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Study of Deactivation of Carbon Nanotubes Supported on Cobalt Catalysts in Fischer-Tropsch Synthesis

Karimi Davani, Zahra | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40092 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Kazemeini, Mohammad; Rohani, Ali Asghar
  7. Abstract:
  8. Purified RIPI–CNT was used as support material for the preparation of cobalt FTS catalysts. Carbon nanotubes supported catalysts (S1–S4) were prepared with loadings of 15, 20, 30 and 40 wt.%. The FT synthesis was carried out in a fixed-bed micro reactor. Deactivation factors of cobalt catalysts supported on carbon nanotubes in FT synthesis is investigated. Using carbon nanotubes as cobalt catalyst support was found to cause the reduction temperature of cobalt oxide species to shift to lower temperatures. The strong metal-support interactions are reduced to a large extent and the reducibility of the catalysts improved significantly. Then, the main reason for the catalyst deactivation will be eliminated. CNT aided in well dispersion of metal clusters and average cobalt clusters size decreased. Besides, the feed which is being used contains no sulphur (the most important catalyst poisoning). According to the temperature of the reaction, the evaporation of metallic phase is not the factor of deactivating, too. Combined with the catalyst deactivation model that the order of X is more than -3, it can be concluded that the sintering is less important for the deactivation of the catalyst. Therefore, water can be considered as the main factor of deactivating catalyst. As a result of the presence of water, some parts of the whole cobalt change into permanent compounds which cannot be regenerated in the catalyst recovery.


  9. Keywords:
  10. Carbon Nanotubes ; Fischer-Tropsch Synthesis ; Catalyst Deactivation ; Deactivation Model ; Cobalt Catalyst

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