Improving Both the Activity and Selectivity of CoMo/δ-Al<sub>2</sub>O<sub>3</sub> by Phosphorous Modification for the Hydrodesulfurization of Fluid Catalytic Cracking Naphtha
Cen Zhang, Yicen Zhang, Huiting Zheng, Jundong Xu, Xinyi Liu, Jing Cao, Congshan Zhou
Abstract
Developing CoMo/Al2O3 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/δ-Al2O3 at the same time. The enhanced HDS performance for CoMoP(2.9)/δ-Al2O3 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.