Modulating Hydrogen Spillover Effect to Boost Ultradeep Hydrodesulfurization of 4,6-Dimethyldibenzothiophene Over Pt-Ni 2 P/Al 2 O 3

Abstract

The design and development of hydrodesulfurization (HDS) catalysts with superior catalytic activity has been highly desirable. Herein, a series of Pt-triggered Ni2P/Al2O3 catalysts were fabricated and examined for 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS. The loading of Pt strengthened the interaction between the Pt and Ni2P and promoted the hydrogen atoms overflowing to the Ni2P surface due to the lower electronegativity of Pt compared to Ni, thereby enhancing the number of Lewis and Brønsted acid sites and facilitating the prehydrogenation and isomerization pathways, thereafter boosting the HDS performances of Pt-Ni2P/Al2O3 catalysts. Therein, 5%Pt-Ni2P/Al2O3 exhibited the optimal HDS performance with 97.1% 4,6-DMDBT conversion, remarkably higher than that of Ni2P/Al2O3 (25.6%) and the-state-of-the-art catalysts reported in literature due to its moderate acidity, temperate interaction between Pt and Ni2P, and excellent reducibility. Further increasing the Pt loading to 10% induced the serious aggregation of Pt particles, resulting in the sharp increase in particle size and subsequent reduction of Pt dispersion, thereby leading to the weakening of interaction between Pt and Ni2P and considerable decrease of the Brønsted acid number, which in turn inhibited the HDS performance of 10%Pt-Ni2P/Al2O3 catalyst. This work present a promising candidate for the ultradeep HDS of heavy oil and may contribute to the understanding of the hydrogen spillover effect in this reaction.

Keywords: hydrodesulfurization, 4, 6-DMDBT, Ni2P-supported catalysts, acidity, reaction kinetics