57
mixed active phase by the location of Co on vacant positions of MoS 2 , followed by
the incorporation of Ni on the available sites.
Guo et al. [56] investigated the hydrogenation activity (alkylation, HDS, and
HDN) of CoMo and NiMo catalysts possessing high Brönsted acid sites for the
hydroprocessing of diesel feedstocks with an objective to achieve optimal HDS
through proper choice of catalysts and stacking systems. For feedstocks with high
sulfur and low nitrogen and aromatic contents, CoMo-type catalysts showed the
highest HDS activity. NiMo-type catalysts showed the highest HDS and HDN activity for feedstocks with high nitrogen and aromatic contents. Stacking of CoMo and
NiMo catalysts was reported as the optimal combination to obtain the highest HDS
activity for processing diesel feedstocks with moderate nitrogen and aromatic contents due to their synergistic effects.
Zhang et al. [48] synthesized various alumina supports by rehydration–dehydration of the γ-Al 2 O 3 under varied hydrothermal temperatures and further prepared
CoMo/Al 2 O 3 catalysts to study the HDS of model FCC naphtha. The improved HDS
selectivity of the catalyst was ascribed to the weak MSI, as well as lower dispersion
of MoS 2 that resulted in large edge-to-corner ratios of CoMoS slabs. Apart from the
improved catalyst, the authors proposed a two-step process scheme involving selective HDS and mercaptan removing catalysts to achieve ultralow sulfur gasoline with
minimum octane loss.
Sharifi et al. [57] synthesized W/HZSM-5 catalysts with different SiO 2 /Al 2 O 3
ratios for simultaneous HDS and octane improvement for heavy naphtha through
aromatization. Optimized catalyst formulations in combination with process
improvements such as HDS and aromatization will result in the restoration of the
lost octane number during HDS. The importance of the role of Co in the MoS 2 HDS
catalyst was investigated by Bin et al. [59] for the selective HDS of FCC gasoline.
Cobalt was found to make a significant difference in catalytic properties by affecting the microstructure and composition of the active phase. The presence of Co
improved HDS activity with only a slight effect on olefin hydrogenation.
Coupling aromatization and HDS reactions for heavy naphtha feed were studied
by Sharifi et al. [58] using the Ni/HZSM-5 catalyst with different SiO 2 /Al 2 O 3 ratios.
Higher HDS activity with total sulfur reduction of 88% was observed with a SiO 2 /
Al 2 O 3 ratio of 60, and the RON increase from 52 to 94 was achieved at the ratio of
40 due to the synergistic effect of Brönsted and Lewis surface acid sites of the
catalyst.
Liu et al. [28] studied the synergy of the Co promoter on the performance of the
MoS 2 phase in selective FCC gasoline HDS by tuning the catalyst preparation steps.
The preparation steps of cobalt and molybdenum species were regulated to adjust
the proportion of Co-Mo-S, Co 9 S 8 , and MoS 2 phases. Initial impregnation of Co on
the support was found to show better HDS activity and selectivity due to weak interaction between Co and MoS 2 phases and decreased cobalt decoration on the MoS 2
phase resulting in the formation of more Co 9 S 8 phase. Hydrogen spillover effects
caused by the Co 9 S 8 phase improved HDS activity and selectivity through creation
of more CUS and SH groups.
Recent Advances in Hydrotreating/Hydrodesulfurization Catalysts: Part II—Catalyst…
mixed active phase by the location of Co on vacant positions of MoS 2 , followed by
the incorporation of Ni on the available sites.
Guo et al. [56] investigated the hydrogenation activity (alkylation, HDS, and
HDN) of CoMo and NiMo catalysts possessing high Brönsted acid sites for the
hydroprocessing of diesel feedstocks with an objective to achieve optimal HDS
through proper choice of catalysts and stacking systems. For feedstocks with high
sulfur and low nitrogen and aromatic contents, CoMo-type catalysts showed the
highest HDS activity. NiMo-type catalysts showed the highest HDS and HDN activity for feedstocks with high nitrogen and aromatic contents. Stacking of CoMo and
NiMo catalysts was reported as the optimal combination to obtain the highest HDS
activity for processing diesel feedstocks with moderate nitrogen and aromatic contents due to their synergistic effects.
Zhang et al. [48] synthesized various alumina supports by rehydration–dehydration of the γ-Al 2 O 3 under varied hydrothermal temperatures and further prepared
CoMo/Al 2 O 3 catalysts to study the HDS of model FCC naphtha. The improved HDS
selectivity of the catalyst was ascribed to the weak MSI, as well as lower dispersion
of MoS 2 that resulted in large edge-to-corner ratios of CoMoS slabs. Apart from the
improved catalyst, the authors proposed a two-step process scheme involving selective HDS and mercaptan removing catalysts to achieve ultralow sulfur gasoline with
minimum octane loss.
Sharifi et al. [57] synthesized W/HZSM-5 catalysts with different SiO 2 /Al 2 O 3
ratios for simultaneous HDS and octane improvement for heavy naphtha through
aromatization. Optimized catalyst formulations in combination with process
improvements such as HDS and aromatization will result in the restoration of the
lost octane number during HDS. The importance of the role of Co in the MoS 2 HDS
catalyst was investigated by Bin et al. [59] for the selective HDS of FCC gasoline.
Cobalt was found to make a significant difference in catalytic properties by affecting the microstructure and composition of the active phase. The presence of Co
improved HDS activity with only a slight effect on olefin hydrogenation.
Coupling aromatization and HDS reactions for heavy naphtha feed were studied
by Sharifi et al. [58] using the Ni/HZSM-5 catalyst with different SiO 2 /Al 2 O 3 ratios.
Higher HDS activity with total sulfur reduction of 88% was observed with a SiO 2 /
Al 2 O 3 ratio of 60, and the RON increase from 52 to 94 was achieved at the ratio of
40 due to the synergistic effect of Brönsted and Lewis surface acid sites of the
catalyst.
Liu et al. [28] studied the synergy of the Co promoter on the performance of the
MoS 2 phase in selective FCC gasoline HDS by tuning the catalyst preparation steps.
The preparation steps of cobalt and molybdenum species were regulated to adjust
the proportion of Co-Mo-S, Co 9 S 8 , and MoS 2 phases. Initial impregnation of Co on
the support was found to show better HDS activity and selectivity due to weak interaction between Co and MoS 2 phases and decreased cobalt decoration on the MoS 2
phase resulting in the formation of more Co 9 S 8 phase. Hydrogen spillover effects
caused by the Co 9 S 8 phase improved HDS activity and selectivity through creation
of more CUS and SH groups.
Recent Advances in Hydrotreating/Hydrodesulfurization Catalysts: Part II—Catalyst…