Rhenium modification on NiMo/Al2O3 catalyst and effects on the hydrodesulfurization reaction route selectivity of 4,6-dimethyldibenzothiophene

A series of Re modified NiMo/Al2O3 hydrodesulfurization (HDS) catalysts with different contents of Re2O7 were successfully synthesized by stepwise impregnation method and co-impregnation method respectively. The effects of Re modification and impregnation methods on the physical-chemical properties of the prepared catalysts were determined by the characterization techniques such as XRD, N2 physical adsorption-desorption, NH3-TPD, PyFTIR and HRTEM. Finally, the effects of the Re modification and the impregnation methods on the catalytic activity and the HDS reaction route selectivity were evaluated using 4,6-dimethyldibenzothiophene (4,6DMDBT) as a probe. The results show that the crystal morphologies and pore structures of the synthesized catalysts varied with the contents of Re2O7 and the impregnation methods and the amounts of acid sites can be modulated by the incorporation of Re2O7 and the impregnation methods. Moreover, Re modification was conducive to the formation of the type II Ni-Mo-S active phase by changing the morphology of the Ni promoted MoS2 slabs. The HDS evaluation of 4,6-DMDBT results show that Re modification can effectively improve the 4,6DMDBT conversions, DDS route selectivity and even 3,3 '-dimethylcyclohexanebenzene (3,3 '-DMCHB) selectivity in varying degrees, and compared with that of co-impregnation method, the Re modification by stepwise impregnation method exhibited a more prominent effect. In general, 1 wt% Re2O7 content was the most favorable to the HDS reaction since excessive Re2O7 content has very little promoting effect.

Automated summary

A series of Re modified NiMo/Al2O3 hydrodesulfurization (HDS) catalysts with different contents of Re2O7 were synthesized using stepwise impregnation and co-impregnation methods. The effects of Re modification and impregnation methods on the catalysts' physical-chemical properties were characterized. The results revealed that Re modification improved the crystal morphologies, pore structures, and acid sites of the catalysts. Furthermore, the HDS evaluation showed that Re modification effectively enhanced the conversions, route selectivity, and even selectivity towards 3,3'-DMCHB of 4,6DMDBT, with the stepwise impregnation method exhibiting a more significant effect compared to co-impregnation.