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Synthesis of Alumina–Zeolite Composite as Catalytic Supports for Hydrodesulfurization of Gas oil

Tabakh, Mohammad Reza | 2026

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58796 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Kazemeini, Mohammad; Mashayekhi, Maryam; Soltanali, Saeed
  7. Abstract:
  8. To improve the hydrodesulfurization (HDS) performance of NiMo/Al2O3 catalysts, Y-zeolite additives were incorporated in either pristine form (at 10, 15 and 30 wt% in support) or as metal-modified materials prepared through a novel post-synthesis dealumination method using NH4HF2 and metal salts (i.e.; of Co, Mn, Zn, Zr, Sn(II), Sn(IV)). This approach aimed to increase mesoporosity, adjust the intrinsic acidity of the Y-zeolite, and weaken metal-support interactions to promote the formation of more active NiMoS-type species. Initial results showed that adding zeolite Y to the catalyst results in a significant decrease in liquid product yield, so that to create a suitable balance between desulfurization and liquid product yield, zeolite Y requires structural modification. The impact of metal modification upon the zeolite structure, metal incorporation behavior, and the resulting catalyst performance was thoroughly evaluated using XRD, XRF, AAS, FTIR, UV-Vis DRS, H2-TPR, FESEM, EDX-mapping, BET-BJH, NH3-TPD, and XPS analyses. It was revealed that, Co-, Mn-, and Zn-modified zeolites preserved structural integrity and enabled successful metal incorporation, whereas Zr- and Sn-modified samples exhibited significant framework deterioration. The Zn-modified catalyst showed the highest improvement, outperforming both the commercial reference and the parent NiMo/Al2O3 + HY catalyst. Under 350℃, 35 bar, H2/HC = 350, and LHSV = 2 h-1, it reduced sulfur content by 22.12% and 17.54% relative to the commercial and unmodified catalysts, yielding an HDS conversion of 83.41%. The NiMo/Al2O3 + ZnY catalyst also improved liquid product yield, compared to the reference catalyst without zinc (98.24 vs. 94.20%). Furthermore, it showed superior performance in reducing nitrogen and polyaromatic species and enhanced fuel quality, as indicated by a nearly 3-point increase in the cetane index (52.8 vs. 49.7). The catalyst additionally maintained stable activity over a 50-hour cycle, underscoring its suitability for long-term and environmentally sustainable applications
  9. Keywords:
  10. Hydrodesulfurization ; Dealumination ; Diesel Fuel ; Zeolite Y ; Metal Incorporation

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