Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis
The effects of electronic properties of inner and outer surfaces of Carbon Nano Tubes (CNTs) on the deactivation of cobalt Fischer-Tropsch (FT) catalysts were studied. The comparative characterization of the fresh and used catalysts by TEM, XRD, TPR, BET and H2 chemisorption showed that cobalt re-ox...
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| Format: | Article |
| Language: | English |
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Iranian Institute of Research and Development in Chemical Industries (IRDCI)-ACECR
2011-03-01
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| Series: | Iranian Journal of Chemistry & Chemical Engineering |
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| Online Access: | http://www.ijcce.ac.ir/article_6275_469c2171b05ba5fb33573c6d64b55f54.pdf |
| _version_ | 1818565562259734528 |
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| author | Mariane Trépanier Ahmad Tavasoli Sanaz Anahid Ajay K. Dalai |
| author_facet | Mariane Trépanier Ahmad Tavasoli Sanaz Anahid Ajay K. Dalai |
| author_sort | Mariane Trépanier |
| collection | DOAJ |
| description | The effects of electronic properties of inner and outer surfaces of Carbon Nano Tubes (CNTs) on the deactivation of cobalt Fischer-Tropsch (FT) catalysts were studied. The comparative characterization of the fresh and used catalysts by TEM, XRD, TPR, BET and H2 chemisorption showed that cobalt re-oxidation, cobalt-support interactions and sintering are the main sources of catalyst deactivation. TEM showed that 480 h continuous FT synthesis increased the average particles size of the particles located inside the pores from 7 to 7.4 nm while the average particles size of the particles located outside of the tubes increased from 11.5 to 25 nm. XRD analysis of the used catalyst confirmed cobalt re-oxidation and interaction between cobalt and CNTs and creation of carbide phases. When the %Co conversion and H2O partial pressure in the reactor are high, the deactivation rate is not dependent on the number of the catalyst active sites and is zero order to %CO conversion. In this case the main deactivation mechanisms are cobalt re-oxidation and metal support interactions. At lower amounts of the %Co conversion and H2O partial pressure, deactivation can be simulated with power law expressions with power orders of 11.4 for the particles outside the tubes and 30.2 for the particles inside the tubes and the main deactivation mechanism is sintering. Due to the electron deficiency of the inner sides of the CNTs, the interaction between the cobalt oxides and the support is stronger leading to lower rates of sintering as compared with the particles located on the outer layers of the CNTs. Regeneration recovered the catalyst activity by 54.3% of the total activity loss. |
| first_indexed | 2024-12-14T01:42:53Z |
| format | Article |
| id | doaj.art-0d967776d9164c2ea31fbfa0a597ea52 |
| institution | Directory Open Access Journal |
| issn | 1021-9986 1021-9986 |
| language | English |
| last_indexed | 2024-12-14T01:42:53Z |
| publishDate | 2011-03-01 |
| publisher | Iranian Institute of Research and Development in Chemical Industries (IRDCI)-ACECR |
| record_format | Article |
| series | Iranian Journal of Chemistry & Chemical Engineering |
| spelling | doaj.art-0d967776d9164c2ea31fbfa0a597ea522022-12-21T23:21:40ZengIranian Institute of Research and Development in Chemical Industries (IRDCI)-ACECRIranian Journal of Chemistry & Chemical Engineering1021-99861021-99862011-03-0130137476275Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch SynthesisMariane Trépanier0Ahmad Tavasoli1Sanaz Anahid2Ajay K. Dalai3Department of Chemical Engineering, University of Saskatchewan, Saskatoon, SK, S7N5C5 CANADASchool of Chemistry, College of Science, University of Tehran, Tehran, I.R. IRANSchool of Chemistry, College of Science, University of Tehran, Tehran, I.R. IRANDepartment of Chemical Engineering, University of Saskatchewan, Saskatoon, SK, S7N5C5 CANADAThe effects of electronic properties of inner and outer surfaces of Carbon Nano Tubes (CNTs) on the deactivation of cobalt Fischer-Tropsch (FT) catalysts were studied. The comparative characterization of the fresh and used catalysts by TEM, XRD, TPR, BET and H2 chemisorption showed that cobalt re-oxidation, cobalt-support interactions and sintering are the main sources of catalyst deactivation. TEM showed that 480 h continuous FT synthesis increased the average particles size of the particles located inside the pores from 7 to 7.4 nm while the average particles size of the particles located outside of the tubes increased from 11.5 to 25 nm. XRD analysis of the used catalyst confirmed cobalt re-oxidation and interaction between cobalt and CNTs and creation of carbide phases. When the %Co conversion and H2O partial pressure in the reactor are high, the deactivation rate is not dependent on the number of the catalyst active sites and is zero order to %CO conversion. In this case the main deactivation mechanisms are cobalt re-oxidation and metal support interactions. At lower amounts of the %Co conversion and H2O partial pressure, deactivation can be simulated with power law expressions with power orders of 11.4 for the particles outside the tubes and 30.2 for the particles inside the tubes and the main deactivation mechanism is sintering. Due to the electron deficiency of the inner sides of the CNTs, the interaction between the cobalt oxides and the support is stronger leading to lower rates of sintering as compared with the particles located on the outer layers of the CNTs. Regeneration recovered the catalyst activity by 54.3% of the total activity loss.http://www.ijcce.ac.ir/article_6275_469c2171b05ba5fb33573c6d64b55f54.pdffischer-tropschcobaltcarbon nanotubesdeactivationsintering |
| spellingShingle | Mariane Trépanier Ahmad Tavasoli Sanaz Anahid Ajay K. Dalai Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis Iranian Journal of Chemistry & Chemical Engineering fischer-tropsch cobalt carbon nanotubes deactivation sintering |
| title | Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis |
| title_full | Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis |
| title_fullStr | Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis |
| title_full_unstemmed | Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis |
| title_short | Deactivation Behavior of Carbon Nanotubes Supported Cobalt Catalysts in Fischer-Tropsch Synthesis |
| title_sort | deactivation behavior of carbon nanotubes supported cobalt catalysts in fischer tropsch synthesis |
| topic | fischer-tropsch cobalt carbon nanotubes deactivation sintering |
| url | http://www.ijcce.ac.ir/article_6275_469c2171b05ba5fb33573c6d64b55f54.pdf |
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