Improving Both the Activity and Selectivity of CoMo/δ-Al2O3 by Phosphorous Modification for the Hydrodesulfurization of Fluid Catalytic Cracking Naphtha

Developing CoMo/Al(2)O(3 )catalysts with both high hydrodesulfurization (HDS) activity and selectivity is of great importance in the HDS of fluid catalytic cracking (FCC) naphtha. However, most of the reported studies achieved improved selectivity at the expense of HDS activity. Herein, we report a phosphorous modification method to improve the HDS activity and selectivity of CoMo/delta-Al2O3 at the same time. The enhanced HDS performance for CoMoP(2.9)/delta-Al(2)O(3 )was attributed to appropriately weakened metal-support interaction, which resulted in a large amount of the (Co)MoS2 active phase with a higher stacking and Co promotion degree (type II Co-Mo-S). The improved Co promotion degree promotes the HDS activity, and increased stacking decreases the ratio of rim sites, which is beneficial for lowering the olefin hydrogenation activity. When dealing with a real FCC naphtha, the sulfur content could be reduced to 5.4 ppm while achieving a total research octane number loss of only 0.7 units. This work provides a rational catalyst design for FCC naphtha hydrorefining to meet the stringent environmental regulations of the future.

Automated summary

A phosphorous modification method was reported to improve the HDS activity and selectivity of CoMo/δ-Al2O3 catalyst simultaneously. The enhanced HDS performance was attributed to weakened metal-support interaction, resulting in the formation of a large amount of active (Co)MoS2 phase with higher stacking and Co promotion degree. The improved Co promotion degree promotes the HDS activity, while increased stacking decreases the olefin hydrogenation activity. When applied to a real FCC naphtha, the sulfur content could be reduced to 5.4 ppm with only a total research octane number loss of 0.7 units.