Synthesis of NiMo catalysts supported on mesoporous Al2O3 with different crystal forms and superior catalytic performance for the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

Mesoporous Al2O3 (MA) materials with different crystal forms were synthesized from the boehmite sol. A series of MA materials were used as supports for sulfided NiMo catalysts in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The as-synthesized MA materials with different crystal forms and the corresponding NiMo catalysts were characterized using XRD, nitrogen physisorption, FTIR, pyridine FTIR, UV-vis, Raman, H-2 TPR, XPS, and HRTEM characterization methods. The NiMo/delta-Al2O3 (NiMo/delta-MA) catalyst exhibited the highest DBT and 4,6-DMDBT conversion at all the weight hourly space velocities (WHSVs); moreover, its DBT conversion (99.6%) was about twice that of the commercial NiMo/Al2O3 (NiMo/C-MA) catalyst (50.2%), while its 4,6-DMDBT conversion (65.8%) was more than four times that of the NiMo/C-MA catalyst (15.5%) at 613 K, 4.0 MPa, 200 ml/ml, and 150 h(-1). The superior catalytic performance of the NiMo/delta-MA catalyst could be ascribed to the synergistic effect of desirable textural properties, moderate acidity, suitable metal-support interaction, appropriate dispersion, and excellent stacking morphology of the active phases. 4,6-DMDBT HDS over the NiMo/delta-MA catalyst showed the highest HYD/DDS ratio (3.08), indicating that the HYD pathway was the main reaction route. Furthermore, an HDS reaction network was proposed for 4,6-DMDBT over NiMo/delta-MA. (C) 2016 Elsevier Inc. All rights reserved.