Structure-performance relationship of NiMo/Al2O3-HY catalysts in selective hydrocracking of poly-aromatics to mono-aromatics

Abstract

Oriented conversion of poly-aromatic hydrocarbons into mono-aromatic hydrocarbons (MAHs) via selective hydrocracking over non-noble metal-based zeolite-binder composite catalysts is an effective way to upgrade light cycle oil, which is a poor blending component in diesel pool. However, the lack of understanding of the key structural factors that influence the performance of composite catalysts has hindered their development. In this study, a series of NiMo/Al2O3-HY bi-functional catalysts with different Al2O3 contents were prepared, characterized, and evaluated. Tetralin and 1-methylnaphthalene were used as model compounds to study the structure-performance relationship of catalysts. It was demonstrated that the hydrogenation activity and MAHs yield of catalysts depended strongly and positively on the density of MoS2 active sites (CMoS2, the amount of MoS2 located on the edges and corners per surface area of catalysts) and the density of Brønsted acid sites (CBAS, the amount of Brønsted acid sites per surface area of catalysts), respectively. Among all catalysts investigated, NiMo/A30Y50 with 30 wt% Al2O3 showed the best performance in selective hydrocracking reactions owing to its high CMoS2 and CBAS, even in the presence of ammonia in the feed. The findings of this study will aid the development of selective hydrocracking catalysts with high performance at the industrial level.