Catalytic performance of CoMo catalysts supported on mesoporous ZSM-5 zeolite-alumina composites in the hydrodesulfurization of 4,6-dimethyldibenzothiophene

Composite materials (AZ-M-x) were prepared by mechanically mixing the mesoporous zeolite ZSM-5 (MZSM-5) and gamma-Al2O3. This composite was employed as a support for CoMo catalysts (CoMoS/AZ-M-x). The CoMoS/AZ-M-x catalysts show high activity (TOF = 2.1-3.0 x 10(-3) s(-1)) in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) as compared to the CoMo catalyst supported on gamma-Al2O3 (CoMoS/gamma-Al2O3, TOF = 1.9 x 10(-4)s(-1)), and the HDS activity increased with the MZSM-5 content in the composites. In contrast, the HDS activity of a mixture of microporous ZSM-5 with gamma-Al2O3 supported CoMo catalyst is similar to that of the CoMoS/gamma-Al2O3 catalyst. Compared with microporous ZSM-5, introducing MZSM-5 into gamma-Al2O3 improves the mesoporous structure of the composites, which benefits mass transfer of the reactant molecules. Furthermore, MZSM-5 in the composites modifies their surface properties with abundant acidic hydroxyl groups, which can weaken the Mo-support interaction, leading to modifications in the morphology of the MoS2 phases to form multi-stacked MoS2 active phases on the CoMoS/AZ-M-x catalysts. (C) 2017 Published by Elsevier B.V.