Hierarchically porous Beta/SBA-16 with different silica-alumina ratios and the hydrodesulfurization performances of DBT and 4,6-DMDBT

Abstract

Hierarchically porous Beta/SBA-16 (BS) composite materials, combining the characteristics of the acidity from the Beta zeolite and the three-dimensional structure from SBA-16, were synthesized successfully through a two-step in-situ assembly hydrothermal crystallization method. A series of NiMo catalysts supported on BS with different silica-alumina ratios were prepared. The supports and the corresponding catalysts were characterized by XRD, N2 physisorption, 27Al MAS NMR, TEM, pyridine-FTIR, Raman, XPS and HRTEM. The activities of series catalysts were evaluated by the hydrodesulfurization (HDS) performances of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). It was found that the Beta crystallites were embedded into SBA-16 through silanols accompanied by dealumination on the T3–T9 sites of Beta crystallites. NiMo/BS-3 with a silica-alumina ratio of 100 exhibited the highest DBT and 4,6-DMDBT HDS activities at the WHSV value of 10 h−1, with the conversions of 95.9% and 86.9% respectively, due to the synergistic effects of the suitable specific surface areas, the relatively large pore size, appropriate acidity, the relatively high sulfidation degree, moderate dispersity and good stacking degree of MoS2 active phases.