Effect of hydrogen spillover in selective hydrodesulfurization of FCC gasoline over the CoMo catalyst

Abstract The synergism of promoter Co on the performance of MoS 2 phase in selective hydrodesulfurization (HDS) of FCC gasoline was studied by regulating the step impregnation-sulfurization sequence of Co and Mo species to adjust the proportion of Co-Mo-S phase, separated Co 9 S 8 and MoS 2 phases. The evaluation results demonstrated that the CoMo/γ-Al 2 O 3 catalyst with Co species first impregnation-sulfurization showed higher HDS activity and selectivity. The characterization by XRD, HRTEM, XPS, TPR and FT-IR showed that, on this catalyst, the interaction between the sulfurized Co and MoS 2 phases was weak, and lead to the lower Co decoration on the MoS 2 phase, thus forming more Co 9 S 8 phase. The more formed Co 9 S 8 phase could produce more hydrogen spillover (Hso) to create more CUS and SH groups, thus greatly improving the HDS activity and selectivity. Through the layered loading test of Co 9 S 8 /γ-Al 2 O 3 and MoS 2 /γ-Al 2 O 3 catalysts, it was found that the Hso synergetic effect between the Co 9 S 8 and MoS 2 phases could significantly improve the HDS activity, but showed very little effect on the saturation of olefins.