Catalytic hydrotreatment using NiMo/MAS catalysts synthesized from ZSM-5 nano-clusters
Mesostructured alumino-silcate (MAS) materials were synthesized from ZSM-5 nano-clusters and used as catalysts supports for the hydrotreatment of a model compound and real feed stock. Supports and catalysts were thoroughly characterized by using XRD, N2 adsorption analysis, FT-IR, 27Al MAS NMR, Raman, EXAFS and HRTEM techniques. The alumino-silicate materials exhibited different acid strength and textural properties depending on the duration of hydrothermal treatment of the zeolite seeds. Materials synthesized with low seeding time of 4 h showed properties similar to Al-SBA-15 prepared using the direct synthesis route, whereas material with high seeding time (tseed = 24 h) resembled ZSM-5. The EXAFS study of the sulfided catalysts revealed that sulfidation was highest in the NiMo catalyst supported on mesoporous alumino-silicate synthesized from ZSM-5 seeds with 16 h of hydrothermal treatment (MAS-16). Hydrotreating experiments were conducted using model compound (DBT) at 325 °C and 600 psi as well as real feed stock (Coker light gas oil) at industrial conditions. Catalytic activity in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) was found to be maximum for this particular catalyst (MAS-16). The same catalyst also gave higher hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) conversion than NiMo/γ Al2O3 in the hydrotreating of Light Gas Oil.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (112 K)Download as PowerPoint slideHighlights► Effect of hydrothermal treatment duration on mesoporous materials synthesized from ZSM-5 nano-clusters. ► Bronsted acid sites in the materials increased with hydrothermal treatment duration. ► Optimum dispersion of Molybdenum was found on the support synthesized with 16 h of hydrothermal treatment. ► Hydrotreating activity of the optimum catalyst was found to be higher than the conventional NiMo/γ-Al2O3 catalyst. ► EXAFS results indicate that sulfidation of Mo was highest on catalyst with 16 h of hydrothermal treatment.
Journal: Applied Catalysis A: General - Volumes 419–420, 29 March 2012, Pages 1–12