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Synthesis, Evaluation and Modification of Suitable Metal–Organic Frameworks (MOFS) for Desulfurization of Hydrocarbon Cuts

Ghassa, Mahya | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55873 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Khorashe, Farhad; Hajjar, Zeinab; Soltanali, Saeed
  7. Abstract:
  8. During fuel combustion, aromatic sulfur compounds in energy fuels convert into sulfur oxides, which cause major environmental problems such as acidic rain, global warming, and air pollution. Absorption desulfurization is one of the promising and economical methods to remove these sulfur compounds from fuels. Metal-organic frameworks (MOFs) are a class of nanoporous materials that are of interest for use as adsorbents due to their high specific surface area, unique surface adsorption properties, high adsorption capacity, tunable porosity, flexible dynamic behavior, and diversity in functional and metal groups. In this research, we first synthesized five metal-organic frameworks, namely MIL-53(Cr, Al, Fe), Cu-BDC, and Cu-BTC. These synthesized MOFs were characterized by XRD, FTIR, BET and FESEM analyses. The adsorptive desulfurization performance of these MOFs were investigated and MOF with the best adsorption behavior was chosen. The results showed that among the synthesized MOFs, MIL-53(Cr) showed the best desulfurization performance due to its high specific surface area and suitable pore diameter, with absorption percentages of 29%, 39, 61% and 88% for the absorption of thiophene, benzothiophene, dibenzothiophene and dimethyldibenzothiophene, respectively. In the following, to improve the absorption performance and textural and structural properties of this MOF, the composite is made with different activated carbon loadings and these composites were characterized by XRD, FTIR, BET, TGA and FESEM analyses. The desulfurization performance of the composites were investigated for adsorption of dibenzothiophene from the fuel model with different concentrations. The composites of MIL-53(Cr) and activated carbon, especially the composite containing 5/2 wt.% activated carbon, showed significant adsorption desulfurization performance. Adsorption capacities of 55/94%, 88/95%, and 85/91% were obtained for dibenzothiophene adsorption from fuels with initial concentrations of 1000, 1500, and 2000 ppmw over 5/2%AC@MIL-53(Cr) composite. The perfect surface chemistry and improved textural properties of the synthesized composites compared to the intact materials, including high surface area, total pore volume, and mesoporous pore volume, contribute to the improvement of desulfurization performance. 2.5%AC@MIL-53(Cr) composite with a specific surface area of 2642 m2/g and a mesopore volume of 0.801 cm3/g has the highest specific surface area and mesopore volume, and its specific surface area is 40% compared to the main framework, and its mesoporous pore volume has increased by 21% compared to the original framework
  9. Keywords:
  10. Desulfurizing ; Adsorption Kinetics ; Activated Carbon ; Metal-Organic Framework ; Adsorption Isotherms ; Hybrid Materials ; Aromatic Compounds

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