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Reduction of Sulfur Content of Model Feed by Oxidative Process in them Presence of Carbon Structures Based W-Mo Nanocatalysts

Hassannia, Saeed | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54651 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Kazemini, Mohammad; Rashidi, Alimorad; Hajjar, Zeinab
  7. Abstract:
  8. In this research, molybdenum and tungsten catalysts modified with cobalt and nickel on a carbon support have been synthesized and investigated in the oxidation desulfurization process. A model fuel was used to evaluate the synthesized catalysts. This model fuel was n-decane. dibenzothiophene was also used as a sulfur model. The synthesized catalysts were subjected to various analyzes such as XRD, FTIR, Raman, BET-BJH, NH3-TPD, TEM and ICP-OES for structural evaluation. On the other hand, synthetic parameters such as metal loading rate, molar or weight ratio of secondary metal (cobalt and nickel) to primary metal (molybdenum and tungsten) and molar ratio of citric acid to primary metal as well as reactor parameters such as temperature, molar ratio of oxidizing agent to sulfur compound and the molar ratio of catalyst to sulfur compound were evaluated using Design Expert and central composite design method. The final product was evaluated to investigate the selectivity of the process using methods such as FTIR, H-NMR and GC-mass. Of the two catalysts, CoMo (20)/rGO and NiMo (20)/rGO, the cobalt-containing catalyst performed better. Based on the results, the optimal conditions of reactor tests for this catalyst are as follows: molar ratio of oxidant/substrate (sulfur compound) = 30, temperature = 60 °C, molar ratio of catalyst / substrate = 0.09 and time = 60 minutes. On the other hand, for CoW (20)/rGO catalyst as the optimal tungsten catalyst, the conditions related to the highest conversion value are as follows: molar ratio of oxidant/substrate (sulfur composition) = 6, temperature = 75 °C, molar ratio of catalyst/Substrate = 0.08 and time = 60 minutes. One of the most important features that has led to the use of heterogeneous catalysts in chemical processes is their ability to recover and reuse. The results showed that CoMo (20)/rGO catalyst continued to operate for up to 10 catalytic cycles and CoW (20)/rGO catalyst for up to 8 catalytic cycles without significant loss in activity. On the other hand, DFT method was used for further evaluation, such as the evaluation of the effect of the secondary metal
  9. Keywords:
  10. Oxidative Desulfurization ; Density Functional Theory (DFT) ; Dibenzothiophene (DBT) ; Molybdenum ; Tungsten ; Modified Catalyst

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