process, in addition to the decrease in the CO conversion, a significant drop in the oxygenates and CO2 selectivity followed by the formation of NCCs were observed. These results confirmed a sight activity inhibiting effect of ammonia and pointed out the correlation between the presence of oxygenates and the formation of NCCs under FTS and NFTS processes respectively. At the conditions applied, selectivities of up to 17.9 C% of NCCs (predominantly nitriles) could be obtained. This modified process may therefore be considered as an important variation of the FTS process with greatly enhanced chemicals production potential. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/33736 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:49.949Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Department of Chemical Engineering |
| publisherStr | Department of Chemical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/33736 Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process Goho, Danielle Sympathie Claeys, Michael Fischer, Nico Fadlalla, Mohamed Fischer-Tropsch synthesis Iron-based catalysts Oxygenates Nitrogencontaining compounds Research on the co-feeding of ammonia into the Fischer-Tropsch (FTS) process over ironbased catalysts revealed that the presence of ammonia during the FTS leads to the formation of nitrogen-containing compounds (NCCs). Recent studies on the addition of ammonia to the FTS process, now known as the Nitrogen Fischer-Tropsch (NFTS) process, reported that the production of NCCs during the NFTS process is enhanced by the presence of oxygenates. The studies, therefore, suggested that oxygenates are the primary precursors of NCCs. However, due to the gap in knowledge related to the NFTS reactions mechanisms, the validity of this assumption is still unknown. In this thesis, the aim was to investigate the correlation between the presence of oxygenates under the FTS conditions and the formation of NCCs under the NFTS conditions and check the suitability of various iron-based catalysts for the NFTS process. From literature, four ironbased catalysts, known for yielding a high percentage of oxygenates, were identified, synthesised, characterised and then tested under FTS conditions to determine the optimum reaction conditions for oxygenates formation. It was found that high oxygenates selectivity can be achieved at low temperature and high space velocity as at these operating conditions the occurrence of secondary reactions involving oxygenates are limited. Furthermore, the catalysts were tested under NFTS conditions to determine their catalytic performance and their selectivity towards NCCs. During the NFTS process, in addition to the decrease in the CO conversion, a significant drop in the oxygenates and CO2 selectivity followed by the formation of NCCs were observed. These results confirmed a sight activity inhibiting effect of ammonia and pointed out the correlation between the presence of oxygenates and the formation of NCCs under FTS and NFTS processes respectively. At the conditions applied, selectivities of up to 17.9 C% of NCCs (predominantly nitriles) could be obtained. This modified process may therefore be considered as an important variation of the FTS process with greatly enhanced chemicals production potential. 2021-08-12T09:08:05Z 2021-08-12T09:08:05Z 2021 2021-08-10T11:30:35Z Master Thesis Masters MSc http://hdl.handle.net/11427/33736 eng application/pdf Department of Chemical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Fischer-Tropsch synthesis Iron-based catalysts Oxygenates Nitrogencontaining compounds Goho, Danielle Sympathie Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| thesis_degree_str | Master's |
| title | Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| title_full | Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| title_fullStr | Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| title_full_unstemmed | Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| title_short | Selective production of nitrogen-containing compounds via a modified Fischer-Tropsch process |
| title_sort | selective production of nitrogen containing compounds via a modified fischer tropsch process |
| topic | Fischer-Tropsch synthesis Iron-based catalysts Oxygenates Nitrogencontaining compounds |
| url | http://hdl.handle.net/11427/33736 |
| work_keys_str_mv | AT gohodaniellesympathie selectiveproductionofnitrogencontainingcompoundsviaamodifiedfischertropschprocess |