Nickel phosphide (Ni₂P) dispersed as small particles (~5 nm) on oxide supports (SiO₂, Al₂O₃) has attracted interest as a catalyst for a number of processes, including heteroatom removal reactions. The current study focuses on modification of the properties (activity, selectivity) of Ni₂P by incorporation of Ru into the supported phosphide phase or by modifying the oxide support by B addition prior to synthesis of the phosphide. The deep hydrodesulfurization (HDS) properties of series of Ni_2-xRu_xP/SiO₂ (0 ≤ x ≤ 2) and Ni₂P/xB-Al₂O₃ (x = 0-7.2 wt% B) catalysts were probed using a model feed of 4,6-dimethyldibenzothiophene (1000 ppm) in decalin over a range of temperatures (513-593 K). Incorporation of a small amount of Ru into Ni₂P to form Ni_1.85Ru_0.15P/SiO₂ resulted in a 15-fold increase in HDS activity (relative to Ni₂P/SiO₂), while increasing the amount of incorporated Ru caused the activity to decrease. Likewise, boron modification of the γ-Al₂O₃ support of Ni₂P/xB-Al₂O₃ catalysts resulted in as much as an 8-fold increase in HDS activity relative to the B-free catalyst (Ni₂P/Al₂O₃), with the activity increase dependent on the amount of added B. Physicochemical characterization of the catalysts yielded atomic level details on the roles of incorporated Ru and added B, providing insight into how these synthetic levers can be used to optimize the properties of Ni₂P-based catalysts.

Catherine Miles

Rutgers The State University of New Jersey

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